1. Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo Metropolitan University , St.Olavs plass, Oslo 0130 , Norway
2. Centre for Patient Centered Heart and Lung Research, Department of Cardiothoracic Surgery, Oslo University Hospital , Kirkeveien 166, Oslo 0450 , Norway
3. Department of Health Sciences in Gjøvik, Norwegian University of Science and Technology , Gjøvik , Norway