Most patients benefit from supplemental oxygen in the postoperative period, although special care should be exercised in patients with COPD. Oxygenation can easily be monitored by pulse oximetry. Anemia is detrimental because of loss of oxygen-carrying capacity and resultant tachycardia and should, therefore, be carefully corrected in high-risk patients. Although transfusion criteria are not absolute, all patients with a hemoglobin less than 6 mg/dL, and hemoglobin of 6 to 10 mg/dL with significant cardiac risk factors should be offered blood transfusion (193).
Patients with coronary artery disease may benefit from pharmacologic control of hyperadrenergic states that result from increased postoperative catecholamine production. Beta-blockers decrease heart rate, myocardial contractility, and systemic blood pressure, all of which are increased by adrenergic stimulation. Perioperative use of β1 selective beta-blocker is shown to significantly reduce perioperative ischemia, myocardial infarction, and overall mortality caused by cardiac death and congestive heart failure in the perioperative period (194–196). The POISE (Perioperative Ischemic Evaluation) trial, a randomized controlled trial of metoprolol, enrolling 8,000 patients undergoing noncardiac surgery, revealed a reduction in cardiovascular death, myocardial infarction, and cardiac arrest. There was an increased risk of stroke and total mortality (197). The AHA provides the following guidelines: Continue beta-blocker therapy in patients on baseline beta-blockers for treatment of cardiac disease. Consider initiating and titrating beta-blockers in patients with coronary artery disease or high cardiac risk (as defined by the presence of more than one clinical risk factor) who are undergoing intermediate-risk surgery (155). Therapy should be initiated at least 1 week before surgery to allow for proper titration. The timing and optimal duration of beta-blocker therapy remains an area of uncertainty. Nevertheless, for patients already on beta-blocker therapy, they should continue it perioperatively because abrupt withdrawal results in a rebound hyperadrenergic state.
Prophylactic use of other agents such as nitroglycerin and calcium-channel blockers remains controversial, as data did not show a consistent benefit toward reducing risk of ischemic cardiac events. Nitroglycerin may cause hypotension, which may worsen cardiac status (155).
Congestive Heart Failure Patients with congestive heart failure (CHF) face a substantially increased risk of myocardial infarction during and after surgery (177). The postoperative development of pulmonary edema may be associated with a high mortality rate, especially if it occurs in the setting of cardiac ischemia (198,199). Because patients with heart failure at the time of surgery are significantly more likely to develop complications, every effort should be made to diagnose and treat CHF before surgery (178,200). The signs and symptoms of CHF are listed in Table 22.17 and should be assessed based on preoperative history and physical examination. Patients who are able to
Table 22.17 Signs and Symptoms of Congestive Heart Failure 1.
Presence of an S3 gallop 2.
3.
Lateral shift of the point of maximal impulse 4.
5.
6.
7.
Evidence of pulmonary edema or cardiac enlargement on chest radiograph 8.
perform usual daily activities without developing CHF are at limited risk of perioperative heart failure.
To prevent severe postoperative complications, CHF must be corrected preoperatively.