32 EVALUATION OF TOLOZOLINE TEST IN THE TREATMENT OF PERSISTENT PULMONARY HYPERTENSION OF THE NEWBORN (PPHN) BY DOPPLER ECHOCARDIOGRAPHY

Abstract

To reverse pulmonary hypertension and to improve hypoxemia in PPHN, tolazoline (TZ) was tested to assess its ability to decrease pulmonary resistances. We aim to study the response to TZ vasodilation by Doppler echocardiography. We sequentially studied profiles of blood velocities in the left pulmonary artery. Through the second intercostal space, the zero angle incidence beam with the LPA allows reproducibility of repeated measurements. The ductal flow was recorded arid gradient calculated. After baseline, TZ bolus infusion was started at 1 mg/kg for 15 min, then increased by steps of 1 mg/kg if no response. Measurements were done every 5 min during the test. Material: The cohort included seven cases of PPHN:Diaphragmatic hernia, respiratory distress syndrome, Strepto, Coli and Mycoplasma sepsis. Results: the different responses were I-Immediate increased pulmonary blood flow and increase in PaO2, 2-TZ dose dependent increased PBF, 3-immediaic increase in flow and deferred increase in PaO2, 4 -Absence of response. In conclusion, Doppler evaluation of PBF, during TZ infusion, demonstrates immediate response on PBF allowing dose adaptation. It also demonstrates the magnitude of reversed shunt across the ductus to increase diastolic PBF. Transductal gradient gives estimation of pulmonary arterial pressure. It shows presence of intrapulmonary right to left shunt and evidence of hypoventilation. Then increased doses of TZ leading to ominous side-effects are avoided.