The psychometric and cardiac effects of pseudoephedrine in the hyperbaric environment.
OBJECTIVE
To examine the psychometric and cardiac effects of pseudoephedrine at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the agent's safety in the diving environment.


METHODS
Double-blind, placebo-controlled, crossover study.


METHODS
Monoplace hyperbaric chamber of a university hospital.


METHODS
Thirty active divers (mean age 38 yrs).


METHODS
A bank of seven tests was used to assess cognitive function during four different simulated dive combinations: placebo-1 atm, placebo3 atm, pseudoephedrine-1 atm, and pseudoephedrine-3 atm.


RESULTS
Heart rate and cardiac rhythm were recorded during all dives. Repeated-measures analysis of variance was used to analyze the effects of pseudoephedrine, depth, and drug-depth interaction. No significant, independent effects of pseudoephedrine were seen on any of the seven psychometric test scores (p>0.05), although the drug tended to increase anxiety scores (p=0.092). Depth resulted in a significant increase in anxiety scores (p=0.021) and a significant decrease in verbal fluency test scores (p=0.041); it had no significant effects on the other five psychometric tests (p>0.05). Pseudoephedrine caused a significant increase (p=0.036) in mean heart rate, and depth caused a significant decrease (p=0.013). Neither pseudoephedrine nor depth affected cardiac rhythm.


CONCLUSIONS
Pseudoephedrine does not cause significant alterations in psychometric performance at 3 atm of pressure that might increase the risk of diving. Depth causes significant adverse effects on anxiety levels and semantic memory at 3 atm. Pseudoephedrine and depth have significant but opposite effects on heart rate; although, these effects are unlikely to be clinically significant during diving. It is unlikely that pseudoephedrine adds significant risk to the diver.
Taylor
D M
DM
Department of Emergency Medicine, University of Pittsburgh, Pennsylvania, USA.
O'Toole
K S
KS
Auble
T E
TE
Ryan
C M
CM
Sherman
D R
DR
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001007:Anxiety / Q000503:physiopathology; D001273:Atmosphere Exposure Chambers; D001274:Atmospheric Pressure; D018880:Atrial Premature Complexes / Q000139:chemically induced; D001993:Bronchodilator Agents / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D018592:Cross-Over Studies; D004242:Diving / Q000502:physiology*; D004311:Double-Blind Method; D004809:Ephedrine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D018879:Ventricular Premature Complexes / Q000139:chemically induced
D001993:Bronchodilator Agents; D004809:Ephedrine