Forced Expiration Technique (FET) Overview Vector

Forced Expiration Technique (FET): An Overview (2024)

by | Updated: Jun 12, 2024

The forced expiration technique (FET) is a breathing technique designed to help individuals with respiratory conditions clear their airways.

It involves the deliberate and controlled exhalation of breath in order to mobilize and expel trapped secretions from the lungs.

This article provides an overview of the key principles and steps involved in the forced expiration technique, as well as its potential benefits for individuals dealing with respiratory challenges. 

What is the Forced Expiration Technique?

The forced expiration technique (FET), also known as the huff coughing, is a breathing exercise used primarily in respiratory physiotherapy. It’s designed to help clear mucus from the lungs and improve lung function, especially in patients with chronic obstructive pulmonary disease (COPD), cystic fibrosis, bronchiectasis, or other conditions that produce excess mucus.

Forced Expiration Technique (FET) Huff Breathing Vector Illustration


The forced expiration technique (FET) involves the active and forceful exhalation of air from the lungs.

During this process, the diaphragm and external intercostal muscles relax, while the internal intercostal and abdominal muscles contract.

These muscle contractions increase the pressure within the thoracic cavity, forcing the air out of the lungs.


The forced expiration technique (FET) serves several important purposes in respiratory care, particularly for individuals with lung conditions that lead to increased mucus production or decreased mucus clearance.

The primary objectives of FET are:

  • Mucus Clearance: The primary goal of FET is to help clear mucus from the lungs. Conditions such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, bronchiectasis, and other respiratory diseases often result in the accumulation of thick, sticky mucus in the airways. FET aids in loosening and mobilizing this mucus, making it easier to cough up and expel.
  • Preventing Lung Infections: Accumulated mucus in the lungs can become a breeding ground for bacteria, leading to infections like pneumonia. Regular clearance of mucus reduces this risk, contributing to overall lung health and reducing the frequency of respiratory infections.
  • Improving Lung Function: By clearing mucus, FET can help improve airflow in the lungs, enhancing overall lung function. This is particularly important for patients with chronic lung conditions, where airway obstruction can lead to difficulties in breathing and decreased oxygenation.
  • Reducing Breathlessness: Patients with respiratory conditions often experience breathlessness due to obstructed airways. FET can alleviate this symptom by improving airway patency and reducing air trapping, making breathing easier and more efficient.
  • Enhancing Gas Exchange: Clear airways facilitate better gas exchange in the lungs. By removing mucus blockages, FET can improve the exchange of oxygen and carbon dioxide, which is crucial for maintaining the body’s metabolic processes.
  • Preventing Airway Collapse: In diseases like COPD, where the elasticity of the airways is compromised, forceful coughing can lead to airway collapse. FET provides a safer alternative to coughing for mucus clearance, minimizing the risk of airway collapse.
  • Reducing Hyperinflation: In some chronic lung conditions, hyperinflation (over-expansion of the lungs) occurs due to air trapping. FET can help in reducing this by improving the clearance of air and mucus, thereby reducing lung volumes to more normal levels and improving breathing comfort.
  • Enhancing Physical Activity and Quality of Life: Improved lung function and reduced symptoms can lead to increased ability to participate in physical activities and an overall better quality of life for patients.
  • Self-management of Symptoms: FET empowers patients to actively manage their symptoms at home, reducing dependence on medical interventions and improving their ability to cope with their condition.
  • Complementing Medical Treatments: FET is often used alongside other medical treatments like bronchodilators, antibiotics, or steroids. It complements these treatments by physically aiding mucus clearance and improving lung function.

Note: FET is a valuable technique in respiratory therapy, primarily aimed at improving mucus clearance, enhancing lung function, reducing infection risk, and improving the overall quality of life for patients with chronic respiratory conditions.

Contraindications and Precautions

The forced expiration technique (FET) is generally safe and effective for many individuals with respiratory conditions, but there are certain contraindications and precautions to consider.

These ensure the safety and appropriateness of the technique for each individual.


  • Recent Surgery: Particularly chest or abdominal surgery, as FET can put stress on the surgical sites.
  • Rib Fractures: The forceful nature of the technique could exacerbate the injury.
  • Pneumothorax: FET could worsen the condition.
  • Hemoptysis: This could indicate a serious underlying condition, and forceful expiration might exacerbate bleeding.
  • Untreated Tuberculosis: Risk of spreading the infection due to forceful exhalation.
  • Severe Cardiovascular Conditions: Such as recent heart attack or unstable angina, where increased pressure from coughing or forceful breathing might be detrimental.
  • Severe Pulmonary Embolism: FET might exacerbate the condition.
  • Acute Exacerbation of Asthma: Until the exacerbation is under control, FET might not be advisable.
  • Raised Intracranial Pressure: FET could potentially increase this pressure further.


  • Moderate to Severe Dyspnea: Should be carefully monitored as FET might initially increase the sensation of breathlessness.
  • Osteoporosis or Weakened Bones: Care should be taken due to the increased risk of fractures.
  • Anxiety and Hyperventilation: FET should be used cautiously as it can sometimes induce anxiety or hyperventilation in sensitive individuals.
  • Bloating or Recent Meal Consumption: The technique can increase abdominal pressure, causing discomfort or reflux.
  • Uncontrolled Hypertension: The technique could potentially increase blood pressure.
  • Vocal Cord Dysfunction: FET may be challenging if there are existing voice or airway issues.
  • Pregnancy: Particularly in the later stages, due to increased abdominal pressure.

General Considerations

  • Patient Comfort: It’s important to ensure the patient is comfortable and not experiencing undue stress or pain during the technique.
  • Individual Assessment: Each patient should be individually assessed by a healthcare professional to determine if FET is appropriate for their condition.
  • Monitoring: Especially when first learning the technique, it should be performed under supervision.
  • Progression: The intensity and duration of FET should be gradually increased as tolerated.

Note: While FET is beneficial for many with chronic respiratory conditions, it’s not suitable for everyone. Patient-specific factors and existing health conditions should be carefully considered before incorporating FET into a treatment plan.

How to Perform the Forced Expiration Technique

Performing the forced expiration technique (FET) involves several steps, and it’s often best learned under the guidance of a physician or respiratory therapist.

Here’s a general guide on how to perform FET:

  • Preparation: Sit or stand in a comfortable position. If you’re severely short of breath, sitting might be better. Begin with a few minutes of relaxed, diaphragmatic breathing to stabilize your breathing pattern.
  • Deep Breathing: Inhale slowly and deeply through your nose, expanding your lower chest and abdomen rather than your upper chest. Hold your breath for 2-3 seconds. This allows the air to get behind the mucus in the airways.
  • Forced Expiratory Technique (Huffing): Open your mouth and exhale forcefully but steadily. Imagine you are trying to fog up a mirror with your breath. It’s less forceful than a cough but stronger than a normal breath. Perform both short and long huffs. Short huffs help move mucus from the lower airways, and long huffs help move it from the upper airways. Do 2-3 huffs per cycle, and repeat the cycle a few times.
  • Coughing: After several cycles of huffing, if you feel mucus has moved into the larger airways and you feel an urge to cough, do so gently and effectively. Try not to cough too forcefully, as this can tire you out and cause airway collapse, especially in conditions like COPD.
  • Rest and Repeat: Take a moment to rest and breathe normally. If you still feel mucus in your airways, repeat the cycle of deep breaths and huffing.
  • Finishing Up: Finish with a few minutes of relaxed, controlled breathing.

Be sure to stay well-hydrated, as this can help thin the mucus, making it easier to clear. Regular practice of FET, as advised by your healthcare provider, is key to its effectiveness.

Sometimes, FET can be combined with postural drainage, where you position yourself to help mucus drain due to gravity.

If you’re new to FET, it’s advisable to perform it under supervision initially. A healthcare professional may adjust the technique to suit your specific needs and conditions.

Be aware of contraindications and precautions as discussed earlier. If you feel dizzy, short of breath, or experience chest pain, stop the exercise and seek medical advice.

What is Huff Coughing?

Huff coughing, often used as part of the forced expiration technique (FET), is a method of clearing mucus from the lungs and airways.

It’s particularly beneficial for individuals with conditions that produce excessive mucus, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, or bronchiectasis.

Huff coughing is a gentler alternative to traditional coughing and can be more effective in clearing mucus without causing the potential negative effects of vigorous coughing.

FAQs About the Forced Expiration Technique

Is the Forced Expiratory Technique the Same as Huffing?

The forced expiratory technique (FET) and huffing are related but not exactly the same.

FET is a broader method that encompasses a series of steps including controlled breathing, deep inhalation, and the huffing maneuver.

Huffing, on the other hand, is a specific part of this technique. It involves a forceful, controlled exhalation that helps move mucus from the smaller to the larger airways, making it easier to cough out.

While huffing is a key component of FET, it is just one part of the entire technique.

What are the Benefits of the Forced Expiration Technique?

The benefits of the forced expiration technique (FET) include improved mucus clearance from the lungs, reduced risk of respiratory infections, enhanced lung function, and alleviation of breathlessness.

FET is particularly beneficial for people with obstructive lung diseases.

It helps in loosening and mobilizing mucus, which can improve breathing efficiency, increase oxygenation, and ultimately enhance the overall quality of life for patients with chronic lung diseases.

What is the Active Cycle of Breathing Technique (ACBT)?

The active cycle of breathing technique (ACBT) is a set of breathing exercises designed to improve mucus clearance and lung function.

It involves three main phases: breathing control, thoracic expansion exercises, and the forced expiratory technique (including huffing).

ACBT is particularly useful for patients with conditions like COPD, cystic fibrosis, and bronchiectasis.

It helps in loosening the mucus, facilitating its movement towards the larger airways, and then effectively expelling it from the lungs.

ACBT is often taught and supervised by respiratory therapists or physiotherapists and can be tailored to individual patient needs.

Final Thoughts

The forced expiration technique (FET) is effective in individuals suffering from conditions that lead to excessive mucus production.

It offers a methodical approach to mobilize and clear mucus from the airways, thereby enhancing lung function, reducing the risk of infections, and improving overall quality of life for patients.

While the technique is widely beneficial, it’s crucial to consider contraindications and precautions to ensure its safe application.

Learning and performing FET under the guidance of a healthcare professional ensures that the technique is tailored to the individual’s specific needs and carried out effectively. 

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.


  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Sutton PP, Parker RA, Webber BA, Newman SP, Garland N, Lopez-Vidriero MT, Pavia D, Clarke SW. Assessment of the forced expiration technique, postural drainage and directed coughing in chest physiotherapy. Eur J Respir Dis. 1983.

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