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Positive Expiratory Pressure (PEP) Therapy

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One of the most frequently prescribed airway clearance therapy (ACT) options for patients with chronic lung conditions or decreased lung volumes are positive expiratory pressure therapy (PEP) devices.

Positive Expiratory Pressure

During PEP therapy, the patient exhales against a fixed-orifice resistor, generating pressures during expiration that usually range from 10 to 20 cm H2O.(14-24) PEP does not require a pressurized external gas source.

The therapy, which is administered by breathing through a special device helps:

  • Air get behind the mucus
  • Move mucus from lung and airway walls
  • To hold the airways open for longer

Increased geriatric population coupled with higher incidences of chronic conditions drive the PEP devices market growth.

  • Increasing prevalence of chronic obstructive pulmonary disease (COPD) along with asthma is one of the major driving factors for the industry.
  • eg.according to CDC (the Centres for Disease Control and Prevention), in 2018, around 9 million adults were diagnosed with chronic bronchitis which eventually leads to higher requirements for PEP devices, fueling the market.

Mechanism of PEP

The increase in pressure is transmitted to airways creating back pressure stenting them during exhalation, preventing premature airway closure and reducing gas trapping.

  • Promotes collateral ventilation, allowing pressure to build up distal to the obstruction (collateral ventilation is a phenomenon found in the human lungs where alveolar structures are ventilated through channels that bypass normal airways).
  • Retains airways from collapsing and prolongs expiratory flow
  • Effective airway clearance promotes movement of mucus proximally.

Types of PEP

Two types of airway clearance devices are the positive expiratory pressure device (PEP) and the oscillating positive pressure device.

1. A PEP device increases resistance to expiratory airflow to promote mucus clearance by preventing airway closure and increasing collateral ventilation.

  • Examples of this type of device include the TheraPEP®, Resistex PEP Mask, and the Pari RC Cornet Mucus Clearing DeviceTM.

2. An oscillating (or vibratory) positive expiratory pressure (OscPEP) device is a form of PEP that combines high-frequency air flow oscillations with positive expiratory. The person blows all the way out many times through a device. Commonly known by their brand names (Flutter®, Acapella®, AerobikA®, and RC-Cornet®), these types of oscillating PEP devices work in two ways.

  • They use resistance to make it more difficult during the breath out, like non-oscillating PEP devices.
  • Also create vibrations when a patient breathes out. The vibrations move mucus from the surface of the airways. After blowing through the device several times, the person will huff and cough to clear the mucus from the lungs.

Indications for PEP

  • Acute and chronic respiratory failure for reasons of surgery 
  • Neurological or musculoskeletal dysfunction eg MND
  • Old age and immobility
  • To increase lung volume by increasing FRC and VT
  • Reduce hyperinflation/ Air trapping in eg : emphysema, bronchitis, asthma
  • Improve airway clearance in; cystic fibrosis (over 4 y.o); chronic bronchitis; bronchiectasis; bronchiolitis obliterans 
  • To maximise the delivery of bronchodilators in patient's receiving bronchial hygiene therapy

Relative Contraindications for PEP

  • Untreated pneumothorax 
  • Intracranial pressure > 20mm Hg
  • Active haemoptysis 
  • Recent trauma or surgery to skull, face, mouth, or oesophagus
  • Patient with acute asthma attack or acute worsening of Chronic Obstructive Pulmonary Disease (COPD) unable to tolerate increased work of breathing 
  • Acute sinusitis or epistaxis
  • Tympanic membrane rupture or other known or suspected inner ear pathology
  • Nausea 

There are no absolute contraindications to PEP that have been noted by literature

Physiology of PEP

1. Increasing lung volume FRC and VT

  • A progressively temporary increase in FRC has been found to be proportionally correlated when increasing PEP
  • An increase in FRC is attained by alteration of breathing pattern that is a product of a decrease in expiratory flow and an increase in expiratory time leading to exhalation of smaller volumes.
  • lung volume increase is achieved by altering breathing pattern, thereby increasing VT and decreasing respiratory frequency, which is due to an increase in muscle activity of inspiratory and expiratory muscles.
  • Improved gas exchange is a result of breathing during a prolonged period with normalized lung volumes.

2. Reduction of hyperinflation

  • Hyperinflation is a result of air entrapment causing the lungs to over inflate. It is caused by muscle spasm, mucosal inflammation, hyper-secretions, reduced lung elasticity due to destruction of lung parenchyma. If Untreated may lead to inspiratory muscle exhaustion, decreased ventilation, and deficient gas exchange.
  • PEP reduces expiratory flow, which in return decreases the declining pressure across the airway wall thereby reducing collapse
  • Increasing pressure within airways transports EPP centrally and in stable airways therefore stenting them. Reduction of airway collapse increases expired volume leading to additional emptying of lung volume thus lowering FRC and improving ventilation distribution and gas exchange.

3. Airway Clearance

When using HiPEP

  • It homogenously mobilize secretions in collapsed airways. It aims towards increasing FRC by recruiting collapsed lung volumes and uses resistance to obtain progressive homogenization emptying of the lungs.
  • Homogenization is achieved by the facilitation of EPP to move peripherally during expiration avoiding collapsed airways, trapped gas, and atelectasis. This results in reduction of respiratory flow and an increase in expiratory flow combined with an increase in FRC. In doing so secretion is mobilized in closed or collapsed and unreachable parts of the lungs. HiPEP is proven to be an airway clearance technique equally or more effective than PEP.

When using OscPEP

  • The oscillating property is achieved by bursts and turbulent expiratory airflow due to the opening and closing of the valve. Oscillations during expiration decreases the viscoelasticity properties of mucus, effecting its movement which depends on the oscillating frequency. OscPEP is equally as effective as other Airway Clearance Technique (ACT) as PEP and Active Cycle Breathing Technique (ACBT).

Different PEP devices

!. OscPEP - applied with a threshold-dependent mechanism with a high density steel "movable ball" that is interposed on a funnel or circular cone between the exhalation tract of the device causing a vibration that is transmitted to the lungs, examples are:

  • Aerobika OPEP - Monaghan Medical’s Aerobika oscillating positive expiratory pressure (OPEP) device assists mucociliary clearance and helps prevent COPD progression, according to the company.
  • Flutter - The Flutter mucus clearance device, manufactured by Aptalis Pharma US Inc, provides PEP therapy for patients with atelectasis, bronchitis, bronchiectasis, cystic fibrosis, COPD, asthma or other conditions producing retained secretions, according to the company
  • Pari O-PEP - Coming soon to the US market is Pari O-PEP, an oscillating positive expiratory pressure device manufactured by Pari Respiratory. The device is designed to mobilize secretions in the lower respiratory tract, strengthen the respiratory tract and alleviate shortness of breath for patients five and older.

PEP therapy may be applied through e.g.

  • PEP Bottle - A very common threshold-dependent system is "PEP Bottle" or bubble PEP that consists of a bottle filled with a predetermined quantity of water in which a tube that draws from the bottom. Patient blows into the tube and has to overcome the pressure opposed by the level of water until bubbles are produced.Face mask with a one-way valve to which expiratory resistors are attached or face-mask connected to a plastic ring drilled by holes of different caliber that act as resistors. Both devices could be suited to mouthpiece application if necessary. These systems are considered to be flux-dependent.

Instructions for the use of PEP devices

Physiotherapist will set device to the amount of pressure needed (Can be used as an adjunct to Active Cycle of Breathing Technique)


Repeat below steps at least 5 times to make 1 cycle. Repeat the following steps as many times as directed to complete 1 cycle:

Loosen mucus:

  • Sit up with your back straight and your chin slightly up. This position allows your throat to be open so air can move easily without blockage.
  • You may need to put your elbows on a table. This may keep you from slouching and blocking air from moving freely.
  • Take a deep breath and hold it for 2 to 3 seconds.
  • While you hold your breath, place the mouthpiece in your mouth or the mask over your mouth and nose.
  • Breathe out at a steady rate for 4 to 6 seconds or as long as you can. Keep your cheeks as flat as possible. You may have to use your fingers to hold your cheeks down. Try not to cough.
  • You may be able to keep the mouthpiece in, or your mask on, as you repeat. Take a deep breath in through your nose.

Cough and bring up mucus:

  • Remove the mouthpiece from your mouth or the mask from your face.
  • Do 2 to 3 huff coughs. Take a deep breath in. Use your stomach muscles to breathe out 3 quick, forceful breaths. Make a ha, ha, ha sound.
  • Then cough hard to bring up mucus. Spit the mucus out. Do not swallow the mucus.
  • You may need to rest for 1 to 2 minutes.
  • This cycle should continue for 10-20 minutes or until you have cleared all your sputum.
  • Instructions for PEP devices may vary. Please see manufacturers instructions.

Scientific literature about PEP

  • Following meta-analyses of the effects of PEP versus other airway clearance techniques on lung function and patient preference, a cochrane review demonstrated that there was a significant reduction in pulmonary exacerbations in people using PEP where exacerbation rate was a primary outcome measure.
  • Another Cochrane review suggests that PEP therapy appears to have similar effects on health-related quality of life, symptoms of breathlessness, sputum expectoration, and lung volumes compared to other ACTs when prescribed within a stable clinical state or during an acute exacerbation.
  • A systematic review" investigated the effect of PEP breathing after an open upper abdominal or thoracic surgery. Questionable quality standards, different protocols and PEP devices used among the six RCTs included concur to uncertainty about PEP effect. It is not possible to assume that a prophylactic chest physiotherapy treatment is superior to a PEP device protocol in preventing within five-days postoperative complications.
  • A single-arm pilot study analyzing the impact of a specific Oscillating positive expiratory pressure (oPEP) - Aerobika® device in COPD patients' lung dynamics and drug deposition suggests that the Aerobika® device usage led to an improved airflow causing a shift in internal airflow distribution and impacted the drug deposition patterns of the medication in patients with COPD.
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