Oxygenation improvement with nitric oxide in right-to-left shunt without significant effects on pulmonary arterial pressure.

Following surgical closure of an interventricular communication complicating an anterior myocardial infarction, a 74-year-old woman developed severe right ventricular failure and hypoxemia due to the opening of a patent foramen ovale (PFO). Mean pulmonary artery pressure was 24 mm Hg. Treatment with inhaled nitric oxide (5 ppm) increased PaO2 from 47 to 90 mm Hg (FIo(2)1). The present observation points out that nitric oxide inhalation could be useful in the management of severe hypoxemia from a right-to-left shunt due to a PFO even when there is no significant pulmonary hypertension present.