1. Volume 97, Issue 3, Pages 645-650 (March 1990)
Long-Term Treatment of Chronic Bronchitis with Positive Expiratory Pressure Mask and Chest Physiotherapy 
Erika Frischknecht Christensen, M.D., Tonny Nedergaard, Ronald Dahl, M.D. 
CHEST 
Volume 97, Issue 3, Pages (March 1990)
DOI: /chest
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

2. Figure 1
PEP mask is a face mask connected to a T-tube where inspiratory and expiratory airflow are separated by a valve. Variable expiratory resistances can be applied onto the expiratory tube as connections of different diameters. In this way, a positive airway pressure is created during expiration. The pressure can be controlled by a manometer.
CHEST  , DOI: ( /chest )
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

3. Figure 2
The number of acute exacerbations in the PEF-treated group (20 patients) and in the control group (23 patients).
CHEST  , DOI: ( /chest )
Copyright © 1990 The American College of Chest Physicians Terms and Conditions