Hypoxic-Ischaemic Encephalopathy

Question 1

What is Hypoxic-Ischaemic Encephalopathy?

Answer 1

Brain injury caused by oxygen deprivation to the brain

Also known as intrapartum asphyxia

Remains an important cause of brain damage, resulting in disability or death

HIE prevention is one of the key aims of modern obstetric care

Question 2

What causes cardiopulmonary depression in the pathogenesis of HIE?

Answer 2

• In perinatal asphyxia, gas exchange, either placental or pulmonary, is compromised or
ceases altogether → leads to cardiopulmonary depression

Hypoxia, hypercarbia and respiratory acidosis follow

Question 3

How does metabolic acidosis arise in HIE?

Answer 3

Compromised cardiac output diminishes tissue perfusion, causing hypoxic-ischaemic
injury to the brain and other organs → leads to metabolic acidosis

Question 4

What can cause HIE?

Answer 4

o Failure of gas exchange across the placenta (excessive or prolonged uterine
contractions, placental abruption, ruptured uterus)
o Interruption of umbilical blood flow (e.g. cord compression including shoulder
dystocia, cord prolapse)
o Inadequate maternal placental perfusion, maternal hypotension and
hypertension
o Compromised foetus (anaemia, IUGR)
o Failure of cardiorespiratory adaptation at birth (failure to breathe)

Question 5

What is a reperfusion injury?

Answer 5

tissue damage caused when blood supply returns to tissue
after a period of ischaemia. The absence of oxygen and nutrients from blood
during the ischaemic period creates a condition in which the restoration of
circulation results in inflammation and oxidative damage through the
induction of oxidative stress rather than (or along with) restoration of normal
function

Question 6

What are the clinical features of mild HIE?

Answer 6

infant is irritable and responds excessively to stimulation, may have
staring eyes, hyperventilation, hypertonia and impaired feeding

Question 7

What are the clinical features of moderate HIE?

Answer 7

infant shows marked abnormalities of movement, hypotonic,

cannot feed and may have seizures

Question 8

What are the clinical features of severe HIE?

Answer 8

NO normal spontaneous movements or response to pain, tone in
limbs may fluctuate between hypotonia to hypertonia, seizures are often
prolonged and refractory to treatment, multi-organ failure present

Question 9

What is HIE characterised by?

Answer 9

HIE is characterised by fetal distress, metabolic acidosis and the need for artificial
ventilation from birth