Adenosine Infusion Improves Oxygenation in Term Infants With Respiratory Failure

Abstract

Adenosine infusion causes selective pulmonary vasodilation in fetal and neonatal lambs with pulmonary hypertension. We investigated the effects of a continuous infusion of adenosine on oxygenation in term infants with persistent pulmonary hypertension of newborn (PPHN). A randomized, placebo-controlled, masked trial comparing the efficacy of intravenous infusion of adenosine to normal saline infusion over a 24-hour period. Inborn and outborn level III neonatal intensive care units at a university medical center. Eighteen term infants with PPHN and arterial postductal PO2 of 60 to 100 Torr on inspired O2 concentration of 100% and optimal hyperventilation (PaCO2 <30 Torr) were enrolled into the study. Study infants were randomly assigned to receive a placebo infusion of normal saline, or adenosine infusion in doses of 25 to 50 microg/kg/min over a 24-hour period. Eighteen term infants with PPHN and arterial postductal PO2 of 60 to 100 Torr on inspired O2 concentration of 100% and optimal hyperventilation (PaCO2 <30 Torr) were enrolled into the study. Study infants were randomly assigned to receive a placebo infusion of normal saline, or adenosine infusion in doses of 25 to 50 microg/kg/min over a 24-hour period. Nine infants each received adenosine or placebo. The two groups did not differ in birth weight, gestational age, or blood gases and ventilaator requirements at the time of entry into the study. Four of nine infants in the adenosine group and none of the placebo group had a significant improvement in oxygenation, defined as an increase in postductal PaO2 of > or =20 Torr from preinfusion baseline. The mean PaO2 in the adenosine group increased from 69 +/- 19 at baseline to 94 +/- 15 during 50 microg/kg/min infusion rate of adenossine and did not change significantly in the placebo group. Arterial blood pressure and heart rate did not change during the study in either group. The need for extracorporeal membrane oxygenation, incidence of bronchopulmonary dysplasia, and mortality were not different in the two groups. Data from this pilot study indicate that adenosine infusion at a dose of 50 microg/kg/min improves PaO2 in infants with PPHN without causing hypotension or tachycardia. Larger trials are needed to determine its effects on mortality and/or need for extracorporeal membrane oxygenation in infants with PPHN.