Abstract 15332: Post-Resuscitation Epinephrine Infusion Restores Blood Pressure but Not Blood Flow in a Rat Model of Severe Pediatric Cardiac Arrest

Abstract

Introduction: In children resuscitated from cardiac arrest (CA), post-arrest hypotension occurs often and worsens outcomes. Continuous infusion of epinephrine (Epi) is the 1st-line treatment for post-arrest hypotension but may worsen organ perfusion due to vasoconstriction. Hypothesis: Epi infusion after resuscitation from pediatric asphyxial CA restores blood pressure but not organ perfusion. Methods: Immature rats (PND18-22, n=34) underwent 11.5 minutes of asphyxial CA followed by resuscitation. Rats with hypotension (mean arterial pressure (MAP)<80% baseline) after resuscitation received infusions of either 0.9% NaCl (NS) or Epinephrine (Epi). MAP, carotid and femoral arterial blood flows (Fc, Ff) and renal oxygen tension (PrO2) were recorded. Results: One hour after resuscitation, MAP, Fc and Ff were 61.73 ± 2.68; 42.58 ± 3.84; and 19.53 ± 7.00 % of baseline, respectively. Epi infusion increased MAP in a dose-dependent manner, reaching 95.13 ± 7.93 % of baseline at 0.5 μg/kg/min. In contrast, Epi infusion up to 0.5 μg/kg/min increased Fc only to 49.55 ± 6.49 and Ff to 53.28 ± 7.13 % of baseline. NS infusion at equivalent volume had a more salutary effect than Epi on improving blood flow (Fc 64.62 ± 6.64 and Ff 60.25 ± 7.60 % of baseline). PrO2 reached 100% of baseline with Epi infusion and inspired O2 fraction (FiO2) = 1. However, at FiO2 = 0.21, Epi failed to restore PrO2 which reached 42% of baseline. Interestingly, a single 10 cc/kg NS bolus increased PrO2 to 100% of baseline at all FiO2 tested. Conclusions: In this rat model of severe pediatric asphyxial CA and resuscitation, post-resuscitation Epi infusion failed to restore carotid and femoral arterial blood flow despite normalizing blood pressure. Furthermore, Epi infusion restored neither renal perfusion nor oxygenation. In contrast, infusion of NS at comparable volumes was more effective than Epi at normalizing carotid and femoral blood flows as well as renal oxygenation. If validated in a large animal model, these results may indicate that Epi infusion after CA resuscitation contributes to organ injury and morbidity in children.