1 Department of Anaesthesiology, Intensive Care, Emergency and Pain Medicine, University Medicine Greifswald, Ferdinand Sauerbruch Str, Greifswald, Germany.
2 Department of General Practice, School of Medicine, University College Dublin, Ireland.
3 Department of Anaesthesiology and Pain Medicine, Bern University Hospital, University of Bern, Bern, Switzerland.
4 School of Medicine, Sigmund Freud University Vienna, Vienna, Austria.