Perioperative microbiologic monitoring of tracheal aspirates as a predictor of pulmonary complications after cardiac operations.

The value of preoperative and early postoperative microbiologic testing of tracheal aspirates as a prognostic indicator of the development of pneumonia was evaluated in a prospective study of 213 cardiac surgical patients. Tracheal aspirates were obtained immediately after intubation and after the patient's arrival at the intensive care unit. Diagnosis of pneumonia was accepted if at least three of the following criteria were fulfilled: leukocytosis > 15,000 cells/mm3, body temperature >38.5 degrees C, positive results of auscultation, positive results of radiography (new infiltrates that seemed to be consistent with pneumonia), and increased core-reactive protein for more than 2 days after operation. Potentially pathogenic microorganisms were found in 54 (25.4%) of the preoperative tracheal aspirates and in 27 (12.7%) of the early postoperative tracheal aspirates. Positive microbiologic findings correlated with pneumonia in the postoperative course in 24.1% (p < 0.001) if the preoperative culture results were positive, in 48.2% (p < 0.001) if the postoperative culture results were positive, and in 44.0% (p < 0.001) if both were positive. The risk of pneumonia was increased in male patients (p < 0.05) and in patients with chronic obstructive pulmonary disease (p < 0.05). Demographic variables, smoking, acute pulmonary symptoms, temperature, leukocyte count at the day of the operation, and data on the operation and the extracorporeal circulation were not significantly related to pneumonia in the early postoperative course. The risk of development of postoperative pneumonia is significantly higher among patients with colonization of the lower respiratory tract. Positive culture results in routine microbiologic monitoring of tracheal aspirates are predictive of pulmonary complications after cardiac operations.