IMPROVED OXYGENATION AND VENTILATION WITH LOW-DOSE INHALED NITRIC OXIDE IN PEDIATRIC SEVERE RESPIRATORY DISEASE. † 295

Inhaled nitric oxide (NO) has been reported to improve oxygenation in severe respiratory disease, possibly by decreasing ventilation-perfusion mismatching. However, an optimal dose of NO has not been defined and excessive NO could reduce efficacy by increasing perfusion in non-ventilated areas. We examined the effect of increasing doses of inhaled NO on P_aO₂& P_aCO₂ in patients with severe respiratory disease, hypothesizing that low dose NO would be as effective in improving oxygenation as the higher doses. Methods: Mechanically ventilated infants and children with primary, acute severe respiratory failure were eligible for study if they required a PEEP ≥ 10 cmH₂O and a F_iO₂≥50% to maintain a P_aO₂≥80 or had a P_aO₂/F_iO₂≤150. NO was given through the ventilator at 1, 5, 10 and 20 parts per million (PPM). An arterial blood gas was obtained before NO (base) and at each dose after 15 min of stability. Ventilator settings were unchanged during the study. Statistical analysis used a repeated measures ANOVA and Tukey's protected T-test. Results: 13 patients (ages 1 mo-13 y) were evaluated. NO significantly increased P_aO₂ (p=0.038) and reduced P_aCO₂ (p=0.0056). An effect (p<0.05) of NO on P_aCO₂ was observed at 5,10 & 20 PPM and on P_aO₂ at all doses. There was no difference(p>0.05) in the response for any of the doses. The% change from baseline for all doses was similar (p>0.05) for both P_aO₂ & P_aCO₂. Conclusions: In agreement with previous reports, inhaled NO improved oxygenation in acute, severe respiratory disease in infants and children. However, NO also significantly improved ventilation. NO at 5 PPM was as effective as the higher doses; this may be important in minimizing toxicity. Inhaled NO may be a useful adjunct in the treatment of ventilated patients with severe lung disease. Table

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