Treatment of status asthmaticus

Opiate action in the pulmonary circulation

To gain insight into the mechanisms underlying the association between acute pulmonary edema and narcotic abuse, the direct action of morphine was examined in isolated, perfused left lower lobe (LLL) preparations in dogs and cats. Morphine sulphate injected (0.6 mg/kg) into the pulmonary artery of the LLL increased the pulmonary vascular resistance (PVR) by about 100% in both species. The increase in PVR was primarily due to constriction of the veins, as determined with the arterial and venous occlusion technique. The increase in PVR with morphine injection was unaffected by alpha-adrenergic antagonists, but was reversed by chlorpheniramine, a histamine H1-receptor antagonist. Pretreatment, but not post-treatment with the opiate antagonist, naloxone, blocked the effect of morphine on PVR. Thus, the rapid administration of morphine produces pulmonary venoconstriction via histamine release from the lung, and the latter may account for the well-documented association between acute pulmonary edema and narcotic abuse.

Mechanical ventilation

Among the many advances made in intensive care therapeutics in recent years, few have rivaled the impact of mechanical ventilators. Their expanded use affects all who practice in the critical care setting. This article reviews the physiologic basis for mechanical ventilation, how ventilators are classified, the various modes, and specific indications. A basic introduction is made into ventilator set up, weaning techniques, adjunctive drug therapy, and complications. The pharmacotherapy specialist who understands interactions between patients and ventilators, and the effects of mechanical ventilation on cardiopulmonary function will be best equipped to individualize drug therapy.