RANGE OF ECHOCARDIOGRAPHIC FINDINGS IN TERM NEONATES WITH HIGH OXYGENREQUIREMENTS

Aims-To examine the hypothesis that right to left shunting occurs main ly in the lungs rather than through the fetal channels in neonates. Me thods-Thirty two term babies requiring over 70% oxygen had daily colou r Doppler echocardiograms until recovery. Measurements included left v entricular fractional shortening, right and left ventricular outputs, colour and pulsed Doppler ductal and atrial shunting and systolic pulm onary artery pressure (SPAP) derived from ductal shunt or tricuspid in competence velocities. Results-The babies were retrospectively classif ied into a respiratory group (n=19) and a persistent pulmonary hyperte nsion (PPHN) group (n=13) on the basis of clinical history and radiolo gy. At the initial echocardiogram, just 50% of babies had suprasystemi c SPAP. Despite better oxygenation, more of the PPHN group had suprasy stemic PAP (85% vs 26%). A correlation between SPAP and Oxygen index ( OI) was present only in the respiratory group (r=0.7). Low ventricular outputs (<150 ml/kg/min) were common in both groups (53% and 79%). Th e respiratory group had more closed ducts (47% vs 0%) and those ducts which were patent were more constricted (1.75mm vs 2.6 mm). Pure right to left ductal shunts were seen in just 15% and pure right to left at rial shunts in just 6% of all babies. The serial echocardiograms showe d that SPAP fell and ducts closed well before oxygenation improved. Ve ntricular outputs increased with age in both groups. Conclusions-Apart from early on in the sickest babies with a primarily respiratory diag nosis and the babies with primary PPHN, most right to left shunting oc curred at an intrapulmonary level.