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

Comparison of Sine Waveform High Frequency Chest Wall Oscillation Using Different Settings in Cystic Fibrosis

Our primary hypothesis is that airway clearance therapy with sine waveform HFCWO using higher inflation pressures combined with both low and high oscillator frequencies will result in greater sputum production compared to sine waveform HFCWO with lower inflation pressures and mid-frequency oscillations.

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.

Inclusion Criteria:

1. Diagnosis of CF established by sweat chloride > 60 mmol/L.
2. Age older than 18 years.
3. History of chronic daily sputum production.
4. Currently on a home therapeutic regimen that includes some form of airway clearance performed with a HFCWO device at least once daily that also includes concomitant use of an inhaled mucolytic and inhaled bronchodilator.
5. FVC and FEV1 > 40%-predicted, and with stable lung function (no greater than a 10% variation in lung function parameters over the preceding 3 months).
6. Evaluated at the University of Minnesota CF Center 3 or more times in the preceding 12 months.

Exclusion criteria:

1. Hospitalization for CF pulmonary complications in the 2 months preceding enrollment.
2. Hemoptysis > 60 cc in a single episode in the 4 weeks preceding enrollment.
3. Chest pain requiring use of narcotic for pain control.
4. Current participation in another clinical trial.
5. Use of intravenous antibiotics for CF respiratory complications in the 2 months preceding enrollment.
6. No prior experience using HFCWO devices for airway clearance