Abstract 277: Hypothermia Treatment Attenuates Inotropic and Lusitropic Effects of Milrinone on Post-Cardiac Arrest Myocardial Dysfunction
Introduction: Milrinone is effective positive inotropic and lusitropic agent for post-cardiac arrest myocardial dysfunction. Hypothermia could alter the pharmacological effects of drugs used in the post-cardiac arrest period. The influence of post-cardiac arrest hypothermia treatment on pharmacological effects of milrinone remains unclear.
Hypothesis: Hypothermia treatment alters the pharmacological effects of milrinone on post-cardiac myocardial dysfunction.
Methods: Asphyxial cardiac arrest was induced by airway obstruction for 6.5 minutes followed by cardiopulmonary resuscitation with mechanical ventilation in male adult Wistar rats. Immediately after return of spontaneous circulation(ROSC), therapeutic hypothermia with the target temperature of 31oC was started and maintained for 4 hours. The resuscitated animals were equally randomized to receive continuously intravenous infusion of low dose milrinone (0.375 ug/kg/min), high dose (0.75 ug/kg/min) milrinone or equivalent volume of 0.9% saline as placebo, respectively, after ROSC.
Results: The hemodynamic parameters were continuously monitored for 4 hours after cardiac arrest and resuscitation. The pre-arrest hemodynamic parameters, including heart rate, blood pressure and left ventricular pressure were not different among different groups. The LV systolic pressure, LV systolic function presented by dP/dt40 , and diastolic function by maximal negative dP/dt improved after administration of low and high dose milrinone under normothermia (37oC) environment at post resuscitation 1st to 4th hours (Figure). Under the hypothermia treatment period (31oC), the post resuscitation LV systolic and diastolic function did not improve under either dose of milrinone administration.
Conclusions: The positive inotropic and lusitropic effects of milrinone treatment on post-cardiac arrest myocardial dysfunction become blunt under hypothermia treatment.
- © 2010 by American Heart Association, Inc.