[1] Department of Anaesthetics, Royal Postgraduate Medical School, Hammersmith Hospital, London, W12, Du Cane Road
[2] Department of Anaesthetics, Royal Postgraduate Medical School, Hammersmith Hospital, London, W12 OHS, Du Cane Road
[3] Department of Anaesthetics, Royal Postgraduate Medical School, Hammersmith Hospital, London, W12 OHS, Du Cane Road