A Combined Doppler Echocardiographic Investigation in Premature Infants with and without Respiratory Distress Syndrome
Premature infants often develop the Respiratory Distress Syndrome (RDS). In the traditional view, this is due to a lack of surfactant causing a collapse of lung alveoli. In a number of cases of RDS, a Patent Ductus Arteriosus (PDA) with Left to Right (L-R) shunt is diagnosed during the recovery phase of the syndrome from the presence of a murmur, bounding pulses and an increased Left Atrium/Aorta ratio (LA/Ao). This diagnosis of the PDA has wrongly led to the conclusion that this L-R shunt first arises in the recovery phase; perhaps because routine clinical examination is not always sufficient to detect a PDA, since a large PDA with L-R shunt is not always acompanied by a heart murmur and even the echocardiographic demonstration of an increase in LA dimension or LA/Ao ratio is not conclusive evidence for the existence of a PDA with L-R shunt. Theoretically, a PDA with L-R shunt can cause respiratory problems, especially in small infants, as a result of pulmonary vessel engorgement, leading in turn to surfactant deficiency due to anoxaemia. So we have the situation indicated below:
In our investigation we demonstrated the existence of a PDA with L-R shunt in premature infants by means of a combined Doppler echocardiographic (DE) technique. The moment of closure of the ducus could be estimated from successive measurements. We also measured the LA/Ao ratio by means of echocardiography to determine the magnitude of the L-R shunt.
KeywordsPremature Infant Patent Ductus Arteriosus Doppler Echocardiographic Main Pulmonary Artery Respiratory Problem
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