Psychomotor function during mild narcosis induced by subanesthetic level of nitrous oxide: Individual susceptibility beyond gender effect

摘要

Objective: We investigated the effect of narcosis induced by subanesthetic concentrations of nitrous oxide (N2O), a behavioral analogue for hyperbaric nitrogen, on psychomotor performance. In particular, we assessed individual susceptibility to narcosis. Methods: The participants were 12 female and 12 male undergraduate students. Psychomotor assessment was conducted with a computerized Visual Simple Reaction Time (VSRT) test, and Trail Making Tests Part A (TMT-A) and Part B (TMT-B). The tests were conducted on two separate occasions in the following order: VSRT, TMT-A, TMT-B. On the first occasion participants conducted the tests breathing room air (air trial), and during the second test they conducted the tests while breathing a normoxic mixture containing 30% N2O (N2O trial). Results: Males had significantly (p = 0.036) shorter VSRT in the air trials. There was no effect of gender on psychomotor performance in the N2O trials. Overall, mean performance in the N2O trials degraded significantly (p = 0.004) only in VSRT. Performance of individual participants exhibited different and inconsistent direction of change in the N2O trials. Conclusion: N 2O-induced alterations in psychomotor function are primarily dependent on individual susceptibility to narcosis (i.e., concentration threshold).