Currently, the only available treatment for hypoxic-ischemic encephalopathy (HIE), besides supportive care and therapy to mitigate the symptoms, is hypothermia therapy. This involves cooling a baby down to a below-normal temperature in order to allow the brain to recover from a hypoxic-ischemic injury and limit the spread of damage. Hypothermia therapy is known to reduce the chance of death, as well as the extent and occurrence of permanent disability.
Thus far, research has indicated that in order to be effective, hypothermia therapy must be administered within six hours of birth or the oxygen-depriving insult. However, a recently-published study in the Journal of the American Medical Association (JAMA) suggests otherwise.
Laptook et al. (2017) conducted a randomized clinical trial to evaluate how infants with HIE would be impacted by hypothermia therapy administered six to 24 hours after birth. The infants included in their study had moderate or severe HIE, and had been born no earlier than 36 weeks gestation. 83 infants were given hypothermia therapy, while 85 were maintained at a normal body temperature (this was the control group). The authors followed up with these cohorts between 18 and 22 months of age.
While their results were non-significant under traditional frequentist analysis, Bayesian analysis revealed a couple of interesting patterns. First, there was a 76% probability that hypothermia therapy reduced the chance of death or disability. Second, there was a 64% probability that the risk of death and disability were reduced by at least 2%.
What Do These Findings Mean for Babies with HIE?
For the layperson, these statistics may be difficult to interpret. Essentially, it means that the results of their study were not conclusive, but that there is some suggestion that hypothermia therapy can still be helpful more than six hours after birth. The neuroprotective effects appear not to be as powerful as they are when therapy is administered within six hours, but there may still be a positive impact. Laptook et al. stress that further research is warranted, because an improved prognosis in even a small percentage of patients could be of clinical importance due to the severity of HIE-related brain damage. Moreover, they found “no evidence of commensurate harm” – in other words, the potential benefits of administering hypothermia therapy between six to 24 hours may outweigh the costs.
Regardless of whether future studies indicate that this treatment can be useful beyond the six-hour mark, physicians should still prioritize early identification of hypoxic-ischemic encephalopathy, and administer hypothermia therapy as promptly as possible.