Neonatal hypothermia is defined as a low body temperature <36.5°C(97.7°F) or rectal temperature lower than 35°C ( 95°F). In premature infants, hypothermia increases morbidity and mortality. There may be cold stress at higher temperatures whenever heat loss requires an increase in metabolic heat production.
Thermal equilibrium is affected by relative humidity, air flow, direct contact with cool surfaces, proximity to cool objects, and ambient air temperature. Neonates are prone to rapid heat loss and consequent hypothermia because of a high surface area to volume ratio, which is even higher in low birth weight neonates. There are several mechanisms for heat loss –
• Radiant heat loss – Bare skin is exposed to an environment containing objects of cooler temperature.
• Evaporative heat loss – Neonates are wet with amniotic fluid
• Conductive heat loss – Neonates are placed in contact with a cool surface or object
• Convective heat loss – A flow of cooler ambient air carries heat away from the neonate
Prolonged, unrecognised coId stress may divert calories to produce heat, impairing growth. In neonates with respiratory insufficiency (eg, the preterm infant with respiratory distress syndrome), cold stress may also result in tissue hypoxia and neurologic damage. Activation of glycogen stores can cause transient hypoglycemia. Persistent hypothermia can result in hypoglycemia and metabolic acidosis and increases the risk of late-onset-sepsis and mortality.
Despite their compensatory mechanisms, neonates particularly low birthweight infants, have limited capacity to thermoregulate and are prone to decreased core temperature. Even before temperature decreases, cold stress occurs when heat Ioss requires an increase in metabolic heat production.
Signs & Symptoms –
▪︎ Peripheral vasoconstriction
• Cool extremities
• Decreased peripheral perfusion
• Poor feeding
• Metabolic acidosis
▪︎ Increase of pulmonary artery pressure
▪︎ Chronic signs
• Weight loss, poor weight gain
• Premature birth and low birth weight babies
• Cold birth environment
• Infection such as meningitis, sepsis
Risk Factors –
Neonatal hypothermia is related to a number of risk factors, which are categorised in four main groups –
These factors are related to the geographical area in which the baby is born, as well as time of the year and room temperature at the time of birth.
These factors mainly pertain to neonatal issues such as prematurity, low birth weight and intrauterine growth restriction. Hypoglycemic babies are also at increased risk for hypothermia.
These factors are considered for cultural reasons such as bathing of the newborn immediately after birth , massaging the baby with essential oils after birth.
There factors can also contribute to neonatal hypothermia. Socially mothers who are either young an inexperienced,or multiparas who are minding many children, babies born in families with a low income or from poor countries are also more likely to be socially and economically disadvantaged.
Complication of neonatal hypothermia includes –
• Pulmonary vasoconstriction
• Reduction of peripheral perfusion
• Metabolic acidosis
• Respiratory distress
• Growth retardation
• Pulmonary haemorrhage
• Necrotising enterocolitis
• Impaired cardiac function
• Disseminated intravascular coagulopathy (DIC)
• Cardiac Arrhythmia
• If trunk and extremeties of baby are cold, then its the clear indication of hypothermia.
• Rectal temperature lower than 35°C ( 95°F)
A hypothermic baby has to be rewarmed as quickly as possible. The method selected will depend on the severity of hypothermia.
The methods to use include –
• Skin to skin contact
• A warm room or bed
• A 200 watt bulb
• A radiant heater or an incubator
Infection should be suspected if hypothermia persists despite of above measures.
In addition –
• Start IV 10% Dextrose @ 60-80 ml/kg/day
• Give injection Vit K 1 mg for term, 0.5 mg in preterm babies
• Provide oxygen
• Conduct delivery in a warm room
• Dry baby including head immediately with warm clean towel
• Wrap baby in pre-warmed linen, cover the head and the limbs
• Place the baby skin to skin on the mother
• Postpone bathing
• Kangroo care assists in maintaining temperature
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