The Influence of Non-invasive Ventilation on Metabolism in Healthy Volunteers

Before inclusion in the trial. Careful medical history and medication use will be asked. Once included, 5 healthy subjects non-invasive ventilation(V60, Philips, Eindhoven, The Netherlands) will be administered at a level of positive end expiratory pressure (PEEP) of 4 cmH2O and without additional inspiratory support. Inspiratory support will then increase by 2 cmH2O every 2 minutes until 8 cmH2O is achieved for 2 minutes. The energy expenditure is measured using indirect calorimetry (Q-NRG®, Cosmed, Italy). To measure respiratory effort, the reversed RPE-scale was created for the purpose of the study. It uses the validated "rate of perceived exertion" scale (RPE-scale) which was altered by adding a reversed part. This could result in a score of -10 (no respiratory effort) until +10 ( maximal respiratory effort) where 0 represents the basal respiratory condition. Monitoring of heart rate, blood pressure and cardiac output will be done ( Nexfin®, BMEYE, Amsterdam, The Netherlands). After termination of the study clinical observation by principal investigator or co-investigator will be done for 15 minutes or until all side effects have worn off. If no side effects are observed, subjects will be released.