Therapeutic Hypothermia/ Cooling Therapy

Therapeutic Hypothermia  – which is a cooling treatment,  is a relatively new option for treating newborn babies who have suffering from asphyxiation, or insufficient oxygen during labour and delivery. It involves reducing the infant’s body temperature by 2-3 degrees Celsius, resulting in modest hypothermia. The treatment works by reducing the brain’s use of energy, which slows disease progression and reduces the chances of the baby suffering from severe brain damage.

To meet the criteria for this treatment, the baby must be at least 36 weeks’ gestation. The baby must be less than 6 hours old to start cooling treatment.  After 6 hours of age, cooling does not provide the same level of protection. Babies may not be eligible for the treatment if they have certain congenital abnormalities or if they have a very low birth weight. Cooling is only used in very specific situations – the baby must have severe acidosis demonstrated by a low umbilical cord pH, abnormal blood gases or base deficit, and a complicated delivery and low apgar scores, or have needed at least 10 minutes of help breathing. In other words, it must be shown that the baby’s condition is due to lack of oxygen around the time of birth. The baby must also show evidence of moderate to severe encephalopathy, demonstrated by a combination of signs and symptoms such as seizures, lethargy or coma, decreased or no activity, abnormal posture, decreased muscle tone, weak or absent reflexes and abnormal heart rate, pupils or breathing.

There are two main methods of cooling the infant – whole body cooling and selective head cooling. The type of cooling used depends on the hospital, but both methods have been shown to be safe and effective in bringing core body temperature down to therapeutic levels. Rewarming begins after 72 hours of cooling, and serial monitoring of the infant’s core temperature is important to prevent overheating.

Research suggests that therapeutic hypothermia is safe and provides long-term protection for the brain. Reducing the metabolic rate (or energy requirement) of the baby’s brain has the effect of reducing the impact of a brain injury that a baby has suffered. A brain injury may have occurred because there was a period of time where the baby did not receive enough oxygen. Cells in the brain are more at risk of dying if they have an insufficient oxygen supply and the brain itself can also become swollen. Cooling reduces the swelling and cell death and so can reduce the likelihood of the baby having a disability or dying, especially if the treatment is started within 3 hours of birth.

Keeping a baby’s core temperature at a lower level than normal must be done in a controlled manner with close monitoring of the baby’s heart rate, breathing and blood pressure. If a baby’s temperature becomes cooler than the temperature targeted by cooling therapy, then this can potentially worsen the brain injury. The core temperature, therefore, also needs to be carefully monitored so that a baby is not cooled too much. With this careful monitoring in place, cooling therapy is considered to be safe.

In Canada, cooling therapy is offered by hospitals with a neonatal intensive care department and, if a hospital is not equipped to provide it, then babies can be transferred to a hospital where this treatment is available. In these situations, cooling may be started in the birth hospital and continued by the team transferring the baby to the higher level of care hospital where it will be continued.