The effects of intravenous lorazepam alone and with meperidine on ventilation in man.

The respiratory effects of lorazepam (a 1, 4 benzodiazepine) were studied using a modified Read rebreathing technique in healthy adult males about to undergo elective surgery. Lorazepam 0.05 mg/kg (IV) produced an increase in slope and a shift to the left of the CO2 response curve. These effects were also detectable but of smaller magnitude when the same lorazepam dose (IV) was given with meperidine (IV). End-expiratory CO2 (PeCO2), which was significantly elevated in all drug groups, is not a sensitive indicator of either the time course or the degree of respiratory depression.