What is hypoxic ischaemic encephalopathy (HIE) and what does it mean for my child?

Hypoxic ischaemic encephalopathy (HIE) is a type of brain injury. It is caused by a shortage of oxygen in the blood supply to the brain. Hypoxic brain injury has many causes and can affect people of all ages, but most HIE claims for children arise from hypoxic birth injury.

In babies, brain injury from HIE is commonly caused by poor monitoring and delays in delivery and resuscitation of a baby whose oxygen supply is interrupted by prolonged or obstructed labour, cord compression, hyperstimulation, uterine rupture or meconium aspiration. HIE birth injury can also be caused by problems during pregnancy, such as placental abruption and haemorrhage or infection.

HIE birth injury can cause lasting physical, cognitive, learning and behavioural disability.

What is HIE?

HIE is an abbreviation of hypoxic ischaemic encephalopathy.

• Hypoxia means deprivation of oxygen. 
• Ischaemia means there is not enough blood supply to the affected area of the body.
• Encephalopathy means disease or damage which affects the brain.

Perinatal HIE refers to brain injury caused by a lack of oxygen in the blood supply to the baby’s brain during labour and delivery and immediately after the baby’s birth.  Severe hypoxia is sometimes known as anoxia (without oxygen).  Another phrase that is used to describe brain injury at birth from lack of oxygen is birth asphyxia.

How is HIE diagnosed?

There are various ways in which HIE is diagnosed.

• Umbilical cord blood gases

The most reliable way of finding out whether a baby has suffered from lack of oxygen (hypoxia) during labour and delivery is by the umbilical cord blood test that is carried out immediately after birth.

At birth, the maternity team test samples of blood from the blood vessels in the umbilical cord. The vein in the umbilical cord carries oxygenated blood from the mother to the fetus (unborn baby). The two arteries in the cord carry de-oxygenated blood (containing carbon dioxide, lactic acid etc) back from the fetus to the mother. When a baby has been deprived of oxygen in labour, the blood sample from the umbilical artery contains an abnormally high level of acid. Newborn babies displaying signs of recent oxygen deprivation are sometimes described as acidotic.

• APGAR scores

The APGAR score is another method of checking a newborn baby’s condition. The maternity team rate the baby’s appearance, pulse, grimace, activity and respiration, at one minute, five minutes and ten minutes of age, giving each a score between zero and two. The combined score (out of ten) gives an overall impression of the baby’s health. This method depends on the midwife’s observation of the baby and is less reliable than the cord blood gas test, but low APGAR scores at five and ten minutes may indicate that a newborn baby has HIE.

• MRI brain scan

An MRI scan can reveal the areas of the baby’s brain that have suffered damage. The timing, severity and cause of injury can often be diagnosed from the pattern of injury on the MRI scan of the baby’s brain.

• Signs and symptoms of HIE

Babies with HIE may have any of the following signs and symptoms in the days immediately after birth:

• low APGAR scores;
• blue or pale skin colour;
• low heart rate;
• breathing (respiration) difficulties, grunting;
• fits (seizures);
• feeding difficulties;
• hypotonia (floppiness, reduced muscle tone);
• organ failure;
• abnormal response to light;
• abnormal level of consciousness.

Babies with HIE often have difficulty with breathing and may need resuscitation immediately after birth. Babies with HIE birth injury should be transferred to the neonatal unit (SCBU, NNU or NICU) for intensive care, particularly if they need ventilation to help them breathe. Most newborn babies with moderate or severe HIE are now treated with therapeutic hypothermia (cooling).  

What is cooling?

Cooling is an important treatment that has been used in specialist neonatal units since 2010 to reduce the permanent disability experienced by babies who have suffered moderate or severe HIE during labour, delivery and immediately after birth.

Birth asphyxia causes severe brain injury and permanent disability, such as cerebral palsy, which cannot be cured. Cooling works by lowering the temperature of the baby’s brain to a temperature which slows down the rate of damage to the brain. If correctly administered, controlled cooling has been proven to reduce the damage to the brain and the resulting severe physical disability.

In our experience, children who have been cooled are often significantly less physically disabled, despite their severe brain injury. They may still experience more subtle, neurological impairments which only become evident in later childhood and adolescence.

NICE guidance recommends that babies with moderate or severe HIE should be cooled under strict safety conditions. These conditions include ensuring that parents understand what is involved and agree to the treatment, and that the treatment is carried out by neonatal specialists with careful monitoring.

Why is a diagnosis of HIE important?

Brain injury affects individuals in different ways. Understanding the severity, type and location of the damage within the baby’s brain helps the neonatal and paediatric doctors predict and prepare the child’s parents for the disability and difficulties that the child may experience in the future.

The precise impact of the brain injury on the child will only become fully apparent as the child grows and develops. Where a baby with HIE birth injury has been cooled and suffers no apparent physical disability, it may be many years before related difficulties with learning, behaviour or autism spectrum disorder (ASD) become evident. If the child’s parents are not properly informed, they remain unaware that their child’s difficulties are the result of a negligent HIE birth injury, and that their child has the right to be compensated for their disability and its consequences.

Claiming compensation for HIE brain injury and cerebral palsy

If maternity mistakes during pregnancy, labour, delivery or immediately after birth caused your child to suffer HIE birth injury, cerebral palsy or other neurodevelopmental disability, your child may be entitled to claim substantial compensation.

Boyes Turner’s cerebral palsy and birth injury specialists have helped countless families affected by birth-related HIE recover compensation to pay for care, adapted accommodation, therapies, specialist aids and equipment, special education and provide lifelong financial security for their child.

Read more about how we help families affected by HIE birth injury.

If your child has cerebral palsy or neurological disability as a result of medical negligence, or you have been contacted by HSSIB/MNSI or NHS Resolution, you can talk to a solicitor, free and confidentially, for advice about how to respond or make a claim by contacting us.