Doppler Echocardiographic Assessment of the Changes in Pulmonary Arterial Pressure in Preterm Infants with Respiratory Distress Syndrome

Sohn, Sejung; Park, Eun Ae

Abstract

PURPOSE: The ratio of time to peak velocity(AT) and right ventricular ejection time(ET) as measured from the pulmonary artery Doppler waveform showed a close inverse correlation with pulmonary arterial pressure. The purpose of this study was to see the pattern of change in pulmonary arterial pressure assessed by AT/ET in preterm infants with respiratory distress syndrome (RDS).
METHODS
The changes in pulmonary arterial pressure were assessed by serial AT/ET measurements in 18 preterm infants with RDS.
RESULTS
The mean AT/ET was significantly lower in the acute phase of RDS. The pattern of change in AT/ET during recovery from RDS fell into three groups. In group 1(n=11), there was a normalization of AT/ET. Four infants showed a rapid normalization of the ratio within 24 hours of the oxygen requirements falling and the remaining 7 showed a delayed normalization. In group 2(n=4), AT/ET did not rise into the normal range during the time of study. All of the infants developed bronchopulmonary dysplasia(BPD). In 2 of the 4 infants, the ratio rose towards the normal range in the early recovery phase, but fell as the recovery period continued whereas in the remaining 2, the ratio remained at a consistent low level throughout the recovery period. One infant died of severe BPD at 36 days of age and 3 were breathing air at the time of discharge. In group 3(n=3), AT/ET decreased during a relatively short period, leading to death in all infants.
CONCLUSION
Pulmonary hypertension in the acute phase of RDS is usually normalized during the recovery period. In infants who develop BPD, however, pulmonary pressure persistently remains high and in those with mortality, it is aggravated during a short-term interval.