246 - Vasopressin as adjunctive therapy in pulmonary hypertension associated with refractory systemic hypotension in the newborn

Poster Number: 246
Publication Number: 246.222

Felipe Santelices, Universidad Catolica de Chile, Santiago, Region Metropolitana, Chile; Matias Luco, Pontificia Universidad Catolica de Chile, Santiago, Region Metropolitana, Chile; Daniela Masoli, Pontificia Universidad Católica de Chile, Santiago, Region Metropolitana, Chile

Background: Persistent pulmonary hypertension (PPHN) is a syndrome characterized by elevated pulmonary vascular resistance, right-to-left shunting through the ductus arteriosus and prolonged exposure of the right ventricle to an increased afterload, leading to severe hypoxemia. It determines hemodynamic compromise. There has been interest in the use of vasopressin (VP) as a potent vasoconstrictor and venopressor. Studies have shown that low doses of VP cause selective vasodilatation in coronary, pulmonary, and renal vascular beds. These properties, along with its minimal inotropic and chronotropic effects, make VP an attractive therapy in neonates with systemic hypotension and oxygenation failure due to PPHN.

Objective: The use of vasopressin as an adjunctive therapy in pulmonary hypertension associated with refractory systemic hypotension has increased. The objective of our study is to describe its effects on term infants.

Design/Methods: Retrospective observational study. Setting in a referral level IV neonatal intensive care unit. The patients are term neonates admitted to our NICU who required vasopressin due to severe Pulmonary Hypertension and refractory hypotension during a 16-month period.

Results: We identified 22 neonates with a median gestational age of 37.2 weeks. The main cause of PPHN was congenital diaphragmatic hernia (81.8%). Median age at initiating VP was 6 days. All patients were on mechanical ventilation and receiving inhaled nitric oxide. Mean duration of vasopressin therapy was 53.2 hours. Regarding hemodynamic outcome: diastolic, systolic, and median systemic pressure significantly increased during the first 4 hours of treatment, as well as pH and urine output. Lactate and Vasoactive Inotropic Score decreased after 4 and 8 hours, respectively, after VP was started. Regarding oxygenation markers: oxygen requirements and mean airway pressure decreased significantly (and therefore the oxygenation index) after 4 hours of vasopressin. Echocardiographic indices of pulmonary hypertension improved after vasopressin with a significant decrease of tricuspid ingurgitation velocities and rate of right-to- left ductal shunt through the ductus arteriosus. Also left and right ventricular output increased after the initiation of vasopressin.Conclusion(s): This study showed that the use of vasopressin in neonates with persistent pulmonary hypertension was associated with a rapid and significant improvement in oxygenation and hemodynamic markers of perfusion, including blood pressure. Its effects begin early during the first hours of treatment and vasopressin can be safely withdrawn after 3 days of treatment.
Table.Patient characteristics.
Figure 1.Changes in mean, systolic, diastolic blood pressure, Vasoactive-inotropic score, lactate and urine output following vasopressin therapy.