Presented at the Neonatal Society 2002 Autumn Meeting.
Horan M1 (introduced by Professor David Field), Ichiba S2, Firmin RK2, Killer HM2, Edwards AD3, Azzopardi D3, Hodge R1, Kotecha S1, Field D1
1 The Child Health Department, University of Leicester, Leicester UK
2 The HeartLink ECMO Centre, The Glenfield Hospital, Leicester UK
3 Department of Paediatrics, Imperial College School of Medicine, London UK
Background: Neonates receiving extracorporeal membrane oxygenation (ECMO) represent a group at risk of hypoxic-ischaemic brain injury. Mild hypothermia appears to be a promising means of offering neuroprotection with the potential, in this group, of causing adverse effects both to the patient and the extracorporeal circuit. A pilot study was therefore performed to investigate the safety of the approach before considering a randomised controlled trial of hypothermia as a neuroprotective strategy during ECMO.
Methods: Twenty five neonates (gestation median 40 weeks (38-40)) referred for ECMO at the Glenfield Hospital, Leicester were recruited. Whole body cooling was commenced immediately following ECMO cannulation and achieved by adjustment of the extracorporeal circuit water bath temperature. The median (range) age at cooling was 25 hours (6-482 hours). Five groups (N=5 per group) were each studied for the first five days of ECMO. The first group was maintained at 37ºC throughout the study period. Subsequent groups were cooled to 36ºC, 35ºC and finally 34ºC respectively for twenty four hours and the final group to 34ºC for forty eight hours before being rewarmed to 37ºC. Patients were carefully assessed clinically and biologically. In addition to routine laboratory tests, cytokines (IL-6 and IL-8) complement (C3a) and molecular markers of coagulation (thrombin -antithrombin III, antithrombin III and plasmin a 2 plasminogen) were measured.
Results: There were no problems of bleeding or circuit dysfunction. No systematic difference was found between groups in terms of molecular markers of coagulation, complement, cytokines and platelet transfusions. Comparing study groups a marked rise and fall in heparin requirement was observed during cooling for forty eight hours. Five infants had a heart rate below 85beats/minute for more than one hour during cooling but remained normotensive. No episodes of cardiac arrhythmias were observed.
Conclusions : Applying mild hypothermia (34ºC) for 24 or 48 hours to neonates receiving ECMO is both feasible and safe.