Cardiovascular and pulmonary complications continue to account for major morbidity and mortality in patients undergoing noncardiac surgery. Emerging evidence-based practices dictate that the internist should perform an individualized evaluation of the surgical patient to provide an accurate preoperative risk assessment and stratification to guide optimum perioperative risk-reduction strategies. This chapter reviews cardiovascular and pulmonary preoperative risk assessment, targeting intermediate- and high-risk patients to strategically guide perioperative therapies to improve outcome. It also reviews perioperative management and prophylaxis of diabetes mellitus, endocarditis, and venous thromboembolism.
Mortality is low with safe delivery of modern anesthesia, especially in low-risk patients undergoing low-risk surgery (Table 8-1). Inhaled anesthetics have predictable circulatory and respiratory effects; all decrease arterial pressure in a dose-dependent manner by reducing sympathetic tone, causing systemic vasodilation, myocardial depression, and decreased cardiac output. Inhaled anesthetics also cause respiratory depression with diminished responses to both hypercapnia and hypoxemia in a dose-dependent manner, and they have a variable effect on heart rate. In combination with neuromuscular blockade, inhaled anesthetic agents also cause reduction in functional residual lung capacity due to loss of diaphragmatic and intercostal muscle function. This decreases lung volume, which may lead to atelectasis in the dependent lung regions and, in turn, may result in arterial hypoxemia from ventilation-perfusion mismatch as well as an increased risk of postoperative pulmonary complications.
Table 8-1 Surgery: Gradation of Risk of Common Noncardiac Surgical Procedures |Favorite Table|Download (.pdf)
Table 8-1 Surgery: Gradation of Risk of Common Noncardiac Surgical Procedures
- Emergent major operations, especially elderly
- Aortic and other noncarotid major vascular surgery (endovascular and nonendovascular)
- Prolonged surgery associated with large fluid shift and/or blood loss
- Major thoracic surgery
- Major abdominal surgery
- Carotid endarterectomy surgery
- Head/neck surgery
- Orthopedic surgery
- Prostate surgery
- Eye, skin, and superficial surgery
- Endoscopic procedures
Several meta-analyses have shown that overall mortality was lower in patients receiving neuroaxial anesthesia (epidural or spinal) as compared to general (inhaled) anesthesia. Lower rates of venous thrombosis, pulmonary embolism, pneumonia, and respiratory depression were also observed in patients who were provided neuroaxial anesthesia; however, there were no significant differences in cardiac events between the two approaches. A combination of neuroaxial blockade and general anesthesia is useful when it is desired to reduce general anesthesia requirements. Evidence from a meta-analysis of randomized controlled trials also supports postoperative epidural analgesia for the purpose of pain relief for more than 24 h.
Simple, standardized preoperative screening questionnaires, such as the one shown in Table 8-2, have been developed for the purpose of identifying patients at intermediate or high risk who may benefit from a more detailed clinical evaluation. Evaluation of such patients for operation should always begin with a thorough history and physical examination and with a 12-lead resting ECG, in accordance with the American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations. The history should focus ...