1 From the Department of Medical Sciences, Clinical Physiology (G.H.) the Department of Surgical Sciences, the Hedenstierna Laboratory (G.P., A.L.), Uppsala University, Sweden the Department of Anaesthesia and Intensive Care, Bispebjerg and Frederiksberg Hospital, University of Copenhagen (C.S.M.) the Copenhagen Trial Unit, Centre for Clinical Intervention Research, Rigshospitalet, Copenhagen University Hospital (J.W.) the Department of Anesthesia, Rigshospitalet University of Copenhagen (L.S.R.), Denmark.