Servo-controlled cooling during neonatal transport for babies with hypoxic-ischaemic encephalopathy is practical and beneficial: Experience from a large UK neonatal transport service

Abstract

Aim: Servo-controlled therapeutic hypothermia is a routine therapy for babies with hypoxic-ischaemic encephalopathy in the neonatal unit and is delivered in designated cooling centres. It is increasingly being used during neonatal transport in the UK to deliver this therapy in a timelier manner for babies not born in a cooling centre. Prior to the implementation of this treatment, passive cooling alone was used in transport. Comparison of passive and servo-controlled cooling during neonatal transfers with reference to: (i) the proportion of babies in the therapeutic range (33-34°C) at three time points during the transport mission (arrival of the team at the referring unit, departure of the team from the referring unit and at the completion of transport); (ii) the proportion of babies overcooled at any point once the transport team was present (<33°C); and (iii) duration of phases of the transfer to evaluate the impact of active cooling on how long it takes to undertake transfer.

Methods: This was a retrospective observational study comparing babies with passive and servo-controlled hypothermia (January 2015 to May 2016) following introduction of the servo-controlled cooling mattress.

Results: A total of 48 patients were treated with hypothermia in transit (29 passive, 19 servo-controlled). The median gestational age (GA) was 40 weeks (interquartile range: 39-41) and mean birthweight (BW) 3420 g (standard deviation 600 g); there was no differences in GA, BW and clinical characteristics between the groups. There was a statistically significant difference in the temperature at the end of the transport, where 94% (n = 18) of babies who received servo-controlled cooling were in the target temperature in comparison with only 65% (n = 19) of the passive cooling group babies (P = 0.045). In addition, none of the babies in the servo-controlled group were warm (>34°C) at the end of the transfer. Babies who underwent servo-controlled cooling are more likely to maintain a target temperature (33-34°C) (17 (89%) vs. 17 (58%), P = 0.021); in particular, there is less overcooling (<33°C) in this group (2 (10%) vs. 15 (51%), P = 0.004). Total mission time was not significantly different.

Conclusion: The use of servo-controlled cooling devices during neonatal transport improves the ability to maintain the baby's temperature within the target range (33-34°C) with less overcooling.

Keywords: cooling during transport; hypoxic-ischemic encephalopathy; passive cooling; servo-controlled cooling; therapeutic hypothermia.