Study note

Neonatal heat production and consequences of temperature disturbance

THE CONTEXT

Brown fat contributes to neonatal heat production, while hypothermia and hyperthermia produce distinct physiological problems.

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Norepinephrine release uncouples beta-oxidation in fat, generating heat.

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Blood passing through brown fat becomes warmer and helps maintain neonatal warmth.

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Preterm and small for gestational age infants have scanty brown fat stores.

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Hypothermia-induced peripheral vasoconstriction leads to increased metabolism and excess oxygen and glucose utilization.

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Below 32°C, hemoglobin cannot release oxygen, resulting in tissue hypoxia.

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Consequent anaerobic metabolism causes metabolic acidosis, followed by pulmonary vasoconstriction and further hypoxemia.

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Severe hypothermia, hypoxemia, bradycardia, hypoglycemia, and metabolic acidosis increase mortality in hypothermic neonates.

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Immature thermoregulation and a reduced ability to sweat predispose newborns to hyperthermia.

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Common contributing factors include overclothing, high environmental temperature in summer, poor feeding, and dehydration.

NEETx

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