The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

THE FUTURE OF INHALED NITRIC OXIDE IN OTHER DISEASE STATES

Dean Hess, PhD, RRT Assistant Professor of Anaesthesia Harvard Medical School Assistant Director of Respiratory Care Massachusetts General Hospital Boston, MA 02114

Therapeutic applications of inhaled nitric oxide have involved primarily its effects as a selective pulmonary vasodilator. It is becoming increasingly recognized that inhaled nitric oxide may have other important physiologic effects. Nitric oxide affects the functions of blood components such as red blood cells, platelets, and leukocytes. Because all of the cardiac output normally flows through the lungs, there may be clinically significant effects of inhaled nitric oxide on blood components. In-vitro and in-vivo studies have reported that inhaled nitric oxide produces a left-shift of the oxyhemoglobin dissociation curve in the blood of individuals with sickle cell disease. This may reduce hemoglobin polymerization in individuals with this disease and this is presently being evaluated in a multi-center double-blind placebo-controlled trial. Inhaled nitric oxide is also known to affect hemoglobin aggregation and agglutination. Although this effect is often listed as a potential adverse effect of inhaled nitric oxide, its antithrombotic effects may be beneficial in some applications. For example, the antiplatelet effects of inhaled nitric oxide may be beneficial to improve coronary artery patency after thrombolysis and in the treatment of pulmonary embolism. Inhaled nitric oxide may also be useful in the treatment of ischemia-reperfusion injury, which occurs clinically with removal of a large pulmonary embolus, surgery involving cardiopulmonary bypass, and following transplantation. It has been reported that inhaled nitric oxide at the correct dose (e.g., 30 ppm) and at the correct time (e.g., during reperfusion rather than during ischemia) can decrease endothelial permeability and can decrease neutrophil sequestration in the lungs. The use of nitric oxide to measure pulmonary diffusion capacity has been reported. This suggests that inhaled nitric oxide might be used to asses lung function in mechanically ventilated patients. At the Massachusetts General Hospital, we are presently investigating this possibility. Each of these potential clinical applications for inhaled nitric oxide is in its infancy and must be confirmed using properly designed scientific studies with appropriate outcome variables.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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