Etiology

Extrinsic causes include choking, toxic gases, exhaust gas (principally carbon monoxide), electric shock, drugs, anesthesia, trauma, crushing injuries of the chest, compression of the chest, injury of the respiratory nerves or centers, diminished environmental oxygenation, and drowning.

Intrinsic causes include hemorrhage into the lungs or pleural cavity, foreign bodies in the throat, swelling of the airways, diseases of the airways, ruptured aneurysm or abscess, edema of the lung, cardiac deficiency, tumors such as goiter, and pharyngeal and retropharyngeal abscesses. Other causes include paralysis of the respiratory center or of respiratory muscles, anesthesia, pneumothorax, narcotic drugs, electrocution, and child abuse.

Symptoms

In general, symptoms range in severity from dyspnea, palpitations, and impairment of consciousness, to coma, seizures, permanent brain injury, and death.