Effects of Halothane Anesthesia on Hemodynamics and Oxygenation during Continuous Infusion of Diltiazem in Dogs

Kim, Chong Duk; Kim, Seong Deok

Abstract

In order to assess the interaction between halothane and diltiazem on the cardiovascular system and oxygenation, eight mongrel dogs were instrumented so that the following measurements could be made under the influence of drugs heart rate(HR), mean arterial pressure(MAP), central venous pressure(CVP), pulmonary arterial pressure(PAP), pulmonary capillary wedge pressure(PCWP), hemoglobin(Hb) and cardiac output(CO). Systemic and pulmonary vascular resistance(SVR and PVR), coronary perfusion pressure(CPP), cardiac index(CI), oxygen transpor(O2 Flux), oxygen consumption VO2, oxygen extraction ratio(O2ER) and intrapulmonary shunt(Qs/Qt), etc, were calculated by using the above measured parameters. Infusion of diltiazem (8ug/kg/min) following an IV bolus of 0.2mg/kg resulted in a potent vasodilator effect with significant decreases in MAP and SVR, and an increase in CI. Importantly, however, the systemic vasodilator effect of diltiazem was associated with no significant compensatory increase in HR. Halothane anesthesia during continuous infusion of diltiazem produced dose related decrease in HR, CI, MAP, CPP, RPP and O2 Flux, but the previously decreased SVR by diltiazem was not affected by halothane. PCWP, CVP and PVR were not changed throughout the study. So halothane anesthesia during infusion of diltiazem might have some dose related direct negative inotropic and chronotropic effects. Because the decrease in oxygen demand-indicating parameters such as HR and RPP was greater than that in oxygen transport (O2 Flux), the combined use of halothane and diltiazem can be recommended for the patient with ischemic heart disease and angina pectoris, especially in the therapy for decreasing heart rate.