Pulmonary Circulatory Effects of Norepinephrine in Newborn Infants with Persistent Pulmonary Hypertension

ObjectiveTo evaluate the respiratory and the pulmonary circulatory effects of norepinephrine in newborn infants with persistent pulmonary hypertension (PPHN)-induced cardiac dysfunction.Study designInclusion criteria were: 1) Newborn infants >35 weeks gestational age; 2) PPHN treated with inhaled nitric oxide; and 3) symptoms of circulatory failure despite adequate fluid resuscitation. Lung function and pulmonary hemodynamic variables assessed with Doppler echocardiography were recorded prospectively before and after starting norepinephrine.ResultsEighteen newborns were included (gestational age: 37 ± 3 weeks; birth weight: 2800 ± 700 g). After starting norepinephrine, systemic pressure and left ventricular output increased respectively from 33 ± 4 mm Hg to 49 ± 4 mm Hg and from 172 ± 79 mL/kg/min to 209±90 mL/kg/min (P < .05). Although the mechanical ventilatory variables have not been changed, the post-ductal transcutaneous arterial oxygen saturation increased from 89% ± 1% to 95% ± 4%, whereas the oxygen need decreased from 51% ± 24% to 41% ± 20% (P < .05). The pulmonary/systemic pressure ratio decreased from 0.98 ± 0.1 to 0.87 ± 0.1 (P < .05). Mean left pulmonary artery blood flow velocity increased by 20% (P < .05).ConclusionNorepinephrine may improve lung function in newborn infants with PPHN through a decrease in pulmonary/systemic artery pressure ratio and improved cardiac performance.