The anesthetic effect of air at atmospheric pressure

Abstract

Nitrogen has recognized narcotic potential at hyperbaric pressures. No narcotic effect of helium has been demonstrated at any pressure. The authors evaluated the effect of nitrogen in air at one atmosphere on human performance by comparing it with helium oxygen using a four alternative divided attention task that requires rapid response to auditory and visual signal changes. There was a 9.3% decrease in response time when subjects breathed helium oxygen, a significant change (P < 0.001). This change could not be ascribed to practice since the order of presentation of gases did not have a significant effect. It is concluded that the nitrogen in ambient air slightly but measurably impairs human performance compared with a non anesthetic gas such as helium.