Department of Physiotherapy, Queen Mary Hospital
When chest physiotherapy with manual percussion, postural drainage and vibration was first introduced in 1901in assisting the bronchiectatic children1, for several decades, it was synonymous with airway clearance technique. During the years, various devices were developed to assist in airway clearance or, at the very least, allow for effective, self-administered therapy. One of these adjuncts was the positive expiratory pressure (PEP) therapy devices.
PEP therapy was first developed in Denmark in the 1970s, as a low-pressure system. The main components of the PEP device consist of a one way valve connected to either a small-exit orifice or an adjustable expiratory resistor. Sometimes a disposable manometer is incorporated to measure the expiratory pressure. Low pressure PEP devices typically generate a pressure range of 10–20 cm H2O at mid-expiration.2
It aims to reduce air trapping and optimize delivery of bronchodilators (e.g. in asthma and COPD), enhance secretion mobilization (e.g. in cystic fibrosis, chronic bronchitis and bronchiectasis) and treat atelectasis, thus preventing recurring infection and disease progression. Theoretically, it promotes mucus clearance by either preventing airway collapse through stenting the airways 3 or by increasing intrathoracic pressure distal to retained secretions through collateral ventilation or by increasing functional residual capacity4.
Some common PEP therapy equipments use in local scene are: Flutter (Axcan Scandipharm, Birmingham, Alabama), Acapella (Smiths Medical, Watford, United Kingdom) (fig.1), TheraPEP (DHD Healthcare, New York, United States) (fig.2), PEP Mask (AstraTech, Mölndal, Sweden) (fig.3). The first two are also known as oscillatory PEP therapy devices which combines PEP with airway vibrations. It is believed that these oscillations help to decrease the viscoelasticity of the mucus and facilitate mobilization of the mucus up the airways.
There is no absolute contraindications to the use of PEP therapy but the following conditions require careful evaluation: ICP>20mmHg, recent facial, oral, or skull surgery or trauma, acute sinusitis, epistaxis, esophageal surgery, known or suspected tympanic membrane rupture or other middle ear pathology, untreated pneumothorax, active haemoptysis, nausea, haemodynamic instability2.
The duration and frequency of treatment should be tailored for each individual, based on the patient’s specific indications and response to airway clearance therapy.
The general instructions for PEP therapy are as follows5:
1. patient sits upright and comfortably while holding the mask firmly over the nose and mouth or the mouthpiece tightly between the lips (use nose clip as necessary)
2. adjust the expiratory pressure resistor dial to the prescribed setting
3. take in a larger than normal tidal breath from the diaphragm, but not to total lung capacity
4. exhale actively but not forcefully, maintaining a pressure of 5-20 cm H2O
5. exhalation time should last approximately 3 times longer than inhalation
6. perform 10-20 PEP breaths, then follows with 2-3 huffs or cough
7. repeat steps 3-6 as indicated
On evidence-based perspective, two comprehensive reviews of the published literature on airway clearance strategies6 and PEP therapy5 on different disease groups have summarized that PEP therapy may be as effective as the conventional chest physiotherapy techniques. Limitations of the reviews included a paucity of well-designed, adequately-powered, long-term studies. Therefore, the choice of airway clearance strategy lies on the consideration between clinical effectiveness, cost-effectiveness and patient preference that supports good adherence.
References:
1. Ewart W. The treatment of bronchiectasis and of chronic bronchial affections by posture and by respiratory exercises. Lancet 1901;2:70–72.
2. AARC Clinical Practice Guideline: Use of positive airway pressure adjuncts to bronchial hygiene therapy. Respiratory Care 1993; 38(5):516-521.
3. Oberwaldner B, Evans JC, Zach MS. Forced expirations against a variable resistance: a new chest physiotherapy method in cystic fibrosis. Pediatr Pulmonol 1986;2(6):358–367.
4. Groth S, Stafanger G, Dirksen H, Anderson JB, Falk M, Kelstrup M. Positive expiratory pressure (PEP-mask) physiotherapy improves ventilation and reduces volume of trapped gas in cystic fibrosis. Bull Eur Physiopathol Respir 1985;21(4):339–343.
5. Ryers T. Positive expiratory pressure and oscillatory positive expiratory pressure therapies. Respiratory Care 2007; 52(10):1308-1326.
6. Hess DR. The evidence for secretion clearance techniques. Respir Care 2001;46(11):1276-1292.
