1. Department of Anesthesiology and Pre-operative Screening and Pain Center; Rijnstate Hospital Velp; Velp The Netherlands
2. Department of Anesthesiology and Multidisciplinary Pain Center; Ziekenhuis Oost-Limburg; Genk Belgium
3. Department of Anesthesiology; Pain and Palliative Medicine; Radboud University Medical Center; Nijmegen The Netherlands
4. Department of Anesthesiology; Bradford Royal Infirmary; Bradford U.K
5. Department of Anesthesiology; TTUHSC; Lubbock Texas U.S.A
6. Department of Anesthesiology and Pain Management; University Medical Center Groningen; Groningen The Netherlands