A. Introduction. Perioperative pulmonary risks are important causes of patient morbidity and mortality. Examples include atelectasis, bronchospasm, pneumonia, respiratory failure, and exacerbation of chronic lung disease.
B. Patient-Related Risk Factors. Several patient-related risk factors have been shown to increase the risk for perioperative pulmonary complications. These include:
a. Chronic obstructive pulmonary disease (COPD). This is the most important patient-related risk factor. Patients with COPD have approximately twice the risk for developing a postoperative pulmonary complication than those who do not. However, COPD is almost never an absolute contraindication for surgery.
b. Obstructive sleep apnea (OSA). It is now known that OSA poses an increased risk for perioperative pulmonary complications. Although objective risk tools (e.g., STOP-BANG, P-SAP) are effective for OSA screening, there is insufficient evidence to support canceling or delaying surgery for formal sleep apnea testing.
c. General health status (defined by the American Society of Anesthesiology [ASA] class). Although developed to predict the risk for perioperative mortality, the ASA class has also been shown to predict the risk for postoperative pulmonary complications.
d. Cigarette use. Smoking has shown to be a modest risk factor for perioperative pulmonary complications. Although it was once thought that smoking cessation within the weeks before surgery would increase perioperative risk, this has now been discredited.
e. Other factors. Patient age, functional dependence, weight loss, and impaired sensorium have also been shown to increase the risk for perioperative pulmonary complications.
C. Procedure-Related Risk Factors. Procedure-related factors are more important than patient-related factors with respect to perioperative pulmonary complication risk. Unlike patient-related factors, these are generally nonmodifiable. Examples include:
a. Surgical site. The surgical site location is the most important risk factor. The “closest to the diaphragm” rule is used when considering this risk as diaphragmatic dysfunction, and splinting from pain can lower the patient’s vital capacity and functional reserve capacity. Examples of common high-risk surgeries closest to the diaphragm include:
i. Aortic aneurysm repair
ii. Thoracic surgery
iii. Upper abdominal surgery
b. Duration of surgery. Procedures that last longer than 3 hours are known to be an independent risk factor for perioperative pulmonary complications.
d. Emergency surgery. This is thought to pose a modest risk for pulmonary complications.
D. Preoperative Testing
a. Pulmonary function testing (PFTs). PFTs have not been shown to be superior to the history and physical examination to predict postoperative pulmonary complications. There is no spirometric threshold below which nonelective surgery may be denied. In addition to obtaining PFTs to aid in the diagnosis when signs or symptoms are suggestive of underlying lung disease, PFTs are always indicated before lung reduction surgery.
b. Chest radiograph. There is limited evidence to suggest that a preoperative chest radiograph will help predict postoperative pulmonary complications. Studies generally reveal that chest radiographs rarely provide data beyond clinical evaluation and seldom influence preoperative management. A preoperative chest radiograph can be considered in patients with known cardiopulmonary disease undergoing surgery at a higher risk site (e.g., intrathoracic procedures).
E. Risk Reduction Strategies. Although limited, some strategies may reduce the risk for postoperative pulmonary complications. These include:
a. Lung expansion maneuvers. Examples include incentive spirometry, deep breathing exercises, and positive airway pressure. By reducing the expected drop in lung volumes postoperatively, these techniques have shown to significantly reduce the risk for postoperative pulmonary complications and should be used routinely.
b. Smoking cessation. Although cigarette use is a modest risk for pulmonary complications, the perioperative period affords a key opportunity to provide that “teachable moment” on smoking cessation. Smoking cessation within days or weeks before surgery does not pose an increased risk for pulmonary complications as once believed.
c. Optimizing chronic lung disease. Ensuring that the patient’s underlying lung disease (e.g., COPD, asthma) is well-controlled before surgery is essential. Medical optimization, which may include a short course of systemic steroid therapy for more urgent procedures, is important before proceeding to surgery. Surgery (especially if elective or nonurgent) should be delayed until a patient’s chronic lung disease is optimized.
Suggested Further Readings
Chung F, Memtsoudis SG, Ramachandran SK, et al. Society of Anesthesia and Sleep Medicine guidelines on preoperative screening and assessment of adult patients with obstructive sleep apnea. Anesth Analg 2016;123.Find this resource:
Myers K, Hajek P, Hinds C, McRobbie H. Stopping smoking shortly before surgery and postoperative complications: a systematic review and meta-analysis. Arch Intern Med 2011;171:983–9.Find this resource:
Qaseem A, Snow V, Fitterman N, et al. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: a guideline from the American College of Physicians. Ann Intern Med 2006;144:575–80.Find this resource: