Abstract 198: Dexmedetomidine During CPR Blunts the Increase in Oxygen Consumption in Early ROSC

Abstract

Introduction: Cardiac arrest significantly increases endogenous catecholamines, which stimulates increased oxygen consumption after ROSC. In animals, adrenergic blockade during and immediately after CPR improves post arrest cardiac function. Dexmedetomodine has sympatholytic effects both in animal and human studies. Hypothesis: Dexmedetomidine given during CPR reduces oxygen consumption after ROSC as compared with standard CPR. Methods Sixteen anesthetized & ventilated (2 months old) farm pigs (UF Research Swine) of either sex were blindly randomized (8/group) after induction of ventricular fibrillation (via direct right ventricular current) to receive either dexmedetomidine (2 mcg/kg) or saline placebo after the first minute of chest compressions during CPR per AHA guidelines. Chest compressions were delivered at 100/min by a pneumatic compressor device (Thumper, Michigan instruments, USA) and 21% FiO 2 was used for ventilation. Oxygen consumption was measured from exhaled gas analysis at 15, 30, 60, 90 and 120 minutes after ROSC using a metabolic measurement system (TrueOne® 2400, Parvomedics, USA). Data (mean±SD) was analyzed using a mixed linear model (SAS Proc MIXED). We used an unpaired t-test for the differences between groups at each time point; p-value ≤0.05 was considered significant. Results Oxygen consumption (% change from baseline) was significantly lower in the dexmedetomidine group, 121%±4.16, vs. Saline, 143%±5.32, p=0.0093. Dexmedetomidine group had significantly lower oxygen consumption at 15 minutes (111%±22 vs. 150%±29, p =0.0365) and at 30 minutes (114%±24 vs.151%±19, p =0.0122. The oxygen consumption was not significantly different at 60, 90 and 120 minutes. There was no difference between groups with reference to time to ROSC and doses of epinephrine given. Conclusions. Dexmedetomidine, when given during the initial cycle of chest compressions during CPR, attenuates the elevated oxygen consumption during the post ROSC period. Further studies are needed to evaluate the effects of higher doses or continuous infusion and the optimal time of administration.