Therapeutic Hypothermia in Neonates
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Direct answer
Therapeutic hypothermia is controlled cooling of a term newborn with moderate or severe hypoxic ischaemic encephalopathy, started within about six hours of birth and continued for around 72 hours to limit brain injury. It is the main intervention with evidence of neuroprotection in these babies. The usual target is a core temperature of about 33.5 degrees Celsius, followed by slow rewarming.
What you must remember
- Eligibility: moderate or severe encephalopathy, commonly at 36 weeks of gestation or more, with birth weight limits set by the protocol.
- Time window: cooling starts within about six hours of birth, and the benefit falls as the start is delayed.
- Target temperature: a core or rectal temperature of about 33.5 degrees Celsius, with a narrow tolerance around that value.
- Duration: cooling is maintained for around 72 hours, then the baby is rewarmed gradually over several hours.
- Methods: whole-body cooling with a servo-controlled device or selective head cooling, with temperature monitored continuously.
- Monitoring: blood glucose, electrolytes, blood gases, blood pressure and platelets, with avoidance of hypotension, hypoglycaemia and hyperthermia.
- Exclusions: mild encephalopathy, gestation below the protocol threshold, major bleeding and severe congenital anomalies.
A protocol-based pathway
Therapeutic hypothermia is a time-bound protocol, so examiners expect the sequence from eligibility to rewarming. The steps below follow the protocols used in the major trials, which centres adapt to their own equipment and local guidance.
- Eligibility: Confirm moderate or severe encephalopathy on Sarnat grading, gestation of about 36 weeks or more, and no major bleeding or anomaly.
- Timing: Start cooling within about six hours of birth, since the benefit depends on early cooling, and refer without delay if the unit cannot provide it.
- Cooling: Lower the core temperature to about 33.5 degrees Celsius using a cooling device, with rectal temperature monitored continuously.
- Maintenance: Hold the target for around 72 hours, avoiding overshoot, hypotension and hypoglycaemia during this period.
- Rewarming: Warm the baby gradually over several hours, rather than quickly, to avoid sudden changes in temperature and blood pressure.
- Follow-up: Assess the baby with EEG, MRI and developmental review, because the outcome is the reason for the intervention.
In India, cooling is available mainly in tertiary centres, so early recognition and transfer are often the most important steps for a baby with evolving encephalopathy.
Where the exam tries to catch you
Therapeutic hypothermia stems usually test the time window, the target and the rewarming step.
- Trap: starting cooling many hours after birth because the baby is still unwell. Correct: the protocol window is about six hours, and later cooling has not shown the same benefit.
- Trap: treating normal temperature as the goal and calling it cooling. Correct: the target is a deliberate fall to about 33.5 degrees Celsius, held for around 72 hours.
- Trap: rewarming quickly once the 72 hours end. Correct: rewarming is gradual over several hours to avoid sudden swings in temperature and blood pressure.
Frequently asked questions
What is the target temperature in therapeutic hypothermia for neonates?
The target core temperature in therapeutic hypothermia for neonates is about 33.5 degrees Celsius, with a narrow tolerance. The target is held for around 72 hours before gradual rewarming begins.
Within how many hours of birth must therapeutic hypothermia start?
Therapeutic hypothermia for neonates should start within about six hours of birth, because its neuroprotective benefit depends on early cooling. Referral pathways must be fast so that eligibility can be assessed within this window.
How long is therapeutic hypothermia continued in neonates?
Therapeutic hypothermia in neonates is continued for about 72 hours, after which the baby is rewarmed slowly over several hours. Temperature, glucose and electrolytes are monitored throughout the cooling period.
Which neonates are generally excluded from therapeutic hypothermia?
Neonates with mild encephalopathy, gestation below the protocol threshold, major bleeding or a severe congenital anomaly are generally excluded from therapeutic hypothermia. Eligibility criteria vary slightly between protocols, so the local guideline must be followed.