1. Division of Anaesthesia and Intensive Care, Perioperative Services at Landspitali the National University Hospital of Iceland Reykjavik Iceland
2. Faculty of Medicine University of Iceland Reykjavik Iceland
3. Division of Anaesthesia and Intensive Care Perioperative Services at Akureyri Hospital Akureyri Iceland
4. Department of Otorhinolaryngology at Landspitali the National University Hospital of Iceland Reykjavik Iceland
5. Department of Cardiothoracic Surgery at Landspitali the National University Hospital of Iceland Reykjavik Iceland