Overview
Definition:
Neonatal hypothermia is defined as a core body temperature below 36.5°C (97.7°F) in a newborn infant
It can be classified as mild (36.0-36.4°C), moderate (32.0-35.9°C), or severe (<32.0°C).
Epidemiology:
Hypothermia affects a significant proportion of newborns, especially in resource-limited settings, with higher incidence in preterm infants, low birth weight infants, and those born in cold environments
Estimated incidence varies globally but can be as high as 40% in some regions.
Clinical Significance:
Neonatal hypothermia is a major contributor to neonatal morbidity and mortality
It impairs respiratory function, increases metabolic demand, exacerbates hypoglycemia, can lead to increased risk of infection, and is associated with adverse neurological outcomes, making its prevention and prompt management critical for patient survival and well-being.
Risk Factors
Perinatal Factors:
Prematurity
Low birth weight
Intrauterine growth restriction
Prolonged rupture of membranes
Maternal fever
Difficult delivery.
Environmental Factors:
Cold delivery room temperature
Exposure to drafts
Delayed cord clamping in cold environments
Inadequate covering of the infant
Transport in unheated incubators.
Infant Factors:
Sepsis
Congenital anomalies
Neurological impairment
Lack of subcutaneous fat
Inadequate feeding.
Iatrogenic Factors:
Excessive bathing
Exposure during procedures
Inadequate warming before transport.
Prevention Strategies
Immediate Postpartum:
Dry the infant thoroughly immediately after birth
Remove wet linen
Place the infant skin-to-skin on the mother's chest or abdomen
Cover both with a warm blanket and a hat
Avoid separation.
Delivery Room Management:
Maintain ambient room temperature between 24-26°C
Use radiant warmers with pre-warmed mattress
Ensure all equipment used is warmed
Minimize infant exposure during procedures.
Transport:
Use pre-warmed incubators or radiant warmers for transport
Ensure adequate insulation
Monitor infant temperature continuously.
Nursing Care:
Regularly check infant temperature every 15-30 minutes initially, then hourly
Keep infants clothed and covered
Avoid exposing infants unnecessarily
Use warm blankets and hats.
Mother Infant Bonding:
Encourage skin-to-skin contact as much as possible
Educate parents on the importance of maintaining infant warmth.
Clinical Presentation
Signs And Symptoms:
Cold skin, especially extremities
Lethargy or irritability
Weak cry
Poor feeding
Tachypnea or apnea
Bradycardia
Mottled skin
Hypoglycemia
Metabolic acidosis.
Temperature Measurement:
Core body temperature measurement is essential
peripheral temperatures can be misleading
Rectal temperature is most accurate but may be impractical
Esophageal or bladder temperatures are good surrogates for core temperature.
Severity Indicators:
The severity of hypothermia is directly correlated with the duration and degree of cold exposure
Infants with severe hypothermia are at much higher risk for complications.
Rewarming Protocols
Initial Assessment:
Assess infant's temperature, vital signs, and clinical status
Identify and address underlying causes like sepsis or hypoglycemia.
Gradual Rewarming:
Aim for a gradual rewarming rate of 0.5-1°C per hour to prevent potential complications like rapid fluid shifts
Excessive warming can lead to hyperthermia, dehydration, and increased metabolic demand.
Methods Of Rewarming:
Use radiant warmers set to maintain a neutral thermal environment, adjusted based on infant's response
Incubators with controlled humidity and temperature can also be used
Warm humidified oxygen may be administered.
Monitoring During Rewarming:
Continuous monitoring of vital signs and core body temperature is crucial
Monitor for signs of distress, apnea, or circulatory compromise
Blood glucose levels should be checked frequently.
Management Of Severe Hypothermia
Active Warming:
For infants with severe hypothermia (<32°C), aggressive rewarming may be indicated, but with extreme caution
This might involve using warmer blankets or positioning the infant closer to a heat source, under strict supervision.
Addressing Complications:
Manage associated hypoglycemia with intravenous glucose
Treat any suspected sepsis with broad-spectrum antibiotics
Correct metabolic acidosis with sodium bicarbonate if indicated.
Fluid Management:
Careful fluid management is needed due to potential for fluid shifts during rewarming
Monitor urine output and electrolytes closely.
Referral:
Infants with severe hypothermia, especially those requiring aggressive rewarming or with significant complications, may require transfer to a higher level of care facility.
Complications
Metabolic Complications:
Hypoglycemia
Metabolic acidosis
Increased oxygen consumption leading to hypoxia
Intraventricular hemorrhage.
Cardiac Complications:
Bradycardia
Arrhythmias
Persistent pulmonary hypertension of the newborn (PPHN).
Respiratory Complications:
Respiratory distress
Apnea
Increased risk of pneumonia.
Neurological Sequelae:
Increased risk of hypoxic-ischemic encephalopathy (HIE)
Developmental delay
Cerebral palsy
Cognitive impairment
Long-term neurological deficits are more common in infants who experienced severe or prolonged hypothermia.
Other Complications:
Increased susceptibility to infection
Poor weight gain
Jaundice.
Key Points
Exam Focus:
The primary goal is prevention
Understand the classification of hypothermia
Know the rewarming rate and dangers of rapid rewarming
Recognize the importance of skin-to-skin contact.
Clinical Pearls:
Always dry and cover the baby immediately after birth
Warm everything that touches the baby
Never assume a baby is warm
measure the temperature
Hypothermia is a significant risk factor for sepsis and other morbidities.
Common Mistakes:
Delaying drying and covering the infant
Inadequate room temperature
Over-reliance on peripheral temperature measurements
Rewarming too rapidly
Failure to investigate and treat underlying causes.