Cardiac Arrest, Coma, and Cerebral Death
The chapter begins with a discussion of common major clinical features and mechanisms of damage produced by hypoxia and ischemia. Consciousness has three attributes: arousal, wakefulness, and awareness of self and environment. Arousal is the ability to awaken from sleep and wakefulness and awareness are states of alertness. Pathologic states of consciousness include confusion (lack of clarity and coherence with speech at a slower speed than usual), delirium (confusion with agitation, restlessness, and fragmented slurred speech), obtundation (abnormal alertness associated with slow reaction times), stupor or semicoma (unconsciousness requiring constant strong verbal or physical stimuli to remain aroused), and coma (inability to arouse from any stimuli to produce appropriate responses). Etiologies causing coma are divided into 3 categories: supratentorial mass lesions, infratentorial destructive lesions, and metabolic causes.
Cerebral death involves the permanent loss of the capacity for consciousness, combined with the irreversible loss of the capacity to breathe. The U.S. Presidential Commission criteria for brain death heavily emphasize irreversible loss of brainstem functions. Anoxic death of neurons occurs by several factors that cascade once initiated. This chapter discusses the normal and abnormal states of consciousness, how anoxia and ischemia cause neuronal death, and the criteria to diagnose cerebral death. Attention is given to their pathophysiology, major clinical features, major laboratory findings, and principles of management and prognosis.
KeywordsConfusion Delirium Obtundation Cerebral death Coma
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