1 Department of Physiology and Pharmacology, Section of Anaesthesia and Intensive Care, Karolinska Institutet, Stockholm, Sweden. johan.martensson@sll.se.
2 Function Perioperative Medicine and Intensive Care, Karolinska University Hospital, 171 76, Stockholm, Sweden. johan.martensson@sll.se.
3 Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, London, UK.
4 Intensive Care Unit, Imperial College Healthcare NHS Trust, St Mary's Hospital, London, UK.