Is therapeutic hypothermia for hypoxic ischaemic encephalopathy beneficial in late preterm babies?
Date First Published:
March 23, 2015
Last Updated:
March 25, 2015
Report by:
Katie Knight and Suzannah Johnson, SpR / SHO Paediatrics (Homerton University Hospital)
Search checked by:
Paul Fleming, Homerton University Hospital
Three-Part Question:
In a late premature baby (34 weeks) [patient] does therapeutic
hypothermia [intervention] compared to normothermia [comparision] reduce
the neurological adverse outcomes of moderate hypoxic ischaemic encephalopathy?
Clinical Scenario:
A 34 week baby has been delivered following a uterine rupture and is pale and floppy with no heart rate. Resuscitation is started and the baby quickly responds. Apgar scores are 11, 25 and 410. One hour later, the baby develops abnormal movements consistent with a seizure.
Blood gas analysis at this time shows: pH 6.90, PCO2 6.5, PO2 8.2, BE -14, Lactate 11.
Although by gestation this baby is one week below the 35 week limit suggested in the national guideline for therapeutic hypothermia, should this baby be considered for cooling?
Blood gas analysis at this time shows: pH 6.90, PCO2 6.5, PO2 8.2, BE -14, Lactate 11.
Although by gestation this baby is one week below the 35 week limit suggested in the national guideline for therapeutic hypothermia, should this baby be considered for cooling?
Search Strategy:
Online search performed - OVID interface
Search Details:
key words 'Preterm’, ‘Premature’, ‘Hypothermia’, ‘Hypoxic ischaemic encephalopathy’,
‘cooling’, ‘HIE’, ‘encephalopathy’ and ‘late preterm’.
‘cooling’, ‘HIE’, ‘encephalopathy’ and ‘late preterm’.
Outcome:
Secondary sources identified: Cochrane Library-one review article.
Primary sources identified: Medline, Embase, CINAHL databases were searched. There were 11 articles in Medline, 13 articles in Embase and 3 articles in CINAHL. The articles found were in turn hand-searched to identify any further relevant references.
Primary sources identified: Medline, Embase, CINAHL databases were searched. There were 11 articles in Medline, 13 articles in Embase and 3 articles in CINAHL. The articles found were in turn hand-searched to identify any further relevant references.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Therapeutic hypothermia in a late preterm infant Laura, F et al 2012 Italy | One 34+6 week infant | Case study | Case report based on one patient | ||
| To cool or not to cool? Hypothermia treatment outside trial criteria Austin, T et al 2013 UK | Not applicable | Review, expert consensus | Expert consensus | Cautiously advocates cooling for 33-36 week babies with clear diagnosis of hypoxic ischaemic encephalopathy | |
| Brain cooling for preterm infants Gunn, AJ, Bennet L 2008 New Zealand | Not applicable | Review | MRI evidence of brain injury | Significantly reduced in preterm sheep which underwent moderate therapeutic hypothermia | Based on animal models of preterm brain injury |
| Pilot Study of Head Cooling in Preterm Infants With Hypoxic Ischemic Encephalopathy Walsh W et al 2014 United States | Infants 32-35 weeks up to 6 hours old with HIE | Feasibility Study | No results available yet - study in progress Cool cap applied - not whole body cooling |
Author Commentary:
There is limited evidence and few studies that evaluate the effectiveness and benefit of therapeutic hypothermia in 32-35 week gestation babies. The published literature on this topic consists of animal studies, case reports and consensus opinions. The only published guidance
cautiously advocates cooling for 33-36 week infants, if there is a strong clinical suspicion of
an acute hypoxic-ischaemic event. However, data from large randomised controlled
studies is lacking.
Further research is needed before cooling can be routinely considered in 32-35 week babies.
Until then it is crucially important to continue to enter all babies cooled outside of criteria
into the national cooling register so that they are appropriately followed up and that data
can be analysed retrospectively.
cautiously advocates cooling for 33-36 week infants, if there is a strong clinical suspicion of
an acute hypoxic-ischaemic event. However, data from large randomised controlled
studies is lacking.
Further research is needed before cooling can be routinely considered in 32-35 week babies.
Until then it is crucially important to continue to enter all babies cooled outside of criteria
into the national cooling register so that they are appropriately followed up and that data
can be analysed retrospectively.
Bottom Line:
Babies with HIE born between 32-35 weeks who fulfil the criteria for cooling should be promptly discussed directly with a local cooling centre. Any consideration to cool outside nationally defined criteria should be clearly discussed with parents with the risks and benefits outlined.
References:
- Laura, F et al. Therapeutic hypothermia in a late preterm infant
- Austin, T et al. To cool or not to cool? Hypothermia treatment outside trial criteria
- Gunn, AJ, Bennet L. Brain cooling for preterm infants
- Walsh W et al . Pilot Study of Head Cooling in Preterm Infants With Hypoxic Ischemic Encephalopathy