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General internists practicing in the inpatient setting are frequently called upon to provide perioperative care to a broad spectrum of surgical patients, in either a consultative or a comanagement role. Although historically much emphasis has been placed on postoperative cardiac complications, postoperative pulmonary complications are known to occur with equal frequency. The Confederate general, Thomas “Stonewall” Jackson, wounded in the Battle of Chancellorsville in 1863, was perhaps the earliest recorded victim of a postoperative pulmonary complication, dying of pneumonia eight days after the successful amputation of his left arm. Postoperative pulmonary complications contribute significantly to morbidity, mortality, and healthcare costs. It is estimated that over 1 million patients undergoing nonthoracic surgery in the United States annually experience postoperative pulmonary complications. Pulmonary complications produce the highest attributable costs among common categories of postoperative complications and can result in a fivefold increase in the median cost of an operation. The presence of pulmonary complications after major surgery increased 30-day mortality from 2% to 22%, and 1-year mortality from 8.7% to 45.9% based on data from the National Surgical Quality Improvement Program (NSQIP). The most important postoperative pulmonary complications are atelectasis, pneumonia, respiratory failure, and exacerbation of underlying chronic lung disease, although earlier studies have also included transient and self-limited clinical findings. A general principle is that the closer the operative site is to the diaphragm, the higher the likelihood of postoperative pulmonary complications. Interventions to reduce the incidence of these complications depend on the aggressive application of preventive measures to high-risk patients. A recent systematic review characterized patient-related and procedure-related risk factors and provided evidence-based guidelines on preventive strategies.1 This chapter focuses on the pathogenesis, early recognition, and evidence-based treatment of common postoperative pulmonary complications.
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Atelectasis, or reversible alveolar collapse, is a common perioperative phenomenon and occurs in 90% of patients receiving general anesthesia. Computed tomographic (CT) studies have demonstrated collapse of 15–20% of the lung volume near the diaphragm. Dr. William Pasteur, a Swiss physician practicing in England in the early part of the last century, wrote extensively on the postoperative lung and noted, “when the true history of postoperative lung complications comes to be written, active collapse of the lung from deficiency of inspiratory power will be found to occupy an important position among determining causes.” Most atelectasis appearing during general anesthesia resolves within 24 hours after surgery in normal subjects and is of little clinical significance. Atelectasis can persist for two days or longer after major surgery, including abdominal and thoracic surgery, and is thought to represent the starting point in a cascade of events that leads to the more serious complications of pneumonia and acute respiratory failure.
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The formation of perioperative atelectasis can be understood by considering ...