Abstract P92: Decreased Inotropic and Lusitropic Effects of Dobutamine on Post-cardiac Arrest Myocardial Dysfunction Under Hypothermia Treatment
Introduction: Dobutamine improves post-cardiac arrest myocardial dysfunction. Biological activities and metabolism may decrease under hypothermia condition. The dobutamine pharmacological effects under post-cardiac arrest hypothermia treatment remain unclear.
Hypothesis: Hypothermia treatment decreases the dobutamine pharmacological effects on post-cardiac myocardial dysfunction.
Methods: Male adult Wistar rats were used for the prospective randomized animal study. Cardiopulmonary resuscitation with mechanical ventilation was started after 6.5 minutes of asphyxia-induced cardiac arrest. Hypothermia treatment with the target temperature of 31°C was started immediately after return of spontaneous circulation (ROSC). The resuscitated animals received low dose (5 ug/kg/min), high dose (15 ug/kg/min) or equivalent volume of 0.9% saline as placebo intravenously continuous infusion for 4 hours started since 3 minutes after ROSC.
Results: The hemodynamic parameters were continuously monitored for 4 hours after cardiac arrest and resuscitation. The post resuscitation LV systolic function presented by dP/dt40, diastolic function by maximal negative dP/dt and cardiac output improved after administration of low dose and high dose dobutamine under normothermia (37°C) environment. Under the hypothermia treatment (31°C), the post resuscitation LV systolic, diastolic function and cardiac output did not improve under low dose dobutamine administration. With the high dose dobutamine treatment, the LV systolic function and cardiac output improved compared to placebo group, but the diastolic function did not show the significant improvement under hypothermia treatment.
Conclusion: It implies the response to the dobutamine treatment become blunt under hypothermia treatment. High dose dobutamine administration is needed to improve post-resuscitation myocardial dysfunction in the hypothermia status.