Neonatal warming equipment and manifestations of hypothermia
THE CONTEXT
Incubators and radiant warmers provide thermal support through different heat-delivery mechanisms. Hypothermia can affect circulation, respiration, feeding, metabolism, and growth.
Incubators and radiant warmers
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An incubator is a closed transparent acrylic cabin. A fan circulates warm air around the neonate, providing heat by convection; double walls often provide additional thermal protection.
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A radiant warmer is an open system with a radiant heater positioned over a bassinet.
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Access to the baby is easy with a radiant warmer and restricted with an incubator.
Temperature control
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Both devices have an inbuilt feedback system, or servo-control, that alters heater output according to the baby's temperature to maintain normal body temperature.
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Use radiant warmers and incubators in servo-control mode with the skin temperature probe attached to the baby. Set the skin temperature at 36.5°C to 37°C.
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The radiant warmer's manual mode permits manual heater-output adjustment and helps warm the bed before the neonate occupies it.
Clinical effects of hypothermia
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Peripheral vasoconstriction causes acrocyanosis, cool extremities, and delayed capillary refill. The neonate may become restless and lethargic.
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Bradycardia, hypotension, and raised pulmonary artery pressure can cause respiratory distress and hypoxemia. Apnea, poor reflexes, and decreased oral acceptance may occur.
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Abdominal distension and vomiting can make enteral feeding difficult.
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Severe hypothermia can cause acidosis, hypoglycemia, oliguria, azotemia, and generalized bleeding.
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Prolonged hypothermia may impair weight gain.
Methods of maintaining temperature
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Temperature-maintenance methods include skin-to-skin contact, a warm room, radiant warmers, incubators, and heaters that increase ambient temperature.