There are many chest physiotherapy or airway clearance techniques (ACT) available including breathing methods such as the Active Cycle of Breathing Techniques (ACBT) or Autogenic Drainage (AD) and adjuncts such as Positive Expiratory Pressure (PEP), High Frequency Chest Oscillation (the "Vest"), or oscillatory devices such as the Flutter or Acapella. When people with CF have an infection or have severe disease often the effectiveness of ACTs can decrease due to fatigue, shortness of breath or having an overwhelming amount of sputum. At this time it is necessary to re-assess ACTs and the addition of positive pressure to airway clearance techniques has been shown to be helpful in decreasing fatigue during chest physiotherapy.