[Nitrous oxide (NO) in the treatment of adult respiratory distress syndrome].

Inhaled nitric oxide (NO) may be beneficial in patients with adult respiratory distress syndrome (ARDS), by lowering the venous admixture in the lungs and thereby improving the hypoxemia, and by its vasodilator effect which improves pulmonary hypertension. We studied 6 patients with severe ARDS (PaO2/FiO2 9.6 +/- 1.7 kPa and mean pulmonary artery pressure [PAPm] 37 +/- 4 mm Hg) during short term inhalation of NO (30 minutes) at a concentration of 32 ppm. In all patients, we observed the same response, i.e. a significant increase in PaO2 (28 +/- 8% at the same FiO2, p = 0.014) and a decrease in PAPm (15 +/- 5%; p = 0.038) with rapid reversal when NO inhalation was halted. Toxic metabolites of NO, such as NO2, NO3, etc. remained < 1 ppm when measured in different sections of the respiratory circuit. We conclude, in agreement with the study of Rossaint et al. [16], that (1.) inhaled NO may be beneficial in ARDS by improving pulmonary hypertension and gas exchange; (2.) short term NO inhalation is probably safe; (3.) however, the safety of long term administration of NO and a beneficial effect on survival in ARDS patients remain to be shown.