Objective: To examine whether the early response to inhaled nitric oxide (iNO) is a measure of reversibility of lung injury and patient outcome in children with acute hypoxemic respiratory failure (AHRF).
Design: Retrospective review study.
Setting: Pediatric ICUs.
Patients: Thirty infants and children, aged 1 month to 13 years (median, 7 months) with severe AHRF (mean alveolar arterial oxygen gradient of 568±9.3 mm Hg, PaO2/fraction of inspired oxygen of 56±2.3, oxygenation index [OI] of 41±3.8, and acute lung injury score of 2.8±0.1). Eighteen patients had ARDS.
Interventions: The magnitude of the early response to iNO was quantified as the percentage change in OI occurring within 60 min of initiating 20 ppm iNO therapy. This response was compared to patient outcome data.
Measurements and results: There was a significant association between early response to iNO and patient outcome (Kendall tau B r=0.43, p<0.02). All six patients who showed <15% improvement in OI died; 4 of the 11 patients (36%) who had a 15 to 30% improvement in OI survived, while 8 of 13 (61%) who had a >30% improvement in OI survived. Overall, 12 patients (40%) survived, 9 with ongoing conventional treatment including iNO, and 3 with extracorporeal support.
Conclusions: In AHRF in children, greater early response to iNO appears to be associated with improved outcome. This may reflect reversibility of pulmonary pathophysiologic condition and serve as a bedside marker of disease stage.