[1] Cantonal Hosp St Gallen, Div Anaesthesiol Intens Care Rescue & Pain Med, St Gallen, Switzerland
[2] Univ Valencia, Dept Anaesthesiol & Crit Care, Hosp Gen, Valencia, Spain
[3] Univ Europea Valencia, Res Methods Dept, Valencia, Spain
[4] Cantonal Hosp Aarau, Dept Neurosurg, Aarau, Switzerland
[5] Univ Bern, Fac Med, Bern, Switzerland
[6] Ohio State Univ, Coll Med, Dept Anaesthesiol, Columbus, OH 43210 USA
[7] Univ Bern, Univ Hosp Bern, Dept Anaesthesiol & Pain Med, Inselspital, Bern, Switzerland