Visual analogue scales
dyspnoea
Before the mask was taken off and, in the case of exercise, with the subject still pedalling, visual analogue scale (VAS) for dyspnoea (100-mm long, where 0 mm was labelled as ‘no difficulty in breathing’ and 100 mm as ‘great difficulty in breathing’) and mask’s discomfort (where 0 mm was labelled as ‘no discomfort’ and 100 mm as ‘very uncomfortable’) were administered. The VAS for dyspnoea was also administered in the no mask condition.