nitric oxide (NO), 1. a colorless gas and stable free radical commonly found in tissues of humans and other mammals. It is also prepared commercially by passing air through an electric arc. Biologically the effector molecule is commonly synthesized from the amino acid arginine. NO participates in many biological functions, such as neurotransmission, vasodilation, cytotoxicity of macrophages, lipid-lowering therapy, and inhibition of platelet aggregation. NO is involved in smooth muscle action and penile erection. It may improve oxygenation in patients with high-altitude pulmonary edema. NO deprivation may lead to high blood pressure and the formation of atherosclerotic plaque. On contact with air, NO is quickly converted to the very poisonous nitrogen dioxide (NO2). 2. a respiratory inhalant. ▪ INDICATIONS: It is used in combination with other agents and ventilatory support in the treatment of full-term and near-term (34 weeks) neonates with hypoxic respiratory failure associated with pulmonary hypertension. ▪ CONTRAINDICATIONS: Two factors that prohibit its use are dependence on right-to-left shunting of blood and known hypersensitivity. ▪ ADVERSE EFFECTS: Life-threatening effects are pulmonary hemorrhage, intracranial hemorrhage, sepsis, stridor, methemoglobinemia, seizures, cerebral infarction, and posttreatment infection. Other adverse effects include atelectasis, hematuria, hyperglycemia, cellulitis, withdrawal syndrome, and hypotension.
