Abstract 93: Improved Post-Arrest Cardiac Output following Short Duration Cardiac Arrest with Epinephrine
The use of epinephrine during prolonged cardiac arrest has been associated with impaired post-arrest cardiac function. However, the post-arrest effect of standard dose epinephrine in a short duration cardiac arrest is not known. We tested the hypothesis that epinephrine can improve early post resuscitation myocardial function after a short cardiac arrest duration.
Methods: Sixteen male Sprague Dawley rats (401±19g) were anesthetized with IP pentobarbital (50 μg/kg), instrumented for hemodynamic monitoring and ventilated with room air. Cardiac arrest was induced with a KCl bolus (0.04 μg/g). Body temperature was maintained at 37° C. After 2 minutes of cardiac arrest, animals were randomized to receive either epinephrine (0.01 mg/kg) or placebo in a blinded fashion and CPR (chest compressions 200–230/min and ventilation 50% of baseline) was started until restoration of spontaneous circulation (ROSC). ROSC was defined as a spontaneous electrical rhythm with a MAP > 60 mm Hg. Following ROSC, animals were supported with oxygen, mechanical ventilation and IV fluids. Cardiac 2-D and M-mode ultrasound measurements were made pre-arrest, and 5, 30, and 60 min after ROSC at the level of the papillary muscles using an 11 MHz probe. Within and between group comparisons were analyzed using ANOVA.
Results: There were no pre-arrest differences in arterial pressure, fluids, anesthesia, baseline cardiac function (with ultrasound) or post arrest fluids. ROSC was achieved in 8/8 placebo (ROSC time 2:39 ± 16 sec) and 8/8 epinephrine animals (ROSC time 2:21 ± 7 sec). During the 60 min post ROSC period, epinephrine hearts had significantly increased cardiac output, LV end systolic volume, end diastolic volume; but decreased ejection fraction and fractional shortening relative to baseline and compared with placebo hearts at the same time points (p<0.001). Heart rate was similar between groups.
Conclusion: Post-arrest cardiac output is significantly increased after a short cardiac arrest with epinephrine. However, the increased cardiac output observed is at the expense of a reduction in mechanical efficiency as evidenced by increased LV chamber volumes and a decrease in ejection fraction. Epinephrine’s post-arrest effect likely varies with the duration of the cardiac arrest.