Hypoxic-ischaemic encephalopathy and therapeutic hypothermia — formative SAQs

SAQ 1 — The eligible term infant and the cooling decision (20 marks, ~15 minutes)

A term infant (39 weeks, birthweight 3400 g) is born after an emergency caesarean for placental abruption. Cord blood pH is 6.88, base deficit 14 mmol/L. Apgar scores are 1, 3, and 5 at 1, 5, and 10 minutes, with ongoing mask ventilation at 10 minutes. At 2 hours of age the infant is lethargic, with generalised hypotonia and depressed Moro and suck reflexes, and is not seizing. ^[1]

Questions

1. Define the clinical syndrome, grade the encephalopathy using the Sarnat criteria, and state whether this infant meets the cooling eligibility criteria. (5 marks) ^[1]
2. Outline the immediate bedside management before and during the cooling assessment, naming the first bedside test and the principle of temperature management. (5 marks) ^[4]
3. Describe the cooling protocol in full — target temperature, duration, window for initiation, and rewarming rate. State the evidence that supports it. (6 marks) ^[4]
4. Describe the supportive neurocare that must be maintained during the 72 hours of cooling, and name two complications of hypothermia. (4 marks) ^[10]

Model answer (must-hit)

1. The infant has moderate hypoxic-ischaemic encephalopathy (Sarnat stage 2 — lethargy, hypotonia, depressed primitive reflexes) with biochemical evidence of perinatal asphyxia (cord pH under 7.0, base deficit at least 12 mmol/L, Apgar 5 at 10 minutes, ongoing resuscitation). Moderate HIE is cooling-eligible. ^[1]
2. Stabilise airway, breathing, circulation. Check the blood glucose immediately (the first bedside test); treat hypoglycaemia with 10% dextrose 2 mL/kg IV. Keep the infant normothermic (36.5–37.5 °C) — never actively warm an asphyxiated infant, and avoid hyperthermia, which worsens outcome. Send a septic screen and start antibiotics. Assess Sarnat stage and activate cooling within 6 hours of life. ^[4]
3. Therapeutic hypothermia: target core 33.5 to 34.5 °C for 72 hours, started within 6 hours of life, using a servo-controlled whole-body or selective-head device; rewarm at 0.5 °C per hour. Supported by the CoolCap (Gluckman 2005), NICHD (Shankaran 2005) and TOBY (Azzopardi 2009) trials and the Jacobs 2013 Cochrane meta-analysis, which collectively show cooling reduces death and major disability by roughly a quarter. ^{[3] [4] [5]}
4. Maintain normoglycaemia, normoxia, normocapnia and normotension — each secondary insult extends the brain injury cooling is trying to prevent. Treat seizures to an electrographic endpoint with phenobarbital 20 mg/kg IV first-line. Monitor and correct coagulopathy and thrombocytopenia. Two complications: sinus bradycardia (common, benign, not an indication to rewarm) and coagulopathy or thrombocytopenia. Others include pulmonary hypertension and subcutaneous fat necrosis with late hypercalcaemia. ^[10]