Inhaled nitric oxide and high frequency oscillatory ventilation in persistent pulmonary hypertension of the newborn
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Inhaled nitric oxide (iNO) improves oxygenation in near-term and term newborns with persistent pulmonary hypertension of the newborn (PPHN), and decreases the need for treatment with extracorporeal membrane oxygenation. However, some patients with PPHN either do not respond or have only transient improvements in oxygenation during iNO therapy. Extrapulmonary shunting associated with high pulmonary vascular resistance in PPHN can cause critical hypoxaemia; however, the syndrome of PPHN is often associated with severe parenchymal lung disease (e.g., meconium aspiration pneumonitis, bacterial pneumonia, and surfactant deficiency) which causes intrapulmonary shunting. It is increasingly recognized that the effective use of iNO requires adequate lung inflation to optimize delivery of the drug within the lung. High frequency oscillatory ventilation (HFOV) causes safe and effective lung recruitment when an appropriate strategy is applied and has recently been shown to improve the response to iNO when parenchymal lung disease occurs in association with PPHN.
Conclusion Recent studies have shown that HFOV augments the response to iNO in PPHN associated with meconium aspiration syndrome or diffuse parenchymal lung disease (pneumonia, respiratory distress syndrome). Suboptimal lung inflation compromises the efficacy of iNO in PPHN, and may in part explain the reported differences in iNO response rates.