Behavioral effects of trace and subanesthetic halothane and nitrous oxide in man

Using tests of complex reaction time and of immediate recall (digit span), the authors could not demonstrate that trace concentrations of halothane (to 0.02 per cent, or 200 parts per million) or halothane plus nitrous oxide (0.002 per cent plus 0.05 per cent, respectively) or nitrous oxide alone (0.4 per cent) affected mental function of male volunteers. However, subanesthetic concentrations of both nitrous oxide (20 to 30 per cent) and halothane (0.2 per cent) did impair mental function.