AANN Core Curriculum, 7th Edition, Ch. 8 Temperature Management: Digital Version-Chapter 8

Chapter 8
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Human core temperature is normally 36.5–37.5°C and reflects the balance between heat production and loss. The hypothalamus integrates signals from body thermoreceptors: its anterior region regulates heat loss, while the posterior region promotes heat conservation and production through sweating, vasodilation, vasoconstriction, and shivering. Infants rely heavily on heat-producing brown fat and have limited shivering; older adults have less brown fat and muscle, delayed vasodilation, and reduced sweating, increasing risks of accidental hypothermia or heat stress.<br /><br />Fever occurs when pyrogens raise the hypothalamic set point, partly through prostaglandin E2. In brain injury, fever can intensify inflammation, cerebral metabolism, glutamate release, blood–brain barrier disruption, edema, ischemia, and secondary injury. Normothermia (36.5–37.5°C) is generally prioritized in neurocritical care; controlled hypothermia is used for selected conditions. Continuous core-temperature monitoring—often esophageal or bladder—is preferred during targeted temperature management (TTM); oral, axillary, and tympanic readings are less reliable.<br /><br />TTM uses medication and physical cooling to achieve a prescribed goal. Fever control is important after stroke, traumatic brain injury, subarachnoid hemorrhage, and other acute neurologic injuries. Hypothermia is established for selected post-cardiac-arrest patients and neonates with hypoxic–ischemic encephalopathy; its role in other conditions remains limited or under study. It may reduce cerebral metabolism, edema, and intracranial pressure (ICP), but can cause electrolyte shifts, cold diuresis, impaired coagulation, hyperglycemia, bradycardia, arrhythmias, infection, and pneumonia. Rewarming can provoke hypotension, electrolyte changes, rebound fever, or increased ICP.<br /><br />Shivering sharply increases metabolic demand, oxygen consumption, and carbon dioxide production, potentially reducing brain oxygenation. Protocols should specify eligibility, target and duration, continuous monitoring, shivering prevention and treatment, multisystem surveillance, and controlled rewarming. Neurologic prognosis after hypothermia may be confounded by sedation and delayed drug clearance; decisions should generally await rewarming and adequate drug washout, using delayed, multimodal assessment.
Keywords
core temperature
hypothalamus
thermoregulation
fever
pyrogens
prostaglandin E2
targeted temperature management
hypothermia
shivering
neurocritical care