👶 Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat)
Sarnat staging grades neonatal hypoxic-ischemic encephalopathy (HIE) as mild, moderate or severe from the overall pattern of consciousness, tone, reflexes, autonomic function and seizures.
Clinical takeaway
Moderate-to-severe HIE (stage 2–3) within 6 hours of birth, with evidence of perinatal asphyxia, is the trigger for therapeutic hypothermia at 33–34 °C for 72 hours.
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When to use
Use in term/near-term newborns with suspected perinatal asphyxia to grade encephalopathy severity and decide on therapeutic hypothermia.
How it works
A stage-3 pattern in any domain = severe (stage 3); any moderate feature or seizures = moderate (stage 2); otherwise mild (stage 1). Hypothermia eligibility = stage 2–3 + asphyxia evidence + GA ≥ 35 wk + < 6 h of age.
Key points
- Moderate-to-severe HIE (stage 2–3) within 6 hours of birth, with evidence of perinatal asphyxia, is the trigger for therapeutic hypothermia at 33–34 °C for 72 hours.
- Staging is based on the evolving overall pattern, not a single sign; seizures or any moderate-domain feature already place the infant at stage 2.
- Supportive care (normothermia, glucose, perfusion, seizure control) and multimodal prognostication (neuro exam, aEEG/EEG, MRI) accompany staging regardless of cooling.
References
- Sarnat HB, Sarnat MS. Neonatal encephalopathy following fetal distress. Arch Neurol 1976.
- Jacobs SE, et al. Cooling for newborns with HIE. Cochrane Database Syst Rev 2013.
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Level of consciousness | Hyperalert / irritable (1) |
|---|---|
| Muscle tone | Normal or mildly increased (1) |
| Primitive reflexes (suck / Moro) | Active / normal (1) |
| Autonomic function | Sympathetic predominant (mydriasis / tachycardia) (1) |
| Seizures | None |
| Evidence of perinatal asphyxia (cord pH ≤ 7.0 or BE ≤ −12 / 10-min Apgar ≤ 5 / required resuscitation) AND GA ≥ 35 wk AND < 6 h of age | Not met |
→Sarnat stageStage 1 (mild)
- Stage：Stage 1 mild: hyperalert, normal or mildly increased tone, active reflexes, sympathetic overactivity, no seizures, usually < 24 h
- Hypothermia eligibility：Stage 1 (mild) generally does not warrant hypothermia; monitor closely and reassess if it progresses to moderate-to-severe and criteria are met
- Management direction：Supportive care: maintain normothermia (avoid hyperthermia), glucose, electrolytes, perfusion and oxygenation; control seizures; multimodal prognostication (evolving neuro exam + aEEG/EEG + MRI)
| Level of consciousness | Stupor / coma (3) |
|---|---|
| Muscle tone | Flaccid (3) |
| Primitive reflexes (suck / Moro) | Absent (3) |
| Autonomic function | Depressed (fixed pupils / unstable) (3) |
| Seizures | Present |
| Evidence of perinatal asphyxia (cord pH ≤ 7.0 or BE ≤ −12 / 10-min Apgar ≤ 5 / required resuscitation) AND GA ≥ 35 wk AND < 6 h of age | Met |
→Sarnat stageStage 3 (severe)
- Stage：Stage 3 severe: stupor/coma, flaccid, absent reflexes, brainstem and autonomic depression, suppressed EEG
- Hypothermia eligibility：Eligible: moderate-to-severe HIE (stage 2–3) + evidence of perinatal asphyxia + GA ≥ 35 wk + < 6 h of age → start therapeutic hypothermia (target 33–34 °C × 72 h, whole-body or selective head cooling) with continuous monitoring and aEEG/EEG
- Management direction：Supportive care: maintain normothermia (avoid hyperthermia), glucose, electrolytes, perfusion and oxygenation; control seizures; multimodal prognostication (evolving neuro exam + aEEG/EEG + MRI)
Frequently asked questions
- What is Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat)?
- Sarnat staging grades neonatal hypoxic-ischemic encephalopathy (HIE) as mild, moderate or severe from the overall pattern of consciousness, tone, reflexes, autonomic function and seizures.
- How is Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat) calculated? What is the core formula?
- A stage-3 pattern in any domain = severe (stage 3); any moderate feature or seizures = moderate (stage 2); otherwise mild (stage 1). Hypothermia eligibility = stage 2–3 + asphyxia evidence + GA ≥ 35 wk + < 6 h of age.
- When is Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat) used?
- Use in term/near-term newborns with suspected perinatal asphyxia to grade encephalopathy severity and decide on therapeutic hypothermia.
- What are the key clinical points for Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat)?
- Moderate-to-severe HIE (stage 2–3) within 6 hours of birth, with evidence of perinatal asphyxia, is the trigger for therapeutic hypothermia at 33–34 °C for 72 hours. Staging is based on the evolving overall pattern, not a single sign; seizures or any moderate-domain feature already place the infant at stage 2. Supportive care (normothermia, glucose, perfusion, seizure control) and multimodal prognostication (neuro exam, aEEG/EEG, MRI) accompany staging regardless of cooling.
- What are the limits and cautions when using Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Neonatal Hypoxic-Ischemic Encephalopathy Staging (Sarnat) calculated in practice? Can you show a worked example?
- Inputs: Level of consciousness Hyperalert / irritable (1), Muscle tone Normal or mildly increased (1), Primitive reflexes (suck / Moro) Active / normal (1), Autonomic function Sympathetic predominant (mydriasis / tachycardia) (1), Seizures None, Evidence of perinatal asphyxia (cord pH ≤ 7.0 or BE ≤ −12 / 10-min Apgar ≤ 5 / required resuscitation) AND GA ≥ 35 wk AND < 6 h of age Not met → Result: Sarnat stage Stage 1 (mild)（Stage: Stage 1 mild: hyperalert, normal or mildly increased tone, active reflexes, sympathetic overactivity, no seizures, usually < 24 h, Hypothermia eligibility: Stage 1 (mild) generally does not warrant hypothermia; monitor closely and reassess if it progresses to moderate-to-severe and criteria are met, Management direction: Supportive care: maintain normothermia (avoid hyperthermia), glucose, electrolytes, perfusion and oxygenation; control seizures; multimodal prognostication (evolving neuro exam + aEEG/EEG + MRI)） Inputs: Level of consciousness Stupor / coma (3), Muscle tone Flaccid (3), Primitive reflexes (suck / Moro) Absent (3), Autonomic function Depressed (fixed pupils / unstable) (3), Seizures Present, Evidence of perinatal asphyxia (cord pH ≤ 7.0 or BE ≤ −12 / 10-min Apgar ≤ 5 / required resuscitation) AND GA ≥ 35 wk AND < 6 h of age Met → Result: Sarnat stage Stage 3 (severe)（Stage: Stage 3 severe: stupor/coma, flaccid, absent reflexes, brainstem and autonomic depression, suppressed EEG, Hypothermia eligibility: Eligible: moderate-to-severe HIE (stage 2–3) + evidence of perinatal asphyxia + GA ≥ 35 wk + < 6 h of age → start therapeutic hypothermia (target 33–34 °C × 72 h, whole-body or selective head cooling) with continuous monitoring and aEEG/EEG, Management direction: Supportive care: maintain normothermia (avoid hyperthermia), glucose, electrolytes, perfusion and oxygenation; control seizures; multimodal prognostication (evolving neuro exam + aEEG/EEG + MRI)）