A RISK FOR OBSTRUCTION OF THE AIRWAYS IN THE PARENTERAL USE OF LEVOMEPROMAZINE WITH BENZODIAZEPINE

Arrhythmogenic effects of phenothiazines appear to be associated with sudden death, whereas respiratory complications have received little a ttention. In this report we describe 5 cases with accompanying obstruc tion of the airways after intramuscular injections of levomepromazine (LPZ), a potent sedative phenothiazine, in combination with intravenou s injections of benzodiazepine (BZ) during a 3-month period in a psych iatric intensive care unit. Two out of 5 cases were unpredictable beca use obstruction of the airways occurred 2 hours or more after the last injection. As compared with patients who received parenteral (intrave nous or intramuscular) injections during the same period, the dose of intramuscular LPZ was significantly large in the 5 cases with obstruct ion of the airways. All 5 of these cases received intramuscular LPZ 0. 52 mg/kg or more. In contrast, there was no patient with obstruction o f the airways who received only intramuscular LPZ, the combination of LPZ and HDL, or BZ and HDL. The occurrence of obstruction of the airwa ys among patients who received both intramuscular LPZ and intravenous BZ was significantly higher than among patients who received other dru g regimes. These preliminary results suggest that the intramuscular us e of LPZ with intravenous BZ may be a risk for obstruction of the airw ays.