Development of a novel disposable oscillating positive expiratory pressure device

In healthy individuals, mucus is removed from the respiratory tract by the mucociliary system  and is the primary defence mechanism of the lungs against inhaled microbes and irritants. In conditions such as Cystic Fibrosis (CF) and Chronic Obstructive Pulmonary Disease (COPD) this  system is ineffective, leading to hypersecretion and thickening of respiratory mucus. This causes mucus plugging, atelectasis in the small airways, and increased risk of infection.

Airway Clearance Therapy (ACT) has been used for over 40 years to remove excess secretions and break the cycle of obstruction, infection, inflammation, and damage of the pulmonary system in patients with hypersecretory disease. One of the most widely used methods of  performing ACT is the use of hand-held Oscillating Positive Expiratory Pressure (OPEP) devices.  The basic operation of an OPEP devices is firstly that a patient exhale against a small diameter orifice to increase intrapulmonary pressure to 10-20 cmH2O. This pressure splints open the  smaller airways and allows air to enter behind mucus plugs, facilitating their removal. Secondly, oscillations are generated in the intrapulmonary pressure that acts on the mucus to reduce the viscosity and help shear it away from the wall of the airways.

These OPEP devices are reusable for periods of up to six months and require regular cleaning  to prevent them from becoming contaminated and acting as potential reservoirs for pathogenic microbes. This presents a huge burden on patients and their caregivers, which often leads to poor compliance with cleaning regimens. To mitigate this risk, this thesis details the development of the first disposable OPEP device that has been trialled in patient groups. 

Two clinical investigations were undertaken in paediatric patients with CF, and adult patients with COPD respectively. Both studies were fully approved and overseen by the Irish Health Products Regulatory Agency. The paediatric CF group replaced their current OPEP device with  the prototype disposable OPEP for one month and used it for airway clearance therapy as  usual. No deterioration of lung function, exercise tolerance, or quality of life was observed, while patient opinions towards the disposable device were overwhelmingly positive. The COPD group used the disposable device for a period of one month but were not current OPEP users.  Again, no deterioration in lung function, exercise tolerance or quality of life was observed suggesting that this prototype device is safe to use in patients with COPD.

This research culminated in the development of a novel disposable OPEP device that secured  both European and United States patents, resulting in the formation of a spin-out company, and its subsequent acquisition. 

The thesis consists of five experimental chapters:

Chapter 3 explored the current practices and use behaviours of patients with CF while  performing OPEP therapy.

Chapter 4 assessed the microbial load of airway clearance devices used by patients with CF.

Chapter 5 details the design and initial testing of a novel disposable OPEP device. 

Chapter 6 reports the results of a one-month clinical trial of the disposable OPEP device in  paediatric patients with CF.

Chapter 7 reports the results of a one-month clinical trial of the disposable OPEP device in  adult patients with COPD.