[1] Ruhr Univ Bochum, Univ Klinikum, Knappschaftskrankenhaus Bochum Langendreer, Klin Anasthesiol Intens Med & Schmerztherapie, D-44892 Bochum, Germany
[2] Univ Klinikum Munster, Klin & Poliklin Anasthesiol & Operat Intens Med, Munster, Germany
[3] Stadt Klinikum Solingen gGmbH, Klin Anasthesie Operat Intens & Palliat Med, Solingen, Germany