Effect of diazepam on ventilatory responses.

To investigate the effects of diazepam on ventilatroy control, hypoxic and hypercapnic ventilatory responses were studied in 8 normal subjects before and after 10 mg of intramuscular diazepam. There was no significant change in either resting minute ventilation or resting end-tidal CO2 tension, but depression of hypoxic ventilatory response was observed 15 (60% of control) and 30 min (53% of control) after diazepam (p less than 0.05). No significant depression of hypercapnic ventilatory response was noted 70 to 130 min after diazepam. In view of the depression of hypoxic ventilatory response by diazepam in normal subjects, adverse responses along these lines should be considered in patients with impaired ventilatory function, such as chronic airways obstruction, and in those encountering acute hypoxemia.