1 Department of Anesthesiology and Intensive Care Medicine, Zealand University Hospital, Sygehus¬vej 10, DK4000 Roskilde Denmark.
2 Department of Anatomy, Histology and Em¬bryology, Institute of Clinical and Functional Anatomy, Medical University of Innsbruck (MUI), Austria.
3 Department of Anesthesiology and Intensive Care Medicine, Zealand University Hospital, Roskilde Denmark.
4 Department of Anesthesiology and Intensive Care Medicine, Zealand University Hospital, Roskilde Denmark; Department of Clinical Medicine, Faculty of Health and Clinical Science, University of Copenhagen, Denmark.