Flutter Valve and Acapella Device (PEP Therapy)

Flutter Valve and Acapella: Explained (PEP Therapy)

by | Updated: Mar 16, 2024

Positive expiratory pressure (PEP) is a type of airway clearance therapy that helps clear mucus from the lungs. The two primary types of PEP therapy are flutter valves and acapella breathing devices.

Both have been proven effective in clearing lung secretions, but how do they work?

In this article, we’ll take a closer look at PEP therapy and how flutter valves and acapella devices work. We’ll also break down the indications, contraindications, and hazards of this type of therapy.

What is PEP Therapy?

Positive expiratory pressure (PEP) therapy is commonly used to mobilize secretions, reduce air trapping, and prevent the lungs from collapsing.

It requires active expiration into a device against back-pressure, which helps expand the lungs and moves secretions into the larger airways. Then they can be cleared by coughing or suctioning.

As previously mentioned, there are two main types of PEP therapy devices: flutter valves and acapella devices. Let’s take a closer look at how each type works.

What is a Flutter Valve?

A flutter valve is a small, handheld device that is used to help clear mucus from the lungs. It’s the most common type of oscillatory PEP therapy and is commonly used in patients with cystic fibrosis.

The device is triangular-shaped with a fluttering steel ball inside. When you exhale into the flutter valve against backpressure, the ball rattles and creates high-frequency oscillations. This action helps to break up the mucus so it can be cleared more easily.

flutter valve parts


A flutter valve is made up of the following parts:

  • Removable mouthpiece
  • Body
  • Steel ball
  • Expiratory resistance dial
  • One-way valve
  • 22 mm O.D. connection

The user exhales into the mouthpiece, which is connected to the body. This causes the steel ball to rattle, creating high-frequency oscillations.

The expiratory resistance dial can be adjusted to increase or decrease the level of backpressure. The one-way valve prevents air from entering the device when you inhale.

What is an Acapella Device?

An acapella is a small, handheld device that helps clear mucus from the lungs using positive expiratory pressure (PEP).

It has similar characteristics and indications as a flutter valve but uses a different mechanism to create backpressure and oscillations.

Types of acapella breathing devices


There are two types of acapella devices to choose from depending on the patient’s ability to generate expiratory flow:

  1. Green model: This model is more difficult and is indicated for patients with an expiratory flow >15 L/min.
  2. Blue model: This model is easier to use and is indicated for patients with an expiratory flow <15 L/min.

One advantage of using an acapella over a flutter valve is that it can be used in any patient position, where a flutter valve should only be used while the patient is upright.


The indications for using an acapella, flutter valve, or other types of PEP therapy include:

  • To help clear mucus
  • To prevent or reverse atelectasis
  • To reduce air trapping
  • To help mobilize retained secretions
  • To maximize the delivery of aerosolized medications


There are no absolute contraindications for PEP therapy; however, there are some relative contraindications that should be considered. These include:

  • Untreated pneumothorax
  • Intracranial pressure >20 mm Hg
  • Hemodynamic instability
  • Active hemoptysis
  • Recent facial trauma or surgery
  • Patients with acute asthma or COPD
  • Acute sinusitis
  • Acute epistaxis
  • Tympanic membrane rupture
  • Acute nausea

PEP therapy is generally not recommended in children <3 years old because they cannot follow the required instructions to use the device.

Another requirement is that adult users must be able to take a deep breath and generate >10 to 12 mL/kg of expiratory pressure. This is needed to create the oscillations required for effective PEP therapy.


Using a flutter valve or acapella device is generally considered to be safe. However, there are some potential hazards that should be considered, such as:

  • Pulmonary barotrauma
  • Increased work of breathing
  • Increased intracranial pressure (ICP)
  • Air swallowing
  • Myocardial ischemia
  • Decreased venous return to the heart

How to Use a Flutter Valve or Acapella

The steps for using a flutter valve or acapella device are as follows:

  1. Assemble the device.
  2. Get in the correct position. The flutter valve must be held upright, while the acapella can be used in any position..
  3. Take a deep breath.
  4. Place the mouthpiece in your mouth and create a tight seal.
  5. Perform an exhalation against backpressure that is slightly faster than normal.
  6. Adjust the device to create the most amount of vibrations that can be felt in the lungs.
  7. Repeat step 5 and perform up to 10 exhalation maneuvers into the device.
  8. Finish with 1-2 maximal expiratory efforts through the device. This involves inhaling to full capacity, then exhaling as fast as possible.
  9. Perform a cough to clear secretions.
  10. Repeat this process for four to eight cycles.

Delivering Aerosol Drugs with PEP Therapy

Aerosol drug therapy may be used along with PEP therapy to improve the effectiveness of the treatment. This involves using an in-line handheld nebulizer or a metered dose inhaler, which can be attached to the one-way inlet valve of the device.

This combination effectively improves the efficacy of aerosol drug delivery due to better drug distribution in the peripheral airways.


What is Vibratory PEP Therapy?

Vibratory PEP therapy uses high-frequency vibrations or oscillations to move small volumes of air back and forth in the respiratory tract. This action helps loosen secretions, making them easier to cough up for removal.

The two primary types of vibratory PEP therapy include flutter valves and acapella breathing devices. Other less-known types include the RC-Cornet, Lung Flute, Quake, and Aerobika.

How Often Should You Perform PEP Therapy?

The frequency of PEP therapy will depend on the individual patient and their needs. In general, it is recommended to perform two to four treatments per day.

What are the Advantages of PEP Therapy?

PEP therapy is comparable to other airway clearance techniques, such as autogenic drainage, in terms of efficacy.

The primary advantages of PEP therapy include its portability and ease of use. It can be self-administered and is cost-effective.

Final Thoughts

PEP therapy is an airway clearance technique that uses high-frequency vibrations or oscillations to move small volumes of air back and forth in the respiratory tract. This action helps loosen secretions, making them easier to cough up for removal.

The two primary types of vibratory PEP therapy include flutter valves and acapella breathing devices. Both have similar characteristics and are effective in clearing secretions in patients with cystic fibrosis, bronchiectasis, and COPD.

PEP therapy is safe, easy to use, and cost-effective. It can be self-administered, which makes it an attractive option for patients who want to take an active role in their airway clearance therapy. Thanks for reading, and, as always, breathe easy, my friend.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


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