- Perioperative risk assessment by careful history, physical examination, and selective investigation is essential for directing therapy in the high-risk surgical patient.
- To decrease mortality and morbidity, cardiac, pulmonary, and endocrine abnormalities must be identified and appropriately managed.
- Age >70 years, current or prior angina pectoris, prior myocardial infarction, Q wave on resting electrocardiogram, and cardiac failure are significant clinical risk factors for perioperative cardiac complications.
- Perioperative cardiac morbidity can be minimized with pre-emptive medical management which includes the perioperative administration of β-blockers.
- Postoperative pulmonary complications can be reduced by aggressive pre- and postoperative care.
- Diabetes mellitus, abnormalities in thyroid function, and steroid dependence can significantly influence perioperative morbidity and mortality.
As indicated in Chap. 87, surgery and anesthesia trigger a host of physiologic responses. In the average otherwise healthy patient these responses result in no major untoward postoperative sequelae. However, in the medically compromised patient the additional burden of surgical stress can prove to be very challenging and sometimes insurmountable. Such patients frequently require detailed evaluation and monitoring in the preoperative as well as postoperative periods in the intensive care unit (ICU) setting. Careful planning of the preoperative assessment and management of identified abnormalities in these patients are crucial to optimize chances of a good postoperative outcome. A major component of this planning involves the assessment of risks for intraoperative and postoperative morbidity. Patients with cardiac, respiratory and endocrine abnormalities pose special risks for postoperative complications. In this chapter we present guidelines for identifying and managing patients at risk of developing postoperative cardiac-, respiratory-, and endocrine-related postoperative morbidity.
Clinical Assessment of Cardiac Risk
Over 25% of patients presenting for noncardiac surgery have diagnosed or clinically suspected ischemic heart disease with increased risk for perioperative complications.1 The American Society of Anesthesiologists' (ASA) classification of physical status (Table 88-1) is still commonly used as an index of surgical risk.2 Using multivariate analysis of 1001 consecutive patients presenting for noncardiac surgery, Goldman and associates developed an index for perioperative risk (Cardiac Risk Index; CRI) based on clinical, electrocardiographic (ECG), and routine biochemical parameters (Table 88-2).3 The strongest predictors of cardiac morbidity were the severity of coronary artery disease, a recent myocardial infarction (MI) and perioperative heart failure. Detsky and coworkers developed a more elaborate scoring system.4 Such studies suggest an overall perioperative cardiac risk for consecutive patients presenting for noncardiac surgery of 1.4%, and the risk of cardiac death at approximately 1%. However, in patients with previously documented or clinically suspected ischemic heart disease, the rates of perioperative MI (4.1%) and death (1.7%) were markedly higher. The retrospective analysis of 1001 patients from whom the CRI was derived is shown in Table 88-3. Those patients in class IV had a 22% incidence of major cardiac complications and a 56% mortality rate.
Table 88–1. American Society of Anesthesiologists Preoperative Patient Classification