Right now, there is only one treatment available for treating hypoxic-ischemic encephalopathy. This treatment is known as hypothermia therapy, and can also be known as ‘cooling therapy,’ ‘cooling treatment,’ or ‘hypothermia treatment.’ This treatment involves cooling the baby down to a temperature below homeostatic temperature to allow the baby’s brain to recover from a hypoxic-ischemic injury, usually to about 33 degrees Celsius (91 degrees Fahrenheit). There are two ways that hypothermia treatment can be administered: using a cooling cap for selective brain cooling (‘head cooling,’) or using a cooling blanket for ‘whole-body cooling.’ Either of these options can be effective; the choice to use one over the other is dependent on what protocols are in place and what equipment a particular NICU has.
How does Hypothermia Therapy Work?
Selective Brain Cooling and Infant Cooling Caps
A cooling cap is a flexible cap that runs cold water or another coolant through channels in the cap. This cold liquid draws heat from the infant’s body and reduces the temperature of the brain. The baby’s temperature is reduced for about 72 hours (3 days), and the baby is warmed back up very slowly.
Whole-Body Cooling and Cooling Blankets
With whole-body cooling, the infant is placed on a cooling blanket while naked (except for a diaper). This cooling blanket drops the temperature of the baby’s entire body. The cooling process lasts for three days, until the baby is slowly re-warmed by degrees.
During both kinds of cooling therapy, doctors, nurses and other medical staff watch the baby’s vital signs, including:
- Heart rate
- Brain wave activity
By monitoring the baby closely, they can determine how well the baby is responding to treatment, and they can make adjustments as necessary.
When Should My Baby Get Hypothermia Therapy?
If your baby was diagnosed with hypoxic-ischemic encephalopathy (HIE), doctors have to begin hypothermia therapy within six hours* of the initial brain injury, which in many cases occurs during birth and delivery. The sooner they start hypothermia therapy, the greater the chance that the baby’s potential disabilities will be minimized. There are certain criteria that babies have to meet in order to qualify for the therapy, and these can vary slightly depending on the hospital your baby is in. Usually, this means that the baby has to be at least 36 weeks’ gestation, and show at least two of the following signs of moderate-to-severe HIE:
- Abnormal tone/posture
- Abnormal reflexes
- Decreased/absent spontaneous activity
- Problems with breathing, heart rate or visual reflexes
- Metabolic acidosis
Re-Warming the Baby After Hypothermia Therapy
Although hypothermia therapy lasts about 72 hours, treatment for brain injuries continues even after the cooling is done. The baby is warmed up by degrees to prevent a condition known as reperfusion injury. Reperfusion injury occurs when blood rushed back too quickly into an area that has already been damaged. When tissue is damaged, the cells are in a state where inflammatory compounds are being released from damaged cells. The rush of blood back into the area can damage cell membranes already unstable due to injury, releasing compounds that then cause further damage to the cells in a cascade reaction. Hypothermia therapy helps to stabilize the cell membranes and prevent this from occurring. Gradual re-warming (as opposed to fast rewarming) helps keep cells stable, minimizing brain damage together with hypothermia therapy.
Where Do Babies Get Hypothermia Therapy?
Not all hospitals will be equipped to provide hypothermia therapy because not all NICUs are the same. Community hospitals, for example, may not have brain cooling equipment, but they should have the ability to transfer the baby to a bigger or more specialized hospital that can provide cooling. Generally, neonatal care units are divided into Grade I, II, III, and IV, and only Grade III or IV units are able to provide hypothermia therapy to a baby. It is a good idea to inquire about what kind of care a neonatal care unit can provide when researching hospitals.
*Research Update: Window of Time to Provide Hypothermia Therapy May Be Longer Than Previously Thought
Traditionally, it has been thought that hypothermia therapy must be administered within six hours of birth in order to be effective. However, recent research indicates that this may not be the case. Laptook et al. (2017) set out to investigate whether hypothermia therapy given six to 24 hours after birth could benefit infants with HIE. They conducted a randomized clinical trial on 168 infants with moderate or severe HIE. Their results were inconclusive. However, Bayesian analysis indicated that hypothermia therapy may have slightly reduced the chance of death and disability. The authors call for further research on the window of time in which hypothermia therapy can be effective, stressing that if belated administration of hypothermia therapy is even slightly better than no hypothermia therapy, that knowledge would still be profoundly important. Of course, the neuroprotective effects of cooling treatment are stronger the sooner it is given, so medical professionals should still administer it as quickly as possible.
- Shankaran, Seetha, et al. Whole-Body Hypothermia for Neonates with Hypoxic–Ischemic Encephalopathy. N Engl J Med 2005; 353:1574-1584. October 13, 2005. DOI: 10.1056/NEJMcps050929.
- Edwards, A.D. Therapeutic Hypothermia Following Perinatal Asphyxia. Archives of Disease in Childhood, Fetal Neonatal Ed. 2006 Mar; 91(2): F127–F131. doi: 10.1136/adc.2005.071787.
- Guillet, R. Seven- to eight-year follow-up of the CoolCap trial of head cooling for neonatal encephalopathy. Pediatr Research 2012 Feb; 71(2):205-9. doi: 10.1038/pr.2011.30. Epub 2011 Dec 21.
- Reference: Aetna Policy History: Hypoxic-Ischemic Encephalopathy.