Perioperative changes in superoxide production in neonates and infants.

We conducted a prospective study to investigate perioperative changes in the production of superoxide anion (O2-) by neutrophils isolated from ten neonates between the ages of five and 16 days (N group) and ten infants ranging in age from one to ten months (I group). They underwent abdominal surgery under general anaesthesia with halothane and nitrous oxide in oxygen. The O2- production (speed and amount) was measured perioperatively using the cytochrome c reduction method. Both groups showed a decrease in the speed and amount of O2- production during and after surgery. The decrease in O2- production reached its lowest level three hours postoperatively or at the end of surgery in both groups. The O2- production in the I group returned to the basal value 48 hr postoperatively. In contrast, the O2- production in the N group was still lower 48 hr after surgery than before anaesthesia. Although the total amount of O2- production by neutrophils in one mL of peripheral blood remained unchanged in the I group, the total amount of O2- production in the N group decreased at the end of surgery and thereafter. These data indicate that even relatively minor abdominal surgery with halothane anaesthesia may be associated with perioperative neutrophil impairment in both neonates and infants. This impairment of neutrophil function in infants but not in neonates may be compensated by an increase in neutrophil numbers. It is possible that perioperative susceptibility of neonates to bacterial infections is attributable, at least in part, to the inhibition of O2- production in neutrophils by surgery and general anaesthesia.