G Suren Arul1, Steve Bree2, Brian Sonka3, Charlie Edwards2, Paul Reavley4. 1. Department of Paediatric Surgery, Birmingham Children's Hospital, Birmingham B4 6NH, UK suren.arul@bch.nhs.uk. 2. Department of Anaesthesia, Derriford Hospital, Plymouth, UK. 3. Department of Surgery, William Beaumont Army Medical Centre, El Paso, USA. 4. Department of Emergency Medicine, Bristol Royal Infirmary, Bristol, UK.