Cooling for newborns with hypoxic ischaemic encephalopathy
Abstract
Background
Newborn animal and human pilot studies suggest that mild hypothermia following peripartum hypoxia‐ischaemia in newborn infants may reduce neurological sequelae, without adverse effects.
Objectives
To determine whether therapeutic hypothermia in encephalopathic asphyxiated newborn infants reduces mortality and long‐term neurodevelopmental disability, without clinically important side effects.
Search methods
The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library (Issue 2, 2003) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue Issue 2, 2003), MEDLINE (1966 to July 2003), previous reviews including cross‐references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.
Selection criteria
Randomised controlled trials comparing the use of therapeutic hypothermia with normothermia in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long‐term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.
Data collection and analysis
Three reviewers independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta‐analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.
Main results
Two randomised controlled trials were included in this review, comprising 50 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. There was no significant effect of therapeutic hypothermia on the combined outcome of death or major neurodevelopmental disability in survivors followed. No adverse effects of hypothermia on short term medical outcomes or on some 'early' indicators of neurodevelopmental outcome were detected.
Authors' conclusions
Although two small randomised controlled trials demonstrated neither evidence of benefit or harm, current evidence is inadequate to assess either safety or efficacy of therapeutic hypothermia in newborn infants with hypoxic ischaemic encephalopathy. Therapeutic hypothermia for encephalopathic asphyxiated newborn infants should be further evaluated in well designed randomised controlled trials.
PICOs
Plain language summary
Not enough evidence that induced hypothermia (cooling) of newborn babies who may have suffered from a lack of oxygen at birth reduces death or disability
A lack of oxygen before and during birth can destroy cells in a newborn baby's brain, and this damage continues for some time afterwards. One way to try and stop this damage is to induce hypothermia ‐ cooling the baby or just the baby's head for some hours to days. This may reduce the amount of damage to brain cells. This review found that there is not enough evidence from trials to show whether or not induced hypothermia helps newborn babies at risk of brain damage. More research is needed.
