Active Cycle of Breathing Technique

The Active Cycle of Breathing Techniques (ACBT) is a patient-directed active breathing technique that can be used to mobilize and clear excess pulmonary secretions as well as increase lung function in general. It’s a versatile care technique that can be used in combination with positioning and tailored to suit the needs of most patients. Depending on the patient’s issue, each variable may be used separately or as part of the ACBT cycle. Once ACBT has been taught, the patient can be encouraged to use it independently. It’s used to:

● Loosen and clear secretions from the lungs.

● Improve ventilation in the lungs.

● Improve the effectiveness of a cough.

ACBT consists of three main phases:

● Breathing Control

● Deep Breathing Exercises or Thoracic Expansion Exercises

● Huffing or Forced Expiratory Technique (FET)

Additionally, if and when indicated, a manual technique (MT) or positive pressure may be applied to create a more complicated cycle to aid in the removal of secretions from the lungs. Percussion or expiratory waves are examples of this.

A randomised control trial showed positive effects of active cyclic breathing technique along with routine chest physiotherapy on arterial oxygenation, heart rate, and pain perception following Coronary Artery Bypass Surgery (CABG).


Breathing regulation is used to relax the airways and alleviate symptoms such as wheezing and tightness that may arise after coughing or being out of breath. It may also be useful to encourage the patient to close their eyes while practicing breathing control to aid in relaxation. It is very important to use breathing control in between the more active exercises of ACBT as it allows for relaxation of the airways.

When someone is experiencing shortness of breath, fear, symptoms of bronchospasm, anxiety, or panic, Breathing Control can help. The length of time spent performing breathing control may vary depending on how breathless the patient feels.

When teaching this technique to a patient as part of ACBT, the patient may be told to take 6 breaths on average.

Instructions to Patient :

● If you can, gently breathe in and out of your nose. If you can’t breathe through your nose, breathe through your mouth instead (patient breathe according to his own rate)

● It’s best to use respiratory control for “pursed lips breathing” if you breathe out of your mouth.

● With each breath out, try to relax your shoulders and let go of any tension in your body.

● Slow down the breathing gradually.

● Close your eyes to help you relax and concentrate on your breathing.

● Breathing control should be maintained until the individual is ready to move on to the next stage of the cycle.


Deep breathing/thoracic expansion exercises are deep breathing exercises that concentrate on inspiration and aid in the loosening of pulmonary secretions.

Instructions to patient :

● Maintain a relaxed chest and shoulders.

● Take a long, steady, and deep breath in, preferably through your nose.

● Keep the air in the lungs for 2–3 seconds at the end of the inhale before exhaling (this is known as an inspiratory hold)

● Exhale slowly and deeply, as if you were sighing. Don’t suffocate the breeze.

● Repeat 3–5 times more. If the patient becomes dizzy, it’s important that they return to the breathing control process of the cycle.

Proprioceptive input, which involves the therapist or patient putting their hands on the thoracic cage, will help with maximum motivation. This has been linked to better ventilation and increased chest wall movement.

Breath-hold (inspiratory hold) used at the end of deep breathing to compensate for asynchronous ventilation that may happen due to sputum retention or atelectasis in some respiratory conditions.


This is a maneuver that is used to transfer secretions downstream towards the mouth after they have been mobilized by deep breathing/thoracic expansion exercises. Instead of coughing, a huff involves exhaling from an open mouth and throat. Huffing assists in the movement of sputum from small airways to larger airways, where it is absorbed by coughing, as coughing alone cannot extract sputum from small airways.

There are two types of huff:

Huffing at a Medium Volume

This aids in the movement of secretions that are located farther down in your airways.

Inhale normally, then exhale actively and deeply until the lungs are fully empty. Assume you’re attempting to steam a mirror.

Huffing at a High Volume

This aids in the movement of secretions in the upper airways.

Inhale deeply, open your mouth wide, and quickly exhale.

Just huff a couple of times at a time, as huffing too much will cause your chest to tighten.

When you huff, listen for crackles. If you can hear them, you will need to cough to clear your secretions; spit them out into a tissue or a sputum bowl if possible. Excessive coughing can reduce the effectiveness of the procedure and render it extremely exhausting.

Rep the loop for another 10 minutes or until your chest feels clearer.

Small long huffs move the sputum from low to high in the chest, while big short huffs move the sputum from lower to higher in the chest; use this huff when it feels ready to come out, but not before; huffs work by dynamic compression.


Coughing should be incorporated if huffing alone does not clear your sputum. However, if it does clear your sputum, then you may not need to cough.

Long bouts of coughing should be avoided at all costs, as they can be exhausting and leave you feeling out of breath, as well as making your throat or chest sore or tight. Cough only if the sputum is quickly cleared; otherwise, return to the beginning of the cycle.


● Post surgical /pain (rib fracture).

● Chronic increased sputum production e.g in Chronic bronchitis, cystic fibrosis.

● Acute increase sputum production.

● Poor expansion.

● Sputum Retention.

● SOBAR: shortness of breath at rest.

● SOBOE: shortness of breath on exertion.

● Cystic Fibrosis.

● Bronchiectasis.

● Atelectasis.

● Respiratory muscle weakness.

● Mechanical ventilation.

● Asthma.

● Increased breathing rate/effort

● Audible rattling in airways

● Palpable secretions


Throughout ACBT, it’s important to keep an eye out for dizziness or shortness of breath. Reduce the amount of deep breaths taken during each period and return to breathing control if a patient becomes dizzy while deep breathing.

● Inadequate pain control where needed

● Bronchospasm

● Acute, unstable head, neck or spinal surgery


● Patients not spontaneously breathing

● Unconscious patient

● Patients who are unable to follow instructions

● Agitated or confused


ACBT may be done while sitting or in a standing position with a postural drainage position. You could begin by sitting until you feel relaxed and secure enough to try different positions. Its usefulness in sitting or gravity-assisted positions is well-documented. Your medical condition and how well the ACBT works for you will determine the best place for you to do it in. Maintain a good breathing pattern when seated, with relaxed shoulders and neck and a supported back, as this facilitates diaphragm control and reduces musculoskeletal tension. Make sure you’re comfortable, well-supported, and relaxed in whatever place you choose.

The ACBT may be done with or without the assistance of an individual who provides vibration, percussion, and shaking. The patient can engage in self-percussion/compression.


ACBT should be performed for around 10 minutes, or until the chest is free of sputum.

When you’re feeling good, you may just need to do ACBT once or twice a day. You will need to do it more often if you have more sputum. You can need to do shorter and/or more frequent sessions if you are sick or have a lot of sputum.


Bronchospasm with hyper-reactive airways

Reduced oxygen saturations/ shortness of breath

Cardiac arrhythmias



The technique can be performed in any breath enhancing position and no equipment is required. When used to clear secretions, it may also be effective when performed in the shower, where steam can assist with the humidification of the airways.

ACBT has been found to be an effective technique for clearing secretions in patients with both acute and chronic respiratory conditions.

More recently, many COVID-19 patients are also facing similar issues.

According to a study published in The Lancet in July 2020, patients of COVID-19 may have a productive cough as a presenting symptom at the onset of the infection or develop it at a later stage. The UK’s National Health Service (NHS) also indicates that you may have mucus or phlegm in your lungs if you’ve contracted the COVID-19 infection. This is the reason why focusing on clearing out your lungs during recovery is very important. If done correctly, it helps in increasing lung capacity, aiding in better oxygenation and exhalation of carbon dioxide.


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