Conditions That May Indicate Airway Clearance

Oxygen transport is the primary purpose of the cardiopulmonary system (see Chapter 2). Ventilation of the alveoli is an important step in the oxygen transport chain; it allows optimal delivery of oxygen to the tissues. Several medical and surgical conditions may interfere with this process. Retained secretions or mucus plugs in the airways may interfere with the exchange of oxygen. The secretions must be mobilized from the peripheral, or smaller, airways to the larger, more central airways, where coughing or suction may remove them.

The following conditions may be associated with difficulty in mobilizing airway secretions. Difficulty in effectively mobilizing secretions can result from a combination of factors including impaired ciliary motion, reduced lung inflation, impaired lung elasticity, impaired chest wall mobility and biomechanics, and weak or fatigued respiratory muscles. These factors can be coupled with increased viscosity of airway secretions.

Airway Clearance Techniques

Airway clearance techniques differ with respect to equipment needs, the skill level required to perform them, and their usefulness with various clinical problems. Matching a patient with an appropriate method or combination of methods may increase effectiveness, reduce complications, and promote long-term adherence to the treatment. This will, in turn, assist with achieving the goals of airway clearance: reducing airway obstruction, improving ventilation, and optimizing gas exchange.

Preparation for any secretion removal technique should include evaluation of the patient’s pulmonary status so that measures may be compared before and after a treatment is provided. A physical examination, including inspection, palpation, measurement of vital signs, and chest auscultation, provides assessment of a treatment’s effectiveness. Other outcome measures include chest radiographs, arterial blood gas measurements, and pulmonary function studies. An adequate intake of fluids (as allowed) decreases the viscosity of the secretions, allowing easier mobilization.

Several factors must be taken into account when scheduling an optimal time for airway clearance. At least 30 minutes to 1 hour should be allowed for the completion of tube feedings or meals. The inhalation of bronchodilator medications should take place before airway clearance maneuvers to improve secretion removal by opening the airways. Inhaled antibiotics are best scheduled after airway clearance has taken place for optimal deposition of medication. If necessary, adequate pain control should be provided to receive a patient’s best effort and cooperation with a treatment.

Exercise for Airway Clearance

In addition to improving many outcomes in patients with lung disease, exercise has been shown to assist in secretion clearance.25–28 Exercise increases mucociliary transport in patients with chronic bronchitis.²⁸ Higher transpulmonary pressure with aerobic exercise may open closed bronchi, as well as increase collateral ventilation to allow mucus to be moved.²⁶ It has also been shown that exercise-induced hyperventilation is more effective than eucapnic hyperventilation in mobilizing bronchial secretions.²⁹ The contribution of increased expiratory airflow and exercise-induced coughing are other factors in improving secretion removal. Exercise for secretion clearance has focused on aerobic or endurance exercise; however, any form of exercise must be adapted to the individual patient’s status and abilities.

Based on a lack of decrease in lung function following the cessation of PD and percussion but the continuation of an exercise program, or based on the improvement in pulmonary function, exercise has been recommended as a replacement for a conventional chest physiotherapy routine in some patients or at some stages of lung disease.26,27,30,31 In hospitalized patients with cystic fibrosis, no significant change in pulmonary function was reported when exercise was substituted for two of three daily treatments of PD, percussion, and vibration, and the weight of the sputum produced was equivalent.³⁰ In terms of mucus cleared, no significant differences were found among exercise on a cycle ergometer, postural drainage, and PEP mask breathing.³² Increases in sputum expectoration on exercise days as opposed to nonexercise days have also been reported.^27,33

However, other studies conclude that exercise alone is not sufficient and recommend its use as a complement to other forms of airway clearance. Airway clearance using PD and FET was shown to be more effective than exercise with a cycle ergometer in inducing sputum expectoration.³⁴ Results from Bilton and colleagues³⁵ demonstrated that any modality that included the active cycle of breathing technique (ACBT) in PD positions alone or in combination with exercise is better than exercise alone at clearing sputum.

It is difficult to compare these studies, however, because the mode and length of exercise differ, as do the outcome measures of effectiveness of airway clearance. Exercise as an airway clearance technique is not suitable for the very young (younger than 4 to 5 years of age), for patients with neuromuscular limitations, or for patients with limited exercise tolerance. Moreover, the potential need for supplemental oxygen during exercise should be monitored. Nonetheless, evidence suggests that an exercise program, in addition to clearing secretions, may decrease morbidity and mortality by improving exercise capacity.36,37

Treatment with Exercise

 A walking program requires only a suitable pair of shoes and a safe location. Higher-impact exercise, because of increased stress on the knees, requires shoes specifically for that purpose. Clothing should be appropriate for the weather if exercising outdoors.

 Exercise equipment suitable for a patient who is beginning an exercise program includes the treadmill, bicycle ergometer, elliptical trainer, mini-trampoline, or arm ergometer. For more accomplished exercisers or patients with a higher exercise tolerance, equipment may include a stair climber, cross-country ski machine, or rowing machine. Numerous other exercise equipment options are available; the patient’s interests should be the primary factor for choosing.

 Tools to monitor a patient’s response to exercise include a sphygmomanometer, stethoscope, heart rate monitor, pulse oximeter, and a scale to measure patient’s level of perceived exertion (Figure 21-1). In a home setting, patients should be knowledgeable in self-monitoring exercise intensity. For those patients who require closer monitoring, a pulse oximeter may be rented from an oxygen supply company. Monitoring of vital signs before and during exercise, and during recovery, will allow titration of the workload for optimal performance.

 Supplemental oxygen and oxygen delivery supplies will be necessary for those patients who exhibit oxygen desaturation during exercise.

 Patients with hyperreactive airways should be premedicated with a prescribed bronchodilator before an exercise session.

 The principles of an exercise prescription addressing mode, intensity, duration, and frequency, as well as principles of “warm up” and “cool down,” should be followed when using exercise as a form of airway clearance. Individualizing an exercise program for each patient is of the utmost importance.

 Patients hospitalized for an acute exacerbation may not be able to initially perform endurance exercise. These patients should be started slowly and progressed as tolerated; consider using interval training.

 The patient should be instructed in huffing or controlled coughing to expectorate secretions as they are loosened.

 A regular, consistent program of exercise should be scheduled around the patient’s daily activities to achieve adherence (e.g., walking the dog, sports at school, stopping by the health club after work).

Advantages and Disadvantages of Exercise

Exercise has the advantage of being the only airway clearance technique that is performed regularly by people without lung disease. This factor can make it appealing to those patients who do not want to call attention to their differences from their peers. Exercise may improve self-esteem, a sense of well-being, and quality of life. Higher levels of exercise tolerance in patients with cystic fibrosis have been demonstrated to improve survival.³⁷

Some patients may not tolerate the amount or frequency of exercise necessary for this to be the sole method of airway clearance. Thus various airway clearance techniques can be used as adjuncts to exercise. This is particularly true during an acute exacerbation when activity tolerance is limited, or in infants or patients with neurological or musculoskeletal limitations. Andreasson²⁶ observed that regular contact with a caregiver seems to be necessary for successful exercise training, as does family support, especially in young children. This points out the difficulty with adherence to a home program. Adherence will also be affected by a patient’s preference for a particular activity, scheduling conflicts, and commitment by friends and family members.

Precautions for Using Exercise

Several precautions must be observed when using exercise as a form of airway clearance. Care must be taken in prescribing exercise to patients with hyperreactive airways or a tendency toward oxygen desaturation. Desaturation has been shown to occur with exercise in individuals with pulmonary disease,38,39 and therefore it becomes prudent to monitor oxygen saturation, providing supplemental oxygen for the exercise period when indicated. Exercise-induced bronchospasm must also be considered when pulmonary compromise is seen with exercise, especially with higher-intensity exercise.⁴⁰ When medication is indicated, it is recommended to provide an inhaled bronchodilator 20 to 30 minutes before exercise to alleviate this symptom.⁴¹ Use of bronchodilator medication and supplemental oxygen may be necessary to improve exercise tolerance, but these patients require closer monitoring as well. Andreasson²⁶ reports a risk for pneumothorax associated with exercise in patients with extensive bullae.

Contraindications and Precautions for Manual and Mechanical Airway Clearance Techniques

In patients who are very young, who have limited ability to cooperate, or who are not adherent to other ACTs, percussion, shaking, and vibration offer methods for dislodging retained secretions. However, because of the force transmitted to the thoracic cage with these techniques, there are many precautions and contraindications to consider. The therapist should not make this decision alone but should seek direction from the medical team. These treatments are not completely benign and should not be performed in the absence of good indications.⁴²

Percussion has been shown to contribute to a fall in PaO₂ in acutely ill patients,⁴³ especially in patients with cardiovascular instability⁴⁴ and in neonates.⁴⁵ The factor that seems most closely associated with or predictive of this effect is the patient’s baseline PaO₂.⁴² Cardiac dysrhythmias have been associated with chest percussion for bronchial drainage¹¹ and Huseby⁴⁶ hypothesizes that hypoxemia may be the underlying mechanism of CPT-caused cardiac arrhythmias.

Patients with hyperreactive airways (e.g., asthma) show intolerance for percussion as part of airway clearance. Campbell and colleagues⁴⁷ demonstrated a fall in FEV₁ associated with percussion; it was not evident when percussion was omitted. Administration of a bronchodilator before treatment with percussion precluded the fall in FEV₁. Wheezing has also been associated with percussion and vibration in patients with cystic fibrosis and COPD.^48,49

Box 21-1 summarizes the precautions and contraindications for external manipulation of the thorax associated with percussion, shaking, and high-frequency chest compression. Vibration involves less force to the thorax and may be better tolerated than the aforementioned techniques. A nebulized bronchodilator may be administered during a treatment of high-frequency chest compression to avoid the consequences of hyperreactive airways.

Postural Drainage

Postural drainage, also known as bronchial drainage, is a passive technique in which the patient is placed in positions that allow gravity to assist with the drainage of secretions from the bronchopulmonary tree. PD is accomplished by positioning the patient so that the angle of the lung segment to be drained allows gravity to have its greatest effect (Figure 21-2). Positioning the patient to assist the flow of bronchial secretions from the airways has been a standard treatment for some time in patients with retained secretions.⁵⁰

Knowledge of the anatomy of the tracheobronchial tree is vital to effective treatment. Each lobe to be drained must be aligned so that gravity can mobilize the secretions from the periphery to the larger, more central airways. The mechanism of postural drainage is considered to be a direct effect of gravity on bronchial secretions, although observations made by Lannefors (1992)³² that gravity also influences regional lung ventilation and volume suggest that these mechanisms are also involved.

PD has been shown to be effective in mobilizing secretions in patients with cystic fibrosis,51,52 bronchiectasis,¹⁰ and other pulmonary diseases.^53,54 Other treatments, such as percussion, vibration, and the active cycle of breathing technique (ACBT), may be used while the patient is in postural drainage positions.

There are, however, many contraindications to gravity-enhancing positioning for PD. Recent studies have reported adverse effects of head-down or Trendelenburg positions required for the lower lobes. Modified positions should be used for head-down positions unless it has been shown to be effective in a particular patient. The head of the bed should remain flat instead of being tipped into the Trendelenburg (head down) position.

Preparation for Postural Drainage

 For the hospitalized patient, electric beds allow patients to be positioned more easily. Air therapy beds, most often used in the intensive care unit (ICU), are valuable aids for positioning, especially in patients who are large or unresponsive.

 In the ICU, it is imperative to be familiar with the multiple lines, tubes, and other devices attached to the patient (see Chapter 16). Allow enough slack from each device to position a patient for postural drainage.

 Ensure there are enough staff members to position the patient with as little stress to both patient and staff as possible.⁵⁵

 For treatment in the clinic, have foam wedges or pillows available for positioning.

 For home treatment, aids in positioning might include pillows, sofa cushions, or a bean-bag chair.

 Nebulized bronchodilators or mucolytics before PD may facilitate the mobilization of sputum.

 For the patient with an adequate cough to expectorate secretions, have tissues or a specimen cup available. Have suctioning equipment ready to remove secretions from an artificial airway or the patient’s oral or nasal cavity after the treatment. Refer to Chapter 43 for a discussion of suctioning.

Treatment with Postural Drainage

 After determining the lobe of the lung to be treated by auscultation and chest x-ray, position the patient in the appropriate position, supporting the patient comfortably in the position indicated (see Figure 21-2).

 If postural drainage is used exclusively, each position should be maintained for 5 to 10 minutes, if tolerated, or longer when focusing on a specific lobe. Coordinating the positioning with nursing care for skin pressure relief may allow the time spent in a position to be extended. If postural drainage is used in conjunction with another technique, the time in each position may be decreased. For example, if percussion and vibration are performed while the patient is in each PD position, 3 to 5 minutes is sufficient.

 A patient who requires close monitoring should not be left unattended, but this may be appropriate if a patient is alert and able to reposition himself or herself.

 It is not always necessary to treat each affected lung segment during every treatment; this may prove to be too fatiguing for the patient. The most affected lobes should be addressed with the first treatment of the day, with the other affected areas addressed during subsequent treatment(s).

 The patient should be encouraged to take deep breaths and cough after each position, if possible, and again after the treatment is completed. Having the patient sit upright or lean forward optimizes this effort by allowing the use of the abdominals for a stronger cough.⁵⁵

 Mobilization of secretions may not be apparent immediately after the treatment, but this may occur up to 1 hour later. The patient should be thus informed and reminded to clear secretions at a later time. A health care practitioner or family member should be included in this aspect of treatment, especially with patients who need encouragement.⁵⁵

Advantages and Disadvantages of Postural Drainage

Postural drainage is relatively easy to learn; the patient and/or caregiver must be familiar with the appropriate positioning for the affected lung fields. Treatment in the hospital may be coordinated with other patient activities, such as positioning for skin pressure relief, bathing, or positioning for a test or procedure. Home treatment can be coordinated with activities such as reading or watching television.

For many patients, optimal PD positions will be contraindicated for a variety of reasons and modified positions should be used. Adherence to PD may be a challenge because of the length of the treatment; this is especially challenging in the pediatric population, who will require considerable distraction to maintain a desired position for the appropriate length of time. Children who are able to role-play the treatment—for instance, with a doll or stuffed toy—may better understand what is expected and be more cooperative with therapy.

The cost of the equipment required for PD is minimal. The cost of a caregiver’s time to provide the treatment, however, especially in the case of a chronic disease, may be substantial. A family member should be taught the procedure, if possible, to decrease the cost and provide flexibility in scheduling.

General Precautions and Contraindications to Postural Drainage Positioning

It is essential that the therapist and the health care team discuss treatment priorities when deciding to use PD positions. A decision to use postural drainage might be made despite a contraindication if the benefits are thought to outweigh the risks in a particular case. For example, it is known that use of the Trendelenburg (head-down) position increases intracranial pressure in patients after neurosurgery.⁵⁶ However, if the patient develops atelectasis, the stress of respiratory embarrassment may also increase intracranial pressure. In this instance, the decision may be made to position the patient to clear the atelectasis and subsequently return to a modified conservative regimen.⁵⁵

A fall in arterial O₂ saturation has been reported with the use of postural drainage for airway clearance, although the effects of PD were not separated from additional techniques.46,57 Therefore O₂ saturation levels should be monitored during treatment, especially in patients with known low PaO₂ values.

Caution must also be used in treating a patient with end-stage lung disease in postural drainage positions because of the risk for hemoptysis.58,59 Decreased cardiac output^60,61 has been associated with chest physiotherapy treatment; however, the effects of postural drainage were not separated from those of percussion and vibration.

Many physical therapists working with the pediatric population almost never use the head-down position in treating infants but rather a modified routine that excludes the Trendelenburg position. The head-down position has been shown to increase the incidence of gastroesophageal reflux in neonates.¹⁶ Button and colleagues⁶² found that the head-down position is associated with gastroesophageal reflux, distressed behavior, and lower oxygen saturation in infants with cystic fibrosis. It should be noted that a finding of gastroesophageal reflux can occur even 1 hour after treatment. A modified routine that eliminates head-down positioning is associated with fewer respiratory complications.⁶³ Box 21-2 summarizes the precautions and contraindications concerning postural drainage.

Box 21-2

Contraindications for Postural Drainage

All Positions Are Contraindicated for the Following

 Intracranial pressure (ICP) >20 mm Hg

 Head and neck injury until stabilized

 Active hemorrhage with hemodynamic instability

 Recent spinal surgery (e.g., laminectomy) or acute spinal injury

 Active hemoptysis

 Empyema

 Bronchopleural fistula

 Pulmonary edema associated with heart failure (HF)

 Large pleural effusions

 Pulmonary embolism

 Older, confused, or anxious patients

 Rib fracture, with or without flail chest

 Surgical wound or healing tissue

Trendelenburg Position Is Contraindicated for the Following

 Patients in whom increased ICP is to be avoided

 Uncontrolled hypertension

 Distended abdomen

 Esophageal surgery

 Recent gross hemoptysis related to recent lung carcinoma

 Uncontrolled airway at risk for aspiration

Trendelenburg Position Is Contraindicated for the Following Cases in Neonates

 Untreated tension pneumothorax

 Recent tracheoesophageal fistula repair

 Recent eye or intracranial surgery

 Intraventricular hemorrhage (grades III and IV)

 Acute heart failure or cor pulmonale

From AARC Clinical Practice Guideline: Postural drainage therapy, Respiratory Care 36:1418-1426, 1991; and Crane L: Physical therapy for the neonate with respiratory disease. In Irwin S, Tecklin JS, editors: Cardiopulmonary physical therapy, St. Louis, 1985, Mosby.

Percussion

Percussion, sometimes referred to as chest clapping, is a traditional approach to secretion mobilization. A rhythmical force is applied with a caregiver’s cupped hands against the thorax, over the involved lung segments, trapping air between the patient’s thorax and the caregiver’s hands (Figure 21-3), with the aim of dislodging or loosening bronchial secretions from the airways so they may be removed by suctioning or expectoration. This technique is performed during both the inspiratory and expiratory phases of breathing. Percussion is used in postural drainage positions for increased effectiveness^64,65 and may also be used during ACBT. For individuals with pulmonary disease, percussion in conjunction with postural drainage continues to be a mainstay of the treatment, especially for pediatric patients and patients who are unresponsive.

The proposed mechanism of action of percussion is the transmission of a wave of energy through the chest wall into the lung. This wave loosens secretions from the bronchial wall and moves them proximally, where ciliary motion and cough (or suction) can remove them. The combination of postural drainage and percussion has been shown to be effective in secretion removal.66–68

A handheld mechanical percussor can be used by a caregiver to minimize fatigue or may be used by the patient to self-administer percussion. The effectiveness of mechanical as opposed to manual percussion has been studied. Maxwell and Redmond⁶⁹ found mechanical percussion equivalent to manual percussion in effecting removal of secretions. Although there was a significant increase in pulmonary function with manual techniques, Pryor and colleagues^70,71 supported the use of mechanical percussion in patients, using the forced expiration technique. A study by Rossman and colleagues⁷² was in disagreement, finding that mechanical percussion did not enhance postural drainage in secretion removal.

There are contraindications to percussion. If a patient’s pulmonary status is of greater concern than the relative contraindications, a decision may be made to administer the treatment, with appropriate modifications.

Preparation for Percussion

 The only equipment required for manual percussion is the caregiver’s cupped hands to deliver the force to mobilize secretions.

 For the adult and older pediatric population, electric or pneumatic percussors that mechanically simulate percussion are available. This enables a patient to apply self-percussion more effectively. Several models have variable frequencies of percussion, as well as different levels of intensity.

 Several devices, including padded rubber nipples, pediatric anesthesia masks, padded medicine cups, or the bell end of a stethoscope may be used to provide percussion to infants whose chest walls are too small to accommodate the size of an adult’s hand.

 Placing the patient in appropriate PD positions (as the patient’s condition allows) enhances the effect of percussion.

 A thin towel or hospital gown should cover the patient’s skin where the percussion is to be applied. The force of percussion over bare skin may be uncomfortable; however, padding that is too thick absorbs the force of the percussion without benefit to the patient.

 Adjust the level of the bed so that the caregiver may use proper body mechanics during the treatment. The caregiver may become excessively fatigued or injured as a result of lengthy or numerous treatments if proper body mechanics are ignored.

Treatment with Percussion

 Position the hand in the shape of a cup with the fingers and thumb adducted. It is important to maintain this cupped position with the hands throughout the treatment, while letting the wrists, arms, and shoulders stay relaxed.

 The sound of percussion should be hollow as opposed to a slapping sound. If erythema occurs with percussion, it is usually a result of slapping or not trapping enough air between the hand and the chest wall.⁷³

 The patient will better tolerate an even, steady rhythm. The rate of manual percussion delivered by caregivers can vary between 100 and 480 times per minute.⁷³

 The force applied to the chest wall from each hand should be equal. If the nondominant hand is not able to keep up with the dominant hand, the rate should be slowed to match that of the slower hand. It might be helpful to start with the nondominant hand and let the dominant hand match the nondominant hand.⁵⁵ The force does not have to be excessive to be effective; the amount of force should be adapted to the patient’s comfort.

 If the size of an infant does not allow use of a full hand, percussion may be done manually with four fingers cupped, three fingers with the middle finger “tented,” or the thenar and hypothenar surfaces of the hand.⁷⁴

 Hand position should be such that percussion does not occur over bony prominences of the patient. The spinous processes of the vertebrae, the spine of the scapula, and the clavicle should all be avoided. Percussion over the floating ribs should also be avoided because these ribs have only a single attachment.

 Percussion should not be performed over breast tissue. This will produce discomfort and diminish the effectiveness of the treatment. In the case of very large breasts, it may be necessary to move the breast out of the way with one hand (or ask the patient to do this) and percuss with the other hand.

 A patient may be taught to perform one-handed self-percussion to those areas that can be reached comfortably, either manually or with a mechanical percussor. This does, however, virtually preclude the treatment of the posterior lung segments.

Advantages and Disadvantages of Percussion

The addition of percussion to a PD treatment may enhance secretion clearance and shorten the treatment. Patients, especially young children and infants, often find the rhythm soothing and are relaxed and sedated by percussion.

Patients with chronic lung disease who have used PD and percussion for many years and have found it effective may be reluctant to try an alternative method of airway clearance. Acceptance of this method is dependent on the consistent availability of a family member or other caregiver to provide the treatment. Mechanical percussors allow a patient more independence or decrease fatigue of a caregiver, and they are especially useful in patients requiring ongoing treatment at home.

Percussion is not well tolerated by many patients postoperatively without adequate pain control. The force of percussion may also be contraindicated in patients with osteoporosis or coagulopathy. Percussion has been associated with a fall in oxygen saturation, which can be eliminated with concurrent thoracic expansion exercises and pauses for breathing control.⁷⁵

Delivering percussion for extended periods on an ongoing basis can result in injury to the caregiver, whether a family member or a health care provider; repetitive motion injuries of the upper extremities may occur in long-term delivery of percussion for airway clearance.

The expense of a mechanical device for percussion is minimal compared with the ongoing cost of a caregiver to provide percussion and PD, either in the hospital setting or at home. In the case of young children or unresponsive patients, there are few choices for airway clearance. For other populations, however, a more independent method can prove to be more cost-effective if adequate adherence is achieved.

Vibration and Shaking

The techniques of vibration and shaking are on opposite ends of a spectrum. Vibration involves a gentle, high-frequency force, whereas shaking is more vigorous in nature. Vibration is delivered through a sustained co-contraction of the caregiver’s upper extremities to produce a vibratory force while applying pressure to the chest wall over the involved lung segment. Shaking is similar in application to vibration, and is described as a bouncing maneuver, sometimes referred to as “rib springing,” supplying a concurrent, compressive force to the chest wall. Like percussion, vibration and shaking are used in conjunction with PD positioning. Unlike percussion, they are performed only during the expiratory phase of breathing, starting with peak inspiration and continuing until the end of expiration. The compressive forces follow the movement of the chest wall. Both techniques require the assistance of a caregiver, but a mechanical vibrator may be used in place of manual vibration.

It is proposed that vibration and shaking enhance mucociliary transport from the periphery of the lung fields to the larger, central airways. Because the compressive force to the thorax is greater with shaking than vibration, it produces increased chest wall displacement, and the stretch of the respiratory muscles may produce an increased inspiratory effort and lung volume.⁷⁶ The same relative contraindications for percussion should be observed for shaking, because it involves the application of force to the thorax.

Pavia⁷⁷ demonstrated a higher, though not statistically significant, rate of secretion clearance and sputum production with vibration. However, this study was conducted while subjects were in the upright position only, which does not replicate the use of vibration clinically. Many studies do not separate the effects of vibration from the components of PD and percussion because they are often used in conjunction. In fact, many studies describe the techniques of PD, percussion, and vibration or shaking as a single entity and refer to the treatment as chest physical therapy or postural drainage therapy. Mackenzie and colleagues⁷⁸ demonstrated significant improvement in total lung/thorax compliance after treatment with postural drainage, percussion, and vibration in mechanically ventilated patients. Feldman and colleagues⁴⁸ demonstrated improved ventilatory function by improved expiratory flow rates in patients receiving postural drainage, percussion, vibration, and directed coughing.

Preparation for Vibration and Shaking

 For manual techniques, the caregiver’s hands are the only “equipment” required.

 Mechanical vibrators are available to administer the treatment and are useful for self-treatment by a patient or to reduce fatigue in the caregiver.

 For infants, a padded electric toothbrush may be used.⁷⁴

 Place the patient in the appropriate PD position or modified position, as the patient’s status allows.

 Place a thin towel or hospital gown over the patient’s skin. The material should not be thick enough to absorb the effect of the vibration or shaking.

 Proper body position of the caregiver is important to deliver an effective treatment and to decrease caregiver fatigue.

Treatment with Vibration and Shaking

 For vibration, the hands may be placed side by side or on top of each other, as shown in Figure 21-4. As with shaking, the patient is instructed to take in a deep breath while in a proper PD position. A gentle but steady co-contraction of the upper extremities is performed to vibrate the chest wall, beginning at the peak of inspiration and following the movement of chest deflation. The frequency of manual vibration is between 12 and 20 Hz.^44,53

 For shaking, with the patient in the appropriate PD position, place your hands over the lobe of the lung to be treated and instruct the patient to take in a deep breath. At the peak of inspiration, apply a slow (approximately 2 times per second), rhythmic bouncing pressure to the chest wall until the end of expiration. The hands follow the movement of the chest as the air is exhaled. The frequency of shaking is 2 Hz.44,53

 If the patient is mechanically ventilated, the previously described techniques needs to be coordinated with ventilator-controlled exhalation.

 If the patient has a rapid respiratory rate, either voluntary or ventilator-controlled, it may be necessary to apply vibration or shaking only during every other exhalation.

 A mobile chest wall is necessary to apply a compressive force without causing discomfort. If a patient has limited chest wall compliance, vibration will probably be better tolerated than shaking.

 Mechanical vibrators may be used by the unattended patient, although only limited attention can be paid to the posterior portions of the lungs.

Advantages and Disadvantages of Vibration and Shaking

The use of vibration and/or shaking in addition to PD may enhance the mobilization of secretions. Shaking or vibration may be better tolerated than percussion, especially in the postsurgical patient. Manual vibration and shaking allows the caregiver to assess the pattern and depth of respiration. The stretch on the muscles of respiration during expiration may encourage a deeper subsequent inspiration. A mechanical vibrator, more commonly used with pediatric patients, may be preferable for delivery of airway clearance in the long-term.

The patient cannot apply these techniques without assistance, except in a limited manner with a mechanical vibrator, so adherence and regular administration of vibration depends on caregiver availability.

The same contraindications for percussion apply because shaking and vibration involve compression to the thorax. The technique of vibration is less constrained by these contraindications than is shaking.

Active Cycle of Breathing Technique

In New Zealand, Thompson⁸⁵ described clearing bronchial secretions in patients with asthma by using a technique of forced expirations and diaphragmatic breathing. British physiotherapists modified the technique and further described it in the literature, first as the forced expiration technique (FET)⁷⁰ and later as the active cycle of breathing technique.⁸⁶

As described by Webber and Pryor,⁸⁶ ACBT consists of repeated cycles of three ventilatory phases: breathing control, thoracic expansion exercises, and FET. Breathing control is described as gentle tidal volume breathing with relaxation of the upper chest and shoulders. The thoracic expansion phase consists of deep inspiration and may be accompanied by percussion or vibration performed by a caregiver or the patient. This phase helps to loosen secretions. The forced expiration technique involves one or two huffs, as when fogging a window or cleaning glasses with one’s breath. Slow huffing from a middle lung volume (a medium-sized inspiration) down to a low lung volume moves secretions from the peripheral to the upper airways, whereas upper airway secretions may be cleared by a quicker huff from a high lung volume or deeper inspiration.⁸⁶

The period of breathing control between the other phases is essential in order to prevent bronchospasm.⁸⁷ The period of thoracic expansion, which increases lung volume and promotes collateral ventilation, allows air to get behind secretions and assist in their mobilization.⁸⁸ Mead and colleagues⁸⁹ described the physiological theory of the equal pressure point (EPP), which is the basis for FET. EPP is the point in the airways where the pressure is equal to the pleural pressure. The forced expiratory maneuver produces compression of the airway peripherally to EPP. A huff from high lung volume causes compression within the trachea and bronchi, which moves secretions from these larger airways. A huff continued to low lung volume shifts the EPP more peripherally, which mobilizes more peripheral secretions.⁸⁴

Because huffing has been shown to stabilize collapsible bronchial walls, it increases the expiratory flow in patients with obstruction without causing airway collapse.⁹⁰ Another benefit of this technique is its ability to maintain oxygen saturation. The decrease in oxygen saturation that has been demonstrated with postural drainage and percussion has been prevented by the use of ACBT.⁷⁵ Hassani and colleagues (1994)⁹¹ showed that unproductive cough and FET resulted in the movement of secretions proximally from all regions of the lung in patients with mild hyposecretion. Therefore, FET may help to avoid prolonged retention of secretions, even in patients who produce little sputum.

ACBT may be performed in the sitting position but has been shown to be more effective in gravity-assisted positions; although horizontal side lying may have fewer adverse effects than the head-down position.50,92 This method encourages active participation of the patient and has been shown to be as effective when performed by the patient alone or with the aid of a caregiver.⁷⁰ FET performed by patients independently has been shown to clear more sputum in a shorter amount of time than PD with self-percussion combined with percussion and shaking by a physical therapist.⁷⁰ Improvements in pulmonary function⁹³ and sputum clearance⁹⁴ have been demonstrated in patients with cystic fibrosis who incorporated FET into their postural drainage treatments. ACBT has been shown to be equally effective as positive expiratory pressure (PEP) in a year-long study.⁵⁰ Additionally, this method of airway clearance may be used with some children as young as 3 or 4 years of age. The sequence of ACBT is shown in Box 21-3.

Box 21-3

Active Cycle of Breathing Technique

 Breathing control

 Diaphragmatic breathing at normal tidal volume

 3-4 thoracic expansion exercises

 Deep inhalation with relaxed exhalation at vital capacity, with or without chest percussion

 Breathing control

 3-4 thoracic expansion exercises

 Breathing control

 Forced expiratory technique

 1-2 huffs at middle to low lung volume

 Abdominal muscle contraction to produce forced exhalation

 Breathing control

Modified from Webber B, Pryor J: Physiotherapy skills: Techniques and adjuncts. In Webber B, Pryor J, editors: Physiotherapy for respiratory and cardiac problems, Edinburgh, 1993, Churchill Livingstone.

Preparation for Active Cycle of Breathing Technique

 The only equipment required for this manual technique is the patient’s or caregiver’s hands to percuss or shake/vibrate the chest wall during the thoracic expansion phase.

 Mechanical percussors or vibrators may be used during the thoracic expansion phase, either for self-percussion by the patient or for use by the caregiver.

 To teach the huffing maneuver (part of FET), it may be helpful to use a peak flow meter mouthpiece to maintain the mouth and glottis open (Figure 21-5). Young children may be taught games of huffing at cotton balls or tissue to improve the effect of the technique.⁸⁶ To help them focus on the expiratory maneuver, small children may also be taught to flap their arms to their lateral chest as they perform the huff, a technique referred to as the “chicken breath.”⁹⁵

 The patient should be in a PD position to stimulate drainage of a productive area of the lungs, although the entire treatment may also be performed in the upright sitting position. If PD positions are used, equipment for positioning will be required.

 Most patients tolerate treatment of two or three productive areas during one session.

 A minimum of 10 minutes in any productive position may be necessary to clear a patient with a moderate amount of secretions. Patients after surgery or with minimal secretions may not require as much time, and very ill patients may fatigue before optimal treatment is given.⁸⁶

Treatment with Active Cycle of Breathing Technique

 During the breathing control phase, the patient is instructed to breathe in a relaxed manner using normal tidal volume. The upper chest and shoulders should remain relaxed, and the lower chest and abdomen should be active. The breathing control phase should last as long as is required for the patient to relax and prepare for the next phases, usually 5 to 10 seconds.

 The emphasis during the thoracic expansion phase is on inspiration. The patient is instructed to take in a deep breath to the inspiratory reserve volume; expiration is passive and relaxed. The caregiver or the patient may place a hand over the area of the thorax being treated to facilitate increased chest wall movement.

 Chest percussion, shaking, or vibration may be performed in combination with thoracic expansion as the patient exhales. For surgical patients or those with lung collapse, a breath hold or a sniff at the end of inspiration encourages collateral ventilation to redistribute air into collapsed segments and assist with reexpansion of the lung.

 The FET phase consists of huffing interspersed with breathing control. A huff is a rapid, forced exhalation without maximal effort. This maneuver is comparable to fogging a pair of eyeglasses with warm breath so they may be cleaned. Unlike a cough, in which the glottis is closed, a huff requires the glottis to remain open. In an effective huff, the muscles of the abdomen should contract to provide greater expiratory force. Other characteristics of effective versus ineffective huffing are shown in Box 21-4.

Box 21-4

Effective Versus Ineffective Huffing

Effective Huffing

Ineffective Huffing

Mouth open, O-shaped to keep glottis open Forced expiration From middle to low lung volume moves peripheral secretions From high to middle lung volume moves proximal secretions Muscles of the chest wall and abdomen contract Sound is like a sigh, but forced Rate of expiratory flow varies with the following The individual The disease The degree of airflow obstruction Crackles heard if excess secretions are present

Mouth half or almost closed

Expiration always starting from high lung volume

Abdominal muscles not used

Sound more like hissing or blowing

Mouth shaped as for “E” sound

Incorrect quality of expiration

Too vigorous or long, producing paroxysmal coughing

Too gentle

Too short

“Catching” or “grunting” at the back of the throat

From Partridge C, Pryor J, Webber B: Characteristics of the forced expiration technique, Physiotherapy 75:193-194, 1989.

Advantages and Disadvantages of Active Cycle of Breathing

Incorporation of ACBT into a treatment of PD and percussion allows the patient to participate actively in secretion mobilization and offers the prospect of independently managing airway clearance. ACBT may be introduced at 3 or 4 years of age, with a child becoming independent in the technique at 8 to 10 years of age.

The technique may be adapted for patients with gastroesophageal reflux, bronchospasm, and an acute exacerbation of their pulmonary disease. A decrease in oxygen saturation caused by chest percussion may be avoided by using ACBT.⁷⁵ When the technique is performed independently, the cost of using ACBT for the long term is minimal.

In young children or extremely ill adults, it may be necessary for a caregiver to assist the patient with this technique. An assistant will also be required for the patient in whom percussion or shaking during the thoracic expansion phase increases the effectiveness of the treatment.

Autogenic Drainage

In Belgium in 1976, Chevaillier introduced autogenic drainage (AD), or self-drainage, for the treatment of asthmatic patients. He observed that during sleep, as well as while playing and laughing during the day, mucus was mobilized better than it was during PD and clapping. AD is an “antidyspnea” technique based on quiet expirations in a relaxed state and without use of postural drainage positions.⁹⁷

Schoni⁹⁸ eloquently explained the physiology of AD’s three phases, which use diaphragmatic breathing to mobilize secretions by varying expiratory airflow (Figure 21-6). The first phase starts with a normal inspiration and is followed by a breath hold to ensure equal filling of lung segments by collateral filling; then a deep exhalation is made into the expiratory reserve volume range. By lowering the middle tidal volume below the functional residual capacity level, secretions from peripheral lung regions are mobilized by the compression of peripheral alveolar ducts. Mid-expiratory tidal volume is lowered in the range of normal expiratory reserve volume. Chevaillier⁹⁷ named this phase the “unsticking” phase. The second phase of AD consists of tidal volume breathing gradually changing from the expiratory reserve volume into the inspiratory reserve volume range, which mobilizes secretions from the apical parts of the lungs. The velocity of the airflow must be adjusted at each level of inspiration so that the maximal expiratory airflow is reached without being high enough to cause collapse of the airways. Flow volume curves show that higher flows of longer duration can be achieved with AD,⁹⁹ demonstrating that mucus can be moved farther and at a faster rate. This is the “collecting” phase⁹⁷ The third phase consists of deeper inspiration into the inspiratory reserve volume, with huffing often used to help in evacuating the mobilized secretions. Control of airflow during this final phase is essential to the avoidance of uncontrolled, unproductive coughing. Chevaillier⁹⁷ named this phase the “evacuating” phase.

The Belgian method of AD has been modified by German practitioners using a combination of diaphragmatic and costosternal breathing in a treatment that is not separated into phases.¹⁰⁰ This modification resulted from the observation that many patients had difficulty breathing in the expiratory reserve volume range. The patient varies his or her mid-tidal volume in a passive exhalation followed by an active exhalation through pursed lips or through the nose. The German method of airway clearance includes other maneuvers in conjunction with AD, including inhalation therapy, FET, chest wall exercises, and physical activity.

Assisted AD has been described for use in treating infants and patients who are unable to participate.⁵⁰ Gentle manual pressure is applied to the chest during inspiration in an effort to vary the volume of breath inhaled; no pressure is applied during exhalation. This technique is often applied while gently bouncing the infant on a therapy ball.

AD has been compared with positive expiratory pressure and PD with percussion and/or vibration. It was reported that more sputum was produced with AD in patients with hyperreactive airways.¹⁰¹ In a 2-year crossover trial, AD was found to be as effective as conventional CPT among patients with cystic fibrosis for improving pulmonary function.¹⁰² However, patients exhibited a strong preference for AD over CPT, increasing the likelihood of adherence. Miller¹⁰³ showed greater clearance of inhaled radioisotopes with AD than with ACBT, with no significant differences in sputum weight, spirometry, or transcutaneous oxygen saturation. Giles¹⁰⁴ also studied oxygen saturation in AD and found greater levels with AD than with PD with percussion; there was also greater sputum evacuated with AD.

Preparation for Autogenic Drainage

 No equipment is needed for a patient to perform the technique of AD. The patient must possess good proprioceptive, tactile, and auditory perception of the mucus moving—this feedback makes it possible to adjust the technique of AD.

 To teach this method to a patient, a caregiver needs keen tactile and auditory senses to coach a patient to move between the phases by listening to and palpating the chest to identify the location and the quality of the secretions.

 The patient should be seated upright in a chair with a back for support. The surroundings should be devoid of distractions, allowing the patient to concentrate on the breathing technique.

 The upper airways (nose and throat) should be cleared of secretions by huffing or blowing the nose.

 The caregiver should be seated to the side and slightly behind the patient, close enough to hear the patient’s breathing. One hand should be placed to feel the work of the abdominal muscles and the other hand placed on the upper chest (Figure 21-7).

Treatment with Autogenic Drainage

 In all phases, inhalation should be done slowly, through the nose if possible, using the diaphragm or lower chest. A 2- to 3-second breath hold should follow, allowing collateral ventilation to get air behind the secretions.

 Exhalation should occur actively with the mouth and glottis open, listening for the movement of mucus while avoiding a wheeze. The vibrations of the mucus may also be felt with the hand placed on the upper chest. The frequency of these vibrations reveals their location. High frequencies mean that the secretions are located in the small airways; low frequencies mean that the secretions have moved to the large airways.⁹⁷

 In practice, inspiration is followed by a deep expiration into the expiratory reserve volume. The patient attempts to exhale as far into the expiratory reserve volume as possible, contracting the abdominal muscles to achieve this. This low lung volume breathing continues until the mucus is loosened and starts to move into the larger airways.

 The second phase collects the mucus in the middle airways by increasing the lung volume to a greater level than in the initial phase. Tidal volume breathing is then changed gradually from expiratory reserve volume toward the inspiratory reserve volume range⁹⁸ so that the lungs are expanded more with each inspiration. The patient increases both inspiration and expiration to move a greater volume of air. This low to middle lung volume breathing continues until the sound of the mucus decreases, signaling its movement into the central airways to be evacuated.

 In the evacuation phase, the patient increases inspiration into the inspiratory reserve volume range. This middle-to-high lung volume breathing continues until the secretions are in the trachea and are ready to be expectorated. The collected mucus can be evacuated by a stronger expiration or a high-volume huff. Nonproductive coughing should be avoided, since it may result in collapse of airways. See Figure 21-6 for a diagram of the three phases of AD.

 Compression of the airways should be avoided. If wheezing is heard, the expiratory flow rate must be decreased. Beginners may have to use pursed lips to avoid airway compression.⁹⁷ Instructing the patient to roll the tongue (if possible) may assist in controlling the expiratory flow rate.

 In the simplified German procedure, the patient begins by varying the mid-tidal volume without excessive effort. After a passive but rapid expiration, an actively performed expiration follows, achieving exhalation to a low expiratory reserve volume (Figure 21-8).

 The duration of each phase of AD depends on the location of the secretions. The duration of a session depends on the amount and viscosity of the secretions. An average treatment will be 30 to 45 minutes in length. However, a patient who is experienced in performing AD will clear secretions in a shorter amount of time than a beginner.

Positive Expiratory Pressure

The development and use of positive expiratory pressure (PEP) breathing came about in the 1980s in Denmark and is now widely used in the United States. Although high- or low-pressure PEP is prescribed worldwide, only low-pressure PEP is approved in the United States. Several devices deliver PEP in either oscillatory or smooth flow methods. Oscillatory PEP provides (1) positive expiratory pressure, (2) oscillation of the airways and (3) accelerated expiratory flow rates to loosen secretions and move them centrally.

Positive expiratory pressure includes a one-way breathing valve and an adjustable level of expiratory resistance that creates a back pressure to stent the airways open during exhalation. It is theorized that PEP breathing reinflates collapsed alveoli by allowing air to be redistributed through collateral channels—the pores of Kohn and the Lambert canals—allowing pressure to build up distal to the obstruction and promoting the movement of secretions toward the larger airways.107,108 In addition, supplemental oxygen and nebulized medication can be effectively delivered during treatment with PEP.¹⁰⁹ A manometer in the circuit determines and monitors the pressure generated by the patient. In low-pressure PEP breathing, the resistance is regulated to achieve 10 to 20 cm of H₂O during slightly active expiration. The appropriate resistor is one that produces a flow volume curve demonstrating a maximal forced vital capacity, good plateau, and no curvilinearity.⁸⁸ Low-pressure PEP breathing is used more often than high-pressure PEP, as it offers equal effectiveness at a lower presumed risk for pneumothorax.

High-pressure PEP uses the same principles but at much higher levels of pressure (50 to 120 cm H₂O). Inspiration is performed to total lung capacity; this is followed by a forced expiratory maneuver against the PEP mask, which is connected to a spirometer. For high-pressure PEP therapy, the Pep/Rmt (Astra Tech Healthcare, Molndal, Sweden) mask is used. The equipment consists of a ventilation mask, a one-way valve, and various resistors. Spirometry is used to determine the appropriate resistance for each individual patient, but generally, a -mm resistor is used for infants, a resistor of up to to 3 mm for older children and adults, and mm for adults with COPD.

Airway stability is maintained with PEP breathing, which results in improved ventilation and gas exchange as well as airway clearance.¹¹⁰ PEP breathing has been shown to benefit patients at risk for postoperative atelectasis but has gained wider practice in the area of airway clearance, especially in patients with cystic fibrosis.⁹⁵ Numerous studies have demonstrated the effectiveness of PEP breathing. Tyrrell¹¹¹ has shown the PEP mask to be as effective as conventional physiotherapy over a 1-month period, with no difference in pulmonary function. Falk^112,113 demonstrated increased sputum production and clearance with the use of PEP over FET alone. However, Hofmeyer¹¹⁴ found FET produced a greater quantity of sputum without the addition of PEP. Oberwaldner¹¹⁵ evaluated lung function during 10 months of regular treatments with high-pressure PEP and found reduced pulmonary hyperinflation and airway instability and higher flow rates with PEP than with conventional CPT. These improvements in lung function deteriorated only 2 months after a return to conventional CPT. A study by Pfleger and colleagues¹⁰⁵ compared PEP with AD and found that PEP cleared higher amounts of sputum and demonstrated increased lung function. Finally, decreased duration of hospitalization has been cited as a benefit of using PEP breathing for airway clearance.¹¹⁶

Two of the most commonly used devices in the United States are the Acapella (Figure 21-9, A and B) and TheraPEP (DHD Healthcare, Wampsville, New York) (Figure 21-9, C). The TheraPEP device consists of a mouthpiece and an expiratory resistor that can accommodate many levels of expiratory flow. It comes with a detachable pressure monitoring port and indicator to show 10 to 20 cm of H₂O. The TheraPEP can accommodate a mask of different sizes. The Acapella has performance characteristics similar to those of the Flutter.¹¹⁷ It comes in several models: green for patients who can maintain an expiratory flow of 15 L/min or more, blue for patients whose expiratory flow rate is less than 15 L/min, and the Acapella Choice. The Acapella Choice disassembles more easily than the original models for ease of cleaning (Figure 21-9, D). The Acapella consists of a mouthpiece attached to the body of the unit that uses a counterweighted plug and magnet to create airflow oscillation and a dial for expiratory resistance at the other end.

A device developed in Switzerland to deliver high-frequency oscillation PEP breathing and decrease the collapsibility of the airways is the Flutter VRP1 (VarioRaw, Aubonne, Switzerland). Axcan Pharma (Birmingham, Alabama) markets the Flutter VRP1 valve in the United States, the first oscillatory PEP device available in this country. This pipelike device consists of a steel ball, a plastic cone, a perforated cover, and a mouthpiece. Exhaled air causes the steel ball to roll up and down the cone causing airflow vibration. The PEP maintained by the Flutter (5 to 35 cm of H₂O) prevents dynamic airway compression and improves airflow acceleration.¹¹⁸ The full effects of the vibration induced by the Flutter (6 to 20 Hz) may be received by changing the angle of the device. Movement of the Flutter upward increases the pressure and frequency while movement of the device downward results in lower pressure and frequency.¹¹⁸ The vibration of the chest can be palpated to provide feedback as to the optimal angle of the device. The recommended procedure for use of the Flutter is shown in Box 21-5.

This early form of oscillatory PEP has been well studied. Konstan and colleagues¹¹⁹ compared the amount of sputum expectorated with the Flutter with that expectorated with vigorous voluntary cough, with PD, with percussion, and with vibration. Subjects with cystic fibrosis produced more than three times the amount of sputum when using the Flutter than when using the other two methods, and no adverse effects were reported. The improvement in expectoration is based on the increase in airway diameter and the improvement in airflow acceleration.¹²⁰ Ambrosino¹²¹ reported success in the treatment of patients with chronic obstructive pulmonary disease by using the device. When compared with AD, the Flutter was found to produce equal amounts of expectorated mucus.¹²² The advantages of the Flutter device lie in its portability and the ease with which its use can be learned. Increased independence and better compliance have also been cited as advantages of this technique. However, frequent assessment of patient technique and appropriate level of resistance is recommended.⁸⁷

Another device that provides PEP with oscillations is the Quake (Thayer Medical, Tucson, Arizona), which consists of a mouthpiece integrated into the outer housing and a crank that interrupts airflow and allows the user to manually adjust the frequency of the vibration. This allows a wider range of oscillation frequencies than other devices, such as the Flutter. When using the Quake, it is recommended to rotate the handle at a steady and comfortable rate of about 1 to 2 rotations per second during exhalation. At the end of exhalation, the user may either remove the Quake from the mouth to inhale or continue to rotate the handle and slowly begin to breathe in deeply, then repeat the exhalation cycle. Both the inhalation and exhalation rate and the speed of the handle rotation may be varied to produce the ideal level of vibration in the lungs. This device can be used with a mouthpiece or a facemask, whereas the Flutter can only be used with a mouthpiece. The disadvantage of the Quake is that it requires both hands—one to hold the device and one to turn the crank. The other devices can be used with only one hand.

Treatment with Positive Expiratory Pressure

 To determine the correct level of resistance for PEP, the patient inhales using tidal volume and exhales actively into the mask or mouthpiece. The resistor valve is adjusted while the level of PEP is monitored on the manometer. The resistance is gradually decreased until the PEP level supplying 10 to 20 cm of water pressure has been identified.¹¹³ Mahlmeister⁹⁵ reports most patients achieve this pressure range with flow resistors of 2.5 to 4.0 mm in diameter. Selection of the proper resistor produces the desired inspiratory to expiratory ratio of 1 : 3 or 1 : 4.⁹⁵ The use of too great a resistance will create an increased respiratory rate or too low a pressure, whereas too small a resistor will create a slow respiratory rate or too high a pressure.¹²⁵

 For high-pressure PEP, appropriate resistance is determined by connecting the outlet of the PEP mask to a spirometer. The resistor producing the highest forced vital capacity through the PEP mask is selected for continued use.¹¹⁵ The patient breathes in and out through the mask at tidal volume for 6 to 10 breaths; then inspiration is done to total lung capacity and a forced expiratory maneuver is performed against the PEP mask. This is repeated until all the mucus is mobilized.¹²⁵

 For a PEP therapy treatment, the patient should be seated upright with elbows resting on a table. Use of a mask may require securing the device with both hands for a tight seal. If needed, the patient may be in a reclining position for all PEP devices except the Flutter, which is position dependent. To use the Flutter valve, the patient should be seated upright (Figure 21-10).

 The patient should be instructed to breathe into the mask or mouthpiece to tidal volume, using the lower chest and abdomen, and pause for an inspiratory hold for 2 to 3 seconds to equalize ventilation before exhaling.¹²³ Exhalation into the mask or mouthpiece should be slightly active but not forced. The patient continues breathing into the mask or mouthpiece for 10 to 15 breaths, using a normal respiratory rate. After a series of 10 to 15 breaths, the mask or mouthpiece is removed from the face and the patient performs a series of huffs and/or coughing to expectorate any mucus that has been mobilized.¹²⁶ It may be necessary to pause every 5 to 10 exhalations before resuming the session.¹¹⁸

 The series of PEP breaths followed by huffs should be repeated about four to six times. The total treatment lasts about 15 to 20 minutes and should be performed twice during the day or as needed. The frequency and duration of the treatment must be individualized for each patient. During periods of pulmonary exacerbation, patients are encouraged to increase the frequency of PEP treatments rather than extend the length of individual sessions.⁹⁵ Some patients have a tendency to hyperventilate and become dizzy; an inspiratory pause will prevent this.¹²³

 Initially, the patient and caregiver monitor the effort by means of the manometer, ensuring that a pressure of 10 to 20 cm of H₂O is achieved throughout exhalation (this is not possible with the Flutter). After the technique is mastered with the appropriate resistor, the manometer may be removed from the system. The appropriate resistance should be rechecked periodically during clinical visits or periods of hospitalization.

 For Bubble PEP, the patient is instructed to blow through the tube with enough force to cause the bubbles to rise up to the top of the container. After a number of breaths, the patient is asked to do huffing or coughing before resuming the treatment. The therapist may prescribe the height of the column of water to alter the pressure, the number of breaths taken, and the huffs or coughs needed to tailor the treatment to each patient.¹²³

High-Frequency Chest Wall Oscillation

Efforts aimed at mucus clearance by creating a differential airflow rate led to the development of a high-frequency chest wall oscillation (HFCWO) system. Hansen and Warwick¹²⁸ designed a large-volume, variable-frequency air-pulse delivery system that can be used by patients with obstructive lung disease to promote mucus clearance.

High-frequency chest wall oscillation, also referred to as high-frequency chest compression, consists of an inflatable vest linked to an air-pulse generator. Although the sensation of the device is somewhat akin to mechanical percussion, it differs significantly in its mechanism of action. HFCWO works by differential airflow (i.e., the expiratory flow rate is higher than the inspiratory flow rate), allowing the mucus to be transported from the periphery to the central airways for expectoration (Figure 21-11). HFCWO has also been shown to decrease the viscosity of mucus, making it easier to mobilize.

The first HFCWO system developed was the Vest (Hill ROM, St. Paul, Minnesota), consisting of an inflatable fitted vest connected to an air-pulse generator by flexible tubing. This device provides oscillation of the entire thoracic cavity at varying frequencies (5 to 25 Hz). The lung volume expired tends to increase with lower frequencies (less than 10 to 12 Hz), whereas the flow rates tend to increase with higher frequencies (12 to 20 Hz). Continuous aerosolized medication or saline administered concurrently may assist with secretion mobilization.¹²⁹ The original, larger unit of the Vest is best used in a clinical setting; it can be placed on a wheeled stand for easy mobility. Newer models weigh as little as 17 pounds, providing more mobility than earlier models; these units fit under an airplane seat and are easier to manage during travel.

Two probable mechanisms of action have been offered to explain the significant increase in sputum mobilization that occurs with HFCWO.¹³⁰ One mechanism proposes that oscillatory airflow leads to changes in the consistency of mucus, which results in increased mobilization of secretions. Considerable decreases in mucus viscoelasticity were observed during administration of oscillatory airflow.¹³¹ Another mechanism proposes that the difference between the expiratory and inspiratory velocities produces shear forces strong enough to move mucus. Chang and colleagues¹³² demonstrated that nonsymmetrical airflow (peak expiratory flow rates greater than inspiratory flow rates) could be an important factor leading to increases in mucus clearance during the administration of HFCWO. The chest compressions produce a transient flow pulse similar to that observed during coughing, and by using the flows with the greatest rates and volumes, sufficient force is obtained to move mucus in the airway.¹³³

HFCWO has been shown to increase mucus clearance rates in animal models, with the most pronounced effect in the 11 to 15 Hz frequency range.¹³⁴ Radford and colleagues⁶⁸ used bronchoscopy to demonstrate a marked increase in the speed and flow of mucus produced by oscillations at even higher frequencies than those attainable by manual percussion. Results of short-term use of the Vest have been mixed, but they show HFCWO to be at least as effective as conventional CPT. Robinson¹³⁵ showed no significant improvement or deterioration of lung function with its use. In additional studies, Kluft and Faverio^136,137 demonstrated increased wet and dry sputum weights using HFCWO as opposed to manual CPT, and Arens (1993)¹³⁸ showed similar dry sputum weight but an increase in wet sputum weight and a significant improvement in pulmonary function with HFCWO as opposed to conventional CPT. One 2-year study showed improved lung function and greater sputum production in subjects with cystic fibrosis with the use of HFCWO rather than manual CPT.¹³³ No adverse effects were observed with long-term use of the Vest. Hospitalized patients with acute exacerbation of lung disease have been shown to tolerate HFCWO well,¹³⁹ and the safety and tolerance of this method have been demonstrated in long-term mechanically ventilated patients.¹⁴⁰

The fit of the vest requires attention because nausea, abdominal and chest wall discomfort, and complaints of urinary urgency may occur with an ill-fitting vest.¹⁰⁶ HFCWO systems are much more costly than other mechanical aids for airway clearance; thus expense may be a deterrent for some potential users. However, in a study of HFCWO users insured by Blue Cross and Blue Shield, a 49% reduction in health care costs was shown in the year following initial use of the vest as compared with the year before HFCWO use.¹⁴¹ The impact of the use of the HFCWO device in a hospital department demonstrated a substantial savings resulting from therapy self-administration by patients.¹⁴²

Intrapulmonary Percussive Ventilation

Intrapulmonary percussive ventilation (IPV) is an airway clearance method that simultaneously delivers intrathoracic percussion and aerosolized solution for bronchodilation.¹⁴³ An apparatus known as the Phasitron is the functional component in the intrapulmonary percussive ventilator. The Phasitron provides high-frequency impulses during inspiration, while positive expiratory pressure is maintained throughout passive exhalation. The pressure generated is between 10 and 30 cm of H₂O.

The intrapulmonary percussive ventilation device made by Percussionaire (Sandpoint, Idaho) works in a manner similar to that of the HFCWO except that a pneumatic device delivers the oscillation internally instead of externally. A mouthpiece delivers high flow rate mini-bursts of gases into the lungs at rates of 100 to 240 cycles per minute. Continuous pressure in the airways is maintained while pulsatile, percussive intraairway pressure rises and dilates the airways, enhancing intrabronchial secretion mobilization. This device provides percussion at 6 to 14 Hz, with a positive expiratory pressure of 10 to 20 cm of water pressure and simultaneous delivery of an aerosol. The aerosol mist within the lungs reduces adhesive forces of retained secretions.

It is theorized that changes in the frequency and pressure of the airflow delivered through the IPV device assist in stabilizing the airways and decrease the viscosity of the secretions; this results in increased sputum mobilization.¹⁰⁶ IPV has been found to be as effective as postural drainage and percussion in improving pulmonary function and sputum expectoration.¹⁴⁴ Marks¹⁴⁵ found no difference between IPV and Flutter in number of hospital or antibiotic days required to treat an exacerbation and reported good acceptance of this method of airway clearance by patients. IPV may be beneficial for patients with asthma and neuromuscular disease, as well as those with cystic fibrosis.^146,147

Acoustic Airway Clearance

A recent form of airway clearance uses acoustic vibrations to clear secretions from the lungs. The Frequencer (Dymedso Inc., Boisbriand, Quebec) is a device that provides mechanical vibration in addition to acoustic oscillation to mobilize secretions through a variety of tissue depths. The sound level (56-78 dB) generated at maximal power is below the level that would cause hearing damage.¹⁴⁹ Normal human hearing is limited to frequencies of 20 to 20,000 Hz, and the Frequencer operates between 20 and 65 Hz. The device adjusts to the resonant frequency of the airways of the lungs and is able to target small portions of the lungs as opposed to affecting the entire lung fields at once. It is similar to HFCWO in that the vibrations thin the viscosity of the pulmonary secretions. However, unlike HFCWO, which has an upper frequency of 25 Hz, the frequency of oscillation provided by the Frequencer is substantially higher at 20 to 65 Hz.

In a pilot study comparing the Frequencer with traditional postural drainage and percussion, the amount of sputum produced by the Frequencer was the same as or more than PD and patients reported less discomfort.¹⁴⁹ Another small study by Vallejos¹⁵⁰ described the use of the Frequencer in a clinical environment; treatment with the device produced sputum 75% of the time, and patients showed a preference for ACT by this method.

Factors Affecting Selection of Airway Clearance Techniques

The process of prescribing an appropriate technique for secretion mobilization should be ongoing, with periodic reevaluation of the method and its effects on the patient. Mobilization and exercise are exploited to the maximal degree to mobilize secretions as indicated, and its effects may need to be augmented with manual or mechanical airway clearance techniques. Clinical judgment is needed to establish whether mobilization or exercise is sufficient or whether additional airway clearance support is needed. If it is determined that additional airway clearance techniques are warranted, clinical judgment must also be used to decide which specific techniques are indicated.

Among patients with pulmonary disorders, poor adherence to the performance of airway clearance on a regular basis has been well documented.4,151–153 Litt¹⁵¹ has shown that the complexity and increased duration of a prescribed treatment has a negative influence on patient adherence. It has been suggested that better adherence may be achieved if the treatment is specifically tailored to the individual patient’s needs with regard to clinical status, family functioning, and family concerns (Box 21-6). Negotiation between the patient and the caregiver is also effective; patients are more likely to adhere to a prescribed treatment regimen to which they have agreed in collaboration with their caregiver.¹⁵⁴ The regular use of a particular ACT by a patient is governed by personal belief in the effectiveness of the method for his or her own disease process, the manner in which the method affects the family’s life habits, and the patient’s willingness to use the technique on a daily basis. Adherence is ultimately the best index of an ACT’s effectiveness. For this reason, it is incumbent upon caregivers to consider the many factors that may alter a patient’s adherence to a particular method when recommending a specific technique, especially in a patient with a chronic disease. These factors include the availability of the caregiver to teach the technique and the willingness of the patient to learn it; the patient’s concurrent medical problems; the effectiveness of the technique (subjective and objective); support for the technique from family, friends, and health care personnel; age and lifestyle of the patient; and the cost of the treatment.¹⁰⁶ Table 21-1 summarizes factors that can influence the choice of an airway clearance technique.

Summary

Numerous ACTs have been shown to reduce obstruction, enhance mucociliary clearance, and improve ventilation, accomplishing the goal of improved oxygen transport. The effectiveness of various techniques has been demonstrated in multiple studies and evaluated with numerous outcome measures. In some cases, routine application of ACTs has not been shown to be effective in achieving improved oxygen transport. Acute asthma, bronchitis, pneumonia without copious secretions, bronchiolitis, and routine postoperative conditions were not shown to benefit from PD, percussion, and vibration.18,21 ACTs are not without side effects or complications; routine use of these methods is not recommended without clear indications. Indications for ACTs have been established for acute illness and for chronic conditions. In acute illness, traditional methods (i.e., PD, percussion, and vibration) have been shown to be beneficial in patients with copious secretions and in the treatment of atelectasis.¹⁵⁵ For patients with cystic fibrosis, treatment with PEP and exercise in conjunction with PD, percussion, and vibration were also shown to be effective in an acute exacerbation.¹⁵⁶ In chronic disease states, patients with cystic fibrosis and bronchiectasis have been found to benefit from PD, percussion, and vibration, as well as PEP, autogenic drainage, ACBT, acoustic airway clearance, IPV, and exercise.^{106,149,155,156}

The health care provider needs to consider many factors in recommending a technique of airway clearance for a patient. In addition to the availability of the technique and its effectiveness, these factors include consideration of several variables—physiological, psychological, and practical—that affect a patient’s response to treatment. Treatments aimed at secretion clearance require monitoring the response of a patient to treatment and periodic reevaluation of this response. Caregivers need to incorporate this information into the real life situations presented by patients and choose a technique or combination of techniques that best suits each patient’s needs. Acceptance of a specific treatment technique by the patient and family is paramount; adherence is the key to achieving effective treatment, especially in chronic lung conditions.

Health care providers are challenged to keep abreast of techniques and their modifications to best meet the patient’s needs. The role of the caregiver involves more than technical expertise. The caregiver is uniquely positioned to simplify medical language for patients and families and encourage adherence to airway clearance. Support of a treatment by a health care provider can increase the benefit derived from the treatment.

Further research in the area of airway clearance is needed to compare and standardize techniques, follow long-term outcomes, and establish optimal treatment guidelines. This information will assist caregivers in evaluating and recommending a given technique of airway clearance for a particular patient or clinical population.