Airway clearance therapy is treatment that uses a number of airway clearance techniques to clear the

respiratory airways The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to t ...

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

and other secretions. Several

respiratory disease Respiratory diseases, or lung diseases, are pathology, pathological conditions affecting the organs and tissues that make gas exchange difficult in Breathing, air-breathing animals. They include conditions of the respiratory tract including the t ...

s cause the normal mucociliary clearance mechanism to become impaired resulting in a build-up of mucus which obstructs breathing, and also affects the

cough reflex The cough reflex occurs when stimulation of cough receptors in the respiratory tract by dust or other foreign particles produces a cough, which causes rapidly moving air which usually remove the foreign material before it reaches the lungs. This ty ...

. Mucus build-up can also cause infection, and inflammation, and repeated infections can result in damage to the airways, and the lung tissue. All airway clearance therapy involves the techniques of

coughing A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three phas ...

, or huffing that need to be used in conjunction with another airway clearance technique.

Respiratory therapist A respiratory therapist is a specialized healthcare practitioner trained in critical care and cardio-pulmonary medicine in order to work therapeutically with people who have acute critical conditions, cardiac and pulmonary disease. Respirator ...

s make recommendations and give guidance for appropriate airway clearance therapies. They also give instruction in the use of various airway clearance techniques.

Clearance techniques

Airway clearance therapy uses different airway clearance techniques (ACTs) in a number of respiratory disorders including,

cystic fibrosis Cystic fibrosis (CF) is a rare genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections. O ...

bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...

bronchiectasis Bronchiectasis is a disease in which there is permanent enlargement of parts of the bronchi, airways of the lung. Symptoms typically include a chronic cough with sputum, mucus production. Other symptoms include shortness of breath, hemoptysis, co ...

, and

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...

to maintain respiratory health, and prevent the damaging consequences of inflammation. Techniques used are breathing, manual, and mechanical. They all need to be used with either

or huffing which moves mucus from the large airways. To move mucus from the small airways an additional ACT needs to be employed.

Breathing

Breathing techniques include the active cycle of breathing which includes huffing; and autogenic drainage, a technique that requires concentrated effort.

Huffing

Huffing or a huff cough, is also called ''forced expiration technique'', and helps to move mucus away from the lung wall so that it can finally be coughed out. Huffing needs to be carried out in a sitting position with the chin raised a little, and the mouth remaining open. A deep breath is taken to fill the lungs about 75 per cent, and held for two or three seconds. Breathing out is forceful and slow which helps to move the mucus from the smaller to the larger airways. A normal urge to cough at this point is repressed, and the breathing pattern is repeated a few times. A strong cough then follows to expel the mucus. Huffing forms part of the active cycle of breathing. Huffing as a clearance technique is different to the term of

huffing Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They ...

used in substance

inhalation Inhalation (or Inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...

Active cycle of breathing

The active cycle of breathing technique is carried out in three phases. Phase one is used to relax the airways; phase two involves moving the inhaled air to behind the mucus in order to clear it; phase three helps to clear the mucus out from the lungs. ;Phase one Gentle effortless breathing, in through the nose, and out through the mouth is used in phase one to relax the airways. The shoulders and upper chest are kept relaxed. On breathing out, the pursed lips method is advised. Keeping the lips pursed (as in kissing somebody) when exhaling creates a back pressure that keeps the airways open for longer. One recommendation is for six breaths of control to take place before phase two of the cycle. ;Phase two Phase two involves using exercises to expand the chest. Breathing is deep and may use a breath-hold of three seconds to move the air into the smaller airways, and reach behind the mucus. The out breath is unforced and may include some

percussive A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater including attached or enclosed beaters or rattles struck, scraped or rubbed by hand or struck against another similar instrument. Excl ...

clapping A clap is the percussive sound made by striking together two flat surfaces, as in the body parts of humans or animals. Humans clap with the palms of their hands, often quickly and repeatedly to express appreciation or approval (see applause), b ...

, or vibration. ;Phase three Using huffing coughing, mucus is moved from the smaller airways to the larger airways, and huffing needs to be continued until all the mucus is expelled.

Autogenic drainage

Autogenic drainage is a controlled airway clearance technique using different depths of inhalation, and different speeds of exhalation that enables mucus to be moved up the airway producing a voluntary cough. This method does not require any equipment, however, it is challenging to perform and appropriate training is required. Evidence supporting different techniques is limited. A review of the studies that have been conducted concluded that there is no strong evidence that autogenic drainage is better than other airway clearance techniques.

Manual

Chest physiotherapy is a manual airway clearance therapy that uses

chest percussion A respiratory examination, or lung examination, is performed as part of a physical examination, in response to respiratory symptoms such as shortness of breath, cough, or chest pain, and is often carried out with a cardiac examination. The four ...

(

, and vibration), and

postural drainage Postural drainage (PD) is the drainage of lung secretions using gravity. It is used to treat a variety of conditions that cause the build-up of secretions in the lungs. Uses Postural drainage is used to treat any condition that causes the build- ...

. However, they are labour-intensive, and time-consuming, and mechanical devices are often used instead.

Mechanical

Mechanical devices used include positive expiratory pressure (PEP), intrapulmonary percussive ventilators, mechanical insufflation-exsufflation known as a mechanically assisted cough, and airway oscillatory devices. Several mechanical techniques are used to dislodge mucus and encourage its expectoration. Chest percussion can be administered as a manual technique but can also be performed using specific devices that use

chest wall oscillation Chest wall oscillation is when devices are used in airway clearance therapy to clear excess mucus from lung airways (bronchi and bronchioles). It is principally used in the treatment of cystic fibrosis, but is gaining use in the treatment of other ...

or intrapulmonary percussive ventilation. Intrapulmonary percussive ventilators (IPVs) are machines which deliver short bursts of air through a mouthpiece to help to clear mucus. The air is delivered at a rate of approximately 150 pulses per minute and may be used with nebulized

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

. Chest wall oscillation is a passive system that is not dependent on effort from the user. It involves the use of a special vest that employs the use of a compressor to inflate and deflate the vest rhythmically at timed intervals, and thus imposes high frequency chest wall oscillations that are transferred to the lungs. These oscillations thin airway mucus, and facilitate its removal by coughing. Delivery of air to the vest can be controlled manually. Other methods such as

biphasic cuirass ventilation An iron lung is a type of negative pressure ventilator (NPV), a mechanical respirator which encloses most of a person's body, and varies the air pressure in the enclosed space, to stimulate breathing.Shneerson, Dr. John M., Newmarket General ...

, and associated clearance mode available in such devices, integrate a cough assistance phase, as well as a vibration phase for dislodging secretions. These are portable and adapted for home use. Positive expiratory pressure physiotherapy consists of providing a back pressure to the airways during expiration. This effect is provided by devices that consist of a mask or a mouthpiece in which a resistance is applied only on the expiration phase. Operating principles of this technique seems to be the increase of gas pressure behind mucus through

collateral ventilation Collateral ventilation (CV) is a back-up system of alveolar ventilation that can bypass the normal route of airflow when airways are restricted or obstructed. The pathways involved include those between adjacent alveoli ( pores of Kohn), between br ...

along with a temporary increase in

functional residual capacity Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm ...

preventing the early collapse of small airways during exhalation.

References

{{reflist Respiratory system procedures Respiratory therapy