Acute effects of inhaled nitric oxide in adult respiratory distress syndrome

G. A. Iotti, M. C. Olivei, A. Palo, C. Galbusera, R. Veronesi, A. Braschi

Research output: Contribution to journalArticlepeer-review


This study evaluated the dose-response effect of inhaled nitric oxide (NO) on gas exchange, haemodynamics, and respiratory mechanics in patients with adult respiratory distress syndrome (ARDS). Of 19 consecutive ARDS patients on mechanical ventilation, eight (42%) responded to a test of 10 parts per million (ppm) NO inhalation with a 25% increase in arterial oxygen tension (P(a,O2)) over the baseline value. The eight NO-responders were extensively studied during administration of seven inhaled NO doses: 0.5, 1, 5, 10, 20, 50 and 100 ppm. Pulmonary pressure and pulmonary vascular resistance exhibited a dose-dependent decrease at NO doses of 0.5-5 ppm, with a plateau at higher doses. At all doses, inhaled NO improved O2 exchange via a reduction in venous admixture. On average, the increase in P(a,O2) was maximal at 5 ppm NO. Some patients, however, exhibited maximal improvement in P(a,O2) at 100 ppm NO. In all patients, the increase in arterial O2 content was maximal at 5 ppm NO. The lack of further increase in arterial O2 content above 5 ppm partly depended on an NO-induced increase in methaemoglobin. Respiratory mechanics were not affected by NO inhalation. In conclusion, NO doses ≤5 ppm are effective for optimal treatment both of hypoxaemia and of pulmonary hypertension in adult respiratory distress syndrome. Although NO doses as high as 100 ppm may further increase arterial oxygen tension, this effect may not lead to an improvement in arterial O2 content, due to the NO- induced increase in methaemoglobin. It is important to consider the effect of NO not only on arterial oxygen tension, but also on arterial O2 content for correct management of inhaled nitric oxide therapy.

Original languageEnglish
Pages (from-to)1164-1171
Number of pages8
JournalEuropean Respiratory Journal
Issue number5
Publication statusPublished - Nov 1998


  • Adult respiratory distress syndrome
  • Inhaled nitric oxide
  • Methaemoglobin
  • Nitric oxide
  • Oxygenation
  • Pulmonary hypertension

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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