The effect of smoking nicotine tobacco versus smoking deprivation on motion sickness.

BACKGROUND

The experienced smoker maintains adequate nicotine levels by 'puff-by-puff self-control' which also avoids symptomatic nauseating effects of nicotine overdose. It is postulated that there is a varying 'dynamic threshold for nausea' into which motion sickness susceptibility provides an objective toxin-free probe. Hypotheses were that: (i) nicotine promotes motion sickness whereas deprivation protects; and (ii) pleasurable effects of nicotine protect against motion sickness whereas adverse effects of withdrawal have the opposite effect.

METHODS

Twenty-six healthy habitual cigarette smokers (mean ± SD) 15.3 ± 7.6 cigs/day, were exposed to a provocative cross-coupled (coriolis) motion on a turntable, with sequences of 8 head movements every 30s. This continued to the point of moderate nausea. Subjects were tested after either ad-lib normal smoking (SMOKE) or after overnight deprivation (DEPRIV), according to a repeated measures design counter-balanced for order with 1-week interval between tests.

RESULTS

Deprivation from recent smoking was confirmed by objective measures: exhaled carbon monoxide CO was lower (P<0.001) for DEPRIV (8.5 ± 5.6 ppm) versus SMOKE (16.0 ± 6.3 ppm); resting heart rate was lower (P<0.001) for DEPRIV (67.9 ± 8.4 bpm) versus SMOKE (74.3 ± 9.5 bpm). Mean ± SD sequences of head movements tolerated to achieve moderate nausea were more (P = 0.014) for DEPRIV (21.3 ± 9.9) versus SMOKE (18.3 ± 8.5).

DISCUSSION

Tolerance to motion sickness was aided by short-term smoking deprivation, supporting Hypothesis (i) but not Hypothesis (ii). The effect was was approximately equivalent to half of the effect of an anti-motion sickness drug. Temporary nicotine withdrawal peri-operatively may explain why smokers have reduced risk for postoperative nausea and vomiting (PONV).