Neonatal Hypothermia - Pathophysiology, Causes, Risk Factors, Clinical Features, and Treatment

Introduction

Hypothermia is one of the significant causes of morbidity and mortality in newborns. According to the World Health Organization, thermal regulation is vital for newborns. Therefore, it is very critical and essential for newborn care. Hypothermia is also known as a silent killer in newborns. The warmth is very crucial for the survival of the infant. It is commonly seen in newborns and associated with various risk factors, such as environmental and physiological factors.

What Is Neonatal Hypothermia?

According to the World health organization, neonatal Hypothermia is a core body temperature of fewer than 36.5 degrees Celsius. It can be due to environmental factors or interlinked with illness. The average rectal temperature in preterm infants is between 36.5 and 37.5 degrees Celsius. There is impaired thermoregulation and metabolic heat production. The skin temperature of the newborn is measured by the thermometer in the skin of the abdomen, whereas auxiliary temperature is recorded for three minutes during routine monitoring.

What Is Pathophysiology of Hypothermia in Neonates?

The thermal equilibrium of neonates is affected by various factors, such as humidity, airflow, proximity to cool surfaces, and ambient room temperature—the newborn's body loses rapid heat due to metabolic reasons. A high character and volume ratio is present, leading to the consequent Hypothermia. Children with low birth weight are at higher risk of Hypothermia. Prolonged persistent and unrecognized Hypothermia leads to impaired growth of the child.

The sympathetic nerve discharge of norepinephrine regulates the chemical thermogenesis of the newborn. There is a presence of specialized tissue in the nape of the neck, scapulae, and around the kidneys. It helps in lipolysis, followed by oxidation and esterification of the fatty acids. It helps in increasing metabolic consumption. The neonate thermoneutrality depends on the weather, gestational age, and low weight. Metabolic regulation is essential for thermal regulation in children. A neutral thermal environment is an optimal temperature at which metabolic demands maintain the body temperature. Following are the various mechanisms of Hypothermia in newborns.

• Radiant Heat Loss - Radiant skin loss occurs if a child's skin is exposed to an environment with low temperature.

• Evaporative Heat Loss - This heat loss occurs with newborns wet with amniotic fluid.

• Convective Heat Loss - In this type of heat loss, air carries away heat from the newborn.

• Conductive Heat Loss occurs if the newborn is in close contact with a more excellent surface.

What Is the Etiology of Neonatal Hypothermia?

Various factors affect thermoregulation in newborns. Following are the different causes of neonatal Hypothermia.

1. The wet and naked body of the newborn.

2. Cold environment.

3. The situation causes excessive heat loss.

4. Cold surface and cold linen.

5. Bath procedures.

6. Blood sampling and Infusion.

7. Poor energy to conserve body heat.

8. Poor metabolic heat production in the body.

9. Sepsis.

10. Intracranial Hemorrhage.

11. Drug Withdrawal.

12. Decreased subcutaneous fat.

13. Alteration in skin and blood flow.

14. Presence of large area-to-body mass ratio.

What Are the Risk Factors of Neonatal Hypothermia?

Following are the risk factors that increase the possibility of neonatal Hypothermia.

• Birth factors such as premature birth of the child, low birth weight, asphyxia, congenital disorder, and intrauterine growth restriction are the factors that increase the risk of neonatal Hypothermia.

• The temperature of the delivery room also increases the risk of Neonatal Hypothermia.

• Improper care post delivery and bathing of newborn right after birth.

• Removal of vernix caseosa.

• Reduced contact of a newborn with the mother.

• Delayed initiation of breastfeeding increases the risk of neonatal Hypothermia.

• Improper knowledge of the physiology of thermoregulation in parents and healthcare providers.

• Presence of low ambient temperature.

• Presence of lower maternal temperature.

• Surgical procedures such as the placement of umbilical lines.

• Radiological investigation in newborns, such as Magnetic resonance imaging, also increases the risk of neonatal Hypothermia.

• Presence of maternal hypertension.

• The low temperature of the delivery room also increases the risk of neonatal Hypothermia.

• The presence of low appearance pulse grimace activity and respiration score in newborns increases the risk of neonatal Hypothermia.

What Are the Clinical Features of Neonatal Hypothermia?

Following are the clinical features of neonatal Hypothermia.

• Peripheral vasoconstriction.

• Increased metabolism.

• Decreased peripheral perfusion.

• Hypoglycemia.

• Metabolic acidosis and Hypoxia.

• Respiratory distress.

• Poor weight gain.

• Central nervous system depression.

What Are the Types of Neonatal Hypothermia?

According to the world health organization, neonatal Hypothermia is categorized into three categories according to temperature.

• Mild Hypothermia - In this condition, the body temperature of the newborn ranges between 36 to 36.4 degree Celsius.

• Moderate Hypothermia - In this condition, the body temperature of the newborn ranges between 32 to 35.9 degree Celsius.

• Severe Hypothermia - In this condition, the body temperature of the newborn ranges below the temperature of 32-degree celsius

How to Treat Neonatal Hypothermia?

Following is the treatment plan for neonatal Hypothermia.

• Rewarming is indicated with the help of an incubator and radiant warmer.

• The neonates are monitored for hypoglycemia, hypoxemia, and apnea.

• Specific treatment is required for underlying causes such as sepsis and intracranial hemorrhage.

• Kangaroo care, also known as skin-to-skin contact, is indicated when the child is upright between the mother's breasts.

How to Prevent Neonatal Hypothermia?

Following are the preventive measures for neonatal Hypothermia.

• The delivery of the baby should be conducted at a warm room temperature.

• The head of the baby should be dried immediately with a warm, clean towel after the birth.

• The baby should be wrapped in pre-warmed linen from the head to the toes.

• The bathing of the baby should be postponed.

Conclusion

Neonatal Hypothermia is one of the prevalent causes of newborn morbidity. It is one of the potentially life-threatening conditions. Neonatal Hypothermia can be prevented by managing environmental factors and intervening in critical care. Health professionals should maintain temperatures between twenty-five degrees celsius and twenty-eight degrees celsius for preterm babies. Adequate temperature maintenance is essential in newborns. Cold temperatures have adverse effects on the health of newborn infants. It is vital to understand the etiology and to take preventive measures. It is imperative to process to provide a safe and secure environment for the birth of a baby.