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General Considerations
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Coma is defined as the total absence of arousal and awareness lasting at least 1 hour associated with injury or functional disruption of the ascending reticular activating system in the brainstem or bilateral cortical structures. Comatose patients demonstrate no eye opening, speech, or spontaneous movements, and motor activity elicited by painful stimuli (if present) is abnormal or reflexive rather than purposeful. Coma must be differentiated from other pathologic changes in consciousness such as brain death, vegetative state, and delirium, although it may be difficult to do so in the emergency department.
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Initial management of the comatose patient involves the same steps needed to manage any critically ill patient presenting to the emergency department. Immediate assessment and support of airway, breathing, and circulation should be performed before efforts to diagnose or address specific causes of coma are undertaken, with the caveat that consideration may be given to postponing intubation until administration of empiric therapy for coma. Empiric therapy, often abbreviated by the acronym “D.O.N.T.” consists of IV dextrose, supplemental oxygen, IV naloxone, and thiamine. Dextrose (50 mL of 50% solution in adults) reverses coma secondary to hypoglycemia and is indicated if rapid testing of blood glucose is unavailable. Oxygen therapy should be initiated to immediately correct possible hypoxemic induced coma. Naloxone (0.4–2.0 mg IV) rapidly reverses coma and respiratory depression secondary to narcotic overdose but because of short half-life, multiple doses may be required. Thiamine (100 mg IV) is commonly given along with dextrose to avoid precipitating Wernicke encephalopathy in predisposed patients. Flumazenil (0.2 mg/min IV) specifically antagonizes benzodiazepines but is not routinely given empirically as it may precipitate seizures that are then refractory to benzodiazepines. It may be indicated in iatrogenic coma secondary to excess benzodiazepine administration.
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If coma persists following the administration of naloxone and dextrose, definitive management of airway and breathing should be considered. IV access with two large-bore IVs should be obtained and blood pressure (especially hypotension) managed aggressively. A complete set of vital signs, including temperature and pulse oximetry, is essential to avoid missing coma complicated by severe hypo- or hyperthermia and hypoxia. Cervical spine immobilization should be maintained if there is any suspicion of trauma. A focused physical examination should be performed to evaluate for potential precipitating factors (evidence of drug use, systemic trauma, etc). Obtaining additional history from friends, relatives, bystanders, and EMS personnel is essential.
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Neurologic assessment in comatose patients is of paramount importance, and a structured evaluation should be conducted as soon as possible once immediate threats to life have been addressed. Level of consciousness, cranial nerve examination, and motor examination should be performed. Lateralizing deficits and a rostrocaudal progression of brainstem dysfunction ...