Nitric oxide for ARDS--what is the evidence?

We critically reviewed English-language articles indexed on MEDLINE from 1966-1998 and those cited in indexed articles describing or investigating administration of nitric oxide (NO) in adult respiratory distress syndrome (ARDS). Studies evaluating NO exclusively in the pediatric population and in conditions other than ARDS (chronic obstructive pulmonary disease, asthma, cardiac surgery, pulmonary hypertension) were excluded, as were those published exclusively as abstracts. Of the 22 papers selected, 5 studies were dose-response trials, eight were comparative, and the rest were noncomparative. Dose-dependent decreases in pulmonary artery pressures and increases in arterial oxygenation were observed; however, the minimal effective dose varied. Several short-term noncomparative and small noncomparative prospective trials concluded that NO improves oxygenation and decreases pulmonary vasoconstriction without effects on systemic hemodynamics. However, evidence that NO improves outcomes in patients with ARDS is insufficient because mortality remained high, and the number of subjects in each study was low. Since improvements in oxygenation are not seen in all patients and outcomes or mortality might not be altered, NO should be reserved for selected patients in whom conventional therapy is not sufficient to maintain acceptable oxygenation levels.