HEMODYNAMIC-EFFECTS OF EPINEPHRINE, BICARBONATE AND CALCIUM IN THE EARLY POSTNATAL-PERIOD IN A LAMB MODEL OF SINGLE-VENTRICLE PHYSIOLOGY CREATED IN-UTERO

Objectives, A reproducible fetal animal model of single ventricle phys iology was created to examine the effects of pharmacologic agents comm only used in the perinatal and perioperative intensive care management of patients with a single ventricle, Background, Single-ventricle phy siology is characterized by parallel pulmonary and systemic circulatio ns, with effective blood flow to each determined by the relative resis tances in the pulmonary and systemic vascular beds, Perinatal and peri operative management of these patients is largely based on empiric obs ervations and differs considerably between institutions and is further complicated by the transitional physiology of the newborn, The lack o f animal models of single-ventricle physiology has hindered the unders tanding of this problem,Methods, A 10-mm, Damus-Kaye-Stansel-type aort opulmonary anastomosis was created in 10 fetal sheep at 140 +/- 1.2 da ys of gestation, The main pulmonary artery was ligated distally, and p ulmonary blood how (Qp) was provided through a 5-mm aorto-pulmonary sh unt, Eight lambs were delivered at term and placed on cardiopulmonary bypass (30 min) 48 to 72 h after birth, Pharmacologic interventions (0 .1 mu g/kg-body weight per min of epinephrine, 2 mEq/kg of sodium bica rbonate and 10 mg/kg of calcium chloride) were performed before and af ter bypass, and hemodynamic responses were observed, The response to t he epinephrine bolus was determined only in the postbypass study, Resu lts, Both before and after bypass, epinephrine infusion and calcium an d bicarbonate administration increased Qp and systemic blood flow (Qs) (total cardiac output) but produced only small changes in the Qp/Qs r atio (-0.5% to -7.3% change), With the epinephrine bolus, Qp increased enormously, and the Qp/Qs ratio increased by 584% (p < 0.001), Conclu sions, In neonatal lambs with single-ventricle physiology created in u tero, epinephrine infusion and calcium and bicarbonate administration increased total cardiac output without significantly compromising the Qp/Qs ratio, However, epinephrine bolus seems to be hemodynamically de trimental in circumstances of single-ventricle physiology and should b e used with caution and probably in relatively lower doses in the resu scitation of patients with single-ventricle physiology, Further invest igation of the dose dependent effects and the effects of prolonged adm inistration of common pharmacologic agents will enable better manageme nt of patients with single-ventricle physiology. (C) 1996 by the Ameri can College of Cardiology