Withdrawal of inhaled nitric oxide from nonresponders after short exposure

Abstract

Introduction: Inhaled nitric oxide has been approved by FDA for treatment of hypoxic respiratory failure in term and near-term neonates. The safety of withdrawing NO in patients who fail to respond is a major concern. Objective: To obtain further insight into the safety of withdrawing NO in patients who do not initially respond to this therapy, the charts of patients enrolled at our center in the Neonatal Nitric Oxide Study (NINOS) were reviewed. Oxygenation indices (OI) before, during and after exposure to NO or placebo were compared. Methods: The charts of 110 neonates who received NO or placebo within the NINOS trial guidelines from 1995 to 1999 were reviewed. Arterial blood gases of nonresponders before, during and after a 30-minute exposure to different doses of NO or placebo were analyzed. Results: For both high-dose and 20 ppm nonresponders who received NO, there was no significant change in OI from baseline after withdrawing NO. For patients receiving placebo, there was a significant increase in OI following a 30-minute exposure to placebo. Conclusions: NO has been shown to be effective in the treatment of neonatal respiratory failure; however, not all recipients demonstrate clinical improvement. This study showed that withdrawing NO in nonresponders did not cause increased respiratory morbidity when NO exposure was limited to 30 min. Differences between our results and others showing refractory hypoxia after withdrawing NO may be due to different durations of NO exposure and, possibly, its effect on endogenous NO metabolism.