Chapter 6. Overview of Preoperative Assessment and Management

1. Comprehensive preoperative evaluation and management improve patient satisfaction, outcomes, and safety.

2. Inadequate preoperative evaluation and management increase perioperative adverse events and often lead to delays or cancellations of procedures.

3. At a minimum, the preanesthesia visit should include an interview with the patient to review the medical history (including medications, allergies, comorbid conditions, previous operations, and anesthetics), an appropriate physical examination, review of diagnostic data, assignment of an American Society of Anesthesiologists physical status score, and a formulation and discussion with the patient of the anesthetic plan.

4. The medical history is the most important component of preoperative assessment.

5. Findings from the history and physical examination determine the need, if any, for further diagnostic testing.

6. Diagnostic tests should only be ordered if the results will alter the planned anesthetic or procedure or establish an already suspected diagnosis. "Screening" tests are never appropriate.

7. Cardiovascular morbidity and mortality are the leading cause of significant perioperative adverse events.

8. Identification and management of cardiovascular disease is an important goal of preoperative evaluation.

9. Knowledge of risk factors for cardiovascular disease and familiarity with the American College of Cardiology–American Heart Association guidelines for cardiovascular evaluation for noncardiac surgery is essential.

10. A determination of functional capacity or the patient's cardiorespiratory fitness can guide further testing and predict a wide range of complications and outcome.

11. Potentially high-risk patients include those with the following conditions:

    1. Ischemic heart disease

    2. Heart failure

    3. Murmurs

    4. Pacemakers, implantable cardioverter-defibrillators (ICDs)

    5. Vascular stents

    6. Pulmonary disease

    7. Obstructive sleep apnea

    8. Obesity

    9. Diabetes mellitus

    10. Poorly controlled hypertension

    11. Renal disease

    12. Hepatic disease

    13. Substance abuse

    14. Advanced age

    15. Difficult airway

12. Knowledge and management of antiplatelet therapy in patients with coronary stents is imperative in the perioperative period.

13. Poor communication is a common source of medical errors, patient dissatisfaction, and malpractice claims.

14. Practice guidelines can standardize care, decrease delays, and improve outcomes.

15. Anesthesia-directed preoperative evaluation centers can be cost-effective, improve care and safety, and offer services beyond history acquisition, physical examinations, and diagnostic testing.

As the practice of medicine becomes increasingly outcomes driven and cost conscious, clinicians need to reevaluate and streamline methods of patient care. The role of the anesthesiologist as a consultant is more important than ever. No single clinician is better informed and capable than the anesthesiologist to evaluate patients who require anesthesia. Preoperative assessment and management have evolved as the role of the anesthesiologist has expanded outside of the operating theater and as an increasing number of procedures are performed on patients who are not hospitalized before their anesthetics. Reasons for preoperative assessment may entail some or all of the following:

1. To screen for and properly manage comorbid conditions.

2. To assess the risk of anesthesia and surgery and lower it.

3. To identify patients who may require special anesthetic techniques or postoperative care.

4. To establish baseline results for perioperative decisions.

5. To educate patients and families about the objectives and risks of anesthesia and the anesthesiologist's role in perioperative care.

6. To obtain informed consent.

7. To facilitate timely care and avoid cancellations on the day of operation.

8. To determine the appropriateness of patients to undergo anesthesia in out-of-operating room or ambulatory surgical facilities.

9. To motivate patients to stop smoking, lose weight, or commit to other preventive care.

10. To train personnel in the art and science of preoperative assessment and optimization of a patient's condition.

The Australian Incident Monitoring Study (AIMS) found that 3.1% (197 of the first 6271 reports) of adverse events were unequivocally related to insufficient, and 11% to inadequate, preoperative assessment.1 More than half of incidents were considered preventable. An analysis of the first 2000 reports to AIMS found a 6-fold increase in mortality in patients who were inadequately assessed preoperatively.2 Davis concluded that 53 (39%) of 135 deaths attributed to anesthesia involved inadequate preoperative assessment and management.3 Delays, complications, and unanticipated postoperative admissions are significantly reduced by preoperative screening and patient contact. Others have shown that preoperative health status can predict operative outcomes and resource use. Preoperative preparation and education can facilitate recovery and reduce the incidence of postoperative morbidity. In France, a preoperative consultation has been mandated since 1994. Although debates continue regarding both the financial implications and convenience to society and patients, this process has been associated with a greater than 10-fold decrease in anesthetic-related complications.4 Anxiety, postoperative pain, and length of stay have been positively affected by comprehensive preoperative care. Adequate pain management correlates significantly with patients receiving sufficient preoperative information.5 From the patient's perspective, an opportunity to meet an anesthesiologist (preferably the one providing anesthesia on the day of surgery) is very important. In a study conducted in Canada and Scotland, patients rated meeting the anesthesiologist as the highest priority, above that of information on pain relief, alternative methods of anesthesia, and complications.6

Preoperative evaluation must be efficient for both patient and hospital personnel. It can be cost-effective and can reduce turnover times, cancellations, and length of hospital stays. In a retrospective analysis of practices at one major US teaching hospital, significant reductions in case cancellations were observed for same-day surgery patients (8.4% vs 16.2%) and main operating room patients (5.3% vs 13%) when patients had a preoperative evaluation.7 Preoperative visits should be comprehensive, including plans for postdischarge patient care. Many anesthesiologists perform preoperative evaluations, review diagnostic studies (often chosen and ordered by someone else), discuss anesthetic risks, and obtain informed consent moments before a patient undergoes a major, potentially life-threatening or disfiguring procedure. This choice offers little opportunity to manage comorbid conditions or alter risk. Legally, morally, and psychologically, anesthesiologists and patients are in awkward, and often unpleasant, situations. The effects of extensive disclosure are stressful for patients and families at a time when they may be ill prepared to consider the implications rationally. An increase in preoperative anxiety may adversely affect postoperative outcomes because increased anxiety correlates with increased postoperative analgesic requirements and prolonged recovery and hospital stay. Anxiety impairs retention of information, which could result in legal action because of inadequate communication or discussion of the risks of anesthesia.

At a minimum, the guidelines of the American Society of Anesthesiologists (ASA) indicate that a preanesthesia visit should include the following:8

1. Interview with the patient to review medical, anesthesia, and medication history

2. Appropriate physical examination

3. Review of appropriate diagnostic data (laboratory, electrocardiograms, radiographs)

4. Assignment of ASA physical status score

5. Formulation and discussion of the anesthesia plan with the patient or a responsible adult

Table 6-1 outlines the criteria and medical conditions of patients likely to benefit from evaluation in a preanesthetic clinic before the day of surgery.

The current ASA risk classification system was developed in 1941 by Meyer Saklad at the request of the ASA (Table 6-2). This classification was the first attempt to quantify risk associated with anesthesia and surgery. The type of anesthesia and the operation are not even considered in this classification system. Moreover, this system attempted to estimate the mortality rate based only on the patient's preoperative medical condition. Since then, other studies have corroborated an association of mortality and morbidity with ASA physical status (ASA PS) scores. Studies also have shown a correlation between ASA PS and unanticipated intensive care unit admissions, longer hospital stays for some procedures, and adverse cardiopulmonary outcomes. No correlation was shown between ASA PS class and cancellations, unplanned admissions, and other perioperative complications and cost.9 Few studies have evaluated the effect of combining the risk of the surgical procedure and the ASA PS score. Among the first was the Johns Hopkins Risk Classification System.10 Many institutions use a more simplified version of high, intermediate, and low risk.11 Figure 6-1 offers one example of such a risk stratification.

Goldman et al further advanced risk assessment by identifying risk factors and cardiac complications in noncardiac surgery. Several studies followed, culminating in the joint guideline publication by the American College of Cardiology and the American Heart Association (ACC/AHA) in 1996, which was most recently updated in 2007.11 (see "Heart Disease" later and Chapter 9 for more detailed discussions of the ACC/AHA guidelines.) However, there are limited studies or guidelines addressing specific disease states and their effects on perioperative risk. Pulmonary and renal risk and the implications of certain laboratory abnormalities (albumin and hematocrit levels) have been evaluated.12-15

Some assessment of risk is important to prepare for the anesthetic and surgical procedure. The need for invasive monitoring, blood salvage and hypothermic techniques, postoperative care in the intensive care unit, and special monitoring must be considered. Patients must be informed during the consent process. Technical terms used in the consent may be misunderstood.16 Risk assessment is useful to compare outcomes, control costs, allocate compensation, and assist in the difficult decision of canceling or recommending a procedure not be done when the risks are too high. Yet risk assessment, at its best, is hampered by individual patient variability.

Timing of Assessment

The Practice Advisory for Preanesthesia Evaluation commissioned by the ASA determined that the time of the preanesthesia assessment depends on the patient's condition, the type of procedure, the health care system, and the patient's access to care providers.8 The recommendations, which were based on the opinions of experts and randomly selected ASA members, favor assessments on or before the day of surgery for low to medium invasive procedures and before the day of operation for highly invasive procedures. The consensus is for assessments before the day of surgery for patients with less severe disease if they are scheduled for highly invasive procedures and for patients with severe disease for less invasive procedures. For selected patients, evaluations on the day of surgery can be safe and effective.

The importance of a visit to the preoperative clinic before a surgical procedure cannot be overstated.17 A Canadian survey found that more than 60% of patients thought it was important to see an anesthesiologist preoperatively, more than 30% thought it was extremely important, and more than half indicated that the visit should be before the day of operation.18 Anesthesiologists at Massachusetts General Hospital demonstrated that a preoperative visit before the day of surgery was as good as or better than medication in reducing preoperative anxiety and postoperative pain.

Detecting Disease

Several studies have proved the usefulness of the history and physical examination in deciding a diagnosis. A study of patients in a general medical clinic found that 56% of correct diagnoses were made with the history alone and rose to 73% with the physical examination. In patients with cardiovascular disease, the history established the diagnosis 66% of the time, and the physical examination contributed to 25% of diagnoses. Moreover, routine investigations, mainly chest radiography and electrocardiography (ECG), helped with only 3% of diagnoses, and special tests, mainly exercise ECG, assisted with 6%.19 ECG alone was only 14% predictive in the diagnosis of left ventricular dysfunction in patients with suspected neuromuscular disease.20 History is also the most important diagnostic method in respiratory, urinary, and neurologic conditions. The skill of performing a clinical examination derives from pattern recognition learned by seeing patients and listening to the stories of their illnesses. The diagnostic acumen of the physician is a result of the ability to assimilate information and develop an overall impression, rather than just reviewing a compilation of facts.

Medical History

One common problem is the variability of the medical history. Asking and recording symptoms in ordinary words leads to greater interobserver agreement between practitioners. History taking is not simply asking the questions; history taking includes interpreting and carefully recording the answers. Complete and thorough histories not only assist in planning appropriate and safe anesthesia care, but they also are more accurate and cost-effective in establishing diagnoses than screening laboratory tests.

The patient's medical problems, past operations, previous anesthesia-related complications, allergies, and use of tobacco, alcohol, or illicit drugs should be documented. Equally important to identifying the presence of a disease is establishing the severity, the stability, and prior treatment of the condition. A screening review of systems needs special emphasis on airway abnormalities, personal or family history of adverse events related to anesthesia, and cardiovascular, pulmonary, endocrine, or neurologic symptoms.

The patient's medical problems, previous operations, and responses to questions elicit further questions to establish the severity of disease, its stability, current or recent exacerbations, and recent or planned interventions. Rarely is a simple notation of diseases or symptoms such as hypertension (HTN), diabetes mellitus (DM), coronary artery disease (CAD), shortness of breath (SOB), or chest pain sufficient. The severity, extent, degree of control, and the activity-limiting nature of the problems are equally important.

A determination of the patient's cardiorespiratory fitness or functional capacity is useful in guiding additional preanesthetic evaluation and predicting outcome and perioperative complications.11,21 Exercise or work activity can be quantified in the metabolic equivalent of task score (METS), which refer to the volume of oxygen consumed during an activity.22 One's ability to exercise is two pronged in that better fitness decreases mortality through improved lipid and glucose profiles and reductions in blood pressure and obesity. An inability to exercise may be a result of cardiopulmonary disease. Several studies show that inability to perform average levels of exercise, equivalent to 4 to 5 METS (walking 4 blocks on level ground, climbing 2 flights of stairs or 1 flight of stairs carrying 20 lb), identifies patients at risk of perioperative complications.

Table 6-3 shows the important components of an anesthesia history. The form can be completed by the patient in person (paper or electronic version), via Internet-based programs, via a telephone interview, or by anesthesia staff. A more detailed discussion of important components of the history for specific medical conditions is presented later (see "High-Risk Patients").

Physical Examination

At a minimum, the preanesthetic examination should include the airway, a heart and lung examination, vital signs, including oxygen saturation, and height and weight. Increased body mass index (BMI) is one of many factors associated with development of chronic diseases such as heart disease, cancer, and DM, and it can be calculated from an individual's height and weight. The two formulas for calculating the BMI are the English and the metric.

English formula:

Metric formula:

or

See "Obesity" for further discussion and for definitions of BMI categories for adults.

Components of the airway examination should include the following23:

• Length of upper incisors
• Condition of the teeth
• Relationship of upper (maxillary) incisors to lower (mandibular) incisors
• Ability to protrude or advance lower (mandibular) incisors in front of upper (maxillary) incisors
• Interincisor or intergum (if edentulous) distance
• Visibility of uvula
• Presence of heavy facial hair
• Compliance of mandibular space
• Thyromental distance
• Length of neck
• Thickness of neck
• Range of motion of head and neck

Because of the relatively frequent incidence of dental injuries during anesthesia, a thorough documentation of preexisting tooth and gum abnormalities is useful. Either a tooth chart (Fig. 6-2) or standard nomenclature (eg, right upper central incisor, left lower lateral incisor, or right lower bicuspid) can be helpful.

It is important to discuss potential dental risks, especially in the presence of poor dentition.24 A good time to discuss with patients variant options of airway management, including possible fiberoptic intubation when necessary, is after examination of the airway. Findings from the airway examination may predict difficult intubations.25 When challenging airways are identified, advance planning ensures that necessary equipment and skilled personnel are available.

Auscultation of the heart and inspection of the pulses, peripheral veins, and extremities for the presence of edema are important diagnostically and for risk assessment in development of care plans. One should auscultate for murmurs, rhythm disturbances, and signs of volume overload. Murmurs, without a clear etiology (anemia, hyperthyroidism, or pregnancy, with confirmation that the murmur was not present prior to these conditions), warrant further evaluation (see "Heart Disease").

The pulmonary examination includes auscultation for wheezing, decreased or abnormal breath sounds, notation of cyanosis or clubbing, and effort of breathing. Observing whether the patient can walk up 1 to 2 flights of stairs can predict a variety of postoperative complications, including pulmonary and cardiac events and mortality, and aid in decisions regarding the need for further specialized testing such as pulmonary function tests (PFTs) or noninvasive cardiac stress testing.11,26,27 For selective patients (eg, those with deficits or disease who are undergoing neurologic surgery or regional anesthesia), a neurologic examination is necessary to document preexisting abnormalities that may aid in diagnosis, interfere with positioning, or establish a baseline in defense of potential malpractice claims of adverse events.28

Obesity, HTN, and large neck circumference predict an increased incidence of obstructive sleep apnea (OSA). See "Obstructive Sleep Apnea."

Preoperative testing is performed to evaluate existing medical conditions and to diagnose asymptomatic conditions based on known risk factors for particular diseases. Diagnostic tests can aid in the assessment of the risk of anesthesia and operation, guide medical intervention to lower this risk, and provide baseline results to direct intra- and postoperative decisions. The choices of laboratory tests depend on the probable impact of the test results on the differential diagnosis and on patient management. A test is ordered only if the results will have an impact on the decision to proceed with the planned procedure or alter the care plans, The history and physical examination are used to direct test ordering. Table 6-4 contains recommendations for testing based on specific medical conditions. Guidelines in this table are not intended for all patients with those conditions but to aid in diagnosing a disease, to optimize the patient if the disease state is out of control, or for high-risk surgeries.

Preoperative tests without specific indications lack clinical usefulness and may actually lead to patient injury because of unnecessary interventions, delay of surgery, anxiety, and even inappropriate therapies. The history is responsible for the diagnosis 75% of the time and is more important than the physical examination and laboratory investigations combined. In addition, the evaluation of abnormal results is costly. Many studies have evaluated the benefits of disease/condition-indicated testing versus screening batteries of tests.29 Few abnormalities detected by nonspecific testing resulted in changes in management, and rarely have such changes had a beneficial patient effect.30 At most 1 in 1000 patients has benefited from findings derived from nonindicated testing.31 Blery et al found that 0.4% of tests without specific indications provided useful clinical information.30 However, 1 in 2000 preoperative tests resulted in patient harm from pursuit of abnormalities detected by those tests; only 1 in 10,000 was of benefit to the patient.9 It has been suggested that not following up on an abnormal result is a greater medicolegal risk than not identifying the abnormality to begin with. Several studies have demonstrated that routine preoperative testing in ambulatory surgery patients is not useful and cite disparity in requirements for tests among anesthesia providers.29,32

Preoperative ECGs are one of the most frequently ordered and costly noninvasive tests. Occult heart disease is common in the middle-age population and increases with advancing age. Preexisting heart disease increases perioperative risk. Recommendations for age-based testing were derived from the high incidence of abnormalities found on ECGs of elderly patients. The Centers for Medicare and Medicaid Services (CMS) do not reimburse for "preoperative" or age-based ECGs; one must provide a supporting diagnosis with an acceptable International Classification of Diseases, Ninth Revision (ICD-9) code. (Centers for Medicare and Medicaid Services. Available at http://www.cms.hhs.org. Accessed May 19, 2010.) Even the ASA Practice Advisory for Preanesthesia Evaluation states, "The Task Force recognizes that age alone may not be an indication for an electrocardiogram."8 A resting ECG is not a reliable screen for CAD and is a poor predictor of heart disease (without a supporting history) in nonsurgical patients. It appears that only some ECG abnormalities are important in the perioperative period (eg, new Q waves and arrhythmias). One study found only 2% of patients had one or both of these abnormalities.33 The frequency of silent Q-wave infarctions found only by ECG in men age 75 years or older (the highest risk group) is approximately 0.5%. Gold et al found that in ambulatory surgical patients, the incidence of abnormal ECGs was 43%. Only 1.6% (12 of 751) of patients had an adverse perioperative cardiac event and in only half (6 of 751) of these was the preoperative ECG of potential value.34 History is far more important. An abnormal ECG will be found in 62% of patients with known cardiac disease, in 44% of patients with strong risk factors for ischemic heart disease, and in only 7% of patients older than 50 years with no risk factors. Results are abnormal in only 3% of patients between ages 50 and 70 years without risk factors for heart disease.35

Some abnormalities may have implications for anesthesia care beyond the detection of CAD. Arrhythmias, such as atrial fibrillation, which can be detected on physical examination and confirmed by ECG, conduction abnormalities, and left ventricular hypertrophy, may alter anesthesia plans. Adjustments may be necessary to avoid hemodynamic instability, ischemia, or pulmonary edema because of drug interactions or the stress of surgery combined with previous, but not necessarily clinically significant, disease. Plans can be made on the day of operation when monitors are placed in the preoperative area or the operating room rather than incurring the expense of a 12-lead ECG beforehand. Many practitioners espouse the need to establish a baseline. However, this approach is misguided and costly. A preoperative 12-lead ECG is rarely comparable with the intraoperative ECG due to varying lead placement. Anesthetic drugs, position, and volume changes affect the ECG. An unchanged ECG does not eliminate the possibility of ischemia; nor does any change on an ECG absolutely establish a diagnosis. A better comparison can be obtained once the patient is in the operating room with the monitoring ECG in place right before induction of anesthesia by printing off rhythm strips of various leads, most importantly leads II, V4, or V5.

The ACC/AHA Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery no longer consider ECG abnormalities in deciding on further noninvasive stress testing.11 A prospective observational study in patients 50 years or older having noncardiac surgery found abnormalities in 45% of the preoperative ECGs, and bundle branch blocks were associated with postoperative myocardial infarction (MI) and death but had no added predictive value over clinical risk factors.36 The ASA Preoperative Evaluation Practice Advisory recognized that ECG did not improve prediction beyond risk factors identified by patient history.8 Chung et al showed that elimination of testing did not increase risk as long as patients had a clinical evaluation preoperatively.29 In a retrospective study of 23,036 patients, patients undergoing low- to intermediate-risk noncardiac surgery with abnormalities on their preoperative ECG had only a 0.5% increase in cardiovascular mortality as compared with cohorts with normal ECGs.37 In summary, the prevalence of abnormalities on ECG may incur costly evaluation, delaying necessary surgery, and the yield of these workups is quite low. Table 6-4 provides guidance for ECG testing.

Hemoglobin (Hgb) and hematocrit (Hct) levels are frequently abnormal in otherwise healthy patients, but they rarely have an impact on anesthetic care or management unless the planned procedure involves the potential for significant bleeding. Abnormal Hgb levels (both higher and lower than normal) predict postoperative complications and mortality. However, interventions to correct anemia such as transfusion or erythropoietin carry risks of their own. Anemia is often an indication of disease related or unrelated to the planned surgery. If the discovery of anemia will lead to an alteration in surgical plans or prompt further evaluation for disease, such as colonoscopy, and previous laboratory values are unavailable, then testing is warranted.12,15

Coagulation studies (platelet count, prothrombin, or activated partial thromboplastin time) are not recommended unless the patient history suggests a coagulation disorder. If a patient has a negative history for a bleeding disorder, the cost of screening coagulation tests before most surgeries outweighs the benefit. Many practitioners mistakenly believe that a screening prothrombin time (PT) is more likely to be abnormal because of the numbers of patients with liver disease, malnutrition, or warfarin use, conditions that should be readily identified by history. If "screening" tests (not based on history) are ordered, a platelet count and activated partial thromboplastin time (aPTT) are indicated to detect the uncommon patient with thrombocytopenia, an acquired anticoagulant (eg, lupus anticoagulant), or a reduced level of a contact activation factor (eg, von Willebrand disease or factor VIII, IX, XI, or XII deficiencies). Additionally, a short aPTT may be equally as important as a prolonged aPTT. A short aPTT increases the risk of postoperative thromboembolism. The CMS does not reimburse for "routine" or "preoperative" PT/aPTT without an appropriate ICD-9 code.38

There are few data to recommend age-based testing. No correlation has been established, independent of coexisting disease, a positive history, or findings on physical examination, between age and abnormalities in Hgb, serum chemistries, radiographs, or PFTs.31,39,40 Chest radiographs are indicated only in patients with pulmonary signs or symptoms of undetermined cause or severity.13

There is much controversy about and no consensus regarding routine pregnancy testing, especially in adolescents.41 Surveys show that 30% to 50% of practitioners mandate testing in women of childbearing age, primarily because of the unreliability of the history, especially from minors, and the concern over the potential harm to the pregnancy or fetus with anesthesia and surgery, with the attendant medicolegal implications.42,43 Opponents of mandatory testing cite the false-positive rate, cost, the belief that history is reliable if taken in privacy, and the paucity of data establishing risks of anesthesia in early pregnancy. When minors are pregnant, their privacy is governed by state laws. One must be familiar with local statutes and how unexpected positive pregnancy results will be handled. With the high reliability of urine testing, it is best to delay testing until the day of operation instead of testing in the preoperative clinic, unless the patient suspects pregnancy or the menstrual period is delayed. This delay in testing will obviate a negative test days before surgery that may be positive on the day of surgery. The ASA Preoperative Evaluation Practice Advisory "[r]ecognizes the literature is insufficient to inform patients or physicians on whether anesthesia causes harmful effects on early pregnancy. Pregnancy testing may be offered to female patients of childbearing age and for whom the result would alter the patient's management.8

Healthy patients or those with chronic, stable diseases, of any age undergoing low- or intermediate-risk procedures without expected significant blood loss are unlikely to benefit from any tests (Tables 6-4 and 6-5).29 Exceptions are a procedure with the injection of contrast (creatinine level is indicated) or the possibility of pregnancy (a pregnancy test should be done) as shown in Table 6-5. If significant blood loss is expected, Hgb and/or Hct and type and screen are indicated (Table 6-5). Table 6-4 contains the recommendations for diagnostic tests for patients who either have poorly managed coexisting diseases or are suspected of having a condition that has not been diagnosed. Even these tests may not be indicated in this same patient population if they are anticipating low-risk operations, especially with sedation only. In general, tests are recommended only if the results may:

• Change, cancel, or postpone the surgical procedure
• Change anesthetic and medical management
• Change monitoring or intra- or postoperative care
• Establish a diagnosis in a patient who has not been adequately prepared

Many facilities have developed diagnostic testing guidelines to improve patient care, standardize clinical practice, improve efficiency, and reduce costs. With implementation of guidelines, one facility reduced the tests ordered by 60%, improved testing by 81%, and saved almost $80,000 per year. The Mayo Clinic reduced preoperative testing and its costs without a change in outcomes. A cost-to-benefit analysis found that routine urinalysis for all knee replacement surgery in the United States would cost $1.5 million to prevent 1 wound infection.44 Interestingly, one study found 50% more routine ECGs and 40% more chest radiographs were done in a fee-for-service versus a prepaid practice.45

Many of these conditions are discussed in greater detail in other chapters of this text, but here is a brief review of some common diseases that often require perioperative intervention. Identification of patients with these comorbid conditions often presents an opportunity for the anesthesiologist to intervene to lower risk. The following conditions are best managed before the day of surgery, which allows ample time for thoughtful evaluation, consultation, and planning.

Heart Disease

Cardiovascular complications are the most common serious adverse event perioperatively. It is estimated that 1% to 5% of unselected noncardiac surgical patients will suffer a cardiac morbidity. Next is a brief discussion of a few high-risk issues that are likely to be encountered in the preoperative clinic. The patient with ischemic heart disease, coronary stent(s), heart failure (HF), a rhythm disturbance, an abnormal ECG, an undiagnosed murmur, or a cardiac rhythm management device is discussed. Chapter 9 provides a comprehensive review of cardiovascular disease.

Ischemic Heart Disease

The goals in the preanesthetic encounter are to:

• Identify the risk of heart disease based on comorbid diseases (Fig. 6-1)
• Identify the presence and severity of heart disease from symptoms, physical findings, or diagnostic tests
• Determine the need for preoperative interventions
• Modify the risk of perioperative adverse events

The basis of cardiac assessment is the history, the physical examination, and the ECG. The guidelines for cardiac evaluation before noncardiac surgery published by the ACC/AHA are the national standard of care.11 Figure 6-1 presents a simplified approach to the evaluation of patients at risk of heart disease before noncardiac surgery. The complete ACC/AHA algorithm is found in Chapter 9. The goal is to identify patients with heart disease who have a significantly high risk of cardiac morbidity and mortality perioperatively, not to simply find patients with mild or stable ischemic coronary artery disease. Clinical predictors, functional or exercise capacity, and level of surgical risk guide further diagnostic and therapeutic interventions. Not included in the ACC/AHA guidelines are conditions such as chronic inflammatory diseases (eg, rheumatoid arthritis, systemic lupus erythematous); chronic steroid use, and chest irradiation, that either alone or associated with more traditional risk factors, identifies patients at risk for CAD and cardiac complications.46-48

Anesthesiologists who apply the ACC/AHA recommendations and develop practice guidelines (Fig. 6-1) are well positioned to initiate evaluation with stress tests. Results may obviate the need for a cardiac consultation or be available at the time of consultation. Exercise treadmill testing is indicated for patients with normal ECGs who can exercise. Pharmacologic tests, such as dobutamine echocardiography or nuclear perfusion imaging, are necessary for those unable to exercise or who have significant ECG abnormalities that may interfere with the interpretation of ischemia via ECG.

Currently, the benefits versus risk reduction in coronary revascularization before noncardiac surgery are controversial.49 Factors to consider are the urgency of the noncardiac surgery (eg, in cancer cases) and the potential long-term benefits of revascularization. Noncardiac surgery soon after revascularization (bypass grafting and percutaneous coronary intervention with or without stents) is associated with high rates of perioperative cardiac morbidity and mortality.50 Coronary revascularization may offer only moderate protection in patients undergoing elective vascular surgery.51

Patients who have had a percutaneous coronary intervention, especially with newer, drug-eluting stents, require several months, if not a lifetime, of antiplatelet therapy to avoid restenosis or acute thromboses (see "Coronary Stents"). These patients must be identified in the preoperative period and managed in collaboration with a cardiologist. Given that up to half of all perioperative MIs and cardiac deaths can be attributed to plaque rupture in noncritical coronary stenoses, intensive medical management in revascularized patients is likely to be helpful and may account for the lack of benefits of revascularization.49,52 Decisions to revascularize patients before noncardiac surgery should be made only after evaluating the risk of perioperative cardiac-adverse events, the risks and benefits of the various methods of risk reduction, the benefits of the noncardiac surgery, and the patient's preferences. A face-to-face dialogue with all involved parties, similar to "tumor board" discussions, may assist decision making. Because cardiac complications are the leading cause of perioperative morbidity and mortality, anesthesiologists must be current on the latest evidence-based recommendations and be active in decision making and in the management of patients at risk.52

Coronary Stents

More than 1 million patients receive coronary stents each year in the United States. The number of patients presenting for surgery who have stents continues to rise. Bare metal stents (BMS) were the first devices and are still widely used. However, drug-eluting stent (DES) implantation has steadily risen. DES are less likely to cause neointimal hyperplasia and restenosis of the coronary artery, but they are associated with late thrombosis, with an often catastrophic outcome. Thrombosis of either type of stent is more common if antiplatelet therapy is interrupted. Dual antiplatelet therapy with aspirin and a thienopyridine (typically clopidogrel) should not be interrupted for at least 1 month after BMS placement and 12 months after DES insertion.53 See Table 6-6 and Fig. 6-3.

In 2009 the ASA published a practice alert warning practitioners of the risk of premature discontinuation of antiplatelet therapy in patients with coronary stents, and it recommended delaying nonemergency surgery for 1 month in patients following BMS placement and 1 year in patients who had received DES.54 If emergent or urgent surgery is required, it is recommended that aspirin therapy be continued at a minimum through the perioperative period and the thienopyridine restarted as soon as possible after the surgery.54 See Table 6-6, Fig. 6-3, and Table 6-7.

Heart Failure

HF affects 4 to 5 million people in the United States and is a significant risk factor for postoperative adverse events. Asymptomatic left ventricular dysfunction predicts cardiovascular events at 1 month and long term in vascular surgery patients having open procedures.55 The goal in the preoperative period is to identify and minimize the effects of HF. Recent weight gain, complaints of SOB, fatigue, orthopnea, paroxysmal nocturnal dyspnea, edema, recent hospitalizations, and recent changes in management are all significant. Physical findings focus on examination for third or fourth heart sounds, rales, jugular venous distension, ascites, hepatomegaly, and edema. Classifying the patient's medical status according to the New York Heart Association's (NYHA) categories is useful.56

• Class I: no limitation of physical activity; ordinary activity does not cause fatigue, palpitations, or syncope
• Class II: slight limitation of physical activity; ordinary activity results in fatigue, palpitations, or syncope
• Class III: marked limitation of physical activity; less than ordinary activity results in fatigue, palpitations, or syncope; comfortable at rest
• Class IV: inability to do any physical activity without discomfort; symptoms at rest

Diastolic dysfunction may be as common as systolic dysfunction and predicts a poor prognosis outside the perioperative period. The significance of diastolic dysfunction for anesthesia and surgery is less well defined. In a study of patients undergoing major vascular surgery, isolated diastolic dysfunction diagnosed preoperatively by echocardiography was an independent predictor of postoperative HF.57

An objective measure of left ventricular ejection fraction (LVEF) and ventricular performance is helpful, especially in patients with NYHA class III or IV HF. Normal LVEF is greater than 50%; mildly diminished, 41% to 49%; moderately diminished, 26% to 40%; and severely diminished, less than 25%. Patients with class III or IV heart failure should be evaluated by a cardiologist before undergoing general anesthesia or any intermediate- or high-risk procedure. Very minor procedures under monitored anesthesia care can proceed as long as the patient's condition is stable.

Rhythm Disturbances and Electrocardiogram Abnormalities

Arrhythmias and conduction disturbances are common in the perioperative period. Supraventricular and ventricular arrhythmias are associated with a greater risk of perioperative adverse events because of the arrhythmia itself and because they are markers for cardiopulmonary disease. Because uncontrolled atrial fibrillation (AF) and ventricular tachycardia are high-risk clinical markers, elective surgery is postponed until evaluation and stabilization are complete.11 Patients with preexisting paroxysmal AF who progress to persistent AF have worse outcomes due to increases in major cardiovascular events.58

New-onset AF, recent conversion from paroxysmal to sustained AF, AF with a rate more than 100 beats per minute, symptomatic bradycardia, or high-grade heart block (second or third degree) identified preoperatively warrant postponement of elective procedures and referral to cardiology for further evaluation. Left and right bundle branch blocks on preoperative ECG have been shown to predict major cardiac morbidity and mortality, but they had no added predictive value over the clinical history.36 Brugada syndrome is a congenital disease characterized by right bundle branch block (RBBB) with ST-segment elevation in the right precordial leads and is associated with a risk of sudden death and lethal arrhythmias. If the history and physical do not suggest significant pulmonary or congenital heart disease, no further evaluation is warranted because of an isolated RBBB. If congenital heart disease or Brugada syndrome is suspected, a cardiology consultation is indicated. RBBB in a patient with pulmonary symptoms is suggestive of severe respiratory compromise that warrants a pulmonary evaluation and echocardiography if an intermediate- or high-risk operation is planned. Prolonged QT intervals prompt an evaluation of electrolytes, magnesium, and calcium and a cardiology referral.

Murmurs

The quandary is to determine the cause of cardiac murmurs and to distinguish between significant murmurs and clinically unimportant ones. Diastolic murmurs are always pathologic and require further evaluation. Regurgitant disease is tolerated perioperatively much better than stenotic disease.

Aortic stenosis is the most common valvular lesion in the United States, affecting 2% to 4% of adults older than 65 years of age; severe stenosis is associated with a high risk of perioperative complications.11 Once considered a degenerative lesion with increasing age or a congenital bicuspid valve, aortic stenosis is now thought to have much in common with CAD and is an independent marker of CAD.59

Aortic sclerosis, which also causes a systolic ejection murmur similar to that of aortic stenosis, is present in 25% of adults 65 to 74 years of age and almost half of those older than 84 years of age.59 Aortic sclerosis is associated with a 40% increase in the risk of MI and a 50% increase in the risk of cardiovascular death in patients without a history of CAD.60 There is no hemodynamic compromise with aortic sclerosis.

The cardinal symptoms of severe aortic stenosis are angina, HF, and syncope, although patients are much more likely to complain of a decrease in exercise tolerance and exertional dyspnea. Aortic stenosis causes a systolic ejection murmur that is best heard in the right upper sternal border, which often radiates to the neck. Any patient with a previously undiagnosed murmur needs an ECG, and any ECG abnormality warrants an echocardiogram. Because of the difficulties noncardiologists have in distinguishing murmurs of aortic stenosis from those of aortic sclerosis, an echocardiogram should be ordered even without ECG abnormalities, especially if general anesthesia or an intermediate- or high-risk procedure is planned. Current guidelines recommend echocardiography annually for patients with severe aortic stenosis, every 1 to 2 years for moderate stenosis, and every 3 to 5 years for mild stenosis.61

Mitral stenosis is much less common than aortic stenosis and is usually associated with a history of rheumatic heart disease. Mitral stenosis causes a diastolic murmur and should always be further evaluated with ECG and echocardiography. Patients with hypertrophic obstructive cardiomyopathy are often young and male, and they may be asymptomatic and without murmurs. An ECG and echocardiogram is done if there is a personal or family history of syncope with exertion or sudden death, or if a murmur is detected. LVH and ST-segment and T-wave abnormalities on an ECG in an otherwise healthy nonhypertensive patient need to be further evaluated with echocardiography.

Cardiac Rhythm Management Devices: Pacemakers and Implantable Cardioverter-Defibrillators

It is estimated that more than 100000 new cardiac rhythm-management devices (CRMDs), which include both pacemakers and ICDs, are implanted yearly in the United States. Electromagnetic interference is likely to occur with electrocautery, radiofrequency ablation, magnetic resonance imaging, and radiation therapy, and it can result in malfunction or adverse events.62 Some patient monitors and ventilators may cause electromagnetic interference in patients with CRMDs with rate-adaptive mechanisms. The type of device and the features (eg, rate-adaptive mechanisms) likely to malfunction with electromagnetic interference need to be determined during the preoperative evaluation.

Magnets cause most pacemakers to pace asynchronously at a preset rate. Although most ICDs suspend tachydysrhythmia detection (and therefore therapy) when a magnet is appropriately placed, many can be programmed to ignore the magnet. Placement of a magnet may deactivate the device permanently, requiring a programmer to reenable it. Magnets do not affect the pacing function of ICDs.

Ideally, patients with CRMDs have these devices interrogated preoperatively. Consultation with the device manufacturer, cardiologist, or the electrophysiology service may be needed. Special features, such as rate adaptive mechanisms and anti-tachyarrhythmia functions, need to be disabled or the device reprogrammed to an asynchronous pacing mode before surgical procedures and anesthesia where electromagnetic interference is anticipated.62 Newer-generation devices are more complex, and reliance on a magnet, except in emergency situations, is not recommended. ASA guidelines recommend interrogation of the device and disabling the antiarrhythmic function during the procedure. Patients must be in a monitored setting with defibrillation capabilities until the device is reactivated.62 This requires planning so the appropriate device-specific interrogator and trained personnel are available. This may pose a problem for free-standing ambulatory centers.

Pulmonary Disease or Patients with Risk Factors for Postoperative Pulmonary Complications

Postoperative pulmonary complications develop in 5% of patients undergoing nonthoracic surgery, and as many as 1 in 4 deaths occurring within a week of operation are pulmonary related, making it the second most common serious morbidity after cardiovascular-adverse events.63 Established risk factors for an increased risk of pulmonary complications include the following13:

• Advanced age
• Poor general health status
• ASA PS scores >2
• Chronic obstructive pulmonary disease
• Head, neck, thoracic, upper abdominal, aortic, neurologic, vascular, or emergency surgery
• Anticipated prolonged procedures (>2 hours)
• Planned general anesthesia (especially with endotracheal intubation)
• Heart failure

Surprisingly absent predictors in the preceding list are asthma or results from arterial blood gas (ABG) analysis or PFTs. Risk of complications is surprisingly low in well-controlled asthma and in patients treated preoperatively with corticosteroids.64 Risk is greater in patients with asthma with recent exacerbations, a history of postoperative pulmonary complications, recent hospitalizations, or recent intubations for asthma. ABGs are useful in predicting pulmonary function after lung resection surgery but do not predict risk for complications. The extent of airway obstruction, measured by the forced expiratory volume in 1 second is not predictive of pulmonary complications.65 The predicted postoperative diffusing capacity of the lungs for carbon monoxide predicts postoperative pulmonary complications following thoracic surgery.66,67

The focus is on identifying patients at risk for postoperative pulmonary complications and on optimizing those patients with preexisting pulmonary disease. Rarely, PFTs may be indicated to diagnose disease (dyspnea caused by lung disease or heart failure?) or assess management (can dyspnea or wheezing be improved further?) but not as a risk assessment tool or to deny a beneficial procedure.65

The pulmonary status of patients with recent exacerbations or infections needs to be improved whenever possible. Prescriptions for bronchodilators or steroids, referral to pulmonologists or internists, or delay of surgery might be necessary. Training patients preoperatively in lung expansion maneuvers, such as deep-breathing exercises and incentive spirometry, reduces pulmonary complications more than giving the training postoperatively.68 Additionally, a change in perioperative management, including altering the planned surgical procedure if possible, discussing alternatives to general anesthesia, and educating the patient about the benefits of epidural pain management, may provide effective measures to decrease pulmonary complications.69

Patients with pulmonary arterial hypertension have a high rate of perioperative morbidity and mortality. The patient's care should be coordinated with a pulmonologist. An ECG and echocardiogram are useful in patients with more than mild disease. Signs and symptoms of disease severity include the following70:

• Dyspnea at rest
• Metabolic acidosis
• Hypoxemia
• Right heart failure (peripheral edema, hepatomegaly, jugular venous distension)
• History of syncope

Traditionally, especially with children, cases scheduled for elective procedures were cancelled for patients with current or recent upper respiratory tract infections. With modern anesthetic practices, cancellation is not routine.71 In patients with severe symptoms, especially those with underlying conditions that may further compromise a safe anesthetic, elective surgery is postponed for at least 4 weeks. When infection is mild or uncomplicated in healthy patients, there is little risk in proceeding with a procedure to avoid the inconvenience of a cancellation. The dilemma lies with the patients between these extremes. Decisions regarding suitability to proceed should be made on an individual basis. Chapter 20 discusses the pediatric patient with an upper respiratory tract infection in greater detail. Chapter 11 discusses the patient with pulmonary disease in detail.

Obstructive Sleep Apnea

Sleep-disordered breathing affects up to 9% of middle-age women and 24% of middle-age men; fewer than 15% of these cases have been diagnosed. OSA, the most common serious manifestation of sleep-disordered breathing, is caused by intermittent airway obstruction. OSA is characterized by total collapse of the airway with complete obstruction for more than 10 seconds. Obstructive hypopnea is partial collapse (30% to 99%) associated with at least a 4% arterial oxygen desaturation. OSA severity is measured on the apnea-hypopnea index (AHI), the number of apneic and hypopneic episodes per hour of sleep. Patients with severe OSA have more than 30 episodes per hour.

Cardiovascular disease is common in patients with OSA. These patients have an increased incidence of hypertension, atrial fibrillation, bradyarrhythmias, ventricular ectopy, endothelial damage, stroke, HF dilated cardiomyopathy, and atherosclerotic CAD.72 Mask ventilation, direct laryngoscopy, endotracheal intubation, and even fiberoptic visualization of the airway are more difficult in patients with OSA than in healthy patients. Patients with OSA are at risk of postoperative oxygen desaturation.73 There is an association of OSA with obesity.

The STOP-Bang Questionnaire is useful to identify patients with undiagnosed OSA.74 Preoperative evaluation focuses on identification of patients at risk for OSA and improving associated comorbid conditions. Echocardiography may be indicated if HF or pulmonary hypertension is suspected.75 Patients should be instructed to bring their continuous positive airway pressure (CPAP) devices to the hospital on the day of operation. Chapter 11 discusses OSA in detail.

Obesity

An overweight person has a BMI of 25 to 29.9 kg/m2; obesity is defined as a BMI of 30 to 39.9 kg/m2. A BMI of 40 kg/m2 or higher defines extreme obesity. See the formulas for calculating BMI earlier in this chapter. An estimated 64% of adults in the United States are overweight or obese, and 4.7% are extremely obese. Annually 300000 US adults die of obesity-related issues, and almost 10% of health care expenditures in the United States are associated with obesity and inactivity. Obesity is an independent risk factor for heart disease. Hypertension, stroke, hyperlipidemia, osteoarthritis, DM, cancer, and OSA are more common in obese people.

Extremely obese patients may have challenging airways that require specialized equipment, techniques, and personnel. They may need prophylaxis for deep venous thrombosis (DVT) with advanced techniques such as inferior vena cava filter placements. They require special operating room tables and gurneys to support excessive weight. Venous access and invasive and noninvasive monitoring can be difficult. Preoperative identification and planning for these contingencies will avoid delays on the day of the operation. Preoperative evaluation is directed toward coexisting diseases (Table 6-4). Chapter 23 discusses this in greater detail.

Diabetes

An estimated 18 million US adults have DM, which increases the risk of CAD, is considered a CAD equivalent, and is a risk factor for perioperative cardiac complications on a par with angina or a previous MI.11,76 Figure 6-1 and Chapter 9 address cardiac evaluation for noncardiac surgery.

Heart failure is twice as common in males and 5 times as common in females with DM as in those without DM. Poor glycemic control is associated with an increased risk for heart failure, and both systolic and diastolic dysfunction may be present. People with diabetes are also at increased risk for renal failure perioperatively (see Chapters 13, 14, and "Renal Disease" later) and for postoperative infections. Patients with poor preoperative management of glucose are likely to be more out of control intra- and postoperatively.77 Obtaining a glycosylated hemoglobin concentration preoperatively can guide glucose management with intensification of therapy well before the procedure.77 Aggressive management of hyperglycemia decreases postoperative complications. The American College of Endocrinologists' position statement recommends a target fasting glucose of less than 110 mg/dL in noncritically ill patients.78

Preoperatively, the focus is on assessing organ damage and the control of blood sugar. Cardiovascular, renal, and neurologic systems should be evaluated. Ischemic heart disease is often asymptomatic in the person with DM. The goals of perioperative diabetic management include avoidance of hypoglycemia and marked hyperglycemia. Table 6-7 has suggestions for hypoglycemic medication management.

Hypertension

HTN, defined by 2 or more measurements of blood pressure greater than 140/90, affects 1 billion individuals worldwide. The incidence of HTN increases with age. In the United States, 25% of adults and 70% of patients older than 70 years of age have HTN, and fewer than 30% are treated adequately. The degree of end-organ damage and morbidity and mortality correlate with the duration and severity of HTN.

Ischemic heart disease is the most common form of organ damage associated with HTN. The odds ratio for an association between HTN and perioperative cardiac risk is 1.31.79 There is little evidence of an association between preoperative blood pressures lower than 180/110 mm Hg and perioperative cardiac risk. Heart failure, renal insufficiency, and cerebrovascular disease are more common in hypertensive patients.

It is generally recommended that elective surgery be delayed for severe HTN (diastolic blood pressure > 115 mm Hg; systolic blood pressure > 200 mm Hg) until the blood pressure is lower than 180/110 mm Hg. If severe end-organ damage is present, the goal is to normalize blood pressure as much as possible before the operation.79 There is no evidence to justify cancellation of an operation when blood pressure is lower than 180/110 mm Hg, although interventions preoperatively are appropriate. Severely elevated blood pressure should be lowered over several weeks.

Guidelines suggest that cardioselective β-blocker therapy is the best treatment preoperatively because of a favorable profile in lowering cardiovascular risk.80 Effective lowering of risk may require 6 to 8 weeks of therapy to allow regression of vascular changes, and too rapid or extreme lowering of blood pressure may increase cerebral and coronary ischemia. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) showed that effective treatment of HTN is not simply a matter of lowering blood pressure.81 Continuation of antihypertensive treatment preoperatively is critical (Table 6-7). Chapter 9 has more information on the hypertensive patient.

Renal Disease

A normal creatinine level is often not an accurate indicator of renal function. A doubling of serum creatinine from 0.8 to 1.6 mg/dL represents a halving of glomerular filtration rate (GFR). Creatinine does not exceed the normal limits until GFR has fallen below 50 mL/min. GFR decreases with age, and the renal reserve of a healthy 80-year-old is less than half that of a healthy 40-year-old. The focus of the preoperative evaluation of patients with renal insufficiency or failure is on the cardiovascular and cerebrovascular systems, fluid volume, and electrolyte status. Chronic metabolic acidosis is common but usually mild and compensated for by chronic hyperventilation.

Chronic renal disease is a significant risk factor for cardiovascular morbidity and mortality and is an ACC/AHA cardiac risk factor equal to a history of known CAD (Fig. 6-1).11 The annual incidence of death from CAD in patients with both DM and end-stage renal disease requiring hemodialysis is 8.2%. A creatinine of 2.0 mg/dL or higher triggers an assessment of cardiac risk using the ACC/AHA guidelines (Fig. 6-1).11 In a study of 23016 patients undergoing cardiac surgery, those requiring preoperative hemodialysis had an increased 30-day morbidity and mortality equal to patients having urgent surgery, valvular surgery, or an ejection fraction less than 30%.82

In elective cases, hemodialysis needs to be performed within 24 hours of the operation, but not immediately before, due to the risk of hypovolemia and electrolyte shifts. Hemodialysis is associated with fluid and electrolyte (sodium, potassium, magnesium, phosphate) imbalance and shifting of electrolytes between intra- and extracellular compartments. Hemodialysis is performed to correct volume overload, hyperkalemia, and acidosis.

Patients at risk for perioperative renal failure include those with preexisting renal insufficiency and DM, especially in combination, and those undergoing procedures with the administration of contrast medium. If all 3 conditions are present, the risk of renal failure may be as high as 50%. Preoperative identification of at-risk patients may change management, such as administration of sodium bicarbonate, hydration, a change in type of contrast medium, and avoidance of hypovolemia or even vigorous hydration. Chapter 14 has a complete discussion of the patient with renal disease.

Hepatic Disease

Predictors of poor perioperative outcome in patients with liver disease include the following83:

• Acute hepatitis (viral or alcoholic)
• Chronic active hepatitis with jaundice, encephalopathy, coagulopathy, or elevated liver enzymes
• Child C cirrhosis (bilirubin > 3 mg/dL, albumin < 3 g/dL, PT > 6 seconds more than control, poor nutritional status, large amount of ascites, and moderate encephalopathy)
• Abdominal surgery
• PT longer than 3 seconds; prolongation refractive to vitamin K therapy

Salt and water restriction, diuretic therapy (spironolactone is preferred), enteral nutritional supplements, and oral vitamin K (1-5 mg daily for 3-5 days) are indicated preoperatively to correct deficiencies. Delaying elective surgery until after an acute episode of hepatitis or an exacerbation of chronic disease has resolved is appropriate. Chapter 15 discusses the patient with liver disease in detail.

Anemia

The ASA Task Force on Blood Component Therapy concluded that red blood cells should not be transfused solely because of a Hgb level but rather because of risk for complications from inadequate oxygenation.84 Transfusion is rarely indicated when the Hgb is more than 10 mg/dL and almost always needed when the Hgb is less than 6 mg/dL. Anemia is associated with an increase in postoperative mortality independent of transfusion.12,15 The goal in the preoperative period is to determine the etiology, duration, and stability of the anemia, and to consider the extent and type of surgery, the anticipated blood loss, and the patient's comorbid conditions that may impact oxygenation, such as pulmonary, cerebrovascular, or cardiovascular disease. Type and screen testing before the day of operation and planning for the availability of blood will avoid delay of the procedure (Table 6-5). This can ease the burden on the blood bank personnel for same-day admission or outpatient surgery. A protocol can be instituted with the department of surgery and the blood bank. Intraoperative blood salvage can be planned, if appropriate. In special circumstances, such as a patient's refusal of perioperative blood transfusions or for elective procedures with expected significant blood loss in anemic patients, postponement of surgery to treat with iron may be warranted.

Sickle cell disease is a hereditary hemoglobinopathy, and vasoocclusion is responsible for most of the associated complications. Preoperative assessment focuses on identification of organ dysfunction and acute exacerbations.85 Chapter 16 discusses in detail the patient with anemia.

Neurologic Disease

For a patient with neurologic disease (eg, stroke, seizure disorder, multiple sclerosis), a detailed history is required with focus on recent events, exacerbations, or evidence for poor control of the medical condition. A basic neurologic examination documenting deficits in mental status, speech, cranial nerves, gait, and motor and sensory function is important. This baseline enables postoperative comparison and evaluation of new deficits. If a stroke or transient neurologic deficit is not fully evaluated or occurs within 1 month before the operation, elective surgery is typically delayed pending complete evaluation. A carotid bruit requires a careful history of related symptoms. If symptoms are present, carotid Doppler studies are indicated. Significant abnormalities on Doppler studies should prompt a referral to a vascular surgeon or neurologist.

Routinely ordering tests for serum drug levels of antiseizure medications is not warranted unless toxicity is a concern or the patient is having breakthrough seizures. Patients with good control of seizures may have levels outside the therapeutic range and results may be confounded if the timing of the administration of the drugs in relation to when the test is drawn is not considered. Chapter 12 discusses neurologic diseases in detail.

Cancer Patients

Patients with a history of cancer may have complications related to the disease or the treatment. Preoperative evaluation focuses on evaluation of the heart, lungs, and neurologic and hematologic systems. Previous head and neck irradiation may cause carotid artery disease, hypothyroidism, or difficulty with airway management.86 Auscultation for bruits, thyroid function tests (thyroid-stimulating hormone levels), and carotid Doppler studies may be needed.

Mediastinal, chest wall, and left breast irradiation can cause conduction abnormalities, cardiomyopathy, valvular abnormalities, and premature CAD even without traditional risk factors.87 Cardiovascular disease is the second most common cause of mortality in survivors of Hodgkin disease. One study found that 88% of patients had echocardiographic abnormalities 5 to 20 years after treatment, most of them asymptomatic. Treatment at a younger age increases risk. These risk factors were not considered in the ACC/AHA Guidelines for Cardiac Evaluation for Noncardiac Surgery, but they may be important predictors of CAD.87 ECG, echocardiography, and stress testing may be indicated.

Patients with cancer may have significant pain associated with their primary illness and take large amounts of narcotics. Consultation with a pain specialist may be necessary in complicated and difficult pain management cases. A discussion with the patient needs to occur preoperatively to help allay patient concerns and fears about inadequate pain control. Similar issues may occur in patients with chronic pain or who abuse substances.

Substance Abuse

Patients who use alcohol to excess or illicit drugs may not give a reliable history. Addicts may be at risk for a myriad of perioperative complications, including withdrawal, acute intoxication, an altered tolerance to anesthetic and opioid medications, infections, and end-organ damage. Preferably, patients with drug or alcohol dependence should be drug free well before an elective operation. Acute preoperative abstinence in alcoholics, however, is associated with a poorer outcome postoperatively than if drinking is continued.88

Preanesthesia clinic staff should be prepared to refer patients to addiction specialists or programs or prescribe medications to prevent withdrawal in the preoperative period if patients agree to abstinence. Intravenous drug use prompts an evaluation for cardiovascular, pulmonary, neurologic, and infectious complications. Because intravenous access is often limited in users, interventional radiology may be needed to help with line placement. Alcoholics need assessment of cardiovascular, hepatic, and neurologic alterations. Planning for adequate postoperative analgesia is important because these patients often have a higher requirement from chronic abuse and misuse of substances. Testing depends on symptoms and findings from the history and physical. ECG, echocardiography, chest radiography, and chemistry and hepatic panels may be needed. Table 6-4 and Chapter 24 provide additional information.

Patients with or at Risk of Thromboembolism and/or Pulmonary Emboli

Recent arterial or DVT requires postponement of non–lifesaving procedures. Without anticoagulation, the risk of recurrent DVT within 3 months of a proximal DVT is approximately 50%. A month of warfarin treatment reduces the risk to 10%; 3 months of warfarin treatment reduces the risk to 5%. Patients with a hereditary hypercoagulable state, cancer, or multiple episodes of DVT are at higher risk indefinitely. Patients with nonvalvular atrial fibrillation who have had a previous cerebral embolism also are at high risk, as are patients with mechanical heart valves, especially multiple valves. Risk is greater with mitral than with aortic valves. Surgery increases the risk of DVT, but there is no evidence that surgery increases the risk of arterial embolism in patients with atrial fibrillation or mechanical valves.89

An elective operation scheduled for the first month after an episode of venous or arterial thromboembolism should be postponed. If postponement is not possible, then the patient should receive preoperative heparin while the international normalized ratio (INR) is below 2.0.89 Ideally, 3 months of anticoagulation is recommended before an elective operation. In a large cohort study, thromboembolism, excessive bleeding, and death were low when anticoagulation was temporarily suspended for invasive procedures. Patients with cancer had the greatest risk of thrombosis and bleeding as compared with noncancer patients.90 See the section on medication instructions and Table 6-7 for further discussion of warfarin management preoperatively. Chapter 16 discusses patients with coagulation disorders.

Smokers and Those Exposed to Secondhand Smoke

Exposure to tobacco, directly or through "secondhand" smoke, increases the risk of many perioperative complications. Smokers are more likely to experience wound infections, respiratory or airway complications (including oxygen desaturation), and severe coughing.91 Smoking decreases macrophage function, negatively impacts coronary flow reserve, and causes vascular endothelial dysfunction, hypertension, and ischemia. Smoking causes inflammation and may cause immunosuppression. 92 Smokers require longer hospital stays and more often need postoperative intensive care than do nonsmokers.

The greatest benefit of smoking abstinence is probably only realized after several months of cessation. In studies reporting a greater perioperative risk in recent quitters than in smokers, selection bias may have contributed to the results. The patients who were motivated to stop or advised to quit smoking may have been at greater risk because of health status. Soon after a patient quits smoking, carbon monoxide levels decrease, which improves oxygen delivery and use. Cyanide levels decrease, which benefits mitochondrial oxidative metabolism. Lower nicotine levels improve vasodilatation, and many toxic substances that impair wound healing decrease. Patients without a history of ischemic heart disease who smoked shortly before their operation had significantly more episodes of rate-pressure product-related ST-segment depression than did nonsmokers, former smokers, or chronic smokers who did not smoke in the immediate preoperative period.93

A preoperative smoking cessation intervention in patients who underwent knee and hip replacements decreased rates of surgical-site infections from 23% in the conventional group to 4% in those who stopped smoking. The US Public Health Service recommends that "all physicians should strongly advise every patient who smokes to quit because evidence shows that physician advice to quit smoking increases abstinence rates."94 Nearly 70% of smokers want to quit. Patients presenting for surgery are more likely to quit smoking compared with smokers not having surgery.95

Effective interventions include medical advice and pharmacotherapy, such as nicotine-replacement therapy, varenicline (Chantix), and bupropion (Wellbutrin), which are safe in the perioperative period. Nicotine patches, gum, and lozenges are available without a prescription; nasal spray, varenicline, and bupropion require prescriptions. Clonidine is also effective. Varenicline, bupropion, or clonidine should be started 1 to 2 weeks before a quit attempt; nicotine replacement therapy is effective immediately.95 Individual and group counseling may increase rates of long-term abstinence. Many hospitals, insurance companies, and communities offer smoking cessation programs. Excellent resources are available on the Internet and from the US government. Advice and guidelines are available at http://www.surgeongeneral.gov/tobacco/default.htm. Patients can be referred to 1-800-QUITNOW. Tobacco-intervention training during medical school and residency can significantly improve the quality of physician counseling and rates of abstinence.

The Elderly

By the year 2030, almost 70 million persons older than 65 years will be alive in the United States, and a significant portion of these will be 85 years of age or older. The number of patients older than 65 years who will undergo noncardiac surgery will increase from 7 to 14 million by 2025. Chronological age, however, is a less important determinant of operative outcome than are comorbid conditions and physiologic age. Age older than 70 years is an independent predictor of postoperative mortality, cognitive dysfunction, major perioperative complications, and longer hospital stays.13,96 Organ function declines in the elderly, who respond differently to medications and have a greater number of comorbid conditions. Among the conditions are arthritis, hypertension, heart disease, and DM. One study found coexisting disease in 95% of geriatric patients scheduled for surgery. Postoperatively 35% of patients had cardiac or pulmonary complications that were associated with comorbid conditions, and many could have been predicted preoperatively.97 Other studies have found that the rate of perioperative complications among the very elderly (>85 years) is not prohibitive.96

Elderly individuals often do not return home immediately after an operation for various reasons. They need rehabilitation, their recovery takes longer, they have a high incidence of postoperative cognitive dysfunction (41.4% prevalence at discharge, 12.7% at 3 months), or support services are lacking.98 Discharge planning in advance may lessen the costs of perioperative elder care. Preoperative clinics can be designed to offer multidisciplinary care and after-discharge planning that coordinates with surgical, nursing, and social service departments.99

Testing in the elderly patient should be based on disease indications rather than age alone (see Table 6-4 and the section in this chapter on age-based testing, "Preoperative Testing"). Chapter 21 presents an expanded discussion of the evaluation of the geriatric patient.

Cataract Patients

Patients undergoing cataract surgery are often elderly with extensive comorbid disease. The procedure is minor, however, without expected systemic physiologic disturbances or significant postoperative pain. Topical anesthesia is commonly used, and because general anesthesia is rarely required, the risk is lessened. Elective cataract surgery has the enormous benefits of allowing individuals to drive, read, avoid isolation, watch television, and decrease the incidence of falls. The cost of routine medical testing before cataract surgery is estimated at $150 million annually. In a study of more than 18,000 patients randomly allocated to no routine testing before cataract surgery or to a battery of tests, including ECG, complete blood count, and electrolytes, blood urea nitrogen, creatinine, and glucose levels, no differences in postoperative adverse events were found between the two groups.100

The results of this study do not suggest that patients undergoing cataract surgery require no laboratory testing.100 The study of cataract patients eliminated routine tests, not tests indicated for a new or worsening medical problem. The group that crossed over from no testing to some testing had significantly more coexisting illness and poor self-reported health status. This finding suggests that the preoperative care provider screen patients to order tests for those who require them. In the study described, exclusion criteria were general anesthesia or an MI within 3 months. All patients underwent a preoperative medical assessment. More than 85% of enrollees reported good to excellent health status, almost 25% reported no coexisting illnesses (including hypertension, anemia, DM, and heart or lung disease), almost 30% were older than 70 years, and 65% were ASA PS 1 or 2 status, suggesting a fairly healthy group.100 If patients are comparable with those in the study, are routinely evaluated by primary care physicians, have stable mild disease, and will undergo cataract operation under topical or bulbar block, then no special testing is required because of cataract surgery. Serious, poorly controlled conditions must be normalized before surgery, and selective testing suggested by history and physical examination may be necessary. One center showed a 90% savings in laboratory costs in a 4-month period by eliminating routine testing for cataract patients.101

Although testing is rarely necessary because of cataract surgery, patients with limited access to health care services may benefit from medical evaluation. The ACC/AHA Guidelines for Cardiac Evaluation for Noncardiac Surgery consider cataract surgery to be low risk.11

The Difficult Airway

An important part of preoperative evaluation is assessment of the airway. If a patient with a difficult airway can be identified before the day of operation, special equipment or personnel with advanced training and skills in airway management can be available without delaying or postponing procedures or compromising patient safety.1 Patients with the following characteristics may have a challenging airway:

• OSA
• Snoring
• Obesity
• Facial and neck deformities from previous operation
• Head and neck radiation
• Head and neck trauma
• Congenital abnormalities
• Rheumatoid arthritis
• Down syndrome
• Scleroderma
• Cervical spine disease or previous operation

The ease or difficulty of laryngoscopy and intubation are discussed extensively in the literature. However, equally, if not more, important is the ability to predict difficulty with mask ventilation.102 The following patient characteristics independently suggest difficulty with mask ventilation:

• Age older than 55 years
• BMI higher than 26 kg/m2
• Lack of teeth
• A beard
• Snoring history

Patients with Down syndrome or rheumatoid arthritis may have asymptomatic atlantoaxial subluxation and cervical spine instability. A careful history may elicit neurologic deficits or neck and shoulder pain. Patients with neurologic deficits or symptoms and rheumatoid arthritis patients with long-standing, severely deforming disease need cervical spine radiographs with special flexion, extension, and open-mouth odontoid views. Patients with oral piercings are counseled to remove all jewelry on the day of surgery and about the potential risks if piercings are not removed.103

Chapter 10 discusses the evaluation of the patient with a difficult airway. The goals in the preoperative clinic should be documentation of an airway examination, including size of the oral opening, Mallampati score, status of teeth (Fig. 6-2), range of motion of the neck, thyromental distance, body habitus, presence of facial hair, and pertinent deformities. Previous anesthetic records should be obtained and a discussion of awake fiberoptic intubation with the patient may be appropriate. See "Physical Examination" earlier for components of the airway examination.

Anesthesia-Specific Concerns

A personal or family history of pseudocholinesterase deficiency is identified preoperatively. Records from previous anesthetics may clarify an uncertain history. If time allows, a dibucaine number and pseudocholinesterase, chloride, and fluoride levels should be obtained. A history of malignant hyperthermia (MH) or a suggestion of it (hyperthermia, rigidity during anesthesia, or unplanned admission to an ICU following a general anesthetic) either in a patient or family member should be clearly documented and arrangements made before the day of the operation. Chapter 87 provides a comprehensive review of MH, its prevention and management.

Ambulatory Surgery

Approximately 60% to 70% of surgical procedures are performed on an outpatient basis, and of these, 5% to 8% are performed in an office setting. A study of ambulatory surgery in Medicare beneficiaries older than 65 years found no deaths on the day of operation when the procedure was performed in a physician's office; 2.3 deaths per 100,000 procedures when performed in a freestanding ambulatory surgical center; and 2.5 deaths per 100,000 when performed at an outpatient hospital. The 7-day mortality was 35 per 100,000, 25 per 100,000, and 50 per 100,000, respectively. Age older than 85 years, significant comorbidity, and type of procedure predicted adverse events.104

Almost half of ambulatory surgical procedures are performed in patients 65 years and older. Elderly patients may bring specific problems to the ambulatory setting because they often have multiple chronic conditions and poor eyesight, and they may be unable to perform activities of daily living such as feeding themselves or driving. Some patients have limited support during the stress of recovery from anesthesia and surgery.99

Patients with OSA may require skilled and specialized airway management. They are typically sensitive to anesthetic agents (less airway muscle tone than normal, which leads to airway collapse) and narcotics (greater than average respiratory depression). They may require longer postoperative monitoring, and the American Sleep Apnea Association suggests that some patients with sleep apnea might not be candidates for ambulatory surgery. Patients are told to bring their CPAP machines on the day of surgery.

Obese patients may require specialized equipment to accommodate their weight, which might not be readily available in ambulatory facilities. Patients with a history or family history of MH may require prolonged observation in the recovery period, so planning is important. Whether a patient susceptible to MH is a candidate for ambulatory surgery should be decided well before the day of operation. Individuals with pacemakers and ICDs may not be candidates for freestanding ambulatory facilities if electromagnetic interference is likely or sudden patient movement is undesirable, and personnel are not available to reprogram the devices.62 The ACC/AHA Guidelines for Cardiac Evaluation for Noncardiac Surgery consider ambulatory surgery to be low risk.11

Management of comorbid conditions and interventions to reduce risk is as important as identification and diagnosis of medical disease. If anesthesiologists are not going to intervene to improve new or chronic disease states, then close collaboration with primary care physicians, specialists, and surgeons are essential. Far too many anesthesia practices collect information without having processes in place to follow through to manage patients and risk to improve outcomes and reduce adverse events.

Consultations

Collaborative care of patients is often necessary and beneficial. Consultation initiated by the preoperative physician should seek specific advice regarding diagnosis and status of the patient's condition(s). Asking specific questions such as "Does this patient have CAD?" or "Is this patient in the best medical condition for planned thoracotomy with lung resection under general anesthesia?" is the first step. Letters or notes stating "cleared for surgery" are rarely sufficient to design a safe anesthetic. A summary of the patient's medical problems and current status, medical therapy, and results of any recent diagnostic tests is necessary.

Close coordination and good communication among the preoperative anesthesiologist, surgeon, and consultant is vitally important. Miscommunication among care providers was central to most reported incidents in the Australian Incident Monitoring Study (AIMS) whenever preoperative assessment was implicated.1

In many practices the cardiology service is most frequently consulted perioperatively. In one survey, however, the usefulness of such consultations was questioned by anesthesiologists. Unfortunately, only 17% of anesthesiologists felt obligated to follow the consulting cardiologist's recommendations. Forty percent of the consultations contained only the recommendation to "proceed with the case," "cleared for surgery," or "continue with current medications." Recommendations regarding intraoperative monitoring or cardiac medications were largely ignored. Part of this responsibility lies with the consulting physicians (be that surgeons or anesthesiologists) and the long-standing practice of asking for or receiving cardiac "clearance." This is a vague request, and a response (often scribbled on a prescription pad) simply stating "low risk" or "cleared for surgery" is meaningless and unhelpful. In general, preoperative consultations are sought for diagnosis, evaluation, and improvement of a new or poorly controlled condition, and for creation of a clinical risk profile that the patient, anesthesiologist, and surgeon use to make management decisions.

Detailed discussions and communication, preferably oral, are essential for the best management of complicated patients. Copies of diagnostic studies that accompany the consultation letter help the anesthesiologist to make an independent decision about patient risk and to plan anesthetic care. Chapter 8 has a detailed discussion of consultations.

Practice Guidelines

An important element for a successful preoperative evaluation system is a uniform, consistent method for assessment and management. Even though individual judgment is necessary, guidelines and policies for the group should be developed. Cancellations, delays, or demands for additional diagnostic testing on the day of operation after a patient has been evaluated and deemed acceptable for anesthesia by the preoperative clinic is detrimental to the success of a preoperative assessment program.

Practice guidelines improve the process of preoperative evaluation and management and affect surgical outcomes. Guidelines minimize variation in clinical practice and make good use of resources. They may help to avoid cancellations or delays on the day of operation when the anesthesiologist in the preanesthetic clinic and the one performing the anesthesia have differences in opinion about the patient's fitness for operation. This will prevent patient inconvenience and disappointment and surgeon dissatisfaction. Guidelines synthesized from the best, most current sources help practitioners stay up to date with recommendations and the literature by assimilating treatments and diagnostics into their practices. Guidelines can be as simple as an organization of the type and timing of care delivered to typical, uncomplicated patients or as complex as instructions for dealing with a specific issue expressed by decision trees in branching logic format.105 Acceptance is more likely when disease-specific algorithms are developed and agreed to by all stakeholders. The intent is not to design inflexible standards but to provide a consistent, straightforward method to evaluate a particular disease such as hypertension or CAD, a finding such as a murmur, or a symptom such as chest pain. Practice guidelines recommend care based on scientific evidence and broad consensus but leave room for justifiable variations in practice.

Practice guidelines typically rely on evidence-based medicine that examines the data from clinical research. Intuition, personal clinical experience, and pathophysiologic rationale are less important. The practice and teaching of evidence-based medicine requires skills that are not part of traditional medical training. Precisely defining a problem and the information required to resolve the problem are important first steps. The pertinent studies from a well-conducted literature search are selected and applied to the treatment of medical conditions found in patients.

Algorithms such as in Figs. 6-1 and 6-3, and guidelines such as in Tables 6-4, 6-5, 6-6, and 6-7, are examples.

Nothing‐by-Mouth Guidelines

Historically, patients have been told to abstain from oral intake (nothing by mouth [NPO]) after midnight regardless of the time of their procedure to reduce the risk of aspiration. Twenty years ago Miller found that a light breakfast (of tea and toast) 2 to 4 hours before an operation did not negatively impact gastric pH or volume. In many European countries today, patients are allowed to eat a "light breakfast" if an operation is scheduled for noon or after. However, this practice has not received widespread adoption in the United States. Because oral fluids have short gastric transit times, many, if not most, departments of anesthesia modified the "nothing after midnight" approach. The ASA recommends that healthy patients who will undergo elective procedures be allowed to drink clear liquids (eg, water, juice without pulp, coffee or tea without cream or milk) until 2 hours before anesthesia; breast milk until 4 hours before anesthesia; and nonhuman milk, infant formula, or a light breakfast until 6 hours before procedures requiring anesthesia (Table 6-8).106 In a prospective cohort study there were no differences in aspiration, and delays or cancellation of cases between groups who followed traditional NPO versus liberalized (clear fluids until 2-3 hours before surgery) guidelines. There were more cases of regurgitation, and rapid-sequence and awake intubations in the NPO after midnight group.107

Medication Instructions

Some medications should be continued on the day of operation because of their beneficial effects; others may be harmful or contraindicated.108 Medications associated with withdrawal effects (eg, β-blockers, centrally acting sympatholytics, benzodiazepines, and opioid analgesics) should be continued through the preoperative period. Table 6-7 and Fig. 6-3 describe in detail drugs to be continued or discontinued before an operation.

Most antihypertensive medications, with the possible exception of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor–blocking agents (ARBs) should be taken before operation.109 ACEIs and ARBs may be associated with greater risk for hypotension upon induction of general anesthesia. There is no consensus as to whether these agents should be held before anesthesia. No large studies exist to support any specific recommendation. For high-risk procedures with planned neuraxial blockade or general anesthesia in well-controlled hypertensive patients, it may be beneficial to hold these drugs on the day of operation. In our preoperative clinic patients who will undergo minor procedures with monitored anesthesia care, and those with poorly controlled HTN are advised to continue these drugs on the day of operation to reduce the risk of significantly elevated blood pressure in the pre- and postoperative periods. β-Blockers and centrally acting sympatholytics (eg, clonidine) can be associated with rebound hypertension when withdrawn.

Consensus is lacking on the recommendations to discontinue diuretics preoperatively. Diuretics (eg, hydrochlorothiazide) to treat HTN will likely help to control blood pressure when continued on the day of operation. Withholding potent loop diuretics (eg, furosemide) on the day of operation may decrease the risk of volume depletion and renal insufficiency.110 Intravenous admission by the anesthesiologists on the day of operation is an option.

Medications used by patients with a history of or who are at risk for heart disease, such as β-blockers, digoxin, antiarrhythmics, and statins, should not be withdrawn before operation. Not only are they beneficial, but risk may be increased when they are not taken.11

Aspirin, taken for primary prophylaxis of vascular disease or for pain, and other nonsteroidal anti-inflammatory drugs (NSAIDs) are generally discontinued before the day of operation.111,112 Circumstances may dictate otherwise to prevent MI or stroke, to improve patency of vascular grafts, and to achieve better pain control. There is increasing evidence supporting continuation of aspirin when taken for secondary prophylaxis (ie, patients with established vascular disease).111,112 Aspirin is continued for patients scheduled for vascular reconstruction and for those at high risk for cardiovascular and cerebrovascular complications except for intraspinal and intracranial procedures. Aspirin and other NSAIDs do not need to be discontinued for planned neuraxial or regional anesthesia techniques.113 If the decision to discontinue these agents is made, aspirin is stopped 5 to 7 days and other NSAIDs 48 hours before the operation.114 Many cold preparations and over-the-counter drugs (eg, Alka-Seltzer and Pepto-Bismol) may contain aspirin.

More potent antiplatelet agents, such as clopidogrel (Plavix) may be associated with a substantial risk of perioperative bleeding. These drugs are discontinued 7 days before the operation if appropriate.111,112 Patients with DES placed less than 12 months ago, BMS placed less than 4 to 6 weeks previously, or percutaneous coronary interventions without stents less than 2 weeks before surgery should have only lifesaving surgery, preferably while continuing dual antiplatelet therapy (Table 6-6 and Fig. 6-3).

Statins reduce strokes, renal dysfunction, MI, length of hospital stay, and even death.115-117 Patients having coronary artery bypass grafting who take perioperative statins have a dose-dependent reduction in adverse cardiac events.118 No study of perioperative statin therapy has reported serious risks with the use of these drugs.116 Abruptly stopping statins may be associated with an increased risk, including death.117 Statins are continued in the perioperative period. Serious consideration should be given to starting them in patients with risk factors for or known atherosclerotic disease, especially because these patients have indications independent of surgery. This is an important intervention with long-term benefits.

Pulmonary medications, such as theophylline, inhaled β-agonists, inhaled anticholinergics, and inhaled or oral steroids, should be continued preoperatively. These drugs are prescribed for patients with reactive airways who require optimization.119

Oral hypoglycemic agents typically are held the day of operation to avoid hypoglycemia. Taking small amounts of long-acting insulin on the day of operation presents little risk of hypoglycemia but results in improved perioperative control. Patients with types 1 and 2 DM discontinue all short-acting bolus doses of insulin on the day of operation. Patients with type 2 DM take none or up to one-half dose of long-acting (eg, lente or neutral protamine Hagedorn [NPH]) or combination (70/30 preparations) insulins on the day of operation. Ultra–long-acting insulin (eg, glargine) is best continued as scheduled. People with type 1 DM take a small amount (usually a third to a half) of their usual morning long-acting insulin (eg, lente or NPH) on the day of operation to avoid diabetic ketoacidosis. Patients with an insulin pump continue their basal rate only.

Warfarin may be associated with increased bleeding except for minor procedures such as cataract surgery without bulbar blocks. There is no consensus on the optimal perioperative management of patients on warfarin. The usual recommendation is to withhold 4 to 5 doses of warfarin before operation (if the INR is 2.0-3.0) to allow the INR to decrease to less than 1.5, a level considered safe for surgical procedures and neuraxial blockade. 113 If the INR is higher than 3.0, it is necessary to withhold warfarin longer than 4 doses. If the INR is measured the day before the operation and remains higher than 1.8, a small dose of vitamin K (1.0-5.0 mg orally or subcutaneously) can reverse anticoagulation.90

Substitution with shorter-acting anticoagulants such as unfractionated or low-molecular-weight heparin, referred to as bridging, is controversial and should be individualized.89 Kearon recommends preoperative bridging with intravenous heparin only for patients who have had an acute arterial or venous thromboembolism within 1 month before operation if the procedure cannot be postponed.89

Most medications for neurologic and psychological problems should be continued on schedule in the preoperative period. Antiepileptics, antiparkinson medications, antidepressants, including monoamine oxidase inhibitors (MAOIs), antipsychotics, benzodiazepines, and drugs to treat myasthenia gravis are best maintained to avoid exacerbations of symptoms. Antianxiety and psychiatric medications should be continued up until the time of the procedure. Communication is crucial to alert the day of operation caregivers because alterations in anesthesia may be necessary when caring for patients on these medications, especially for patients taking MAOIs. Highly active antiretroviral regimens to treat human immunodeficiency virus require regular dosing to prevent drug resistance. It is important to maintain these as scheduled. Antibiotics should be taken to complete a prescribed course of therapy.

Patients taking narcotic pain medications are told to continue these medications as needed, including on the day of operation. Missed doses may result in withdrawal symptoms and significant pain with the associated stress response and hemodynamic perturbations.

Thyroid replacement drugs and antithyroid medications are continued on schedule.108 Patients taking steroids regularly take their usual dose on the day of operation.120 Patients who have taken more than the equivalent of 7.5 mg of prednisone a day for at least 3 weeks within the previous year may be at risk for stress-associated adrenal insufficiency.

Postmenopausal hormone replacement therapies containing estrogen increase the risk of perioperative thromboembolic complications and should be discontinued before operation.121 Estrogens must be stopped approximately 1 month before the operation to return coagulation to baseline. Most modern oral contraceptives have low doses of estrogen that increase thromboembolic risk minimally. The risk of unanticipated pregnancy may outweigh the benefits of discontinuing oral contraceptives.

Herbals and supplements may interact with anesthetic agents, alter the effects of prescription medications, and increase bleeding. Many patients do not consider supplements to be medications and will not report them in a list of their medications unless asked. Gingko biloba, echinacea, garlic, ginseng, kava, St. John wort, and valerian may be associated with increased bleeding, or a resistance or increased sensitivity to anesthetic and sedative agents.122 Herbals and supplements are discontinued 7 to 14 days before the operation. The exception is valerian, a central nervous system depressant that may cause a benzodiazepine-like withdrawal when discontinued. If time permits, valerian should be tapered before a planned anesthetic.

Patients who are particularly anxious should be offered a prescription for a short course of benzodiazepines, such as lorazepam, to be taken in the days preceding the operation, as well as on the day of operation.

As the practice of surgery has moved into the outpatient arena with most patients presenting to the hospital within minutes to hours of undergoing complex procedures, anesthesiologists have struggled with how best to accomplish their evaluations. Various models exist. Lee originally proposed an anesthesia-based outpatient clinic in 1949. Some clinics do no more than document information provided by the patient, the medical record, or others who have seen the patient. Some anesthesiologists rely on other physicians operating independently to prepare patients for operation, either based on anesthesia-derived guidelines or not. This allows for review of information but little direct oversight of the process. Practices that do not have preanesthesia clinics need to develop guidelines to direct testing and to prepare patients for anesthesia (Fig. 6-1, Tables 6-4, 6-5, 6-6, 6-7, 6-8, and 6-9).

Many surgeons and anesthesiologists rely on prior screening of patients or referrals to primary care physicians, internists, or specialists to "clear" patients or to manage comorbid conditions. Although this reliance may be appropriate for a few, very select diseases and patients, the management of conditions for everyday life and for reducing long-term complications is very different from the stresses of a surgical procedure and anesthesia. Proficiency in preoperative care is a prerequisite for board certification in anesthesia; internists who are not specifically trained in preoperative care may feel insecure when called on to evaluate the preoperative patient because this important aspect of medicine is not formally taught in many training programs.123 Anesthesiologists are best suited to do preoperative assessments because of our comprehensive understanding of surgical procedures, anesthetic techniques, and the pharmacologic and physiologic responses of patients during procedures.

Anesthesiologist-staffed preoperative clinics improve the satisfaction of patients and physicians, reduce operating room cancellations and delays, and decrease unnecessary testing and costs.7 To expand the anesthesiologist's responsibilities beyond the operating room, an educational system must be developed to train anesthesiologists in preoperative care. Concern has been expressed that current anesthesiology training programs are inadequately preparing practitioners to evaluate and manage patients with complicated medical conditions prior to anesthesia and operation.124 Previously, during residency training, honing the cognitive aptitude for preoperative medicine had not been emphasized because of the inordinate amount of time anesthesiologists spend in the operating room learning technical and procedural skills. One study found that fewer than half of residency programs have a formal preoperative management curriculum.124 Recently, the American Board of Anesthesiology mandated a 1-month requirement in preoperative evaluation training for anesthesia residents.

As anesthesiologists assume a greater out-of-operating room presence and take on the tasks of evaluating and managing patients before operation and anesthesia, expert practices using cost-efficient management, outcomes measures, and practice guidelines must be developed. Diagnostic expertise and clinical decision making should be emphasized. It would be unrealistic to expect anesthesiologists to manage the administrative and clinical roles of perioperative medicine without training in these skills during residency.124 Greater involvement of anesthesiologists in preoperative medicine has potential benefits to patients, institutions, the health care system, and the specialty. Preoperative clinics enable anesthesiologists to be responsible for perioperative care resources, to attract a diverse population of health care providers to the specialty, and to establish an expertise beyond the operating suite. Kluger, from the AIMS study, stated, "Anaesthetists must recognize they are responsible for the overall clinical management of the patient rather than simply providing a technical service.1

Preanesthesia clinics vary widely in services offered and the personnel involved in preoperative evaluation. They are staffed by anesthesiologists, internists, or physician extenders, such as nurse practitioners, physician assistants, registered nurses, or some combination.105 Depending on services that are offered, additional staff might include clerks, phlebotomists, ECG technicians, administrators, social workers, case managers, and physical therapists. When outcomes were compared between patients cared for by nurse practitioners versus primary care physicians, no difference in health status of patients or quality of care was found. In one study, a physician's diagnostic accuracy was improved 20% to 30% after a physician's assistant took a detailed history.125 Little data from preanesthetic clinics exist to guide staffing.

Scheduling

Scheduling is based on the anticipated requirements of the preoperative visit, such as the numbers and types of practitioners (eg, nurses, physicians, physical therapists, phlebotomists) who will be seeing the patient, required diagnostic studies, and the general health of the patient. The general health of the patient is estimated by the ASA PS or a screening mechanism offered by various Internet-based tools, a previsit telephone call, or a patient-completed information form sent from the surgeon's office (Table 6-3). Standardized appointment times for all patients inherently result in delays and long waits. Facilities should consider open-access scheduling that accommodates walk-ins for those patients traveling long distances or who have physical disabilities or unexpected scheduling of operation to prevent inconveniencing them with a return appointment. Reserving a block of time to coordinate appointments with high-volume office visits to surgeons might be useful. Scheduling patients far enough in advance allows time for ordering tests, improving the patient's medical condition, and recruiting social services. Evening and weekend hours afford patients the least disruption from work or family responsibilities.

Because long wait times contribute to patient dissatisfaction, strategies should lessen wait times to improve satisfaction. If patients arrive early or late for an appointment, if practitioners take longer than an appointment time, or if patients without appointments delay the evaluation of other patients, wait times will increase. Scheduling appointments that reflect time needed, using longer appointment intervals, providing necessary clinical information, using a computerized anesthesia record, accepting provider idle time, scheduling breaks, and deliberately expecting many "no-show" patients might decrease wait time.

Improving Patient Experience with Preoperative Evaluation

Patients who are scheduled for operation want information, want to have their concerns addressed, and want their questions answered.126 Patient anxiety is reduced when a patient's coping style is not threatened. Too much information, especially detailed information about the dangers of anesthesia and operation, creates anxiety in patients who prefer to cope by avoidance. Patients without prior anesthetic exposure desire more information than patients who have had previous anesthetics. Patients desire information in layperson language.16 Respecting a patient's feelings, explaining complex issues in a simple manner, and learning effective communication skills can improve patient satisfaction.127 Nonverbal communication, dress, and avoidance of jargon are important.16 Videos about anesthesia can be time efficient and well received. Written instructions, especially regarding NPO guidelines, medications, and when and where to go on the day of operation, are essential.

Patient satisfaction questionnaires are used to improve the processes.128 Some questions that might be asked in such a survey are as follows:

• Did the anesthesiologist explain the planned anesthetic in terms you understood?
• How well did the anesthesiologist answer your questions and address your concerns?
• How well did the anesthesiologist explain what you could expect after your anesthesia?
• Did you have to wait long?
• Was the staff courteous and respectful to you?
• Overall, how satisfied were you with your preanesthetic visit?
• How might we improve our services?

Informatics

Modern, up-to-date information systems streamline acquisition, storage, and transfer of data about patients among primary care providers, the laboratory, consultants, surgeons, and operating room and clinic personnel. Many institutions have developed their own computer-based programs (Figs. 6-4, 6-5, and 6-6), and a variety of commercial products are available. These can be as simple as a questionnaire (Table 6-3) or as advanced as complex systems that include decision support tools for diagnostic testing, suggestions for consultations, physician computer order entry, direct links to laboratory databases, and the capability of printing patient preoperative instructions, as well as a summary of the evaluation.

Computerized order-entry, prescription generation, and management programs can improve patient care and reduce costs. Patients can transfer information via e-mail, facsimile machines, and interactive telephone systems. Simple telephone reminders improve appointment keeping, patient satisfaction, patient compliance, use of services, and medication compliance, and they decrease use of alcohol and tobacco (prevention programs).

Computer-program patient interviews save valuable clinician time and may be convenient for the patient. Computer programs that gather information directly from patients allow planning for needed services in advance, and they can provide patient education and instruction. Internet-based sites and telemedicine have been used for preoperative evaluation.105,129 Airway evaluation is particularly enhanced with telemedicine.129

Electronic technology has enhanced the ease and efficiency of data acquisition, and these data can be accessed for patient care simultaneously by multiple providers in diverse locations. Technology can improve management of clinical studies, be used for cost analysis, and used for staffing, resource allocation, and managed care or capitated contract negotiations.

A computerized preanesthetic evaluation system can improve hospital (not just preoperative clinic) reimbursement by improved documentation of diagnosis-related group codes when ICD-9 codes are changed.130

Medicolegal Culpability

As anesthesiologists broaden their scope of practice and responsibilities, concerns over medical liability arise. Professional negligence, or malpractice, is generally characterized as a failure on the part of the physician to possess or exercise reasonable skill or diligence in the diagnosis or treatment of a patient. The essential elements of a medical malpractice claim include a duty toward the patient, a breach of that duty, and an injury to the patient because of the breach of duty. A physician's responsibility is to act in accordance with national standards of care established by the profession, which are defined in terms of care delivered by an average practitioner, not the best practitioner.

Duties of the preoperative physician include examination of the patient and referral to a specialist if necessary. Part of the examination requires the use of diagnostic information or techniques that an average, reasonable practitioner would use in similar circumstances.

Often physicians are concerned about failure to diagnose a condition by failing to order a diagnostic screening test. The traditional system of ordering standard preoperative tests evolved from the mistaken belief that more information, no matter how irrelevant or expensive, will improve care, enhance safety, and decrease liability. In reality, nonselective screening may increase legal culpability. Unanticipated significant abnormalities on laboratory test results are uncommon. The relationship between these abnormalities and surgical and anesthetic morbidity is weak at best. More than half of all abnormal test results obtained in routine preoperative screening are ignored or not noted in the medical record, which is the document of interest to the courts. Failure to follow up an abnormal result is, from a legal point of view, probably riskier than failure to order the test in the first place.

Physicians without malpractice claims are more likely than physicians with malpractice claims to encourage patients to talk and give their opinions. The physicians clarify what has been discussed, and they keep patients informed about what to expect during a visit. One study found that communication problems were predominant in most of the reported incidents involving a failure of preoperative preparation.1 Chapter 94 discusses legal issues in anesthesiology in greater detail.

Economics

Although anesthesiologists do not regularly receive separate payment for preoperative evaluations, the fee for preoperative assessment is part of the total operating room payment, and preoperative assessment by an anesthesiologist is required by both regulatory bodies and CMS.40 One study showed that preanesthetic care can reduce delays and cancellations on the day of operation.7 This can improve revenues by increasing time spent on billable cases rather than incurring personnel costs with an empty operating room. Avoiding delays and cancellations on the day of operation eliminates waste associated with unnecessary setups with disposable products. Preoperative assessment clinics also reduce costs by decreasing unnecessary testing and identifying patients with special needs on the day of operation.

According to CMS, preoperative assessments by anesthesiologists can be billed separately as visits or consultations "if medically necessary" and "beyond a routine preanesthetic assessment."38 When anesthesiologists perform at the level of a perioperative physician by ordering diagnostic studies such as echocardiograms or stress tests, by identifying problems and requesting consultations with specialists, by prescribing therapies such as β-blockers or bronchodilators, and by coordinating care beyond a simple anesthetic plan, they are offering care "beyond a routine preanesthetic assessment" and should bill for consultative services. Chapter 97 describes the criteria required to bill for preoperative consultations.

Physicians working in or administering preanesthetic clinics must become familiar with the CMS Advance Beneficiary Notice (ABN) billing rules. These rules govern whether physicians and other Medicare Part B providers can bill beneficiaries directly if Medicare does not cover services because of a lack of medical necessity. CMS rules relieve beneficiaries from financial liability if the provider fails to disclose that the service is not reimbursable. Unless the physician or facility has followed the ABN rules, payment may not be sought from the patient. ABN rules apply only to outpatient services. Additional information can be obtained from http://www.cms.hhs.gov.

Preoperative clinics are ideal settings for offering comprehensive care beyond anesthesia evaluation. Advanced care and postdischarge planning, respiratory therapy training, counseling about smoking and substance abuse, vaccinations, and end-of-life care discussions have been effectively implemented in preanesthesia clinics.96,131 When a patient is scheduled for operation, the patient may be more focused on health issues and improvement interventions may be particularly successful. These times have been called "teachable moments."95,131

Warner has rightfully challenged the anesthesia community to do its part in reducing the substantial burden of tobacco abuse.95 Physical therapists can offer crutch training, social workers can begin postdischarge planning, especially for patients requiring rehabilitation services, and case managers can coordinate care across many disciplines. A 5-minute intervention in a preoperative clinic significantly increased and improved discussions of advance care planning and increased completion of a durable power of attorney to 25%, compared with 10% by controls.132

Some day it may be possible to identify patients with genetic polymorphisms linked to adverse outcomes during the preoperative assessments. Then pharmacologic interventions and management can directly alter morbidity and mortality.133 Molecular biology is rapidly changing our ability to identify genetic variability and its effects on diseases and responses to therapies. This new approach could dramatically alter the way we perform risk assessment and how we design management plans. It would allow us to move away from expectations of results based on population studies to treatments based on individual patient characteristics. Pharmacogenetics may eventually lead to genetic screening tests to identify patients who are at risk for adverse perioperative outcomes, such as patients with pseudocholinesterase deficiency, halothane hepatitis, and susceptibility to malignant hyperthermia, as well as less familiar traits associated with the duration and response to drugs such as benzodiazepines, opioids, anesthetics, and NSAIDs, and pain tolerance.133

The prevention of complications during and after procedures requiring anesthesia is the most important task for preoperative anesthesiologists. Identification of risk requires fundamentally good medicine, systems of care, clinical and laboratory assessment, and experienced, knowledgeable, and dedicated health care providers. Risk reduction and outcome improvement are the ultimate goals of preoperative assessment and management.

• American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery), American Society of Echocardiography, American Society of Nuclear Cardiology, et al. ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Anesth Analg. 2008;106(3):685-712.
• American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology. 2002;96(2):485-496.
• American Society of Anesthesiologists Task Force on Perioperative Management of Patients With Cardiac Rhythm Management Devices. Practice advisory for the perioperative management of patients with cardiac rhythm management devices: pacemakers and implantable cardioverter-defibrillators: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients With Cardiac Rhythm Management Devices. Anesthesiology. 2005;103(1):186-198.
• Bonow RO, Carabello BA, Chatterjee K, et al. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease). J Am Coll Cardiol. 2008;52(13):e1-142.
• Chassot PG, Delabays A, Spahn DR. Perioperative antiplatelet therapy: the case for continuing therapy in patients at risk of myocardial infarction. Br J Anaesth. 2007;99(3):316-328.
• Chung F, Yegneswaran B, Liao P, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology. 2008;108(5):812-821.
• Chung F, Yuan H, Yin L, Vairavanathan S, Wong DT. Elimination of preoperative testing in ambulatory surgery. Anesth Analg. 2009;108(2):467-475.
• Ferschl MB, Tung A, Sweitzer B, Huo D, Glick DB. Preoperative clinic visits reduce operating room cancellations and delays. Anesthesiology. 2005;103(4):855-859.
• Grines CL, Bonow RO, Casey DE Jr, et al. Prevention of premature discontinuation of dual antiplatelet therapy in patients with coronary artery stents: a science advisory from the American Heart Association, American College of Cardiology, Society for Cardiovascular Angiography and Interventions, American College of Surgeons, and American Dental Association, with representation from the American College of Physicians. J Am Coll Cardiol. 2007;49(6):734-739.
• Horlocker TT, Wedel DJ, Rowlingson JC, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Third Edition). Reg Anesth Pain Med. 2010;35(1):64-101.
• Howell SJ, Sear JW, Foëx P. Hypertension, hypertensive heart disease and perioperative cardiac risk. Br J Anaesth. 2004;92(4):570-583.
• Kearon C, Hirsh J. Management of anticoagulation before and after elective surgery. N Engl J Med. 1997;336(21):1506-1511.
• Le Manach Y, Coriat P, Collard CD, Riedel B. Statin therapy within the perioperative period. Anesthesiology. 2008;108(6):1141-1146.
• Liao P, Yegneswaran B, Vairavanathan S, Zilberman P, Chung F. Postoperative complications in patients with obstructive sleep apnea: a retrospective matched cohort study. Can J Anaesth. 2009;56(11):819-828.
• McFalls EO, Ward HB, Moritz TE, et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med. 2004;351(27):2795-2804.
• Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: a report by the American Society of Anesthesiologist Task Force on Preoperative Fasting. Anesthesiology. 1999;90(3):896-905.
• Shi Y, Warner DO. Surgery as a teachable moment for smoking cessation. Anesthesiology. 2010;112(1):102-107.
• Smetana GW, Lawrence VA, Cornell JE. Preoperative pulmonary risk stratification for noncardiothoracic surgery: systematic review for the American College of Physicians. Ann Intern Med. 2006;144(8):581-595.
• Tait AR, Malviya S. Anesthesia for the child with an upper respiratory tract infection: still a dilemma? Anesth Analg. 2005;100(1):59-65.