1. Centre for Patient Centered Heart and Lung Research, Department of Cardiothoracic Surgery, Oslo University Hospital , Kirkeveien 166, 0450 Oslo , Norway
2. Department of Health Sciences in Gjøvik, Norwegian University of Science and Technology , 2802 Gjøvik , Norway
3. Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo Metropolitan University , St. Olavs Plass, Oslo , Norway