Echocardiography in hypoxemic neonatal pulmonary disease

Sixteen newborn infants with severe pulmonary parenchymal disease and profound hypoxemia were treated with mechanical ventilation, alkalinization, and intravenous tolazoline. Eight infants responded within two hours of initiation of tolazoline therapy with a rise in Pao2 by at least 100% of pretreatment values (mean = 188%, range = 103 to 427%). Eight infants showed little or no change in Pao2 with administration of tolazoline. Echocardiographic evaluation prior to therapy demonstrated marked elevation in both left (LPEP/LVET = 0.52 +/- 0.13) and right (RPEP/RVET = 0.56 +/- 0.08) ventricular systolic time intervals in the eight infants who subsequently responded to tolazoline. Systolic time intervals in nonresponders were within the normal range (LPEP/LVET = 0.37 +/- 0.03, RPEP/RVET = 0.33 +/- 0.04) and were not significantly different from those observed in a control group of 15 infants with pulmonary disease requiring mechanical ventilation but without hypoxemia. Following tolazoline therapy, systolic time intervals in all eight responders fell to normal values. Echocardiography can provide a safe, noninvasive method for identifying those infants with primary pulmonary disease and severe hypoxemia who could be expected to benefit from tolazoline therapy, thereby avoiding tolazoline side effects in infants for whom tolazoline therapy can be predicted to be of little benefit.