Antonio Anto´n PhD, Julia Ta´rrega MD, Jordi Giner RN, Rosa Gu¨ell PhD, and Joaquin Sanchis PhD OBJECTIVE: To assess the efficacy of and patient tolerance for nasal and full-face masks during noninvasive positive-pressure ventilation (NPPV) with patients suffering acute exacerbations of chronic obstructive pulmonary disease. SETTING: A respiratory medicine ward of a referral hospital. METHODS: Fourteen patients were randomized to 2 groups. Seven used nasal masks and 7 used full-face masks. We used a portable ventilator and recorded arterial blood gases and indices of respiratory muscle effort before and after 15 min of NPPV. Patient tolerance was scored as follows: no tolerance (mask had to be withdrawn before the study period ended) 0 points; poor tolerance (patient complained of discomfort from the ventilation devices but nevertheless remainedcompliant) 1 point; fair tolerance (patient seemed uncomfortable but did not complain) 2 points; excellent tolerance (patient felt better than before beginning NPPV) 3 points. RESULTS: The groups were comparable in clinical and pulmonary function variables at baseline. NPPV improved both arterial blood gases and the indices of respiratory effort, with no significant differences between the groups. During NPPV the group that used full-face mask had a greater decrease in respiratory rate, but no other differences. NPPV was well tolerated in both groups. CONCLUSIONS: In patients suffering acute exacerbations of chronic obstructive pulmonary disease NPPV improves arterial blood gases and respiratory effort indices regardless of the type of mask used.Acute physiologic effects of nasal and full-face, Respir Care