RANDOMIZED TRIAL OF 3 DOSES OF INHALED NITRIC-OXIDE IN ACUTE RESPIRATORY-DISTRESS SYNDROME

Background-Inhaled nitric oxide (iNO) is a potential therapeutic agent for the management of acute respiratory distress syndrome (ARDS). Con cerns remain, however, regarding the potential toxicity from iNO and/o r its oxidative derivatives and methaemoglobinaemia. Aims-To determine the risk of toxicity from iNO, which includes worsening of lung injur y, a prospective study evaluating the acute effects of three concentra tions of iNO on gas exchange and haemodynamics in 12 children with ARD S was performed in a tertiary paediatric intensive care unit. Interven tion-iNO was administered for one hour at three concentrations (1, 10, and 20 parts per million (ppm)) in a random order of possible dosing schedules to avoid dose accumulation bias. Arterial blood gas, methaem oglobin concentrations, and haemodynamic parameters were obtained at b aseline before commencement of iNO, at the end of each study hour, and after iNO was discontinued. Nitric oxide and nitrogen dioxide concent rations were continuously monitored during the study. Results-iNO sign ificantly improved the oxygenation ratio (PaO2/FiO(2)) from a mean (SE M) baseline of 11.9 (1.7) kPa to 20 (3.9) kPa, 24 (4.5) kPa, and 21.6 (3.9) kPa at 1, 10, and 20 ppm iNO, respectively. There was no signifi cant difference in the improvement in oxygenation achieved between the three concentrations. Correspondingly, there was a significant improv ement in oxygenation index (pre-iNO 28.3 (5) v post-iNO 18 (3) (1 ppm) , 15 (3) (10 ppm), 16 (3) (20 ppm)). No toxicity from methaemoglobinae mia or nitrogen dioxide was seen during iNO administration. Conclusion -The results show that a low concentration of iNO (1 ppm) is as effect ive as higher concentrations (10 and 20 ppm) in improving oxygenation in children with ARDS and may be important in minimising toxicity duri ng iNO use.