Background: Inhaled nitric oxide (iNO) has been successfully used in infants with severe persistent pulmonary hypertension (PPHN). This therapy, however, is expensive and complex and may not be available n developing countries. Sildenafil, a phosphodiesterase inhibitor (PDI) type V, has been shown to selectively reduce pulmonary vascular resistance in both animal models and patients. Weather Sildenafil could be effective as an alternative to iNO therapy in PPHN, is not known.
Objective: To compare the efficacy of oral Sildenafil therapy and conventional therapy in neonates with PPHN diagnosis, prospectively. DESIGN/METHODS: Term neonates with PPHN diagnosis and oxygenation index (OI) >25 were randomly assigned to placebo (n=11) or to Sildenafil at 2 mg/kg by orogastric tube every 6 h (n=13). Arterial blood gases, OI, mean airway pressure (MAWP) and mean blood pressure (BP) were periodically recorded at least up to 72 hours. Clinical management included IMV, inotropes, but no iNO.
Results: Oxygenation Index was gradually and significantly decreased in both placebo and Sildenafil groups (repeated measures of ANOVA followed by Dunnett multiple comparisons test). These changes in OI were significantly (p<0.01) lower in the Sildenafil-treated patients, starting with the first hour after its administration (ANOVA followed by Bonferroni correction for multiple comparisons). In both groups, PaO2 was also gradually and significantly increase and became significantly more pronounced at 72 hours with Sildenafil treatment (p<0.01). MAWP was significantly lower in the Sildenafil-traeted patients, starting 6 hours after its administration. No significant differences in PaCO2 or BP were observed.The ventilatory days were significantly lower in the Sildenafil group (p<0.01; unpaired t-test). All patients in the Sildenafil-treated patients survived, as compared to 8/11 patients in the placebo group
Conclusions: Oral Sildenafil in term infants with severe PPHN improves oxygenation indices (OI; PaO2; MAWP) without decreasing systemic blood pressure.
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Castillo, J., Herrera, R., Concha, E. et al. 385 Oral Sildenafil Treatment as an Alternative to Inhaled no Therapy for Persistent Pulmonary Hypertension of the Newborn. Pediatr Res 58, 420 (2005). https://doi.org/10.1203/00006450-200508000-00414