Psychomotor function during mild narcosis induced by subanesthetic level of nitrous oxide: individual susceptibility beyond gender effect.
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 (TMTA) 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.


CONCLUSIONS
N2O-induced alterations in psychomotor function are primarily dependent on individual susceptibility to narcosis (i.e., concentration threshold).
International Postgraduate School Jozef Stefan, Ljubljana, Slovenia.
Miroljub
M
Jakovljević
Gaj
G
Vidmar
Igor B
IB
Mekjavic
D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology*; D001288:Attention / Q000187:drug effects / Q000502:physiology; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007222:Inert Gas Narcosis / Q000503:physiopathology*; D008297:Male; D009609:Nitrous Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology; D012737:Sex Factors; D014145:Trail Making Test; D055815:Young Adult
D018685:Anesthetics, Inhalation; D009609:Nitrous Oxide