1265 Combined Cardiotonic and Vasodilator Therapy for Myocardial Dysfunction Associated With Hypertension in Asphyxiated Prematures

Abstract

Infants with acute heart failure due to perinatal asphyxia may have elevation of systemic blood pressure from adrenergic stimulation. This afterload elevation is probably deleterious for myocardial function and tissue perfusion. Treatment needs to be directed towards increasing cardiac contractility and reducing afterload. Dopamine and chlorpromazine were given at 2-8 and 1-2 ugm/kg/min respectively, to 6 preterm infants with hypertension following severe perinatal asphyxia. This therapy improved hemodynamics in all infants: the heart rate did not increase significantly, mean arterial pressure decreased from 52+4 to 46+4, and skin PC02, obtained with an unheated electrode, zecreasez by 8%. These results suggest that improvement in hemodynamics and tissue perfusion occurred without production of myocardial stress by tachycardia. or hypotension. The use of an inotropic agent alone for heart failure in the presence of hypertension, may worsen the condition. Five six-hour daytime studies on each of 13 preterm infants,6 healthy (HPTI) and 7 with previous persistent oxygen dependency (PPOD) were carried out between 36 weeks GA and six months post term and compared with those in normal term infants (NTI) . All babies showed a rise in heart rate between term and one month with a subsequent fall to six months. Only the early heart rates were higher in preterm infants and highest in PPOD infants [e.g. Trancutaneous p02 was measured continuously during consecutive control and infusion periods of equal length in low birth weight infants given intravenous fat emulsion at a rate of 195 f 24 mg/kg of triglyceride per hour for 5 hours. The infants averaged 1000 gms. (range 750-1480 gm) and 28.1 weeks gestation (range 25-31 wks.) at birth, were studied at age 7-21 days, and were on stable FIO2 and/or ventilator settings during the study periods. Plasma triglycerides were measured before the infusion, at 3i0.5 hours during the infusion, and 4 hours post-infusion for each patient. TCpO2 values for each patient were matched at corresponding 30 min. intervals (i.e., at 0-30 mins.., 30-60 mins., etc) for 69 control and 69 infusion periods of 30 mins. each, a i : d the matched periods were analyzed by a paired t-test, as shown: Triglycerides, mg/dl TCPOZ, m H 9 Before 39f18*1p<0.001Control (n=69 62.4f12.0*1p=n~s~ During 93i22 )p<0.001Infusion (n=69) 62.5i14.3 After 56f19 *Mean S.D. In 6 infants breathing spontaneously, respiratory rates were 55f ll/min. during control periods and did not increase during fat infusions. Apneic spells occurred during 11% of control periods (8/69) and 7% of infusion periods (5/69). Low birth weight infants>l week of age and in stable respiratory condition appear to tolerate intravenous fat at 200 mg/kg/hr with no clinically detectable effects on respiratory rate, frequency of apnea, or 02 transport to tissues as estimated by TCpO2.EilDOGEHOUS OPIATES CAUSE NEOiTATAL DEPRESSIO1.I FOLLOW-1267 Ii4G FETAL ASPHYXIA. Victor Chernick and Randy J. Craig Univ. of Manitoba, Dept. of Peds., Winnipeg, Manitoba. Nalo...