Neonatology - Hypoxic ischaemic encephalopathy

Question 1

Definition

Answer 1

Hypoxic-ischaemic encephalopathy (HIE) occurs when there is a reduction in oxygen supply (hypoxia) and/or blood flow (ischaemia) to the neonate’s brain, leading to neuronal damage and dysfunction.

Question 2

When should HIF be suspected

Answer 2

• Hypoxic events occur during perinatal or intrapartum period
• Acidosis (pH<7) on umbilical artery blood gas
• Poor Apgar scores
• Clinical presentation of HIE

Question 3

Aetiology

Answer 3

The primary cause of HIE in neonates is asphyxia. This can be caused by prolapsed or nuchal cord, intrapartum haemorrhage or maternal shock.

Question 4

Epidemiology

Answer 4

The prevalence of HIE is 1-6 per 1000 live births
Maternal risk factors:
- hypertension,
- diabetes,
- substance abuse,
- infection
Obstetric risk factors:
- prolonged labour,
- meconium-stained amniotic fluid,
- placentral abruption,
- umbilical cord prolapse
Infant risk factors:
- prematurity
- low birth weight
- congenital anomalies

Question 5

Signs

Answer 5

Altered level of consciousness
Hypotonia
Weak or absent reflexes
Apnoea or irregular breathing

Question 6

Symptoms

Answer 6

• Poor feeding
• Irritability
• Lethargy
• Seizures

Question 7

Stage scoring system

Answer 7

SARNAT SCORE:
Stage 1 (Mild HIE):
- Poor feeding
- Irritable but alert, mild hypotonia, and no seizures
- Resolves within 24 hours
- Normal prognosis
Stage 2 (Moderate HIE):
- Lethargy, moderate hypotonia, and seizures
- Can take weeks to resolve
- Up to 40% develop cerebral palsy
Stage 4 (Severe HIE)
- Coma
- Severe hypotonia
- Severe seizures
- Up to 50% mortality rate
- Up to 90% develop cerebral palsy

Question 8

Diagnosis

Answer 8

FIRST LINE:
- Blood gas analysis
- Blood tests: to evaluate electrolyte levels, glucose, and infection markers
- Cranial USS: to detect brain injury and rule out other intracranial pathologies
Investigations to consider:
- MRI
- EEG

Question 9

Treatment

Answer 9

FIRST LINE:
- Oxygen therapy
- Fluid and electrolyte management: maintain hydration, electrolyte balance and prevent hypoglycaemia
- Antiepileptic drugs
- Therapeutic hypothermia: decrease metabolic demands and protects against further brain injury. Recommended for moderate to severe HIE within 6 hours of birth
- Supportive care: to provide adequate nutrition maintain body temperature and manage any complications

Question 10

Complications

Answer 10

Cerebra palsy
Cognitive impairment
Epilepsy
Visual and hearing impairment
Developmental delay
Death