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Ms Roberts and her colleagues suggest that extracorporeal membrane
oxygenation (ECMO) lowers neonatal mortality at an acceptable cost.
However, their analysis is based on the UK ECMO trial, in which babies
were randomised to receive either conventional mechanical ventilation in
one of 55 neonatal units or ECMO in one of only five intensive care
units. The five ECMO units had substantially more facilities then many
of the 55 neonatal units.
Fewer children died in the ECMO group, but we cannot be sure that
this difference was because of the ECMO. Mortality may have been lower in
the ECMO group because of better care in the units that provided ECMO -
there is substantial evidence that centralisation of intensive care
services for children reduces mortality. Indeed the relative risk of
0.55 in the ECMO trial is strikingly similar to the odds ratio of 0.48 in
our comparison of paediatric intensive care in Victoria (centralised) with
There were good practical and ethical reasons for the design of the
UK ECMO study, but the decision to leave control babies at the referring
hospital (rather than sending all babies to the ECMO centres) means that
we do not know whether the observed difference in mortality was due to
ECMO or to other differences in management.
Frank Shann MB, BS, MD, FRACP
Director of Intensive Care, Royal Children's Hospital, Melbourne
Professor of Critical Care Medicine, University of Melbourne
1. Roberts TE and the Extracorporeal Membrane Oxygenation Economics
Working Group on behalf of the Extracorporeal Membrane Oxygenation Trial
Steering Group. Economic evaluation and randomised controlled trial of
extracorporeal membrane oxygenation: UK collaborative trial. Br Med J
2. UK Collaborative ECMO Trial Group. UK collaborative randomised
trial of neonatal extracorporeal membrane oxygenation. Lancet 1996;
3. Pearson G, Shann F, Barry P et al. Should paediatric intensive
care be centralised? Trent versus Victoria. Lancet 1997; 349:1213-17.