Inspired superoxide anions attenuate blood lactate concentrations in postoperative patients

OBJECTIVELow concentrations of superoxide (O2) constitute a portion of atmosphere negative ions in the form of O2(H2O)n, which has been reported to have a stimulatory effect on superoxide dismutase activity. If superoxide dismutase is activated by inspired negative ions containing O2, aerobic metabolism could be improved. To test this hypothesis, we examined blood lactate concentrations in postoperative patients with or without inhalation of air from a home humidifier that generates O2(H2O)n. DESIGNProspective, randomized, controlled trial. SETTINGNeurosurgical intensive care unit of a general hospital. PATIENTSTwenty postneurosurgical patients with arterial blood lactate concentrations >1.5 mmol/L were studied and were divided randomly into two groups. INTERVENTIONSOne group received 40 L/min 40% oxygen flow from a home humidifier as an oxygen therapy for 4 hrs, followed by almost the same flow from a jet nebulizer, which generates positive ions, for 4 hrs. The other group received the reverse combination. MEASUREMENTS AND MAIN RESULTSDuring the 8-hr study, arterial blood lactate concentrations were measured every hour. There was a significant difference in the time course of blood lactate concentrations between the groups. In the group in which negative ions were first initiated for 4 hrs and positive ions thereafter, the lactate concentration decreased slightly at 3, 4, and 5 hrs and returned to the baseline concentration thereafter. In the group with the reverse combination, the lactate concentration did not change during the first 4 hrs but decreased thereafter after inhalation of negative ions. CONCLUSIONSInspired O2 attenuates blood lactate concentrations. This may be attributed, in part, to the systemic stimulatory effect on superoxide dismutase activity, which accelerates oxidative phosphorylation in the mitochondria, thus attenuating lactate generation.