LOSS OF ALVEOLAR MACROPHAGES DURING ANESTHESIA AND OPERATION IN HUMANS

Pulmonary macrophages play an important role in the host defense again st infection, and the importance of this role is probably enhanced whe n the upper airway defenses are circumvented by endotracheal intubatio n. Studies in animals suggest that exposure to volatile anesthetics co mpromises the viability and function of alveolar macrophages. We studi ed the effect of surgery and anesthesia on the alveolar macrophages of 41 human subjects undergoing lower abdominal procedures of varying le ngths during nitrous oxide-isoflurane anesthesia. Alveolar macrophages were harvested from bronchoalveolar lavage fluid obtained before inci sion and compared to those recovered just before emergence from anesth esia. Macrophages were analyzed for aggregation and viability, assesse d by the ability of viable cells to exclude trypan blue dye. Operation s lasting 2 h or less led to little aggregation and had little effect on viability. However, there was a strong correlation between loss of macrophages and the duration of surgery and anesthesia. Aggregation in creased and viability decreased as a function of procedure length. Stu dies are needed to determine whether prolonged surgery contributes to the incidence of postoperative pulmonary complications by disturbing t he function and survival of alveolar macrophages in humans.