INTRAOPERATIVE MODULATION OF ALVEOLAR MACROPHAGE FUNCTION DURING ISOFLURANE AND PROPOFOL ANESTHESIA

Background: Alveolar macrophages are a critical part of the defense ag ainst pulmonary infection. Thus the authors determined time-dependent changes in alveolar macrophage functions in patients having surgery wh o were anesthetized with isoflurane or propofol Methods: Patients anes thetized with propofol (n = 30) or isoflurane (n = 30) during orthoped ic surgery were studied. Alveolar macrophages were harvested by bronch oalveolar lavage immediately, and 2, 4, and 6 h after induction anesth esia and at the end of surgery. The fraction of aggregated and nonviab le macrophages was determined. Then phagocytosis was measured by inges tion of opsonized and unopsonized particles. Finally, microbicidal act ivity was determined as the ability of the macrophages to kill Listeri a monocytogenes directly. Results: Demographic and morphometric charac teristics of the patients given propofol and isoflurane were similar, as were their levels of pulmonary function and hemodynamic responses. The fraction of alveolar macrophages ingesting opsonized and unopsoniz ed particles, and the number of particles ingested, decreased signific antly over time, with the decrease slightly but significantly greater during isoflurane anesthesia. Microbicidal function decreased progress ively during anesthesia and surgery, with the decrease almost twice as great during isoflurane compared with propofol anesthesia. The fracti on of aggregated macrophages and recovered neutrophils increased over time in the patients given each anesthetic. Conclusions: Pulmonary imm unologic function changed progressively during anesthesia and surgery. The data from this study suggest that pulmonary defenses are modulate d by the type of anesthesia and by the duration of anesthesia and surg ery.