Asphyxiants: Simple and Chemical

Asphyxiants are gases that cause tissue hypoxia. They are classified as either simple or chemical on the basis of the mechanism of toxicity. Simple asphyxiants decrease FiO2 by displacing oxygen in inspired air, results in hypoxemia. Chemical asphyxiants interfere with oxygen transport system and cellular respiration and thereby cause tissue hypoxia. Mild symptoms of asphyxia include headache, dizziness, nausea, and vomiting. More severe symptoms range from dyspnea, altered sensorium, cardiac dysrhythmia, ischemia, syncope, seizure, and even death. Clinical diagnosis of asphyxiant exposure is limited. A consistent history, myriad spectrum of complaints, group victims, and rapid resolution on away from exposure are generally sufficient. Occupational exposures and fires are the most common sources of inhalation injuries. Working in confined spaces are harzardous to workers. Rapid removal, supportive care and preventing hypoxemia are the mainstay of treatment. Emergency planning should be applicable to both accidental and deliberate chemical disasters. (Ann Disaster Med. 2005;4 Suppl 1:S35-S40)