Low levels of nitric oxide as contaminant in hospital compressed air: physiologic significance?

Crit Care Med. 1997 Jul;25(7):1143-6. doi: 10.1097/00003246-199707000-00014.


Objectives: To determine whether the levels of nitric oxide found in hospital compressed air have a clinically relevant effect on oxygenation in intubated patients with normal lungs.

Design: Prospective study.

Setting: Cardiothoracic and surgical intensive care unit in a university hospital.

Patients: Twelve postoperative patients receiving mechanical ventilation.

Interventions: Pure nitrogen and oxygen were substituted for hospital compressed air as a source of blending for correct FIO2.

Measurements and main results: Hemodynamics and PaO2 were measured in nitrogen and oxygen used for blending oxygen during stable FIO2 levels. Inhaled nitric oxide was measured with a nitric oxide-chemiluminescence detector. There was no clinically relevant change in systemic hemodynamics. However, the PaO2 decreased significantly when nitrogen was used for blending. Inhaled nitric oxide levels varied from 2 to 550 parts per billion during use of hospital compressed air; no nitric oxide was detectable during use of nitrogen.

Conclusions: The low concentration of nitric oxide in hospital compressed air improves oxygenation in patients with normal lungs receiving mechanical ventilation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Gas Analysis
  • Critical Care*
  • Environment, Controlled*
  • Hemodynamics
  • Hospitals, University
  • Humans
  • Intensive Care Units
  • Lung Volume Measurements
  • Nitric Oxide*
  • Nitrogen
  • Oxygen
  • Prospective Studies
  • Respiration, Artificial*


  • Nitric Oxide
  • Nitrogen
  • Oxygen