Active Cycle of Breathing Technique

Introduction[edit | edit source]

The Active Cycle of Breathing Techniques (ACBT) is an active breathing technique performed by the patient and can be used to mobilize and clear excess pulmonary secretions and to generally improve lung function. It is a flexible method of treatment that can be used in conjunction with positioning and adapted for use with most patients. Each component can be used individually or as part of the ACBT cycle depending on the patient's problem. Once ACBT has been taught, the patient can be encouraged to use it independently without the supervision of a physiotherapist. This exercise does not require the use of any special equipment.

It's used to:

  1. Loosen and clear secretions from the lungs[1].This helps reduced the risk of chest infections.
  2. Improve ventilation in the lungs.
  3. Improve the effectiveness of a cough [2][3].

ACBT consists of three main phases:

  1. Breathing Control
  2. Deep Breathing Exercises or Thoracic Expansion Exercises
  3. Huffing or Forced Expiratory Technique (FET) [4]

The technique can be modified according to the condition of the patient. Additionally, a manual technique (MT) or positive pressure can be added if and when indicated, to create a more complex cycle to help improve removal of secretions on the lungs. this may include percussion or expiratory vibrations.

A randomized control trial showed positive effects of active cycle breathing technique along with routine chest physiotherapy on arterial oxygenation, heart rate, and pain perception following Coronary Artery Bypass Surgery (CABG)[5].

Breathing Control[edit | edit source]

Breathing control is used to relax the airways and relieve the symptoms of wheezing and tightness which normally occur after coughing or breathlessness[6]. It is the resting period between the more active parts of the technique.[7] Encouraging the patient to close their eyes while performing breathing control can also be beneficial in helping to promote 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[7].

Breathing Control can also help when one is experiencing shortness of breath, fear, signs of bronchospasm, anxiety or is in a panic. The length of time spent performing breathing control may vary depending on how breathless the patient feels.

When using this technique with a patient as part of the ACBT, the patient may be instructed to usually take 6 breaths.

Instructions to patient:

  1. Breathe in and out gently through your nose if you can. If you cannot, breathe through your mouth instead(patient breathe according to his own rate).
  2. If you breathe out through your mouth, it's best to use breathing control with ‘pursed lips breathing’.
  3. Try to let go of any tension in your body with each breath out and keep your shoulders relaxed.
  4. Gradually try to make the breaths slower.
  5. Try closing your eyes to help you to focus on your breathing and to relax.
  6. Breathing control should continue until the person feels ready to progress to the other stages in the cycle [7][8].
  7. Pay close attention that the individual performing the ACBT is not doing trick movements (extension of neck, trunk leaning forward etc.) and not using the accessory muscles for breathing.

Deep Breathing Exercises or Thoracic Expansion Exercises[edit | edit source]

Deep breathing/thoracic expansion exercises are deep breathing exercises that focus on inspiration[8] and help to loosen secretions accumulated at the lungs [9]. Inspiration is active and usually combined with a three-second, end-inspiratory hold before a passive, relaxed and unforced expiration[10].

Instructions to patient:

  1. Try to keep your chest and shoulders relaxed.
  2. Take a long, slow and deep breath in, through your nose if you can.
  3. At the end of the breath in, hold the air in your lungs for 2-3 seconds before breathing out (this is known as an inspiratory hold).
  4. Breathe out gently and relaxed, like a sigh. Don’t force the air out.
  5. Repeat 3 – 5 times. If the patient feels light-headed then it is important that they revert back to the breathing control phase of the cycle [6][11].

To facilitate a maximal inspiration, proprioceptive feedback, with the therapist, or patient, placing their hands on the thoracic cage, can be beneficial. This has been associated with increased chest wall movement and improved ventilation [8].

A breath hold can be added to the deep breath to compensate for asynchronous ventilation which may be present in some respiratory conditions due to sputum retention and / or atelectasis.[8]

Huffing or Forced Expiratory Technique[edit | edit source]

This is a technique used to move secretions, mobilized by deep breathing/thoracic expansion exercises, downstream towards the Mouth in order to cough it out or remove it through suctioning[8]. A huff is exhaling through an open mouth and throat instead of coughing. Huffing helps moves sputum from the small airways to the larger airways, from where they are removed by coughing[6] as coughing alone can not remove sputum from small airways[7].When initially taught, the patient is instructed to take a medium breath in and to breathe out with mild to moderate force and extended expiratory flow, with the glottis open. The length of the huff and force of contraction of the muscles of expiration should be altered to optimize clearance of secretions by maximizing air flow[10].

There are two types of huff:

  1. Medium Volume Huff
  2. High Volume Huff.

Medium Volume Huff[edit | edit source]

This helps to move secretions that are lower down in your airways.

Take a normal-sized breath in and then an active, long breath out until your lungs feel quite empty. Imagine you are trying to steam up a mirror or your specs.

High Volume Huff[edit | edit source]

This helps to move secretions in your upper airways.

Take a deep breath in, open your mouth wide and huff out quickly.

Only perform 1-2 huffs together, as repeatedly huffing can make your chest tight.

Listen for crackles when you huff, if you can hear these, you may now need to cough and clear secretions; try to spit them out into a tissue or a sputum bowl. Try to avoid excessive coughing as this may reduce how effective the technique is and make it excessively tiring.

Repeat the whole cycle for about 10 minutes or until the chest feels clearer[9].

Small long huffs move sputum from low down into chest whereas big, short huffs move sputum from higher up into chest, so use this huff when it feels ready to come out, but not before; huffs work via dynamic compression[7].

Active Cycle of Breathing Technique

Coughing[edit | edit source]

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[11].

It is very important to avoid long bouts of coughing as these can be very tiring and may make you feel breathless or make your throat or chest sore or tight. You should only cough if the sputum can be cleared easily, if not, return to the beginning of the cycle[3].


Indications[edit | edit source]

Precaution[edit | edit source]

It is important to constantly assess for dizziness or increased shortness of breath throughout ACBT. If a patient feels dizzy during deep breathing, decrease the number of deep breaths taken during each cycle and return to breathing control to reduce dizziness[14].

  • Inadequate pain control where needed.
  • Bronchospasm.
  • Acute, unstable head, neck or spinal surgery.

Contraindications[edit | edit source]

  • Patients not spontaneously breathing.
  • Unconscious patient.
  • Patients who are unable to follow instructions.
  • Agitated or confused.

Positioning[edit | edit source]

ACBT can be performed in sitting or in a postural drainage position. Initially you could start in a sitting position until you are comfortable and confident to try different ones. Extensive evidence supports its effectiveness in sitting or gravity assisted positions [7][9][15]. Although, the best position for you to do the ACBT in will depend on your medical condition and how well it works for you. When in sitting, maintain a good breathing pattern with relaxed shoulders and neck, back supported as this promotes the function of diaphragm and decrease stress on musculoskeletal. Whatever position you use make sure you are comfortable, well supported and relaxed.

The ACBT may be performed with or without an assistant providing vibration, percussion and shaking. Self-percussion/compression may be included by the patient [8][11].

It has been shown that the horizontal, side lying position is as effective as the head down tipped position and preferred by individuals[10].

Duration and Frequency[edit | edit source]

Duration for ACBT should be for about 10 minutes and ideally until your chest feels clear of sputum.

You may need to do ACBT only once or twice a day when you are well. When you have more sputum, you may need to do it more often. When you are unwell or have more sputum, you may need to do shorter and/ or more frequent sessions[7][9].


Possible side effects[edit | edit source]

  • Bronchospasm with hyper-reactive airways.
  • Reduced oxygen saturations/ shortness of breath.
  • Cardiac arrhythmias.
  • Atelectasis.
  • Fatigue.

Resources[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 McKoy NA, Saldanha IJ, Odelola OA, Robinson KA.Active cycle of breathing technique for cystic fibrosis. Cochrane Database of Systematic Reviews. 2016(7).
  2. Thomson A, Skinner A, Piercy J. Tidy's Physiotherapy. 12th edition.Butterworth Heinemann publication.
  3. 3.0 3.1 Guy’s and St Thomas’ NHS Foundation Trust. Active Cycle of Breathing Techniques (ACBT). 2018, 3607:2 (Accessed on 1st July, 2018).
  4. Larner E, Galey P. Active cycle of breathing technique. Available from:
  5. Derakhtanjani AS, Jaberi AA, Haydari S, Bonabi TN. Comparison the Effect of Active Cyclic Breathing Technique and Routine Chest Physiotherapy on Pain and Respiratory Parameters After Coronary Artery Graft Surgery: A Randomized Clinical Trial. Anesthesiology and Pain Medicine. 2019 Oct;9(5).
  6. 6.0 6.1 6.2 Emma Larner & Penny Galey.THE ACTIVE CYCLE OF BREATHING TECHNIQUE (ACBT).Sept 2002 – review date Sept 2004.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 The Active Cycle of Breathing Techniques.Association of Chartered Physiotherapists in Respiratory Care.Leaflet no.GL-05.Available at
  8. 8.0 8.1 8.2 8.3 8.4 8.5 Bronchiectasis Toolbox: The Active Cycle of Breathing. (Accessed on 2nd July, 2018)
  9. 9.0 9.1 9.2 9.3 Oxford University Hospitals. The Active Cycle of Breathing Techniques.p3 (Accessed 2nd July, 2018).
  10. 10.0 10.1 10.2 McIlwaine MP, Van Ginderdeuren F. Physiotherapy for people with cystic fibrosis: from infant to adult.
  11. 11.0 11.1 11.2 Association of Chartered Physiotherapists in Respiratory Care. The Active Cycle of Breathing Techniques. 2011, GL-05 p2 (Accessed 1st July, 2018).
  12. 10 ACBT for Respiratory illness. Available from: (accessed 20 Oct 2013).
  13. Elsayed SH, Basset WK, Fathy KA. Impact of active cycle of breathing technique on functional capacity in patient with bronchiectasis. International Journal of Therapies and Rehabilitation Research. 2015;4(5):287.
  14. Cross J, Broad MA, Harden B, Quint M, Ritson P, Thomas S. Respiratory physiotherapy: An on-call survival guide. Elsevier Health Sciences; 2008 Nov 25.
  15. Lewis LK, Williams MT, Olds TS. The active cycle of breathing technique: a systematic review and meta-analysis. Respiratory medicine. 2012 Feb 1;106(2):155-72.
  16. Active cycle of breathing technique. Available from: 4/4/2020).