CURRENT Essentials of Critical Care.pdf

202 Current Essentials of Critical CareStupor & Coma■ Essentials of Diagnosis• Patient unresponsive to any stimuli• Develops as result of diffuse dysfunction of cerebral cortices orinjury to reticular activating system• Diencephalon lesions: 1- to 2-mm pupils, normal eye movements,flexion abnormalities, Cheyne-Stokes respirations• Midbrain lesions: fixed and midline pupils, disconjugate eyemovements, extension abnormalities, hyperventilation• Pontine lesions: coma, pinpoint pupils, paralysis of extraocularmuscles, extension abnormalities, hyperventilation• Medullary lesions: variable mental status, pupil size, and eyemovements; flaccid muscles, apnea, circulatory collapse• Assess level of consciousness with Glasgow Coma Score; checkfor nuchal rigidity; asymmetry in neurologic examination; funduscopicexamination• Laboratory studies helpful for etiology or monitoring: metabolicpanel, arterial blood gas, toxicologic screen, serum osmolality,serum medication levels• CT or MRI of brain; LP if possible infection; EEG if seizuresuspected• Etiologies: metabolic, toxic, structural brain injury■ Differential Diagnosis• Seizure/postictal state, brainstem herniation• Hypertensive encephalopathy, catatonia• Hypercapnia/hypoventilation syndrome• Increased intracranial pressure■ Treatment• Protect airway; indications for intubation: absent gag reflex, respiratorycompromise, control of PaCO 2 to aid in management ofintracranial hypertension• Avoid sudden drops in blood pressure as this may result in herniationor irreversible brain injury• Intravenous thiamine followed by dextrose and naloxone; considerempiric antibiotics if diagnosis of meningitis or encephalitisentertained■ PearlUnder no circumstances should the pupils in a comatose patient bedilated to aid with retinal examination since changes in the pupil sizeare often the most reliable clinical indication of deterioration followingacute brain injury.ReferenceLiao YJ et al: An approach to critically ill patients in coma. West J Med2002;176:184. [PMID: 12016243]