1. Department of Anaesthesiology and Intensive Care, St Göran's Hospital, Stockholm, Sweden
2. Department of Anaesthesiology and Intensive Care, Huddinge University Hospital, Stockholm, Sweden
3. Department of Anaesthesiology and Intensive Care, Södertälje Hospital, Södertälje, Sweden
4. The Wenner-Gren Institute for Experimental Biology, University of Stockholm, Stockholm, Sweden