Neonatal Hypothermia: Essentials For General Practitioners
Neonatal hypothermia is a condition which is faced by both general practitioners, as well as pediatricians, in routine practice. Neonatal hypothermia has been recognized by the World Health Organization (WHO) as a factor contributing to the morbidity and mortality risk of newborns. Neonatal hypothermia may occur because of exposure to a cold environment, contact with a cold object/surface, if the baby is wet or not clothed properly, neonatal sepsis, intracranial hemorrhage and other reasons. It may result in adverse consequences. It can be easily prevented by giving skin to skin contact and maintaining the warm chain. Here, a practical, clinical approach with preventive measures is discussed.
Normal rectal temperature in term and preterm infants is 36.5 to 37.5° Celsius (C). Hypothermia is present when the core temperature is less than 36.5°C. Hypothermia can be classified into three types depending upon its severity; cold stress (core temperature between 36-36.4°C), moderate hypothermia (core temperature between 32-35.9°C), and severe hypothermia (core temperature less than 32°C). See Figure 1.
HOW COMMON IS IT?
The incidence of hypothermia can vary from about 25% to upto 80% depending upon several factors. It is more likely to occur in preterm babies, low birth weight babies, neonates with sepsis, as well as those who are transported in poor conditions. Environmental temperatures and the usage of measures to prevent hypothermia are also important. Often neonates are left in a state of partial undress in bath tubs, air-conditioned rooms or in windy areas.
HOW TO IDENTIFY THE CONDITION CLINICALLY?
Clinically, whenever all four limbs of neonate are cold and the abdomen remains warm as felt by the back of examiner’s hand, then it is referred to as cold stress. When all the four limbs as well as the abdomen are felt cold on examination, then hypothermia is present. Moderate hypothermia cannot be differentiated from severe hypothermia only based on clinical examination.
HOW OFTEN IS THE TEMPERATURE MEASURED?
The frequency of temperature measurement can be once daily in healthy neonates, twice or thrice daily in healthy but small neonates of birth weight (BW) between 2 to 2.5 kilogram (kg)), four times daily for very small neonates (BW<2kg) and every two-hourly in sick babies.
Mechanism of Action:
Hypothermia induces peripheral vasoconstriction which leads to increased metabolism, excess glucose and oxygen utilization, and ultimately causes the switch over to anaerobic metabolism which leads to metabolic acidosis. With severe hypothermia, the hypoxemia, bradycardia, hypoglycemia and metabolic acidosis contribute towards increased mortality. Hypothermic newborns may present with apnea, failure to thrive, acrocyanosis, cold extremities, lethargy, poor feeding, respiratory distress, and weight loss.
As “Prevention is better than cure” we can prevent hypothermia in many conditions by maintaining the warm chain:
- Warm delivery room
- Warm resuscitation
- Immediate drying
- Skin to skin contact with mother
- Bathing postponed
- Appropriate clothing
- Rooming in (mother and child together)
- Professional alertness
- Warm transportation
The delivery room should have ambient temperature of at least 27° C and it should be free from blowing cold air (open windows and doors). After delivery, the baby should be dried immediately, and kept in direct skin to skin contact on the mother’s abdomen and covered with a pre-heated sheet. The baby should be capped and dressed adequately.
Kangaroo mother care (KMC) is an effective way to prevent hypothermia in low birth weight and preterm babies. Breastfeeding should be encouraged as soon as possible (within half an hour of delivery). It helps in keeping the baby warm. Bathing should be postponed till the umbilical cord falls off (end of first week). Baby should be dressed in multiple layers of warm and light clothes. Mother and baby should be kept together on the bed (‘Rooming in’). Training of the health care providers for detection and management of hypothermia should be done. Radiant warmer and incubators should be used so that the skin temperature is maintained at 36.5-37° C depending on the birth weight of the neonate.[1,2]
Cold stress condition can be managed by removing the wet/cold clothes, replacing with warm clothes and adequately covering the baby, keeping the room/bed warm, taking measures to reduce heat loss, ensuring skin-to-skin contact with mother (which if not possible, keep baby next to mother after fully covering the baby), and early breastfeeding. Monitor axillary temperature every ½ hour till it reaches 36.5° C, then hourly for next 4 hours, 2 hourly for 12 hours thereafter and 3 hourly as a routine.
Moderate hypothermia can be managed by maintaining skin to skin contact, keeping a warm room/bed, take measures to reduce heat loss, provide extra heat using 200-watt bulbs, heater, radiant warmer, incubator and applying warm towels.
Severe hypothermia can be managed by providing extra heat preferably under radiant warmer or air heated incubator; rapidly warm till 34° C, then slowly re-warm. Take measures to reduce heat loss, intravenous fluid administration of 60-80 ml/kg of 10% Dextrose, oxygen, Vitamin K 1mg (term infant) and 0.5 mg (preterm) given intramuscular. If neonate remains hypothermic despite these interventions then antibiotics need to be considered (after appropriate investigations are sent) as it might be sepsis that is causing the hypothermia.
- World Health Organization. Thermal protection of the newborn: A practical guide. World Health Organization; Geneva: 1997. Report No.: WHO/RHT/MSM/97.2.
- Miller SS, Lee HC, Gould JB. Hypothermia in very low birth weight infants: distribution, risk factors and outcomes. J Perinatol. April 2011;31 (1):S49-56.