[1] Heinrich Heine Univ, Univ Hosp Duesseldorf, Med Fac, Interdisciplinary Ctr Palliat Med, D-40225 Dusseldorf, Germany
[2] Heinrich Heine Univ Duesseldorf, Univ Hosp Duesseldorf, Med Fac, Dept Anesthesiol, D-40225 Dusseldorf, Germany
[3] Kings Coll Hosp NHS Fdn Trust, Dept Crit Care, London, England
[4] Harvard Med Sch, Dept Anesthesia Crit Care & Pain Med, Beth Israel Deaconess Med Ctr, Boston, MA 02115 USA