Neutrophil chemotaxis during halothane and halothane-N₂O anesthesia in man

Polymorphonuclear neutrophil (PMN) function was elevated in 21 adult male volunteers anesthetized with 0.8, 1.2, or 1.6% halothane-O₂, and halothane-O₂ plus 20% N₂O and 60% N₂O. Variables measured included PMN chemotactic index (CI), PMN random migration (RM), and total leukocyte (WBC) and PMN counts. Halothane significantly (p<0.025) increased WBC and PMN counts and caused a concentration-dependent decrease in PMN CI and RM. Addition of 20% N₂O did not change any variable; however, adding 60% N₂O increased (p<0.05), PMN CI during 1.2 and 1.6% halothane and RM during 1.6% halothane. Termination of N₂O reduced CI back to halothane-O₂ levels in those receiving 1.2 and 1.6% of the anesthetic but did not significantly alter any other variable. PMN CI and RM remained decreased and WBC and PMN remained elevated during the first 2 postanesthetic hours. WBC and PMN counts were still significantly (p<0.01) elevated the day after anesthesia in the group receiving 1.6% halothane. All other variables returned to control levels 24 hours after anesthesia. These data demonstrate that halothane produces a concentration-dependent reduction in PMN CI which can be partially reversed with the addition of N₂O and suggest that halothane anesthesia may increase susceptibility to bacterial infection by reducing PMN migration toward invading organisms.