Teresa A Volsko, MHHS, RRT, FAARC , MHHS, RRT, FAARC Vice President, Respiratory Services, Advanced Health Systems

Originally printed in:
» US Respiratory Care 2006 - December 2005

Reference Section B USINESS BRIEFING: US RESPIRATORY CARE 2006 1 a report by Teresa A Volsko, MHHS, RRT, FAARC Vice President, Respiratory Services, Advanced Health Systems Introduction In health, a host of mechanisms work harmoniously to maintain optimal function of the respiratory system.

The mucociliary escalator and cough reflex facilitate secretion clearance and prevent airway obstruction.

Many factors, including the aging process, tobacco use, environmental exposures and disease processes, interfere with secretion clearance by reducing the efficacy of ciliary structure and function. Progressive neurodegenerative conditions inhibit the normal cough reflex, while chronic obstructive pulmonary disorders such as cystic fibrosis and bronchiectasis alter the production and composition of mucus. Airway obstruction and structural damage result from recurring infection, inflammatory changes and secretion retention.

Technological and clinical advances offer practitioners a variety of expulsion and breathing techniques, manual therapy and medical devices to aid in secretion clearance.This review discusses the various techniques and devices that have demonstrated therapeutic effectiveness for secretion removal.

Review of the Literature The literature offers a plethora of information with regard to airway clearance therapeutic modalities (see Table 1).However,systematic reviews of airway clearance research suggest a number of methodological limitations exist. Small sample sizes, lack of reproducibility, sparse use of sham therapy and reports limited to short-term outcomes with respect to a single treatment session contribute to the lack of evidence to support the use of a particular device or breathing technique. In practice, clinicians must have integral knowledge of airway clearance techniques, the patient’s cognitive ability and disease processes, as well as therapeutic goals, in order to devise an effective plan of care.

Cough Assist Techniques and Devices Directed and huff coughing are simplistic techniques used to imitate the attributes of an effective, spon- taneous cough. Directed coughing, also known as quad coughing, involves the manual application external pressure to the epigastric region or thoracic rib cage during exhalation to expel secretions from the airway. It is seldom combined with other airway clearance modalities and is usually employed when mucociliary function is unencumbered and neuro- muscular disease is present.

Huff coughing consists of a series of forced expiratory maneuvers from mid to low lung volumes performed with an open glottis.The intent is to facilitate cephalad movement of sputum through the tracheobronchial tree while minimizing changes in pleural pressure and the probability of bronchial collapse. Unlike directed cough, this technique is rarely used alone. Rather, huff coughing is used as an adjunct to other airway clearance techniques to expel secretions in the final phases of therapy. Huff coughing is often used in place of a spontaneous cough in obstructive disease processes, such as cystic fibrosis, where coughing against a closed glottis results in lower airway collapse.

Mechanical devices can also be used to produce the cough. Mechanical cough assist machines, commonly known as mechanical insufflation–exsufflation (MIE) devices, mimic a cough by delivering a positive pressure breath followed by a rapid reversal of airway pressures.The inspiratory maneuver is delivered over a one-second period at pressures of 30–50cm H2O.

Evacuation of that breath immediately follows at pressures of -30 to -50cm H2O. This breath sequencing can be delivered non-invasively (by face mask) or by connection to a temporary or permanent artificial airway (endotracheal or tracheostomy tube).

Initial support for this device was gained in the early 1950s to assist cough generation in polio victims. In recent years, individuals diagnosed with progressive neuromuscular disease have benefited from a resurgence of this therapy to clear secretions and prevent pulmonary compromise.As an added benefit, side effects typically associated with airway clearance therapy in this population, such as bradycardia and hypoxemia, were reported to be minimized.

Conversely, the literature does not substantiate the use of this device with chronic pulmonary conditions in which mucociliary function is compromised.

Secretion Clearance—Principles and Practice Teresa A Volsko, MHHS, RRT, FAARC, is Vice President of Respiratory Services at Advanced Health Systems in Hudson, Ohio. She is a member of the Long Term Care Committee and former Chair of the Committee on Community Acquired Pneumonia of the American Association for Respiratory Care (AARC), member of the Board of Trustees and Vice Chair of the Clinical Simulation Committee and Subcommittee on Credentialing Research of the National Board for Respiratory Care, a reviewer and editorial board member of the Respiratory Care Journal and international editorial board member of Update in Respiratory Technology and Applied Technology. Ms Volsko was awarded the 1996 Glaxo-Wellcome Award for the best paper based on a open forum presentation and was made a Fellow of the AARC in 2001. She is guest editor of Respiratory Clinics of North America and author of several peer reviewed manuscripts and book chapters.

2 B USINESS BRIEFING: US RESPIRATORY CARE 2006 Reference Section Breathing Techniques Autogenic drainage and active cycle of breathing are modifications of the directed cough.The techniques are more complex and require an attentive, self-motivated and cooperative patient to properly execute the maneuvers. Sequential breaths performed at different lung volumes are used to unstick, collect and evacuate secretions from the airways. During autogenic breathing, a series of forced expiratory maneuvers are performed beginning with inspirations at less than a tidal volume. Each exhalation is forced, rather than passive, during this phase to loosen secretions. When instructing patients to perform this technique it is important to encourage the repetition of phase-one breathing until a crackling sensation is either heard or felt. Breathing at normal tidal to mid lung volumes follows to facilitate secretion collection and mobilization to the central airways. Patients may be instructed to imagine the secretions moving from the periphery to the central airways while performing this phase of the maneuver. Often the combination of visualization and breathing enhances performance of this phase, which continues as long as ‘rattling’ sounds are produced.This breathing technique concludes with breathing at high or increased inspired lung volumes and expiratory flows to move secretions into the upper airway (see Figure 1). Often, the expiratory flows generated during this portion of the maneuver are sufficient to produce expectoration without the need to generate a cough. However, huff coughing may be taught to aid in the evacuation of secretions as this technique concludes.The use of autogenic drainage is prevalent among the cystic fibrosis population. Positive patient outcomes are clearly dependent upon adherence to therapy and proper performance of the technique. The literature supports the use of this method of secretion clearance in terms of enhanced sputum production and a reduction in oxygen desaturation episodes.

Active cycle of breathing incorporates alternating repetitive cycles of controlled breathing and thoracic expansion exercises. Diaphragmatic breathing at normal tidal volumes is performed during the controlled breathing cycle. Relaxation of the accessory muscles is encouraged during this phase as a prophylaxis for bronchospasm. Secretions are loosened and the distribution of ventilation improved during thoracic expansion exercises. Manual percussion or vibration may be used as thoracic expansion exercises are performed.Traditionally, a forced expiratory technique follows each series of deep inspiration and passive, relaxed exhalation to aid in secretion mobilization and expectoration (see Figure 2). As with autogenic drainage, the efficacy of this breathing technique has demonstrated favorable results with respect to short- term outcomes. A greater volume of sputum is produced, and the frequency and severity of oxygen desaturations lessened, with the use of autogenic drainage compared with traditional chest physiotherapy in small study samples of patients diagnosed with cystic fibrosis. Patient effort and technique mastery are critical to successful secretion clearance with the aforemen- tioned breathing techniques. Therefore, it may be difficult to achieve optimal results when performed by very young children and/or individuals in the late stages of pulmonary disease.

Manual Therapy Chest physiotherapy was once thought of as the ‘gold standard’ of airway clearance techniques. This manual form of airway clearance requires patient cooperation and caregiver skill to execute its four components.

Rapid external clapping or percussion of the chest wall is performed to cause disturbances in the airways and shake or loosen secretions. Chest wall vibrations are applied during exhalation to enhance ciliary action and move the secretions into the central airways.As with the aforementioned breathing techniques, a forced expiratory technique is used as the final component to enhance secretion mobilization and aid in expectoration. Clapping and chest vibration are externally applied to the chest wall as the patient assumes a variety of positions to facilitate gravity-assisted Table 1: Comparison of Various Airway Clearance Techniques Therapeutic Modality Description Performance Characteristics Motivation Needed Cough Breathing Manual Oscillatory Caregiver Caregiver Self- High N/A Low assist technique therapy device administered assisted administered Directed cough X X X X Forced expiratory technique (FEF) X X X X Mechanical insufflation–exsufflation (MIE) X X X Autogenic drainage X X X Active cycle of breathing X X X Chest physiotherapy X X X X External high frequency chest wall compression X X X Oscillatory positive expiratory pressure X X X Secretion Clearance—Principles and Practice B USINESS BRIEFING: US RESPIRATORY CARE 2006 3 drainage of airway secretions into the central airways.

Since this airway clearance maneuver is predominately caregiver dependent, use is preferred with infants and small children and those with severe lung disease.This therapeutic modality takes approximately 40 to 60 minutes to perform and may be costly in terms of acute or long-term staff salaries dedicated to performing the procedure.The length of time clapping and vibration are performed is directly proportional to the patient’s ability to assume and tolerate the various postural drainage positions. Treatment modification of ‘head-down’ positions may be also necessary to avoid exacerbation of gastroesophageal reflux.

High-frequency Oscillatory Devices Devices producing high-frequency oscillations aid in secretion clearance by physically moving mucus through the airways. Rapid vibrations applied externally to the chest wall or directly to the airway shear mucus from the airway walls, reduce secretion viscosity and physically propel retained secretions cephalad.

A variable air-pulse delivery system and an inflatable vest are used to deliver chest wall compression and high-frequency vibrations to the chest wall. The inflatable vest is comprised of non-stretch material that fits snugly over the patient’s entire torso. Proper fit will allow the vest to extend from the shoulders to the iliac crest.A set of hoses is used to connect the vest to an air- pulse generator that injects and withdraws small volumes of air into the vest at rapid rates.This action is used to create pulses or oscillations against the thorax that are delivered at three different levels in order to loosen, collect and remove airway secretions. Each level is performed for five to 10 minutes, commencing with low frequencies of 5–10Hz, to shear mucus from the airway walls. Medium frequencies (10–15Hz) are used to promote the downstream movement of secretions into the central airways. Expectoration is facilitated by chest wall oscillations delivered at rapid frequencies or rates of 15–25Hz.

Comparable results are noted with respect to the volume of secretions cleared from the airways when high-frequency chest wall oscillation was compared with breathing techniques and chest physiotherapy.

This form of therapy is self-administered and requires minimal patient effort to perform. In addition to the positive clinical outcomes, the literature reports enhanced patient satisfaction and adherence with the use of this therapy.

Currently, two devices are commercially available that produce and apply high-frequency oscillations and positive pressure to the airway during exhalation.The Flutter (Scandapharm, Birmingham,AL) contains a steel ball resting on an inner cone, housed within a pipe-like casing.Airflow oscillations are produced as slightly larger than tidal volume breaths and are passively exhaled through the device, which causes the steel ball to move or vibrate vertically within the casing. The angle at which the Flutter is held by the patient affects the amount of effort needed to move the ball vertically and ultimately controls the frequency and amplitude of the oscillations as well as the positive expiratory pressure.

The Acapella (Smiths Medical ADS,Weston, MA) uses a counterweighted plug attached to a lever and magnet to produce airflow oscillations. The lever vibrates and intermittently occludes the plug as exhaled gas steadily passes through the device. Rather than adjusting the position at which this device is held, frequency, amplitude and mean expiratory pressure are adjusted by a dial located at the distal end of the device.The dial adjusts the proximity of the magnet and counterweighted plug, making it easier or more difficult to move the lever and occlude the plug. Positive expiratory airway pressures (PEP) ranging from 3 to 24cm H2O are generated with these devices. PEP helps to keep the airways open as secretions are moved toward the central airways. Oscillatory PEP devices have been evaluated clinically with breathing techniques and conventional chest physiotherapy and found to have similar outcomes with respect to pulmonary function improvements, reductions in hospital length of stay, stabilization of arterial blood gas values and reduction in Figure 2: An Example of a Spirograph of Lung Volumes During the Breathing Sequence of Active Cycle of Breathing FET VT TEE BC Figure 1: Example of a Spirograph of Lung Volume During the Three Phases of Autogenic Drainage 1 23 IC FRV VT Phase one commences with a full inspiratory capacity (IC) maneuver. Breathing at low lung volumes follows in order to ‘unstick’ mucus. Breathing slightly above tidal to mid lung volumes transpires in the second phase, which allows for the collection of loosened mucus. Phase three involves breathing at high lung volumes to help evacuate airway secretions, and is followed by a forced expiratory technique.

Breathing control (BC) is performed at tidal volume.A series of deep inspirations is performed during thoracic expansion exercises (TEE).A forced expiratory technique (FET) mobilizes the secretions to the central airways.

subjective symptom scores. Laboratory investigations reveal the Acapella produced effective oscillations at very low flows (5 liters/min), facilitating the use of this type of therapy with a broader spectrum of patients. Patients with low expiratory flow rates due to severe airflow obstruction or age may now be included among those who are able to perform and perhaps benefit from this form of airway clearance therapy.

Summary Although there is insufficient evidence to support the use of any single airway clearance modality or technique, the clinical need to achieve and maintain bronchial hygiene remains. In order to achieve optimal patient outcomes, it is essential for clinicians to prescribe a plan of care that matches therapeutic goals to clinical need. Patient and process factors should be taken into consideration before a particular technique or combination of techniques is selected. Knowledge of the patient’s age, cognition, ability to properly perform the therapy, level of motivation and degree of pulmonary impairment may help practitioners select the appropriate airway clearance modality. Professional staff and/or care-giver support, as well as patient preference, plays a vital role in improving adherence to the prescribed regimen. In the development and implementation of an airway clearance care plan it is important to establish measurable goals along with a mechanism to monitor and evaluate patient and process outcomes. This enables clinicians to objectively evaluate the plan of care and make adjustments as needed to maximize patient benefit and optimize outcomes for the management of specific disease processes. a73 B USINESS BRIEFING: US RESPIRATORY CARE 2006 Reference Section 4