Pneumonia and respiratory failure requiring prolonged mechanical ventilation are the most important postoperative pulmonary complications. The occurrence of these complications has been associated with a significant increase in mortality and hospital length of stay. Pulmonary thromboembolism is another serious complication; prophylaxis against venous thromboembolic disease is detailed in Table 14–14.
RISK FACTORS FOR THE DEVELOPMENT OF POSTOPERATIVE PULMONARY COMPLICATIONS
Procedure-related risk factors for postoperative pulmonary complications include location of surgery (highest rates occur in cardiac, thoracic, and upper abdominal cases), prolonged anesthesia, and emergency cases. Operations not requiring general anesthesia tend to have lower rates of postoperative pulmonary complications; laparoscopic procedures tend to have lower risk than comparable open procedures. In one series of over 1500 patients who underwent laparoscopic cholecystectomy, the pulmonary complication rate was less than 1%.
A summary of patient-specific risk factors for pulmonary complications is presented in Table 3–4. Advanced age appears to confer increased risk. The presence and severity of systemic disease of any type is associated with pulmonary complications. In particular, patients with COPD or HF have at least twice the risk of postoperative pulmonary complications compared with patients without these conditions. As with preoperative cardiac risk assessment, physical debility and poor functional capacity predict higher risk of postoperative pulmonary complications. A risk calculator for predicting postoperative respiratory failure based on the NSQIP patient database is available (https://qxmd.com/calculate/calculator_261/postoperative-respiratory-failure-risk-calculator). It includes the type of surgery, emergency surgery, preoperative sepsis, dependency in activities of daily living, and the patient's American Society of Anesthesiologists physical status classification.
Table 3–4.Clinical risk factors for postoperative pulmonary complications. ||Download (.pdf) Table 3–4. Clinical risk factors for postoperative pulmonary complications.
Upper abdominal or cardiothoracic surgery
Prolonged anesthesia time (> 4 hours)
Age > 60 years
Severe systemic disease
Tobacco use (> 20 pack-years)
Impaired cognition or sensorium
Functional dependency or prior stroke
Low serum albumin level
Obstructive sleep apnea
Patients with well-controlled asthma are not at increased risk for pulmonary complications. Obstructive sleep apnea has been associated with a variety of postoperative complications, including postoperative pulmonary complications and atrial fibrillation. The STOP-BANG screening questionnaire asks whether a patient has snoring, tiredness during the day, observed apnea, high blood pressure, BMI greater than 35, age greater than 50, neck circumference greater than 17 inches for males or 16 inches for females, and male gender (https://www.mdcalc.com/stop-bang-score-obstructive-sleep-apnea). The presence of five or more of these findings or at least two STOP criteria plus B, N, or G had a 78% positive predictive value for obstructive sleep apnea and was associated with a doubled risk for postoperative pulmonary complications (see Chapter 9).
PULMONARY FUNCTION TESTING & LABORATORY STUDIES
The main role for preoperative pulmonary function testing (PFT) is to identify pulmonary ...