Comparison of Airway Clearance Therapy in Cystic Fibrosis Using the Same VEST Therapy Device But With Different Settings

• Sputum wet and dry weight [ Time Frame: Produced during each airway clearance therapy session ] [ Designated as safety issue: No ]
  

• Pre vs. post therapy spirometry, lung volumes, and single-breath nitrogen washout [ Time Frame: Prior to and following each airway clearance therapy session ] [ Designated as safety issue: No ]
  
• Rheology and in vitro cough transportability of sputum produced immediately following airway clearance therapy session [ Time Frame: Sputum produced during the 15 minutes immediately following airway clearance therapy sessions will be analyzed ] [ Designated as safety issue: No ]
  
• Patients' perceived comfort using the different settings for the vest device [ Time Frame: Immediately following each airway clearance therapy ] [ Designated as safety issue: No ]
  

Device: VEST Airway Clearance System, Model 205
Randomized crossover trial of airway clearance therapy comparing sine wave HFCWO with high pressures and variable frequency (pressure 10, frequencies 8,9,10 and pressure 6, frequencies 18,19,20) to low pressure and mid frequency (pressure 5, frequency 12). Subjects will have 2-day washout between airway clearance sessions. All sputum collected during sessions.
Other Name: High frequency chest wall oscillation
Device: VEST Airway Clearance System, Model 205
Subjects will perform pulmonary function tests prior to and following each airway clearance therapy. All sputum produced during, and for 15 minutes following airway clearance therapy will be collected. Subjects will complete a questionnaire addressing the comfort of therapy upon completion of the session.
Other Name: high frequency chest wall oscillation

Patients with cystic fibrosis (CF) perform daily airway clearance therapy to facilitate removal of secretions from their airways. Many different techniques are available to achieve this and there is currently no consensus as to which form of therapy is most effective. High frequency chest wall oscillation (HFCWO) is used by CF patients throughout the United States and abroad. To perform this therapy, the patient wears a vest which fits over the entire torso and is connected to an air compressor. The compressor generates oscillating air pulses that are transmitted to the lungs, thereby mobilizing secretions. The most commonly used device is The Vest™ Airway Clearance System, (Hill-Rom Inc, St Paul, MN). Adjustment of the inflation pressure and frequency of oscillations affects the volume of displaced air and flow of air measured at the mouth of the patient. Previous studies indicate this form of therapy is as effective as more traditional and cumbersome forms of therapy. However, it is unclear which inflation pressures and oscillator frequencies provide optimal airway clearance. Some studies of sine waveform HFCWO reported the largest volume of air displacement and highest air flow measured at the mouth when using a combination of high inflation pressures with either low (7 - 10 Hz) or high frequencies (18 - 20 Hz), but most CF centers in the United States use HFCWO with lower pressures combined with mid-range frequencies (10 - 14 Hz). Furthermore, there are no previous studies assessing the affect of sine waveform HFCWO settings on sputum production. As a result, there is no consensus on which pressure and frequency settings are most efficacious for CF patients.