1 Department of Intensive Care and Intermediate Care, University Hospital, Rheinisch-Westfälische Technische Hochschule Aachen; William Harvey Research Institute, Queen Mary University of London. Electronic address: lmartin@ukaachen.de.
2 Department of Intensive Care and Intermediate Care, University Hospital, Rheinisch-Westfälische Technische Hochschule Aachen.
3 William Harvey Research Institute, Queen Mary University of London.
4 Department of Anesthesia and Intensive Care, University Hospital Rostock.