Presented at the Neonatal Society 2009 Autumn Meeting.
Thayyil S1, Ayer M2, Guhan B2, Marlow N1, Jacobs I1, Costello AM3, Shankaran S4, Robertson NJ1 (On the behalf of PeaCock Trial Collaborators)
1 UCL Institute for Women’s Health, London, UK
2 Calicut Medical College, Kerala, India
3 UCL Institute for Child health, London, UK
4 Children’s Hospital Michigan and Wayne University, Detroit, USA
Background: Therapeutic hypothermia (TH) improves neurological outcome following neonatal encephalopathy (NE)(1); however effective low tech cooling equipments, particularly for use in low resource settings, are not available. Phase changing material (PCM) with a melting point 32ºC, induces and maintains TH effectively in a piglet model of neonatal encephalopathy(2).
Aim: To examine cooling efficacy and cost effectiveness of phase changing material for whole body cooling in neonatal encephalopathy.
Methods: We randomised fourteen newborn infants with NE, admitted within 24 hours of age, to a large level II neonatal unit in south India between September 2009 and October 2009, to receive whole body cooling by PCM mattress or standard care, after informed parental consent. We used minimisation (SiMin version 1.1, University College London, UK) based on age (<6 h versus 6-24 h) and Thompson score3 (<9 versus >9) and performed continuous temperature recording using a 4-channel data logger (Grant instruments Ltd, Cambridgeshire, UK). We induced cooling by keeping baby naked on the PCM mattress and used additional blankets, if required, to keep rectal temperature (Trectal) within target range (Trectal 33-34ºC for 72 hours). Local research ethics committee approved study.
Results: Median (IQR) therapeutic hypothermia induction time was 30 (6, 90) min and re-warming time was 10.3 (4.3, 18) h (0.24ºC/h). Median (IQR) number of blanket changes during cooling phase was 3 (2-5) per day. No PCM mattress change was required. All control babies were hypothermic at admission and achieved rectal >36.5ºC after a median (IQR) time of 8 (1.9, 27.2) h. Median (IQR) heart rate was significantly lower during cooling (116 [104, 117] versus 128 [126, 117] per min [p<0.01]); however, no significant difference was seen in respiratory rate, blood pressure, saturation, platelet counts, C-reactive protein, liver enzymes or coagulation profile, between cooled and control groups.
Table 1: Baseline characteristics and neonatal outcomes.
IQR=Interquartile range, SD=Standard deviation
Figure 1: Mean (SD) rectal temperature during the study, according to treatment group.
Conclusion: Mattresses made of phase changing material may be an efficient, low tech and cost-effective method of administering therapeutic hypothermia and may be particularly useful in low resource settings. However, rigorous evaluation of safety and efficacy of whole body cooling in large clinical trials, tailored to local needs, are required, before cooling can be used as standard of care in neonatal encephalopathy in low resource settings. Dilutional effect of natural hypothermia in control babies should be factored into the sample size calculations of such trials.
References
1. Azzopardi D et al. N Engl J Med. 2009 Oct 1;361(14):1349-58
2. Iwata S et al. Arch Dis Child. 2009 May;94(5):387-91
3. Thompson CM et al. Acta Paediatr. 1997 Jul;86(7):757-61