Associate Professor Childrens National Health System, United States
Introduction: In children resuscitated from cardiac arrest, systemic hypotension occurs frequently and is associated with worse outcome. The first-line vasoactive treatment for post-arrest hypotension is continuous infusion of epinephrine. Epinephrine dose is titrated to maintain normal blood pressure for age. Epinephrine, however, also leads to vasoconstriction which may impair organ perfusion. We hypothesized that epinephrine infusion during the post-resuscitation period restores systemic blood pressure but not flow to vital organs.
Methods: We used a model of pediatric asphyxial cardiac arrest in 18-21 day old rats. Rats underwent 11.5 minutes of arrest followed by resuscitation. Blood flow in the carotid (Fc) and the femoral (Ff) arteries was measured directly using Doppler flow probes placed around each vessel. Mean arterial pressure (MAP) was measured with an invasive transducer in the iliac artery. Rats received either epineprine or saline infusion at an equivalent volume when MAP after resuscitation decreased to 60% of baseline. Data were analyzed using Wilcoxon Rank Sum test.
Results: Twenty minutes after resuscitation from 11.5 minutes of asphyxial arrest, ABP, Fc and Ff were 62±3; 43±4; and 20±7.00% of baseline, respectively. Epinephrine infusion increased ABP in a dose-dependent manner, reaching 95±8% of baseline at 0.5 µg/kg/min. Saline infusion at equivalent volumes increased ABP only marginally to 70±3% of baseline. In contrast to its effect on ABP, epinephrine infusion increased Fc only to 50±6 and Ff to 53±7% of baseline. Saline infusion at equivalent volumes, on the other hand, had a more salutary effect than epinephrine on improving blood flow (Fc 65±7 and Ff 60±8% of baseline). Notably, a single 10 cc/kg saline bolus, administered when ABP decreased to ~60% of baseline post-ROSC, increased blood flow and ABP to 100% and 90% of baseline, respectively.
Conclusions: These data in a clinically-realistic preclinical model of pediatric asphyxial cardiac arrest indicate that epinephrine infusion in the post-arrest period may not restore blood flow despite normalizing arterial blood pressure. Future studies need to explore the impact of targeting flow rather than blood pressure in the post-arrest period and its association to post-arrest end-organ function in children.
