Therapeutic Role of Nitric Oxide in Respiratory Disease

Thomas E. Siddons, BSc, Mohammed Asif, MA, BMBCh, FRCS, and Tim W. Higenbottam, MD, MA, BSc, FRCP, University of Sheffield, Sheffield, United Kingdom

In This Article

Inhaled NO in Adult Respiratory Distress Syndrome

Although the morbidity and mortality rates of adult respiratory distress syndrome (ARDS) found in the medical literature in the United States and Europe range between 10% and 90%,[6] these rates are based on different definitions of this condition. Until recently, there was no consensus on the definition of ARDS. It is now defined as an acute-onset, inflammatory condition characterized by increased vascular permeability that is associated with a constellation of clinical, radiologic, and physiologic abnormalities that cannot be explained by, but may coexist with, left atrial or pulmonary capillary hypertension.[6] The alveoli become filled with an exudate that consists of blood protein, water, and electrolytes. This reduces the surface area available for gas exchange and increases the volume of blood passing through the lungs that does not participate in gas exchange. This partially explains the reduction in PaO2, despite breathing 100% oxygen.[7]

Inhaled NO therapy is successful in treating ARDS because of its vasodilator properties. It reduces pulmonary artery pressure and causes vasodilation of the blood vessels that supply the ventilated regions.[8] This reduces the shunt fraction and causes a concomitant increase in PaO2. Although this addresses the pulmonary component of ARDS, the disease is a condition complicated by multiple organ failure and a systemic inflammatory component, which is not yet fully understood.


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