High Frequency Chest Wall Oscillation in Chronic Obstructive Pulmonary Disease (COPD)
Condition: Chronic Obstructive Pulmonary Disease
MeSH terms: Lung Diseases; Lung Diseases, Obstructive; Pulmonary Disease, Chronic Obstructive
Study type: Interventional

Summary: 
      Patients with Chronic obstructive pulmonary disease (COPD) tend to have cough, excess mucus
      production and breathlessness as cardinal features. The excess mucus production often leads
      to frequent infections, exacerbations and poor quality of life. Mucociliary clearance may
      have an impact on improving symptoms, exercise tolerance, quality of life and reduce
      exacerbations.

      High frequency chest wall oscillation(HFCWO) devices use percussion to the chest wall
      delivered from a pump through a close fitting inflatable vest. This technique has been shown
      to enhance mucus clearance in patients with cystic fibrosis and Bronchiectasis. This pilot
      study was designed to explore the feasibility, tolerance and effectiveness of the HFCWO in
      patients with advanced COPD.
    

Detailed description: 
      1.1 Background

      Chronic obstructive pulmonary disease (COPD) is a major health problem across the world and
      its medical, societal and economic impacts continue to grow. COPD is characterized by chronic
      obstruction of expiratory flow affecting peripheral airways, associated with chronic
      bronchitis (mucus hypersecretion with goblet cell and submucosal gland hyperplasia) and
      emphysema (destruction of airway parenchyma), together with fibrosis and tissue damage, and
      inflammation of the small airways1. The beneficial effects of smoking cessation in slowing
      the decline in lung function and the progression of disease have been clearly established.
      Whether other factors such as mucus hypersecretion, respiratory infections and airway
      hyper-reactivity contribute to disease progression independent of cigarette smoking is still
      being debated2.

      Patients with COPD are often distressed by mucus hypersecretion which is one of the hallmarks
      of the disease but little is known about the impact of current therapies on mucus
      hypersecretion due to the logistical challenges of objectively quantifying mucus in clinical
      studies 3. Mucus hypersecretion occurs as a direct result of airway inflammation. Neutrophils
      that die by necrosis disgorge proteases and reactive oxygen species into the lumen. It is
      concluded that neutrophil death via necrosis leads to the high concentrations of free
      neutrophil elastase and reactive oxygen species in the sputum of patients with airway
      neutrophilia and mucus hypersecretion. Inflammatory cells (neutrophils), molecules
      (neutrophil elastase and reactive oxygen species), signaling pathways (EGFR), and cellular
      processes (neutrophil necrosis) contribute to mucus hypersecretion in COPD4.

      Mucus hypersecretion leads to increased work of breathing, reduced exercise tolerance,
      deteriorating lung function and increases dyspnoea and cough. Often the mucus hypersecretion
      also interferes with nocturnal sleep and has a further negative impact on health related
      quality of life. Combined mucus hypersecretion, reduced clearance, and impairment of the lung
      defence mechanisms explain why COPD patients even with stable condition, carry potential
      respiratory pathogens in significant concentration, paving the way for infection and acute
      exacerbations of COPD5;6. In the natural history of COPD chronic mucus hypersecretion is
      thought to be linked to the accelerated decline of forced expiratory volume in one second
      (FEV1)5 7 .

      Although mucoactive drugs (which improve the ease of mucus clearance) may be effective in
      mucus hypersecretion, the uncertainty surrounding their effectiveness, due primarily to the
      relative lack of evidence from randomised controlled trials and an uncertainty from
      epidemiological studies linking mucus hypersecretion with mortality8-11, have led to their
      poor diffusion and adoption in international guidelines 7. However, in combination with newer
      therapeutic strategies currently in research and development phase targeting airway
      inflammation and thus reducing mucus hypersecretion, there is a renewed interest in
      re-evaluating mucus clearance strategies in improving HRQL, exacerbations and morbidity
      associated with COPD 12;13.

      Airway clearance forms a vital part the management of patients with CF14, Bronchiectasis and
      neuro-muscular diseases15 and has a positive impact on lung function, infection rate and
      mortality16;17. Individually tailored chest physiotherapy18 with forced expiratory manoeuvres
      is often considered the gold standard in airway clearance19, although self-administered
      techniques may be equally effective20 and preferred by patients17;21. Self-administered
      airway clearance techniques using devices which create a turbulent airflow thus encourage
      shearing of mucus from bronchial wall, have shown promise in improving HRQL and function in
      COPD patients22.

      High frequency chest wall oscillation (HFCWO)23 is known to reduce respiratory rate but
      improve ventilation in patients with COPD24 and CF25. Experimental results suggest that
      shearing at the air-mucus interface could be a significant factor in the enhanced tracheal
      mucus clearance during HFCWO26. Unlike in CF patients who often have greater support from
      family members and show high levels of motivation and thus compliance in adhering to
      self-administered airway clearance techniques, COPD patients have low motivation and poor
      compliance. Thus self-administered techniques for mucosal clearance may be less effective in
      clinical settings away from dedicated research programs. Thus the HCFWO may offer a more
      passive modality of airway clearance with consequently higher compliance, if found to be
      equally effective and well-tolerated in this group of patients. If HFCWO is shown to improve
      HRQL, symptoms and exercise tolerance then it may have a significant role in reducing
      exacerbations and hospital admissions as well as allowing effective management in the
      community setting. The cost benefit of such improvements will need to be explored in larger
      studies in the future.
    

Intervention name(s): HFCWO - SmartVest
Intervention type(s): Device
Intervention description(s): SmartVest with vest administered for 20min at 11-13Hz
Other intervention name(s): SmartVest
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: COPD; Mucus hypersecretion; HRQL; ESWT; HFCWO