Postural Drainage and Vibration

Anatomy and Physiology

ACTs are grounded in the intricate anatomy and physiology of the respiratory system, particularly focusing on the mechanisms that facilitate or impede mucus clearance. The respiratory tract is lined with ciliated epithelium and mucus-producing glands from the nasal passages down to the smallest bronchioles. This mucus layer traps inhaled particles, including pathogens and debris, which are then moved upwards and out of the airways by the coordinated beating of the cilia, a process known as mucociliary clearance. The efficiency of this natural clearance mechanism can be significantly reduced in conditions where mucus production or viscosity is altered, such as in cystic fibrosis and COPD.

ACTs are designed to augment or mimic this natural clearance process through various techniques, including MCP, PEP devices, HFCWO, and autogenic drainage. These techniques improve mucus clearance by mobilizing the secretions toward the larger airways where they can be more easily expectorated. The effectiveness of these techniques is influenced by the underlying pulmonary anatomy and physiology, including factors such as airway diameter, the presence of airway obstructions, and the patient's ability to generate effective coughing. Understanding each patient's unique physiological and clinical needs is crucial in selecting the most appropriate ACT to optimize respiratory function and health.

Indications

ACTs are employed when respiratory pathology causes mucus retention, impaired airway clearance, and ventilation-perfusion abnormalities. ACTs are especially beneficial in conditions that lead to excessive sputum production, difficulty clearing secretions, or compromised lung function. Common indications include COPD exacerbations, cystic fibrosis, bronchiectasis, pneumonia, atelectasis, neuromuscular disorders affecting respiratory function, and recovery from thoracic and abdominal surgeries.

A range of techniques can aid in treating various respiratory disorders. These techniques include, but are not limited to, postural drainage, suctioning, and breathing exercises. Therapy selection depends on the disease and the patient's general health. 

Postural drainage techniques, whether manual or automatic, oscillatory or mechanical, are typically recommended for individuals with conditions that result in significant mucus production, such as cystic fibrosis, noncystic fibrosis bronchiectasis, and some COPD cases.[1][2] These techniques may also be used when individuals cannot effectively cough up mucus, which may be the case for older adults and individuals with muscle weakness or recovering from surgery, injury, or severe critical illness.

Airway suctioning can be used to help remove secretions from the airways. Suctioning also clears secretions in the presence of a tracheostomy or endotracheal tube (ETT) during ventilation. ETT suctioning may be accomplished by using open or closed suctioning. The use of normal saline solution instillation before suctioning is not recommended, as it may increase the risk of complications such as hypoxia, bradycardia, and vagal stimulation or aspiration.[3]

Respiratory exercises can help alleviate atelectasis and clear thick secretions from the small to the large airways, facilitating expectoration, especially when the cough is weak or natural postural drainage is impaired. Breathing exercises are particularly beneficial for sedentary individuals with COPD or recently weaned from ventilation.[4]

Contraindications

While ACTs benefit many patients with respiratory conditions, clinicians must consider specific contraindications and precautions to ensure patient safety. The main contraindications include but are not limited to unstable hemodynamics, acute respiratory distress syndrome, untreated pneumothorax, recent spinal surgery, acute spinal cord injury, active hemoptysis, rib fractures, and conditions predisposing to increased intracranial pressure.

Postural drainage should not be used in patients who cannot tolerate the required position or have recent hemoptysis, recent rib or vertebral fracture, severe osteoporosis, or a high bleeding risk.[5] Additionally, these techniques should not be used in individuals who do not require removing excess pulmonary mucus secretion.

Caution is advised in patients with severe osteoporosis, active tuberculosis, or conditions like stroke with great aspiration risk. The choice of ACT should be carefully tailored, considering the individual's clinical status and the potential risks associated with each technique. Evaluating each patient's condition and contraindications is crucial to selecting the most appropriate and safe airway clearance strategy.

Equipment

Airway suctioning is performed by inserting an appropriately sized plastic tube through the nose and extending it a few inches into the trachea. Negative pressure is then used to gently suction secretions that the patient cannot actively cough up. The patient must be supplied 100% oxygen before airway suctioning to avoid hypoxia caused by both mechanical interruption and brief oxygen flow cessation during the procedure. The catheter tip must be lubricated with petroleum jelly when suctioning through the nose. The suction catheter should be gently inserted down the nose and mouth. The procedure should be paused briefly to supply the patient with oxygen if resistance is encountered. The catheter should then be inserted to the desired depth before starting suctioning. A brief, 10-second suction duration is typically recommended to avoid mucosal damage and prolonged hypoxia.

Technique or Treatment

Different postural drainage techniques and their uses are supported by literature. These techniques are explained below.

Manual Chest Physiotherapy

MCP-airway clearance, also known as chest percussion and manual postural drainage, is a traditional technique used to mobilize and clear respiratory secretions due to respiratory conditions, including cystic fibrosis, COPD, bronchiectasis, and neuromuscular disorders. Nelson first described this technique in 1934.[6]

The technique entails gently striking or clapping the chest wall with cupped hands or a percussion device. This rhythmic percussion helps to loosen and mobilize mucus trapped within the airways. The patient is positioned in various postures to facilitate mucus drainage from different lung segments.[7] These positions typically include lying in different bed positions, such as head-down, head-up, side-lying, and prone positions. Gravity assists in moving mucus towards larger airways, where it can be cleared more effectively. During and after percussion and postural drainage, patients may be instructed to perform deep breathing and coughing to help expel loosened secretions from the lungs and prevent mucus plugs or lung collapse.[8]

Initial studies have found the usefulness of manual CPT in several respiratory conditions requiring airway clearance. However, no strong evidence supports or rejects manual techniques compared to other ACTs. MCP may be useful in patients who cannot collaborate in the treatment, like those with neuromuscular disease and cognitive issues or who are unconscious or strongly sedated.

The Cystic Fibrosis Foundation recommends ACTs as part of a comprehensive airway clearance regimen for individuals with cystic fibrosis. To date, no studies have found one ACT superior to another in patients with cystic fibrosis. Therefore, ACTs should be chosen based on individual needs, considering factors like comfort, convenience, flexibility, practicality, and cost.[9][10][11]

MCP may be included in a comprehensive airway clearance regimen for certain patients with COPD, particularly those with excessive sputum production and impaired clearance. However, routine use of MCP during acute COPD exacerbations is not currently supported.[12]

Autogenic Drainage

Autogenic drainage is a breathing technique that clears mucus from the airways, comprising 3 stages: unsticking, collecting, and evacuating. This technique particularly benefits individuals with respiratory conditions like cystic fibrosis or COPD. Slow and deep breathing maneuvers help loosen mucus from the airway walls initially. Afterward, slightly faster breathing maneuvers aid in moving the loosened mucus from smaller to larger airways. Deeper and more forceful breathing, including huffing or coughing, facilitates mucus expulsion from the larger airways in the last stages. Autogenic drainage is, therefore, more suitable for patients with bronchospasm or hemoptysis, where a gentler technique is required. 

Previous studies on autogenic drainage have shown it to be effective in mucus clearance and improving lung function in patients with stable COPD and bronchiectasis.[13][14][15] Several studies have been conducted on using autogenic drainage in cystic fibrosis and the technique's benefit on sputum production.[16] A recent study involving pediatric patients younger than 10.5 years with cystic fibrosis showed that autogenic drainage has a positive impact lasting over 12 months on this cohort.[17]

Manual Assisted Coughing

Manual assisted coughing (MAC) is a vital intervention for individuals grappling with compromised cough function, commonly arising from conditions like neuromuscular disorders, spinal cord injuries, and respiratory illnesses. Performed by skilled caregivers or healthcare professionals, MAC involves applying external pressure to the chest and abdomen during a cough's expiratory phase. This pressure enhances the cough's force and efficacy, aiding mucus expulsion from the airways.

MAC can adapt to individual needs and positioning, offering tailored assistance for optimal results. MAC significantly contributes to airway clearance by bolstering the ability to produce a robust cough, mitigating the risk of respiratory complications, and fostering improved respiratory well-being in those with impaired lung function.[18]

Mechanical Insufflation-Exsufflation

MI-E is a positive airway pressure with a rapid shift to a negative pressure that leads to a high expiratory flow rate from the lungs. Contraindications to MI-E use include bullous emphysema, pneumothorax, pneumomediastinum, recent barotrauma, and lack of cooperation.

MI-E assists in airway clearance, particularly in individuals with neuromuscular disorders or conditions that compromise their ability to cough effectively. MI-E involves applying alternating positive and negative pressures to the airways, which helps mobilize and clear mucus. This technique is particularly beneficial in adult and pediatric neuromuscular disorders with potential respiratory complications, including amyotrophic lateral sclerosis, cervical spinal cord injury, Duchenne muscular dystrophy, and spinal muscle atrophy.[19][20][21]

Studies have shown that MI-E can improve vital capacity, peak cough flow, and reduce respiratory infections and hospitalizations in these patient populations. MI-E has also been associated with improved quality of life and respiratory symptoms. MI-E is indicated when traditional ACTs such as coughing, suctioning, or MCP are inadequate or ineffective in clearing secretions from the airways.[22][23]

The main goal of MI-E is to mimic the physiological process of coughing by providing assisted insufflation (positive pressure) to inflate the lungs, followed by rapid exsufflation (negative pressure) to simulate a cough-like expiratory flow. This rapid pressure change helps dislodge and propel mucus from the airways, facilitating its removal.[24][25][26]

The American Thoracic Society recommends regular MI-E use as an effective adjunct therapy for airway clearance in patients with neuromuscular diseases and reduced cough effectiveness that other techniques cannot improve.[27] MI-E has not been studied extensively in patients with cystic fibrosis, including the pediatric population, and has been shown to drain more sputum than autogenic drainage.[28] Although both MI-E and MAC aid in mucus clearance, MI-E employs a device for standardized assistance, delivering alternating positive and negative pressures. In contrast, MAC relies on manual pressure applied to the chest and abdomen to enhance the individual's cough effort.

High-Frequency Chest Wall Oscillation

HFCWO devices typically consist of a vest connected to an air pulse generator. The patient wears the vest, which is inflated and deflated rapidly by the generator, creating oscillatory vibrations. These vibrations are transmitted to the chest wall and airways, causing shear forces that help loosen and mobilize mucus trapped within the airways. The oscillatory motion also enhances airflow and promotes coughing, aiding in mucus expulsion from the lungs.

Research supports HFCWO's efficacy in managing cystic fibrosis, enhancing mucociliary clearance, improving lung function and respiratory symptoms, and reducing cystic fibrosis exacerbations.[29][30] A recent study showed that treatment algorithms involving HFCWO reduced lung function decline, exacerbation rates, and hospitalizations.[31]

HFCWO has shown favorable outcomes for acute COPD exacerbations, including increased sputum production, improved quality of life, and shorter hospital stays.[32][33] This technique also effectively improves mucus clearance and respiratory outcomes in noncystic fibrosis bronchiectasis, making it a valuable adjunct therapy for airway clearance management.[34][35] HFCWO has been studied in patients with neuromuscular disorders, showing improvements in symptoms, slower forced vital capacity decline, and reduced hospitalizations and pneumonia.[36][37] 

Positive Expiratory Pressure

PEP is commonly prescribed as an ACT for individuals with bronchiectasis in the United States. Oscillatory PEP (OPEP) devices combine PEP with oscillations or vibrations to facilitate mucus mobilization and removal from the airways.

OPEP devices typically consist of a handheld device with a one-way valve and a resistive element. The patient exhales against resistance during exhalation, creating positive expiratory airway pressure. The resistive element generates oscillations or vibrations in the airway walls, helping loosen and mobilize mucus trapped within the lungs. These oscillations also stimulate coughing and facilitate mucus expectoration from the airways.

Studies found that OPEP is best used in conditions that produce thick and excessive secretions, such as in cystic fibrosis and noncystic fibrosis bronchiectasis, where it was shown to reduce acute exacerbation rates.[38] OPEP use has been linked to reduced COPD symptoms and exacerbations and improved exercise capacity, according to low-grade evidence.[39] Several studies have reported improvements in lung function, mucus clearance, respiratory symptoms, and hospitalization with OPEP therapy.[40][41][42] Research also supports the efficacy of OPEP in noncystic fibrosis bronchiectasis in reducing sputum production and exacerbations and improving quality of life.[40][38]

Besides respiratory conditions, OPEP/Acapella® devices are useful in managing early postoperative complications after coronary artery bypass grafting, lung, and abdominal surgeries and improving lung volumes and airway clearance.[43][44]

PEP devices typically consist of a handheld device with a one-way valve and a resistor or adjustable expiratory resistance. The patient breathes through the device during exhalation, creating resistance that generates positive pressure in the airways. This positive pressure helps to splint open the airways and mobilize mucus for easy clearance.

Common types of PEP devices include:

• Threshold PEP Devices: These devices feature a one-way valve and a resistor that generates positive pressure during exhalation. The resistance can be adjusted to control the pressure level. Examples include the Acapella® and Flutter® devices.
• Oscillating PEP Devices: Similar to threshold PEP devices, OPEP devices generate positive pressure during exhalation. However, these devices also incorporate an oscillating mechanism that creates vibrations to help mobilize mucus. Examples include the VibraPEP® and Quake® devices.
• Bubble PEP Devices: Bubble PEP devices utilize water's bubbling action to create resistance during exhalation, leading to the development of positive pressure in the airways. Pediatric patients or those who prefer a simpler design often use these devices. Examples include the Bubble-PEP® and Acapella Choice® devices.
• Inspiratory-Expiratory PEP Devices: These devices provide inspiratory and expiratory resistance, promoting mucus clearance through controlled breathing exercises. These devices are particularly useful for patients who require training in breathing techniques. Examples include the Breather® and Pranayama® devices.
• Adjustable PEP Devices: Adjustable PEP devices allow users to customize the resistance level to suit individual needs. These devices offer flexibility in therapy intensity and are suitable for patients with varying degrees of respiratory impairment. Examples include the Pari PEP® and Portex® PEP systems.
• PEP Therapy Masks: PEP therapy masks cover the nose and mouth and are connected to a tubing with an adjustable resistance valve. The valve creates positive pressure, keeping airways open and mobilizing mucus during exhalation. This pressure also aids in collateral ventilation and lung recruitment. PEP masks are adjustable, lightweight, portable, and suitable for clinical and home use. Some include an expiratory flutter valve for additional mucus clearance. A Cochrane review of 28 studies on cystic fibrosis found that OPEP devices significantly reduced pulmonary exacerbations.[45] One study found that a PEP mask was more effective than a flutter valve in reducing hospitalization and antibiotic use.[46][45]

Breathing Exercises

Respiratory exercises are often included in pulmonary rehabilitation programs for patients with chronic respiratory conditions, including COPD, asthma, and neuromuscular-related respiratory disorders.[47][48] Common breathing exercises for airway clearance encompass the following:

• Deep coughing (diaphragmatic breathing): Deep breathing involves inhaling slowly and deeply through the nose, allowing the abdomen to rise while filling the lungs with air. This technique helps fully expand the lungs and promote airway clearance by increasing airflow to the lungs' lower regions, where mucus accumulates. Deep breathing can be performed in a sitting or lying position and should be done several times daily for optimal benefit. 
• Pursed lip breathing: Pursed lip breathing is a technique that involves inhaling slowly through the nose and exhaling through pursed lips as if blowing out a candle. This breathing pattern helps prolong exhalation, create positive airway pressure, and prevent airway collapse. Pursed lip breathing can improve oxygenation, reduce shortness of breath, and enhance airway clearance by maintaining open airways during exhalation. 
• Directed coughing: Directed coughing is a technique used to effectively clear mucus from the airways by generating a strong cough. To perform directed coughing, the patient takes a deep breath, holds it for a few seconds, and then coughs forcefully while bending slightly forward. This technique helps mobilize and propel mucus upward, making it easier to expectorate. Directed coughing should be performed properly to avoid injury or strain.
• Huffing (forced expiratory technique): Huffing is a controlled breathing technique that involves forcefully exhaling with an open mouth while saying "huff" or "huh." This technique helps mobilize mucus from the smaller airways and move it toward the larger airways, making it easier to cough up and expectorate. Huffing can be repeated several times during each session and is often combined with coughing to facilitate mucus clearance.
• Segmental breathing: Segmental breathing focuses on specific lung areas when breathing deeply to promote ventilation and mucus clearance. Patients may be instructed to place their hands on different chest or abdominal regions to guide airflow to targeted areas. Segmental breathing can help improve lung expansion, enhance ventilation-perfusion matching, and facilitate mucus clearance from specific lung segments.
• Incentive spirometry: Incentive spirometry is a breathing exercise that uses a handheld device called a "spirometer" to encourage deep breathing and lung expansion. Patients inhale slowly and deeply through the spirometer to achieve a predetermined target volume, which helps to prevent atelectasis, improve lung function, and enhance airway clearance. Incentive spirometry is often used postoperatively after abdominal and thoracic surgery or during periods of immobility to maintain lung health and prevent respiratory complications.[49][50] Even though the evidence is not as robust, several studies have found the benefits of using incentive spirometry in the postoperative period.[51][52]

Active Cycle of Breathing Techniques 

The ACBT is a structured set of breathing exercises designed to enhance lung function, promote airway clearance, and improve oxygenation in individuals with respiratory conditions like COPD, asthma, and cystic fibrosis. ACBT comprises several phases to regulate breathing patterns, expand the chest, mobilize mucus, and facilitate coughing to clear the airways. 

Patients initially focus on controlled breathing to regulate their respiratory rate and promote relaxation. Thoracic expansion exercises are then performed, involving deep inhalation to expand the chest and increase lung volume. Patients then perform forced expiratory efforts and controlled coughing to effectively mobilize and clear mucus from the airways. Afterward, the relaxation phase allows patients to rest and recover, promoting overall comfort and well-being. 

ACBT is typically taught and supervised by respiratory therapists or healthcare providers to ensure proper technique and maximize its benefits in optimizing respiratory function and alleviating symptoms. Several studies have found the benefits of ACBT in cystic fibrosis, COPD, and bronchiectasis in terms of sputum production and improving pulmonary function.[53][54][55] 

Intrapulmonary Percussive Ventilation

IPV is a therapeutic technique used to improve airway clearance and lung function in individuals with various respiratory conditions, including cystic fibrosis, COPD, and bronchiectasis.[56][57] IPV involves the delivery of small, rapid air bursts at varying frequencies and pressures directly into the lungs through a handheld device. These air bursts create oscillations within the airways, helping mobilize and loosen mucus and secretions, which can then be expelled through coughing or suctioning. IPV therapy can be customized based on the individual's needs, with frequency, pressure, and air burst duration adjustments. This technique can be performed either invasively, through an ETT or tracheostomy tube, or noninvasively, using a mouthpiece or mask interface.

Despite IPV's widespread use by different experts, large-scale studies do not refute or suggest the use of IPV in various respiratory conditions. However, smaller studies have suggested their benefit in cystic fibrosis, COPD, and neuromuscular diseases.[58][59][60]

Manual mechanical and pressure assessment

No well-controlled, long-term comparison data exist on pressure or airway clearance ability. Nevertheless, evaluating the efficacy of ACTs involves measuring their impact on mucus clearance, respiratory function, and overall well-being through several key components:

• Objective measures such as spirometry and peak expiratory flow rate tests allow for monitoring lung function changes, providing valuable insights into respiratory health progression. The presence of restrictive ventilatory defects manifesting with reduced tidal volumes and vital capacity could serve as a sign to initiate MI-E intervention to assist in airway clearance.
• Analyzing sputum characteristics, including volume, color, and consistency, offers a deeper understanding of the effectiveness of mucus clearance strategies.
• Cough peak flow (CPF) assessment is an essential method to determine the ability to monitor cough effectiveness and airway clearance.[61] MI-E, lung volume recruitment, and manually assisted cough when CPF is equal to or below 270 L/min are most routinely recommended according to Canadian and UK surveys and guidelines.[62] 
• Postural drainage should only be used if it leads to more airway clearance and has no adverse effects. 
• Additional strategies to assist secretion clearance must be used when CPF is equal to or less than 160 L/min.[63]
• Targeting the active breathing cycle (during forced expiration) and drainage via PEP (with or without oscillation) for patients with chronic respiratory disorders such as stable COPD to assist in the removal of secretions is recommended by current guidelines.[63]
• Targeting a pressure of 40 cm H2O and CPF greater than 270 L/min is recommended when MI-E therapy is started.
• Obtaining direct feedback from the individual regarding their perception of the effectiveness and comfort of the techniques ensures that interventions are tailored to their specific needs and preferences.

By integrating these comprehensive assessments, healthcare professionals can gain a nuanced understanding of the benefits and limitations of different airway clearance approaches, enabling them to optimize treatment plans to suit each patient's unique circumstances.

Complications

ACTs are generally safe and beneficial, but healthcare providers must carefully monitor patients for complications, tailor treatments to individual needs, and take measures to minimize risks. Potential complications associated with ACTs include respiratory distress, barotrauma (eg, pneumothorax or pneumomediastinum), musculoskeletal strain, hemodynamic instability, skin irritation or injury, aspiration, and psychological distress. The 3 adverse effects related to OPEP device use include hemoptysis (most common), pneumothorax, and bronchospasm.[38]

Patients with unstable cardiovascular conditions, recent thoracic or abdominal surgery, untreated pneumothorax, severe respiratory distress, uncontrolled hemoptysis, active tuberculosis, or facial trauma or fractures may be at increased risk of complications arising from ACTs and should be carefully evaluated before proceeding with therapy. Individualized treatment plans should be developed based on each patient's medical history, clinical status, and potential risk factors to optimize safety and therapeutic outcomes.    

Clinical Significance

ACTs are pivotal in managing respiratory conditions marked by impaired mucus clearance or airway obstruction. These techniques enhance respiratory function by facilitating the removal of mucus, secretions, and foreign particles from the airways, thereby improving ventilation and gas exchange. ACTs help prevent respiratory complications, such as infections, atelectasis, and pneumonia while optimizing lung health and function over time. 

These techniques contribute to maintaining optimal lung volume by clearing mucus and secretions, reducing airway inflammation, and minimizing the risk of progressive lung damage in chronic respiratory diseases. Furthermore, ACTs aid in effectively delivering inhaled medications, enhancing treatment outcomes and overall respiratory health. Overall, ACTs are crucial in comprehensive respiratory care, improving respiratory function, reducing complications, and optimizing patient outcomes.

Enhancing Healthcare Team Outcomes

Improving outcomes for healthcare teams by applying diverse ACTs requires a collaborative effort among various healthcare professionals, including pulmonologists, respiratory therapists, physiotherapists, nurses, and other allied health staff. This collaboration hinges on continuous education, ensuring proficiency in current techniques, and the development of standardized protocols for consistent care delivery. Customizing patient care based on individual needs, ongoing monitoring of treatment effectiveness, and empowering patients through education and involvement in decision-making processes are integral aspects. Moreover, the commitment to continuous quality improvement initiatives ensures the refinement of practices, thereby optimizing airway clearance services and elevating the quality of care provided in various healthcare settings.