Key Point

Pulmonary complications after nonthoracic surgery are more common than previously thought. Several risk factors, such as a positive cough test, nasogastric tube placement, older age, and long duration of anesthesia administration, were independent predictors of postoperative pulmonary complications.

EDMONTON, ALBERTA—Pulmonary complications after nonthoracic surgery may be more common than previously thought—even more prevalent than cardiac complications. New research suggests that several risk factors are independent predictors of the risk of these complications.¹

Finlay A. McAlister, MD, and colleagues prospectively evaluated 1,055 patients who were undergoing nonthoracic surgery—most commonly, lower abdominal (30%) and orthopedic limb surgery (23%). The patients’ mean age was 55, and half of the patients were men. According to Dr. McAlister, an Associate Professor of Internal Medicine at the University of Alberta Hospital in Edmonton, “Of the approximately 45 million North Americans who will undergo nonthoracic surgery in the next year, over one million will experience a postoperative pulmonary complication.”

COMPLICATIONS COMMON

Pulmonary complications occurred within seven days of surgery in 28 patients (2.9%). Thirteen patients developed respiratory failure requiring ventilatory support, nine had postoperative pneumonia, five had atelectasis requiring bronchoscopic intervention, and one had a pneumothorax requiring intervention. One of the pneumonia patients died. “Pulmonary complications after nonthoracic surgery are more frequent than cardiac complications and are associated with greater increases in length of stay,” commented Dr. McAlister. In the study, patients with pulmonary complications remained in the hospital for 28 days versus five days for those who experienced uncomplicated recoveries.

Number of pack-years smoked, FEV¹:FVC ratio, upper abdominal incision, and history of COPD were associated with pulmonary complications but were not independent predictors. There were four variables identified as independent predictors of postoperative pulmonary complications: age older than 65 (odds ratio [OR], 5.9), positive cough test (OR, 3.8), administration of anesthesia lasting longer than 2.5 hours (OR, 3.3), and perioperative insertion of a nasogastric tube (OR, 7.7). The authors noted that theirs is the third study to show an association between pulmonary complications and nasogastric tube placement. They believe their “data [support] calls to minimize the use of routine perioperative nasogastric intubation unless judged to be necessary on clinical grounds.”

The authors noted that the use of patient self-report could have been a potential limitation to their findings.

However, they added, “There seems to be very little reason to believe that patients in this study would systematically over/underestimate their smoking history or exercise capacity compared with patients seen in usual practice.”

AN EYE TOWARDS PREVENTION

The current study was conducted in patients undergoing elective nonthoracic surgery—a population that is relatively healthy. Therefore, it is not known whether these data can be extrapolated to other populations, such as patients requiring emergency surgery. For the relatively healthy patients, the authors acknowledge that “simple bedside maneuvers easily incorporated into the clinical examination (such as the cough test and forced expiratory time) are useful in identifying patients at increased risk for pulmonary complications.” Identifying which patients are at risk is the first step towards preventing pulmonary complications. The at-risk patients can then be observed more carefully during and after surgery to help prevent complications. Moreover, future studies can identify those patients most likely to benefit from interventions.

—Tamara Gibb

Reference
1. McAlister FA, Bertsch K, Man J, et al. Incidence of and risk factors for pulmonary complications after nonthoracic surgery. Am J Respir Crit Care Med. 2005;171:514-517.

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