Abstract 60: Dexmedetomidine Administration During CPR Improves Stroke Volume During the Early Postresuscitation Period

Abstract

Introduction: Elevated sympathetic response after CPR worsens myocardial dysfunction and cardiac output. Dexmedetomodine has sympatholytic effects both in animal and human studies. Hypothesis: Dexmedetomidine given during CPR improves stroke volume (SV) after ROSC 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 (VF; via direct right ventricular current) to receive either dexmedetomidine (2 mcg/kg) or placebo after the first minute of chest compressions per AHA CPR 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. SV was measured at 15, 30, 60, 90 and 120 minutes after ROSC using a Pressure-Volume (P-V) catheter in the left ventricle (Millar instruments, Michigan, USA). Cardiac output was calculated from SV and heart rate. Outcome (mean±SD) was analyzed using 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 Dexmedetomidine group had significantly higher stroke volume (% change from baseline) at 15 minutes (97±24 vs. 44±19, p =0.0006) and 30 minutes (87±26 vs. 51±21 p =0.0153). CO (% change from baseline) was higher in Dex group at 15 minutes (141±53 vs. 61±23, p =0.0061) and at 30 minutes (115±44 vs. 55±17 p =0.0122). SV and CO were higher, but not significantly after 30 minutes. The study group had significantly higher CO (% change from baseline) across all time points combined compared with the control group (89.3±6.14 vs. 60.1±7.15, p=0.0033). End-diastolic volume trended higher in Dexmedetomidine group but was not significant. HR was not different between the two groups. Conclusions Dexmedetomidine, when given during the initial cycle of chest compressions during CPR, increases SV and CO early post ROSC. Further studies are needed to evaluate the appropriate dose, continuous infusion and time of administration.