Introduction
Airway clearance techniques refer to a therapeutic approach that uses various techniques to clear the secretions in the airways. The management of bronchial (larger airways of the lungs) secretions is a significant problem in respiratory disorders such as COPD (chronic obstructive pulmonary disease), cystic fibrosis, and bronchiectasis and in patients undergoing abdominal or thoracic surgery. Airway clearance techniques use a variety of strategies to eliminate these secretions that obstruct the airways.
What Is the Significance of Airway Clearance Techniques?
Airway clearance techniques help clear mucus and other secretions in the airways. Mucus clearance devices are available online and they can also act as breathing trainer. Mucociliary clearance mechanisms usually clear the secretions in the airways. The ciliated structures in the epithelium lining the airways clear the excess secretions. However, the mucociliary clearance mechanism becomes impaired in several respiratory conditions, resulting in mucus build-up. This mucus build-up obstructs the airways and causes shortness of breath. It also affects the cough reflex, which clears the mucus. Mucus build-up causes infection and inflammation. Repeated and persistent infections can damage the airways and the lung tissues.
The main aim of the airway clearance technique is to reduce airway obstruction by clearing the secretions occupying the lumen (space inside the tubular structure) of the airways. Airway clearance prevents respiratory infections, expands the collapsed lungs, improves gas exchanges, and decreases the inflammatory response. Several treatment strategies, techniques, and equipment help manage bronchial secretions in respiratory diseases.
What Are the Various Airway Clearance Techniques?
Several airway clearance techniques are available; some techniques can be performed by the patients, while respiratory therapists perform some methods. Some of the techniques that can be performed by patients include:
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Deep Coughing - It is a deep, controlled reflex. A deep cough encourages the clearance of mucus out of the lungs than an accelerated cough.
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Huff Coughing - A deep breath should be taken to perform a huff cough. Then, air should be blown out onto a mirror or a window to steam the mirror. It is less forceful than a cough but helps clear the secretions.
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Self Drainage - A technique which involves breathing in three different ways to clear mucus out of the lungs. This technique is advised for people over eight years. The strategy behind this technique is that shear generated through the expired air reduces the adhesion of the mucus, detaches the secretions from the airway walls, and transports them to proximal airways for drainage.
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Active Cycle of Breathing Therapy -This technique involves the combination of deep breathing, gentle breathing, and huff coughs. Breathing in cycles helps loosen the mucus and clears it out of the lungs. It consists of distinct breathing techniques performed in sequence, which include breath control, thoracic expansion exercises, and forced exhalation techniques.
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Physical Exercises -These help to clear the mucus in the lungs. The muscles have the ability to work more with less oxygen if a person exercises regularly.
Airway clearance techniques that are performed by respiratory therapists include:
Postural Drainage
Postural drainage was the first technique used to clear the secretions. This technique employs the force of gravity that facilitates the movement of the mucus from the periphery towards the center of the airways, where mucus can be cleared through coughing, forced expiration, or bronchial aspiration. Studies have shown that postural drainage is more effective than an active cycle of breathing techniques or oscillatory positive expiratory pressure techniques. However, this technique is not effective for diseases associated with low amounts of secretions. Therefore, it is indicated for diseases that produce more than 1.01 fluid ounces of secretions.
Manual Techniques
In this technique, certain forces are applied to the patient's chest using the hands. It includes the following:
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Percussion - Clapping or percussion involves the application of a rhythmic succession of light and rapid strokes on the chest wall of the patient using cupped hands. Percussion is applied to the specific segment when the patient breathes at a tidal volume, which implies that it is applied both during inspiration and expiration.
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Vibration- It involves the application of fine oscillatory movements with chest wall compression during the exhalation phase. The force used should be enough to compress the rib cage and increase the airflow during expiration, but the force must not cause any discomfort to the patient.
Mechanical Devices
Cough Assist
The mechanical insufflator/exsufflator is a device that creates changes in the airflow inside the airway in such a way that the cough is stimulated. This device is used in patients with respiratory muscle deficiency or neuromuscular pathologies who have an ineffective cough. A hypo-valid or ineffective cough results in chronic inflammation, retained secretions, infections, and respiratory failure.
Percussive Intrapulmonary Ventilation
This device consists of a high-pressure flow generator that provides high-frequency mini bursts of air while the patient breathes. It also has a valve for adjusting the airflow. The high-frequency airflow creates an internal vibration in the lungs that promotes clearance of the secretions and also provides ventilatory support to patients with neuromuscular diseases.
High-Frequency Chest-Wall Oscillation
This device uses an inflatable device connected to a compressor, which determines the rapid inflation and deflation of the device. The high-frequency chest-wall oscillation device creates oscillations that are transmitted to the airways through the chest wall. These oscillations decrease the viscoelasticity of the secretions and stimulate clearance of the secretions.
Vacuum Technique
A device called Free Aspire uses an expiratory flow accelerator that accelerates the expiratory flow and promotes drainage and removal of secretions without applying pressure in the airways. The secretions reach the upper airways, where they are expelled through the physiological mucociliary clearance mechanism.
Non-Invasive Ventilation
This technique can be used to improve lung volume in patients who cannot perform an active cycle of breathing technique without assistance, specifically those with end-stage disease, dyspnea (shortness of breath), hypoxia (reduced oxygen levels), and inspiratory muscle weakness. This technique is more effective in patients with cystic fibrosis (a disorder that affects the lungs and the digestive system).
Conclusion
Airway clearance techniques reduce airway obstruction by removing the secretions that obstruct the airways, thereby decreasing the inflammatory response. The decision for the use of airway clearance techniques depends on clinical judgment rather than evidence-based data. Choosing the right technique that is comfortable for the patient and that improves the removal of excess secretions depends on the severity of the condition and the disease itself. Clearance procedures are administered when it is essential for the clinical improvement of the patient.
