1. Department of Anaesthesia and Intensive Medicine, 1st Medical Faculty, Charles University in Prague and General University Hospital, U Nemocnice 2, 120 21 Prague, Czech Republic
2. University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
3. Department of Anaesthetics, Antrim Area Hospital, Bush Road, Antrim BT41 4RD, UK
4. Department of Anaesthesia and Intensive Medicine, St. Anne University Hospital, Pekarska 53, 656 91 Brno, Czech Republic