Inspiratory NO Concentration Fluctuation During Inhalational NO Administration
In the presence of pulmonary hypertension inhalation of nitric oxide (NO) in low concentrations produces selective pulmonary vasodilation without an effect on the systemic vasculature . Inhaled NO is delivered predominantly to well ventilated lung areas. Thus, in lung diseases with severe mismatching of ventilation and perfusion (e.g., acute lung injury) pulmonary vasodilation occurs selectively in ventilated alveoli. This is in contrast to other vasodilators such as intravenous prostacyclin or nitroglycerin. Inhaled NO causes a redistribution of the pulmonary blood flow from non- or poorly ventilated areas to ventilated areas of the lung, and consequently improves oxygenation by a reduction of the intrapulmonary right-to-left shunt . The selectivity of NO’s effects are mainly caused by its short action of only a few seconds. NO binds quickly to hemoglobin which is then rapidly converted via nitrosyl Fe(II)-hemoglobin to methemoglobin. Owing to its attractive properties inhalational NO has been proposed as a therapeutic agent in many cardiopulmonary diseases. However, due to its potential chemical reactivity and toxicity the delivery of inhaled NO requires special equipment and techniques.
KeywordsNitric Oxide Minute Ventilation Adult Respiratory Distress Syndrome Inspiratory Flow Concentration Fluctuation
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