DOPAMINE-DEPENDENT DIASTOLIC DYSFUNCTION IN MODERATE HYPOTHERMIA

We designed an experimental animal study to study the effects of dopam ine (DA) on diastolic function in hypothermia. DA was applied at five incremental infusion rates in 6 sheep during normothermia and moderate hypothermia (29 degrees C). Left ventricular end-diastolic pressure ( LVEDP) was increased during hypothermia as compared with normothermia at all doses of DA. Contraction and relaxation velocity were changed o nly slightly during hypothermia; during normothermia, both velocities were markedly increased. The pronounced hemodynamic effect observed du ring hypothermia was further intensified by occurrence of aftercontrac tions, which disappeared at very high DA doses. These paradoxic result s were considered the result of hypothermia-induced reduction in activ e transport mechanisms responsible for regulation of the cytoplasmic C A(2+) concentration. The generally reduced inotropic effect of DA, the risk of paradoxic reactions, and the occurrence of aftercontractions must be taken into account when emergency drugs are administered clini cally during hypothermia.