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Number of babies therapeutically cooled

In 2018, 81% of the liveborn babies reported to Each Baby Counts were actively therapeutically cooled for any length of time. This proportion has remained the same over the 4 years of data (2015 81%, 2016 82%, 2017 81%).

Therapeutic hypothermia (TH), a therapy whereby the whole body is cooled to 33.5 °C for 72 hours, has been shown to be an effective treatment for moderate to severe HIE if initiated within the first 6 hours of life, resulting in a significant reduction in the combined outcome of mortality or major neurodevelopmental disability at 18 months and improved neurocognitive outcome at school age. Early cooling (within 3 hours of birth) is associated with improved motor outcomes at 18 months when compared with cooling initiated at between 3–6 hours after birth.

TH is indicated in infants born at at least 36 weeks of gestation and who fit the criteria adopted in cooling guidelines from the Total Body Hypothermia for Neonatal Encephalopathy (TOBY) clinical trial. Increasingly, TH is considered for use in late preterm neonates. For infants born at 34-35 weeks of gestation and weighing over 1.8 kg, TH should be considered on a case-by-case basis; there is no evidence of benefit (owing to a lack of studies) but there is a growing number of reports of a lack of harm, although these are observational studies only. Any decision should be made by a level 3 NNU neonatologist or transport team, and in conjunction with parents. Caution is advised when considering TH in infants born at less than 36 weeks of gestation, with further research being required to explore the safety and efficacy of TH in this group.

Current guidelines advocate cooling for infants with moderate to severe HIE assessed using the Sarnat staging tool. However, a so-called ‘therapeutic creep’ has been observed whereby infants displaying mild HIE are treated with TH. This is possibly in response to emerging evidence of an increased risk of neurodevelopmental impairment in infants assessed as having mild HIE, or a clinician’s opinion that TH may be of benefit and concern over misdiagnosis of HIE.

The Each Baby Counts figures thus have to be interpreted alongside a known change in threshold for cooling of babies, such that more babies who are less severely compromised are now being cooled compared with when the programme started. This therapeutic creep might well be represented in the Each Baby Counts figures as an increase in case numbers as more babies meet the TH threshold and therefore the Each Baby Counts criterion for reporting despite being less severely compromised. This cannot be confirmed through current data collection, but it is an interesting research or audit question to explore further.

The Healthcare Safety Investigation Branch (HSIB) maternity investigation programme was established in 2018 and achieved full England coverage by April 2019. The driver for the creation of HSIB was the National Maternity Safety Ambition, and HSIB uses the Each Baby Counts criteria to identify cases to investigate. The methodology centres on using a standardised approach working with families and NHS staff and the HSIB review replaces the trust’s own internal investigations. In 2018, a proportion of local reviews in England assessed by Each Baby Counts were HSIB reviews.

During the 2020 changes in maternity safety reporting due to COVID-19, HSIB amended its reporting criteria to say ‘Since 23 March 2020, we have no longer been routinely investigating maternity cases involving cooled babies where there is no neurological injury following cooling therapy’ to reduce the burden on trusts in relation to reporting. It will be interesting to see from HSIB what effect this change has on the numbers of cases reviewed and whether or not the cooling of babies in its own right is reinstated as a criterion once the impact of the pandemic reduces.