VISUAL/VESTIBULAR EFFECTS OF INERT GAS NARCOSIS

Authors
  1. Hamilton, K.
  2. Laliberte, M-F.
  3. Heslegrave, R.
  4. Khan, S.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
Divers breathing compressed air at depths beyond 30 m experience a type of behavioural impairment known as inert gas narcosis. This condition degrades performance on a wide range of tasks and has the potential to compromise safety. Symptoms generally associated with narcosis include slowed response time, amnesia and euphoria. Recent studies have also found that narcosis disrupts mechanisms regulating ocular control during head movement, however, these studies have been limited to very low frequencies. To further examine ocular impairment under narcosis, the vestibular ocular reflex (VOR) was assessed over a set of higher frequency head movements ranging from 2.0 to 4.7 Hz. Seven subjects were tested prior to (pre-), during, and after (post-) exposure to narcosis. Narcosis was induced using 30% nitrous oxide. Air was breathed in the pre- and post-narcosis conditions. Narcosis produced a marked decrease in the velocity of the compensatory eye movements in response to head rotation (decrease in VOR-gain), with more pronounced decreases at higher frequencies. Narcosis also shifted the phase relation between head and eye position with respect to the air breathing control. These results suggest that narcosis disrupts ocular regulatory mechanisms, making it increasingly difficult to maintain visual fixation during rapid head movement.
Report Number
DCIEM-91-48 — Research Paper; Reprint
Date of publication
29 Apr 1991
Number of Pages
8
Reprinted from
Ergonomics, vol 36, no 8, 1993, p 891-898
DSTKIM No
93-04652
CANDIS No
134708
Format(s):
Hardcopy;Originator's fiche received by DSIS

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