SYSTEMIC AND REGIONAL HEMODYNAMIC EFFECTS OF HIGH-DOSE EPINEPHRINE INFUSION IN HYPOXIC PIGLETS RESUSCITATED WITH 100% OXYGEN

Abstract

Shock and poor regional perfusion are common in asphyxiated neonates. We compared the systemic and regional hemodynamic effects of high-dose epinephrine (E) with those of dopamine combined with low-dose epinephrine (DE) infusions in a neonatal model of hypoxia-reoxygenation. Neonatal piglets (1-3 days, 1.5-2.5 kg) were acutely instrumented to continuously monitor systemic arterial pressure (SAP), pulmonary artery pressure, cardiac index (CI), and blood flows at the left common carotid, superior mesenteric, and renal arteries. Either epinephrine (1 microg.kg(-1).min(-1)) or dopamine (10 microg.kg(-1).min(-1)) and epinephrine (0.2 microg.kg(-1).min(-1)) were given for 2 h in hypoxic piglets resuscitated with 100% oxygen (n = 8 per group) in a randomized blinded fashion. Control piglets received hypoxia and reoxygenation but no catecholamine infusion (n = 7). Alveolar hypoxia (PaO2, 33-37 mmHg) caused reduced CI (89-92 vs. 171-186 mL.kg(-1).min(-1) of baseline, P < 0.05), hypotension (SAP, 28-32 mmHg) with pH 7.05 to 7.10, and decreased regional flows. Upon reoxygenation, CI and SAP improved but gradually deteriorated to 131 to 136 mL.kg(-1).min(-1) and 41 to 49 mmHg at 2 h of reoxygenation, respectively. E and DE administration similarly improved CI (167 +/- 60 and 166 +/- 55 vs. 121 +/- 35 mL.kg(-1).min(-1) of controls) and SAP (53 +/- 7 and 56 +/- 10 vs. 39 +/- 8 mmHg of controls), respectively, and the pulmonary vascular resistance (vs. controls, all P < 0.05). Heart rate and pulmonary artery pressure were not different between groups. Systemic oxygen delivery and consumption were increased in E- and DE-treated groups with no difference in extraction ratio between groups. There were no differences in regional blood flows and oxygen delivery between groups. After hyperlactatemia with hypoxia, plasma lactate levels decreased with no difference between groups. Epinephrine given as the sole agent is as effective as dopamine and low-dose epinephrine combined in treating shock and hypotension that follow the resuscitation of hypoxic neonatal piglets, with no reduction in regional perfusion.