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The psychometric and cardiac effects of dimenhydrinate in the hyperbaric environment
D M Taylor1, K S O'Toole, T E Auble
1Department of Emergency Medicine, University of Pittsburgh, Pennsylvania, USA.
Study Objectives:
To examine the psychometric and cardiac effects of dimenhydrinate at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the drug's safety in the diving environment.
Design:
Double-blind, placebo-controlled, crossover study
Setting:
Monoplace hyperbaric chamber of a university hospital.
Subjects:
Thirty active divers (mean age 38 yrs).
Interventions:
A bank of seven tests was used to assess cognitive function during four different dive combinations: placebo-1 atm, placebo-3 atm, dimenhydrinate-1 atm, and dimenhydrinate-3 atm.
Measurements And Main Results:
Heart rate and cardiac rhythm were recorded during all dives. Repeated-measures multivariate analysis of variance was used to analyze the effects of dimenhydrinate, depth, and drug-depth interaction. Dimenhydrinate resulted in a significant decrease in scores of mental flexibility (trail-making, part B, p<0.05) but had no effect on scores in the six other psychometric tests (p>0.05). It had no effect on mean heart rate (p>0.05), although frequent unifocal ventricular ectopic beats occurred in two subjects after ingestion of the drug. Depth resulted in a significant decrease in verbal memory test scores (p=0.001) and mean heart rate (p<0.001).
Conclusion:
Dimenhydrinate adversely affects mental flexibility. This effect, when added to the adverse effect of depth on memory, may contribute to the dangers of diving.