The effect of dopamine on pulmonary hemodynamics and tissue damage after inhalation injury in an ovine model.

Hypoxic pulmonary vasoconstriction and reduced blood flow occur as a result of smoke inhalation. The aim of this study was to investigate how the amelioration of blood flow reduction by the vasodilator dopamine affects histopathologic outcome. We exposed the left lungs of chronically instrumented sheep (n = 12) to smoke, awakened them, and studied them for 24 hours. Six hours after inhalation injury, the sheep received randomized infusions of dopamine (9 micrograms/kg/min) or equal volumes of 0.9% saline solution. Pulmonary resistance in the left lungs of animals in the group that received saline solution rose continuously throughout the study period (624 +/- 48 dyne.sec.cm-5/m2 to 1747 +/- 140 dyne.sec.cm-5/m2, baseline to 24 hours after injury). Dopamine treatment caused a significantly lower vascular resistance in the injured lung than did saline solution between 8 and 24 hours after injury. The histologic evaluation of the injured lungs showed epithelial necrosis and cast formation in both groups in addition to an increased wet/dry ratio. No difference in lung injury between the groups could be distinguished. We conclude that the amelioration of blood flow reduction by treatment with dopamine in the lungs that were exposed to smoke did not affect pulmonary damage after inhalation injury.