Pulmonary insufficiency produced by isoproterenol.

Twelve healthy, anesthetized, mechanically ventilated dogs received an infusion of isoproterenol hydrochloride, 0.1 microgram per kilogram for two hours. There was a rapid and statistically significant increase in the pulmonary shunt, cardiac output and mean pulmonary artery pressure; a significant decrease in the pulmonary vascular resistance, and no significant change in the pulmonary artery wedge pressure. These findings support those of previous studies which demonstrated the beta adrenergic stimulation is important in the pathogenesis of pulmonary insufficiency. The shunt results from ventilation-perfusion inequalities produced by the increased pulmonary blood flow and pulmonary vasodilatation. Because of the production of pulmonary insufficiency, isoproterenol or other beta adrenergic agonists should be used with caution in the critically ill, who often have or may develop the respiratory distress syndrome.