Effect of low dose sedation with diazepam on ventilatory response at moderate altitude

Benzodiazepines are in wide use in out of hospital emergency medicine in at sea level, as well as in alpine rescue services. Ventilatory depression is a common side effect of high dose intravenous benzodiazepines. The objective of our study was to evaluate the effect of low dose benzodiazepines on ventilation at moderate altitude.

Randomized, double blind, placebo controlled crossover trial. Blood gas analysis of 8 healthy subjects was performed before and one hour after 5 mg of oral diazepam or placebo at 171 m and at 3,000 m altitude. PaO2 and PaCO2 before and after diazepam or placebo medication at 171 m did not change significantly. At 3,000 m altitude. PaO2 decreased and PaCO2 increased significantly one hour after 5 mg of oral diazepam (PaO2 64.7 +/- 3.4 vs. 60.0 +/- 1.5 mmHg, PaCO2 28.3 +/- 2.3 vs. 33.3 +/- 1.8 mmHg, p < 0.05). Placebo did not influence PaO2 and PaCO2.

Low dose diazepam inhibits ventilatory adaptation to mild hypoxia at moderate altitude. Caution in benzodiazepine use in moderate altitude is therefore necessary.