Neonatal pulmonary hypertension during extracorporeal membrane oxygenation

Objectives. This prospective study was designed to monitor severe pulmonary hypertension during extra corporeal membrane oxygenation using echo Dopple r variables. Background. All neonates treated with extracorporeal membrane oxygenation also have severe pulmonary hypertension. A study which monitors the reaction of the pre-existing pulmonary hypertension during extracorpor eal oxygenation by frequent sampling of those variables related to pulmonar y pressure is still lacking. Such a study is necessary to analyze the compl ex haemodynamic changes in patients undergoing extracorporeal membrane oxyg enation. Method. In 29 neonates, we estimated pulmonary arterial pressure u sing peakflow velocity of regurgitation across the tricuspid- and pulmonary valve, peakflow velocity of shunting across persistent arterial ductus, an d systolic time intervals of the right ventricle. Correlation between the s everal estimations of pulmonary atterial pressure were analysed with the Sp earman correlation coefficient. Results. Systolic pulmonary arterial pressu re measured by the velocity of tricuspid regurgitation illustrated severe p ulmonary hypertension prior to extra corporeal membrane oxygenation (mean 6 3 mmHg, sd 20). Similar levels for the systolic pulmonary arterial pressure could be derived (mean 73 mmHg, sd 17)from ductal shunting. A fair correla tion of 0.76 (p< 0.002) could be demonstrated. Pulmonary hypertension respo nded well and quickly to treatment by extra corporeal membrane oxygenation, with reductions within 24 hours to mean systolic levels of 35 mmHg, sd 23. This very early reaction has not previously been demonstrated and could be of importance in defining parameters for weaning from cardiopulmonary bypa ss. Diastolic pulmonary arterial pressure was investigated because of its r elation to vascular resistance. It proved mure difficult to measure because of the low incidence of pulmonary regurgitation. Derived diastolic pressur es did not show any good correlations. Conclusion. Pulmonary hypertension i s well documentated prior to extra corporeal membrane oxygenation and respo ns very quickly to the institution of treatment. Ultra sound techniques are indicated at: the bedsite, and prove useful in monitoring pulmonary blood pressure during the procedure.