Pediatrics · Year 3 · from Pediatrics

Case 2: Hypoxic-Ischemic Encephalopathy

Patient Demographics

  • Age: 6-hour-old male
  • Sex: Male

Chief Complaint

Newborn with poor respiratory effort and decreased tone after difficult delivery.

History of Present Illness

A male infant was born at 40 weeks gestation after a prolonged labor complicated by category III fetal heart rate tracing with recurrent late decelerations and absent variability. Emergency cesarean section was performed. At delivery, the infant was limp with no respiratory effort and heart rate of 40 bpm. Bag-mask ventilation was initiated, and after 2 minutes of positive pressure ventilation, heart rate increased to 80 bpm. The infant required intubation at 3 minutes of life due to continued poor respiratory effort. APGAR scores were 1 at 1 minute, 3 at 5 minutes, and 5 at 10 minutes. Cord blood gas showed pH 6.85 with base deficit of -18 mEq/L.

Growth Parameters

  • Birth weight: 3.6 kg (60th percentile)
  • Length: 51 cm (55th percentile)
  • Head circumference: 35 cm (50th percentile)

Physical Examination (at 6 hours of life)

  • General: Intubated, lethargic infant on mechanical ventilation
  • HEENT: Anterior fontanelle full but not bulging, pupils 4mm bilaterally with sluggish reaction to light
  • Cardiovascular: Bradycardia (HR 90), weak peripheral pulses, capillary refill 4 seconds
  • Respiratory: Intubated, minimal respiratory effort over ventilator
  • Abdomen: Soft, decreased bowel sounds
  • Neurologic:
  • Level of consciousness: Lethargy/stupor
  • Tone: Marked hypotonia (floppy)
  • Reflexes: Weak suck, incomplete Moro
  • Posture: Decerebrate posturing with stimulation
  • Seizures: None observed clinically
  • Sarnat staging: Stage II (moderate) HIE

Workup

  • Umbilical cord arterial blood gas: pH 6.85, pCO2 75, pO2 18, BE -18
  • Initial labs:
  • Lactate 12 mmol/L (elevated)
  • Glucose 45 mg/dL
  • Creatinine 1.4 mg/dL (elevated)
  • AST 320 U/L, ALT 180 U/L (elevated)
  • Troponin elevated
  • CBC: Normal
  • aEEG (amplitude-integrated EEG): Moderately abnormal background with reduced amplitude
  • Head ultrasound: No hemorrhage, increased echogenicity of basal ganglia bilaterally

Diagnosis

Moderate hypoxic-ischemic encephalopathy (Sarnat Stage II)

Clinical Reasoning

The diagnosis of HIE is supported by: evidence of intrapartum hypoxia (category III FHR tracing), metabolic acidosis with pH <7.0 and base deficit >-12, 10-minute APGAR <5, need for continued resuscitation at 10 minutes, and clinical signs of moderate encephalopathy (lethargy, hypotonia, autonomic dysfunction). The infant meets criteria for therapeutic hypothermia based on gestational age >=36 weeks, age <=6 hours, and evidence of moderate-severe encephalopathy.

Management

  1. Therapeutic hypothermia: Initiate whole-body cooling to target temperature 33.5C for 72 hours
  2. Continuous EEG monitoring: Monitor for subclinical seizures, treat if identified
  3. Supportive care:
  • Maintain normoglycemia (50-150 mg/dL)
  • Fluid restriction (60 mL/kg/day) for potential SIADH
  • NPO, parenteral nutrition
  • Blood pressure support as needed (dopamine if MAP <40)
  1. Avoid hyperthermia, hyperoxia, hypocapnia (worsen injury)
  2. MRI at day 5-7: Assess extent of injury after rewarming
  3. Neurology consultation: Prognostication, follow-up planning
  4. Family support: Honest communication about prognosis and potential outcomes

Clinical Image

Image Description: Brain MRI demonstrating bilateral basal ganglia and thalamic injury pattern typical of acute profound hypoxic-ischemic encephalopathy.

Source: Radiopaedia URL: https://radiopaedia.org/cases/hypoxic-ischaemic-encephalopathy-term-infant License: CC BY-NC-SA 3.0

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