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.
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.
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
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.
Table 6-6 Recommendations for Perioperative Management of Patients with Coronary Stents Who Are Receiving Antiplatelet Therapy ||Download (.pdf)
Table 6-6 Recommendations for Perioperative Management of Patients with Coronary Stents Who Are Receiving Antiplatelet Therapy
- Health care providers who perform invasive procedures must be aware of the potentially catastrophic risks of premature discontinuation of thienopyridine (eg, clopidogrel or ticlopidine) therapy. Such professionals should contact the patient's cardiologist to discuss optimal strategies if issues regarding antiplatelet therapy are unclear.
- Elective procedures involving risk of bleeding should be deferred until an appropriate course of thienopyridine therapy (12 mo after drug-eluting stents [DES] and 1 mo after bare-metal stents [BMS]) has been completed.
- Patients with DES who must undergo procedures that mandate discontinuing thienopyridine therapy should continue aspirin if at all possible and have the thienopyridine restarted as soon as possible.
Algorithm for preoperative management of patients taking antiplatelet therapy. ACS, acute coronary syndrome; BMS, bare metal stent; DES, drug-eluting stent; MI, myocardial infarction; PAD, peripheral arterial disease; PCI, percutaneous coronary intervention. *High-risk stents: long (>36 mm), proximal, overlapping, or multiple stents, stents in chronic total occlusions, or in small vessels or bifurcated lesions. **Examples of low-risk situations: more than 3 months after BMS, stroke, uncomplicated MI, PCI without stenting. ***Risk of bleeding in closed space: intracranial neurosurgery, intramedullary canal surgery, posterior eye chamber ophthalmic surgery. In these situations, the risk-to-benefit ratio of upholding versus withdrawing aspirin must be evaluated for each case individually; in case of aspirin upholding, early postoperative reinstitution is important. [Adapted from 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;99:316-328. By permission of Oxford University Press.]
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.
Table 6-7 Preoperative Medication Guidelines ||Download (.pdf)
Table 6-7 Preoperative Medication Guidelines
|Continue on Day of Surgery||Discontinue on Day of Surgery|
|Antidepressants, antianxiety, and psychiatric medications (including monoamine oxidase inhibitors)a|
|Generally to be continued|
Consider discontinuing angiotensin-converting enzyme inhibitors or angiotensin receptor blockers 12-24 h before surgery if taken only for hypertension; especially if:
Lengthy procedures, significant blood loss or fluid shifts, use of general anesthesia, multiple antihypertensive medications, well-controlled blood pressure; hypotension is particularly dangerous
- Patients with known vascular disease
- Patients with vascular stents
- Before cataract surgery (if no bulbar block)
- Before vascular surgery
- Taken for secondary prophylaxis
Discontinue 5-7 d before surgery:
- If risk of bleeding > risk of thrombosis
- For surgeries with serious consequences from bleeding
- Taken only for primary prophylaxis (no known vascular disease)
|Methotrexate (if no risk of renal failure)|
|Birth control pills|
- Patients with drug-eluting stents <12 mo
- Patients with bare metal stents <1 mo
- Before cataract surgery (if no bulbar block)
Patients not included in group recommended for continuation
If surgeon concerned about bone healing
|Triamterene, hydrochlorothiazide||Potent loop diuretics|
When used for birth control or cancer therapy
When used to control menopause symptoms or for osteoporosis
|Gastrointestinal reflux medications||Gastrointestinal reflux medications (Tums, Maalox, or other particulate antacids)|
Herbals and nonvitamin supplements
7-14 d before surgery
|Hypoglycemic agents, oral|
- Type 1 diabetes: take about a third of intermediate to long-acting (NPH, lente)
- Type 2 diabetes: up to half long-acting (NPH) or combination (70/30) preparations
- Glargine (Lantus): decrease if dose is >1 unit/kg
- If insulin pump delivery, continue lowest night time basal rate
- Regular insulin (exception: insulin pump, continue lowest basal rate, generally nighttime dose)
- Discontinue if blood sugar level <100
|Narcotics for pain or addiction|
Nonsteroidal anti-inflammatory drugs
48 h before day of surgery
|Statins||Topical creams and ointments|
|Steroids (oral or inhaled)|
Viagra or similar medications
Discontinue 24 h before surgery
|Thyroid medications||Vitamins, minerals, iron|
Cataract surgery, no bulbar block
Discontinue 5 d before surgery
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.
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
- 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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:
- Facial and neck deformities from previous operation
- Head and neck radiation
- Head and neck trauma
- Congenital abnormalities
- Rheumatoid arthritis
- Down syndrome
- 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.
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.
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