Newborn · NICU
Therapeutic Hypothermia for HIE
What therapeutic cooling means for a baby with hypoxic-ischaemic encephalopathy (HIE): 72 hours at 33-34°C, started within 6 hours of birth. SARNAT 2-3 indications. Improves survival without disability (TOBY trial 2009).
Last reviewed 2 June 2026
Therapeutic hypothermia — eligibility
Neonatal cooling for HIE
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Perinatal depression (need ≥ 1)
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pH
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Encephalopathy (need Sarnat II/III OR Thompson > 7)
Sarnat stage
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Enter the criteria to check cooling eligibility.
Educational tool only — not medical advice. Therapeutic hypothermia is a NICU-level intervention requiring trained teams. Cooling reduces death/disability by ~25 % in moderate-severe HIE (Jacobs 2013 Cochrane); strict adherence to eligibility criteria is essential — cooling outside criteria (mild HIE, preterm, late presentation) has not been shown to benefit and may harm.
What does this mean?
Therapeutic hypothermia is one of the highest-evidence interventions in neonatology — cooling babies to 33.5 °C for 72 hours reduces death or major disability by ~25 % in moderate-to-severe HIE (Jacobs 2013 Cochrane meta-analysis, > 1,500 babies). Mechanism: mild hypothermia slows the secondary “reperfusion injury” cascade (excitotoxicity, free-radical damage, apoptosis) that unfolds over hours after the initial hypoxic-ischaemic insult. The 6-hour window matters — cooling started later is less effective. Strict eligibility (term ≥ 36 wk, evidence of perinatal depression, moderate/severe encephalopathy by Sarnat or Thompson) is essential because cooling outside criteria has not been shown to help and may harm (e.g. mild HIE — TOBY-Xe COOLPROP showed no benefit, possibly worse neurodevelopment). Whole-body and head cooling are equivalent. Rewarm slowly (≤ 0.5 °C/h). MRI day 5–7 predicts long-term outcome.
What is therapeutic cooling?
Treatment for babies who experienced lack of oxygen around birth (HIE). Cooling body temperature to 33-34°C for 72 hours then gradual rewarming.
Reduces brain injury cascade after oxygen deprivation. TOBY trial 2009 + others showed significant improvement in survival without disability.
Standard care for moderate-severe HIE in babies ≥36 weeks gestation, started within 6 hours of birth.
Why might my baby need cooling?
HIE causes:
- Placental abruption.
- Cord prolapse.
- Uterine rupture.
- Shoulder dystocia.
- Severe maternal hypotension.
- Severe pre-eclampsia.
- Infection.
Signs at birth:
- Low APGAR (<5 at 10 min).
- Needed resuscitation.
- Severe acidosis (cord pH <7.0).
- Seizures.
- Abnormal neurological exam.
SARNAT severity staging
- Sarnat 1 (mild): hyper-alertness, irritability. Usually recovers.
- Sarnat 2 (moderate): lethargy, low tone, possible seizures. Cooling indication.
- Sarnat 3 (severe): coma, flaccid, seizures, brainstem dysfunction. Cooling indication.
How cooling is done
- NICU admission.
- Cooling mat / blanket / whole-body system.
- Target rectal temperature 33-34°C continuously.
- Sedation (morphine) to prevent shivering.
- Ventilator support if needed.
- Continuous EEG, vital signs, blood gases.
- 72 hours exactly, then slow rewarm over 12 hours.
Outcomes with cooling
Moderate-severe HIE:
- ~50-60% normal or mild impairment.
- ~10-15% mild-moderate disability.
- ~25-35% severe disability or death.
Without cooling: outcomes worse. Number needed to treat: ~7-9 cooled to prevent one bad outcome.
Holding baby during cooling
Very limited. Multiple monitors + cooling system. Gentle touch through portholes possible. Cannot pick up / cuddle.
Voice, reading, recorded music still beneficial. After rewarming: gradual return to normal handling; kangaroo care encouraged once stable.
Breastfeeding
Baby too unwell to feed orally during cooling. Express colostrum + milk from birth — hospital pump or by hand. Stored for when baby ready.
After cooling + stability: gradual oral feed introduction.
Long-term follow-up
- Early intervention (physio, OT, SALT).
- Annual developmental assessments to age 7-8.
- Watch for cerebral palsy, learning disability, vision/hearing, epilepsy.
- Hearing screen (BERA) routine.
Different scenarios
Scenario 1: Cord prolapse at delivery, baby Apgar 3 at 5 min
Sarnat 2-3 assessment. Cooling within 6 hours. NICU + EEG monitoring.
Scenario 2: Mild HIE Sarnat 1, irritable
Usually no cooling. Supportive care + monitoring. Most recover.
Scenario 3: Severe HIE Sarnat 3, multiple seizures
Cooling. Antiepileptic. EEG. Family meetings about prognosis.
Scenario 4: Preterm 33 weeks, HIE
Standard cooling not indicated; some centres trial late-preterm cooling cautiously. Specialist team.
Scenario 5: Cooling complete + rewarmed, MRI shows mild injury
Discharge home with early intervention plan. Annual developmental follow-up.
Care guidance — neonatal cooling
- Start within 6 hours of birth.
- SARNAT 2-3 indicates cooling.
- 72h at 33-34°C then 12h rewarming.
- NICU only.
- Express colostrum from birth.
- Parents at bedside; gentle touch.
- EEG monitoring for seizures.
- MRI within first week.
- BLISS support for families.
- Birth trauma + perinatal mental health support.
Sources
- Azzopardi DV, et al. Moderate hypothermia to treat perinatal asphyxial encephalopathy (TOBY). NEJM 2009.
- BAPM. Therapeutic hypothermia for neonatal encephalopathy.
- NICE IPG347. Therapeutic hypothermia with intracorporeal temperature monitoring.
- BLISS. bliss.org.uk.
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Frequently asked questions
What is therapeutic hypothermia for newborns?
TREATMENT for babies who experienced LACK OF OXYGEN around birth (HIE — hypoxic-ischaemic encephalopathy). Cooling baby's body temperature to 33-34°C (91-93°F) for 72 HOURS, then gradual rewarming. REDUCES brain injury cascade after oxygen deprivation. EVIDENCE: TOBY trial 2009 + others — significantly improves survival without disability. STANDARD CARE for moderate-severe HIE in babies ≥36 weeks gestation, started within 6 HOURS of birth. NEONATAL INTENSIVE CARE only — specialised cooling beds/blankets.
Why does my baby need cooling?
HIE (hypoxic-ischaemic encephalopathy) — baby's brain didn't get enough oxygen around birth. CAUSES: placental abruption, cord prolapse, uterine rupture, shoulder dystocia, severe maternal hypotension, severe pre-eclampsia, infection. SIGNS at birth: low APGAR scores (<5 at 10 min); needed resuscitation; severe acidosis (cord pH <7.0); seizures; abnormal neurological exam. SEVERITY graded SARNAT 1-3 (mild-severe). COOLING for moderate (Sarnat 2) and severe (Sarnat 3) HIE.
How is cooling done?
BABY ADMITTED to NICU. Placed on COOLING MAT / blanket (gel-filled, temperature-controlled) OR special cooling cap (head only) OR whole-body cooling system. RECTAL temperature continuously monitored — target 33-34°C. SEDATION (morphine usually) to prevent shivering + discomfort. VENTILATOR support if needed. CONSTANT MONITORING — EEG, vital signs, blood gases, neurology. DURATION 72 HOURS exactly; then SLOW REWARM over 12 hours (0.5°C/hour). RESTART normal temperature monitoring once warm.
Will cooling save my baby?
IMPROVES OUTCOMES significantly. WITHOUT cooling for moderate-severe HIE: ~50% die or have major disability; WITH cooling: ~40% die or have major disability (~10% absolute reduction in death/disability). NUMBER NEEDED TO TREAT: ~7-9 babies cooled to prevent one bad outcome. NOT GUARANTEED — severity of initial injury matters most. MILD HIE: usually recover without intervention. SEVERE HIE: cooling helps but outcomes can still be poor. EARLY START (within 6 hours) matters.
What's a SARNAT score?
Clinical STAGING of HIE based on neurological signs. SARNAT 1 (MILD): hyper-alertness, irritability, mild tone changes, no seizures; usually recovers. SARNAT 2 (MODERATE): lethargy/obtundation, low tone, suppressed reflexes, possible seizures; INDICATION for cooling. SARNAT 3 (SEVERE): coma, flaccid, absent reflexes, seizures, brainstem dysfunction; INDICATION for cooling; highest mortality. Assessment by experienced neonatologist within first hours of life. SOMETIMES classification changes — repeat assessment.
Can I hold my baby during cooling?
VERY LIMITED. BABY ATTACHED to multiple monitors + cooling system + possibly ventilator. PARENTS encouraged at bedside; gentle touch through portholes possible. SOMETIMES one-handed gentle skin contact. CANNOT pick up / cuddle during cooling (would disrupt temperature, equipment). HEARING your voice + presence still beneficial — talk, read, play recorded music. AFTER rewarming: gradual return to normal handling; KANGAROO CARE encouraged once stable. EMOTIONAL impact significant — counsellors/chaplains often available.
Will my baby remember this?
INFANTS don't form explicit memories of medical experiences. NO long-term emotional / psychological impact from cooling itself. HOWEVER: brain injury (the underlying reason for cooling) may have lasting consequences. ATTACHMENT can develop normally after rewarming + discharge — early skin-to-skin, breastfeeding, eye contact build relationship. PARENTAL TRAUMA significant; can affect parent-infant bonding — counselling helps.
What's the long-term outlook?
DEPENDS on severity of initial brain injury + how well cooling worked. STATISTICS (with cooling, moderate-severe HIE): ~50-60% normal or mild impairment; ~10-15% mild-moderate disability; ~25-35% severe disability or death. OUTCOMES include: cerebral palsy, learning disability, vision/hearing problems, epilepsy, motor delays. EARLY INTERVENTION (physio, OT, SALT) from infancy improves outcomes. ANNUAL DEVELOPMENTAL ASSESSMENTS to age 7-8 standard.
What investigations during cooling?
(1) BRAIN IMAGING — cranial ultrasound (bedside), MRI within first week; (2) AMPLITUDE EEG (continuous bedside monitoring); (3) FORMAL EEG if seizures; (4) BLOOD GASES (acidosis monitoring); (5) GLUCOSE, electrolytes; (6) RENAL + LIVER function; (7) CLOTTING (DIC risk); (8) CARDIAC echo; (9) HEARING screen (CHILD-ABR, BERA). RESULTS guide ongoing care + prognosis discussions. NEUROLOGY + DEVELOPMENTAL follow-up after discharge.
Will my baby have seizures?
COMMON in HIE (~50-65% with moderate-severe HIE). MONITORED with continuous EEG / aEEG. TREATED with PHENOBARBITAL first-line; phenytoin, levetiracetam if not controlled. SEIZURES during cooling concerning — predict worse outcome. RESOLVE in most after acute phase. POSTNATAL EPILEPSY risk: ~10-30% develop epilepsy by 5 years (HIE-related). ANTIEPILEPTIC continued until seizure-free for period; reviewed regularly.
What if my baby is too young / preterm for cooling?
STANDARD cooling protocols for babies ≥36 WEEKS + birth weight ≥1800 g. PRETERM (<36 wk): SOME centres trial cautious cooling for late-preterm (33-35 wk) but evidence less robust; younger preterm not generally cooled (different brain injury patterns; cooling risks higher). PRETERM HIE managed with: supportive care; treat seizures; minimise additional injury; family support; multidisciplinary follow-up. RESEARCH ongoing for preterm cooling protocols.
What if cooling not available at our hospital?
RAPID TRANSFER to cooling centre. ALL UK NICUs offering cooling have transport protocols. CAN start PASSIVE cooling (turn off warmer; ambient cool) at referring hospital while transport organised. AIM: cooling started within 6 HOURS of birth. NEONATAL TRANSPORT TEAMS (NETS) coordinate; family may follow separately. INFORMATION GIVEN at every step.
What support is available?
(1) NICU MULTIDISCIPLINARY team — neonatologists, nurses, neurology consult, psychologists, social workers; (2) FAMILY ROOMS / parents' kitchens; (3) PHOTOGRAPHY service; (4) CHAPLAINCY; (5) BLISS (UK charity for premature/sick babies) — bedside support, peer mentoring; (6) Sands (if outcome poor — bereavement); (7) BIRTH TRAUMA support; (8) PERINATAL MENTAL HEALTH team — PTSD common; (9) BREASTFEEDING SPECIALIST (expressing in NICU); (10) DEVELOPMENTAL services after discharge.
Can I breastfeed during cooling?
BABY usually too unwell to feed orally during cooling. EXPRESS COLOSTRUM + MILK from birth — hospital pump or by hand. STORE in fridge/freezer. GIVEN TO BABY when ready (NGT initially; bottle/breast when wakeful). LACTATION CONSULTANT support essential. PROTECT supply with pumping every 2-3 hours. AFTER COOLING + STABILITY: gradual introduction of oral feeds; breastfeeding possible.
How does this relate to other calculators on BumpBites?
Companion: /calculators/apgar-score; /calculators/sarnat-hie for severity; /calculators/thompson-hie alternative; /calculators/nrp-algorithm resuscitation; /calculators/antenatal-steroids; /calculators/magnesium-sulphate neuroprotection; /calculators/eos-sepsis.