Bronchodilator Effects On Neonatal Cardiovascular Function And Gas-Exchange

The use of bronchodilators in newborn infants is common clinical practice; however, their effects on gas exchange and on the cardiovascular system have not been evaluated. The purpose of this study was to investigate the effects of Isoetharine (I) nebulization, given during the first 3 days of life, on trans-cutaneous PO2 (PtcO2) and PCO2 (PtoCO2), heart rate (HR) and blood pressure (BP) of 12 preterm infants with severe HMD treated with ventilator; BW 1570±537gm, GA 30±3wks. 2ml of I 0.08% were nebulized while connected to the ventilator at the same baseline mean airway pressure each day. Data obtained before (baseline) and 15 min after I were compared. There were no cardiac arrhythmias found during the study. HR, BP, and PtcO2 were not significantly different 15 min after I nebulization, however, PtcCO2 reduced from mean values of 45 to 43 mmHg in day 1(p<.05) from 48 to 44 mmHg in day 2(p<.05) and from 47 to 42 mmHg in day 3(p<.05). The absence of cardiovascular effects after I are explained by its selective action on B2 receptors. The decrease in PtcCO2 suggests that I nebulization, given at constant mean airway pressure, improves ventilation either by relieving bronchoconstrictioh with an increase in minute ventilation or improvement in ventilation-perfusion matching. We conclude that I is an effective drug to improve ventilation without significant cardiovascular side effects in infants with severe HMD.