Effect of Isoflurane on Neutrophil Phagocytic Function During Pregnancy

OBJECTIVE General anesthesia has been considered an independent risk factor for postcesarean infection, but the mechanism for this association has not been delineated. The purpose of this prospective investigation was to determine if phagocytic response of neutrophils was impaired by in vitro exposure to isoflurane, a commonly used anesthetic. METHODS Twelve milliliter venous blood samples were withdrawn from 18 term patients during labor. Neutrophils were separated by Ficoll gradient centrifugation. Aliquots of 2 x 10(6) neutrophils/ml were exposed to anesthesia using an airtight modular incubator chamber through which a 0.5% isoflurane:50% N(2)O + 50% O(2) mixture flowed at a rate of 4 l/min for 90 min at 37. Neutrophils were assayed for phagocytosis by incubation with Escherichia coli conjugated with fluorescein isothiocyanate for 30 min at 37. Phagocytosis was assessed by flow cytometry. Neutrophils from the same patient that were not exposed to anesthesia served as controls. RESULTS The mean percentage of phagocytizing neutrophils in the isoflurane-treated group was 82.8 +/- 24 compared to 83.5 +/- 22 in the control group. The difference between the two groups was not significant. CONCLUSIONS In vitro exposure to the general anesthetic isoflurane for 90 min does not significantly alter the phagocytic capacity of neutrophils.