IN THE WORLD OF AIRWAYS CLEARANCE: PHYSIOLOGY, DEVICES, EVIDENCE AND THE FUTURE

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1 12 IN THE WORLD OF AIRWAYS CLEARANCE Correspondence H. Douglass Dept of Respiratory Medicine Bristol Royal Infirmary Bristol BS2 8HW UK E mail: [email protected] IN THE WORLD OF AIRWAYS CLEARANCE: PHYSIOLOGY, DEVICES, EVIDENCE AND THE FUTURE H. Douglass and J. Bond-Kendall A recent consensus statement describes airway clearance techniques as a cornerstone of management for adults with cystic fibrosis (CF). A large proportion of time as a respiratory physiotherapist is spent teaching, assessing, encouraging and physically administering various airway clearance techniques. Many people with lung disease will spend up to several hours a week clearing their chests. This review presents the issues of airway clearance from the perspective of a physiotherapist, and will be illustrated using respiratory symptoms encountered by CF patients, which can also be related to many other respiratory conditions. CF is the most commonly inherited, progressively debilitating disease among the Caucasian population. The defective gene causes abnormal ion and water transport, which leads to impaired mucociliary transport and chronic airway infections [1]. The patient s clinical course is defined by recurrent, increasingly severe bouts of pulmonary obstruction, inflammation and infection. Among such patients, respiratory infection and compromised pulmonary function are the leading causes of morbidity and mortality; airway clearance thus forms an integral part of their clinical management [1 3]. Clearance of secretions has been shown to relieve atelectasis, reduce coughing and prevent or slow the proteolytic destruction of the airways by discouraging bacterial colonisation. Unfortunately, airway clearance is generally the component of treatment least favoured by those with CF and the most likely to be neglected. It s a waste of time, because I get my phlegm up playing football. I think that exercise is better ; It is the worst thing about having CF ; I can t really be bothered to do it, unless I am really unwell and then I don t mind ; If I could get rid of one thing, that would be it! ; BORING : all these are quotes from patients with CF about airway clearance. Adherence studies appear to show that patients adhered 26 47% of the time to treatment [1], which in part may reflect social, technical, health and emotional or psychosocial reasons. Airway clearance can be seen as a laborious, dull, never-ending task that adds to the burden of care. It is often time-consuming, tiring and lengthy; those with very productive chests and/or problems clearing sputum could expect to undergo several airway clearance sessions in a day. Many find coughing causes a lot of social embarrassment: occasionally, unhelpful and judgemental comments are made such as Give up the cigarettes. Many are embarrassed and disgusted by the thick green sputum that they cough up. Some find the taste of the sputum and the coughing makes them feel nauseous. Clearing sputum is a constant reminder of their disease, highlighting a rather depressing prospect of a future with more sputum, coughing and, of course, more airway clearance. The responsibility of physiotherapists is to assess, teach and provide the individual with the most effective technique, while emphasising the importance and benefits of airway clearance. In reality, we will only achieve compliance with treatment if we take into account these many issues. The aim should be to aid sputum clearance with the least amount of disruption to the lives of patients and to remain open-minded to adapt and change treatments when appropriate. 162 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

2 We make the difference between and The Vest TM Airway Clearance System Helps mobilise pulmonary secretions through high-frequency chest wall oscillation (HFCWO) therapy. Provides safe, consistent, effective therapy. Easy to administer and comfortable for the patient. Helps reduce pulmonary complications and increase clinical stability 1. For further details please contact your local Hill-Rom representative. France +33 (0) United Kingdom +44 (0) Deutschland +49 (0)211/ Nederland +31 (0) Italia Suisse/Schweiz +41 (0)21/ (deutschsprachig) 021/ Österreich +43 (0)2243 / Ireland +353 (0) Iberia + 34 (0) Nordic Countries +46 (0) Export: contact your local Hill-Rom distributor or contact your Area manager via website or call Plioplys AV, Lewis S. Pulmonary vest therapy in pediatric long-term care. Abstract was presented at American Medical Directors Meeting, Atlanta, Georgia, USA, March 15-18, Hill-Rom reserves the right to make changes without notice in design, specifications and models. The only warranty Hill-Rom makes is the express written warranty extended on the sale or rental of its products. Manufactured by Hill-Rom Inc. and imported in Europe by Hill-Rom SAS. - Pluvigner - France 2006 Hill-Rom Services, Inc. - ALL RIGHTS RESERVED.

3 12 IN THE WORLD OF AIRWAYS CLEARANCE Physiological principles behind airway clearance To understand the principles behind airway clearance techniques, we need to review the body s own physiological process alongside changes due to pathology. The respiratory tract provides numerous defence mechanisms to prevent colonisation by bacteria and viruses present in ambient air. The entire respiratory system is lined with goblet cells that secrete mucus. The first line of defence is physical removal by mucus [2]. However, in the damaged lung there is often an over-production of mucus, which leads to an inflammatory response with a vast over-production of white blood cells. These cells release powerful enzymes directed at killing bacteria, but also cause damage to the lung itself, fuelling a continuing inflammatory process in the lungs, the result of which is destruction of lung tissue [3]. The body s response to bacterial infection and excessive mucus production is largely responsible for causing lung damage. The health of the lung is dependent on consistent clearance of these airway secretions [4, 5]. Normal airway clearance is accomplished by the mucociliary clearance system and cough. Bacteria and other airborne particles become trapped in the mucus layer and are swept upwards and outwards by cilia. Normal cilia beat in a coordinated, unidirectional fashion to mobilise mucus and clear particulate matter from the airways, with the final clearance achieved by a combination of coughing and swallowing. In healthy individuals, the rate of mucus secretion is carefully balanced with mucus clearance. The consistency of mucus is maintained such that it is thick enough to trap bacteria and other inhaled particles, but thin enough to be moved easily by the cilia. In diseases such as CF, damage to the cilia as well as the large quantities of sticky, thick mucus that overwhelm the mucociliary apparatus, cause inhibition of normal airway clearance. During times of infection, the sputum may become thicker and more abundant, and even more difficult to clear Cough assists in clearing the airways from the seventh to eighth generation upwards [6]. It is a normal reflex mechanism that commences with a brief rapid inspiration. Glottal closure is followed by a sharp rise in pleural and abdominal pressure resulting from expiratory muscle and diaphragmatic contraction [7 9]. During a forced expiration/cough, the driving pressure, which produces expiratory flow, is the sum of the elastic recoil pressure of the lungs and the pleural pressure. Throughout the expiratory phase of a cough or forced expiration, the crosssectional area of the airways narrows owing to the pressure surrounding it being greater than the pressure within it. Consequently, the velocity of air increases. The high velocity of airflow interacts with the bronchial secretions resulting in a twophase air-liquid flow, by which energy is transferred from the air to the liquid, thereby shearing the liquid secretions and finally producing expectoration of sputum [10]. When the shear force exceeds the surface tension in the mucus layer, the mucus will begin to move in the direction of the airflow [11]. At velocities of 1,000 2,500 cm s -1, the annular type of two-phase flow occurs, while at a velocity of >2500 cm.s -1, mist flow with aerosol formation occurs. Shearing and expectoration are affected by the viscosity, elasticity and surface tension of the bronchial secretions in a complex manner [12].The ability of the airway walls to collapse and increase air velocity are features that aid expectoration of sputum [13, 14]. This is exploited by some airway clearance techniques, such as the forced expiratory technique (FET) to aid sputum clearance, by enhancing dynamic compression of the airway and therefore increasing airflow velocity [15]. Another physiological factor of significance is the presence of the equal pressure point (EPP), and its ability to be manipulated to aid sputum clearance. The EPP is the point within the airway at which intrabronchial pressure is equal to the surrounding pleural pressure. Pressure is greater in the peripheral airways and reduces towards the central airways. In the segment of airway towards the alveoli from the EPP, the pressure is greater than pleural pressure, and therefore no dynamic airway pressure can take place. However, dynamic compression can take place in the segment of airway between the EPP and the mouth, because pleural pressure is greater than the pressure within the airway [16]. Alterations in lung volume and expiratory force can alter the site of the EPP; this principle is used to aid sputum clearance by moving the EPP towards the alveoli, giving greater clearance of peripheral secretions, in the autogenic drainage (AD) technique [17 19]. How lung disease disables the body s natural chest clearance mechanisms In a patient with CF, the elastic structure of the airways is lost [20, 21] and the presence of obstruction leads to a reduced driving pressure during expiration. When the pressure inside the airways reduces during expiration and coughing, there is dynamic compression and often complete collapse of the airways downstream (towards the mouth) of the EPP. This prevents sputum from being able to move freely, thus making clearance of peripheral secretions difficult and causing a major problem in effective chest clearance. Techniques used to reduce the incidence of airways collapse include the PEP mask, flutter, acapella and cornet. These 164 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

4 IN THE WORLD OF AIRWAYS CLEARANCE 12 PRODUCT LISTINGS THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 165

5 12 IN THE WORLD OF AIRWAYS CLEARANCE techniques use the principles of increasing positive pressure in the lungs during expiration to allow dynamic compression of the airways, but prevent complete closure. An effective airways clearance technique will prevent a closing volume within the airways, create a high airflow velocity and manipulate the EPP in the direction of the alveoli. The importance of cough as a means of airway clearance is evident from research. However, progressive lung damage can alter the effectiveness of the cough and reduce airway velocity throughout expiration. This is the result of weak and ineffective respiratory muscles [20] (as a result of altered biomechanics of the thorax and efficiency of the diaphragm and accessory muscles), as well as obstruction of the airways, owing to structural changes, bronchospasm and excess mucus. These effects result in much slower clearance of mucus than in normal subjects [21 29], with a rough correlation between the lung function and mucociliary clearance. Adjuncts such as the cough assist machine and intermittent positive pressure breathing aim to improve airflow velocity and cough efficiency. Vigorous coughing is often discouraged by physiotherapists, as it can cause a number of adverse effects i.e. abnormal cardiovascular responses, urinary incontinence, gastro-oesophageal reflux, rib fractures, bronchospasm, headaches, laryngeal trauma, airflow limitation and pneumothorax, to mention just a few. These effects are mainly due to the high intrathoracic pressures and expiratory velocities associated with vigorous coughing. Physiotherapy aims to discourage vigorous prolonged coughing, and to use techniques that encourage movement of secretions from the peripheral airways to a level at which the cough will clear easily, without prolonged and excessive effort. Airway clearance techniques Airway clearance devices A number of adjunctive techniques and devices have been used to assist those who are unable, for whatever reason, to clear pulmonary secretions effectively [30 31]. The range of techniques is summarised in table 1 and some of the devices are illustrated in figure 1. Any device used to clear secretions should meet the following criteria, based on sound physiology: 1. Increase absolute peak expiratory flow (PEF) to move secretions towards the oropharynx. Figure 1. Some of the available airway clearance devices. 166 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

6 IN THE WORLD OF AIRWAYS CLEARANCE 12 Table 1. Technique Advantages Disadvantages Technique Advantages Disadvantages High-frequency chest compression (HFCC) Vest Airway Clearance System Variable-frequency large volume air pulse delivery system attached to inflatable vest. Pressure pulses that fill the vest vibrate the chest wall. Pulse frequency ranges 0 20 Hz and pressure in the vest ranges kpa (28 39 mmhg). Technique-independent. Passive therapy: requires little physical effort or special skill from either independent users or caregivers. Allows simultaneous involvement in other static activities e.g. reading, computer games. Shows good outcomes compared with conventional chest physiotherapy for both secretion clearance and maintenance or improvement of lung function. Associated with diminution/resolution of atelectasis; treats all lobes of the lungs simultaneously. Self-administered by many users. Can be used in conjunction with other therapies, including nebulised medications. Associated with direct and indirect cost savings, good treatment adherence and quality-of-life gains. Requires equipment and electricity, is relatively expensive and lacks portability. Some people with advanced lung disease complain that it is harder to breathe during treatment. Others, particularly those with thoracic indwelling venous access devices, may find the vest uncomfortable. or Positive expiratory pressure (PEP) and oscillating PEP PEP mask Consists of a face mask and a one-way valve to which expiratory resistors can be attached. A manometer determining the correct PEP level can be inserted between the valve and the resistor. May be self-administered by some users. Requires no postural positioning. Portable. May be used during acute exacerbations. Relatively inexpensive, portable and well tolerated. Unsuitable for uncooperative individuals. Requires specific cognitive abilities and specific physical attributes: Ability to generate sufficient expiratory force. Compliance may be adversely affected by inability to tolerate face mask, physical effort and consequent fatigue and time requirements Theoretical risk that it may increase risk of pneumothorax and heamoptysis Use two-phase gas-liquid flow, both in closed and open airways. In the latter, mucus transport can be achieved by expiratory airflow during forced expiration, as well as tidal breathing. The PEF/peak inspiratory flow ratio needs to be >1.1 to achieve this [18, 32, 33] and the frequency of oscillation needs to be 3 17 Hz, the ideal being ~13 Hz [34]. 3. Decrease mucus visco-elasticity, and hence improve mucus transport [35]. 4. Elicit spontaneous coughs by mechanical stimulation of the airways to remove mucus from the trachea, inner and intermediate regions of the lungs [6, 36]. 5. Increase expectorated mucus volume [37]. 6. Move the EPP towards the alveoli. 7. Increase positive expiratory pressure in the airways, to maintain open airways during expiration, and allow movement of sputum [38]. 8. Increase tidal volumes to improve collateral ventilation and to get air behind the mucus [39]. 9. Dislodge mucus from the inside of airways. What all of these share is a dependence upon the mechanical properties of the lungs of the patient with respiratory disease, which may deteriorate with disease progression [19]. This might mean alternative approaches have to be adopted. As disease progresses, effectiveness of treatment needs to be constantly monitored, assessed and adapted to provide the most appropriate and effective technique for that time. Chest physiotherapy Chest physiotherapy (CPT) may include any combination of postural THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 167

7 12 IN THE WORLD OF AIRWAYS CLEARANCE OMRON Compressor Nebuliser Range Quick relief within reach The new CompAIR nebulisers are simple to operate resulting in better medication compliance. The combination of a powerful compressor with the unique V.V.T. (Virtual Valve Technology) leads to more medication that is atomised into fine particles. More particles effectively reach the lower respiratory tracts. The low particle size (MMAD approx. 3.0µm) even enhances the amount of drug that is delivered to the lungs. V.V.T. s unique design also means that there are fewer parts to lose, less parts to clean. The new compressor range comes as a family; the CompAIR as a basic desktop nebuliser, compact and easy to use, the CompAIR Pro for homecare and hospital use with a convenient storage area and the small portable CompAIR Elite, which comes in a soft carrying case. Just breathe European Respiratory Journal EDITORIAL Particulate matter, science and EU policy ORIGINALS Addition of sildenafil to bosentan monotherapy in pulmonary arterial hypertension ACE I/D but not AGT (-6)A/G polymorphism is a risk factor for mortality in ARDS Interleukin-1R antagonist gene and pre-natal smoke exposure are associated with childhood asthma Inflammatory changes, recovery and recurrence at COPD exacerbation Treatment failure in tuberculosis REVIEW Scientific rationale for using a single inhaler for asthma control SERIES Tools used to measure airway remodelling in research Available at Phone: drainage, chest percussion, clapping, shaking or vibrations [40 43]. For many years CPT was the accepted standard technique for airway clearance. However, in recent years, in most parts of the world, it has been replaced by more comfortable and independent techniques. CPT is typically performed in a drainage position with a cupped hand or a plastic cup, rhythmically clapped onto the chest. The technique is usually performed in a few positions, followed by the active cycle of breathing technique to maximise sputum clearance and effectiveness of treatment. Usually, assistance is needed to perform CPT, although in some of the positions patients can perform their own CPT. During CPT there has been some evidence that oxygen saturation may decrease, and therefore patients with severe lung disease should be monitored closely for signs of low oxygen [44]. CPT is especially useful to treat young children and babies too young for any other airway clearance technique. It is a passive technique and is often the favoured treatment for those who are very fatigued, especially during a pulmonary exacerbation. Postural drainage/gravity-assisted drainage This technique utilises the force of gravity in specific body positions to enhance mucociliary clearance, mobilising mucus from the peripheral airways to more central airways (see chapter 11) [45 47]. Active cycle of breathing The active cycle of breathing technique is a technique that combines breathing control, thoracic expansion and the FET [19, 22, 40]. Breathing control is normal tidal breathing, maximising activity of the diaphragm, and encouraging relaxation of the upper chest and shoulders. Thoracic expansion exercises involve deep breathing, focusing on active inspiration and good basal expansion of the lungs. Breath hold is often encouraged at end inspiration, to encourage uniform ventilation throughout the lungs via channels of collateral ventilation. The FET (sometimes referred to as huffing) is a forced exhalation [48]. Huffing can be performed at various lung volumes to target different parts of the lung. At low lung volumes the huff moves mucus primarily from the more peripheral airways, whereas at high lung volume, the huff clears the secretions from the larger more proximal airways. The huff is a forced but not violent manoeuvre and can be varied by length and force to optimise sputum clearance. This airway clearance technique does not require any assistance or equipment. 168 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

8 IN THE WORLD OF AIRWAYS CLEARANCE 12 Smiths Medical acapella POWERbreathe Medic by by Gaiam Gaiam The acapella is a ready-to-use small hand-held device that combines the resistive features of the positive expiratory pressure of a PEP valve and the vibratory features of a flutter valve to mobilize secretions in the airway. A resistive pressure device works by using a pressurized breath to splint open the airway. Vibratory devices work by using oscillating vibrations that travel into the lungs, shaking free mucus plugs that the patient can cough up. With a pressurized breath and a vibratory effect, the acapella enables additional air to enter into the airways, get behind secretions, improve cough effectiveness and help push secretions out. The acapella is a better alternative to chest percussion and postural drainage because it requires far less therapist time, and can be utilized in patients unable to tolerate CPT & PD. Acapella easily allows for simultaneous administration of bronchodilators by attaching a nebulizer. hone: +44 (0) POWERbreathe POWERbreathe Medic Inspiratory Muscle Trainer is a Medic Inspiratory Muscle Trainer is Drug-Free, Clinically Proven & NHS Approved Treatment* Drug-Free, Clinically Proven NHS Approved Treatment* IMT has been proven to have the following benefits: IMT has been proven to have the following benefits: COPD COPD Reduced Reduced primary primary care care consultations by by 23% 23% Improved quality of life by 21% Improved dyspnoea by 36% Asthma Reduced ß 2 agonists consumption by up to 79% NHS APPROVED FOR Heart Failure PRESCRIPTION Improved exercise tolerance by 19% IN THE UK Improved quality of life by 16% *NHS Drug Tariff listing Part IXA Appliances Inspiratory pressure threshold loading device. PIP Code: For information, facts Phone: & research for healthcare professionals, visit or call Gaiam Ltd. E & OE. 06/ STABILTUBE The B&B Medical Technologies STABILTUBE Endotracheal Tube Holder is the premier, long term stabilizing system for securing the endotracheal tube for adolescents through adults preventing accidental disconnects. The STABILTUBE is a prepackaged kit with a patented releasable Cable-Tie, stretchable Velcro neck-band, non-absorbent face piece and skin-prep. The pre-assembled holder allows for ease of application and securing the endotracheal tube in less than 10 seconds. The STABILTUBE s adjustable, stretchable Velcro neck band allows for changes to the neck band without reapplying the neck holder. The STABILTUBE is latex free and made of hypoallergenic materials for patient comfort and security. The STABILTUBE can be used with the B&B Universal Bite Block to maximize the security of the tube and minimize the effects of a patient biting on the tube. The B&B specialty airway management product line allows for ease of repositioning and oral care to reduce the incidence of VAP. TRACHGUARD 2671_ERS Advert.indd 1 19/6/07 16:53:55 The B&B Medical Technologies TRACHGUARD is is a combination anti-disconnect device and tracheostomy collar made to fit any tracheostomy tube. The TRACHGUARD was developed to protect the patient from possible inadvertent, accidental accidental ventilator disconnects from the ventilator/tracheostomy tracheostomy and prevent the disconnects health care practitioner and the health fromcare practitioner potential cross from contamination. potential cross contamination. The collar is made The of collar hypoallergenic, of hypo-allergenic, latex free material latexfor free patient material comfort and patient safety. comfort The is made and foam safety. collar The securely foam holds collarthe securely tracheostomy holds tube the tracheostomy in place with tube Velcro in fasteners place with to Velcro minimize fasteners movement to and minimize accidental movement and decannulation. accidental decannulation. The collar is adjustable The collar to is allow adjustable for a comfortable to allow a fit comfortable and change fit in and neck change size due in neck to change size due in patient to change condition. in patient condition. The anti-disconnect The anti-disconnect feature helps feature prevent helps periods prevent of periods apnea and of apnea potential and disconnect potential disconnect alarms. The alarms. B&B specialty The B&B airway specialty airway management product line allows for ease of repositioning and security to minimize inadvertent disconnects. Phone: Phone: THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 169

9 12 IN THE WORLD OF AIRWAYS CLEARANCE Autogenic drainage Autogenic drainage (AD) is about breathing at different lung volumes to create the highest possible airflow in different airway generations [23]. The patient breathes tidally below his or her normal functional residual capacity, causing mucus to be cleared from the more peripheral airways [49, 50]. Exhalation is mildly forced to move secretions from the airway walls. (There is a balance between making sure that airflow is rapid enough to move secretions, but not too much to allow airway collapse.) This cycle is repeated several times, gradually increasing inspiratory volume as sputum is moved further up into the larger airways. The aim is to move sputum to the larger airways, to allow easy expectoration without the need for forced coughing. AD can be modified and combined with aspects of the active cycle of breathing technique to find the optimal way to clear secretions. This technique needs no special equipment or assistance. Positive expiratory pressure Positive expiratory pressure (PEP) is an airway clearance technique developed to reduce airway collapse on expiration [51 54]. In more advanced airways disease, bronchiectasis leads to weakening of the airway walls, causing secretions to be trapped in the smaller airways during expiration. There are various modifications of PEP. Low-pressure PEP consists of a mouthpiece or facemask with an expiratory resister attached to it. A manometer can usually be added into the circuit to measure the expiratory pressure. The expiratory valves can be altered to find the optimal resistance to achieve and maintain an expiratory pressure of cmh 2 O without exertion. Techniques differ, but general advice is to cycle between tidal breaths using the PEP mask and forced expiratory technique, until Table 1. continued Advantages Disadvantages Advantages Disadvantages AeroPEP Valved holding chamber designed to combine aerosol therapy from a metered-dose inhaler with a fixed-orifice resister PEP therapy. Acapella; Acapella Choice; Acapella Duet Vibratory PEP device prevents airway collapse, enhances movement of secretions to larger airways and filling of collapsed alveoli. Vibration provides percussive effect disengaging mucus from airway walls, pulsation of mucus toward larger airways, reduces visco-elasticity of mucus. Acapella Choice and its successor, Acapella Duet, have nebulisation attachments enabling clinicians to deliver smallvolume nebuliser treatments and conveniently mobilise secretions at the same time. Both can be disassembled for cleaning in dishwasher, boiled or autoclaved. TheraPEP Six fixed-orifice options and built-in durable pressure indicator. Can accommodate virtually any patient s lung capacity and provides immediate, visual 360º feedback of prescribed pressure. May be used with a mask or mouthpiece. Allows inhalation and exhalation without removing from mouth. May be self-administered by some users. Requires no postural positioning. May be used by alert, cooperative children aged 4 years. Portable. May be used during acute exacerbations. Relatively inexpensive, portable and well tolerated. Unsuitable for uncooperative individuals. Requires specific cognitive abilities and specific physical attributes: Ability to manage mechanical components of the device. Ability to maintain mouth feel, pursed lips and taut cheeks. Ability to generate sufficient expiratory force. Compliance may be adversely affected by inability to tolerate tight-fitting face mask, physical effort and consequent fatigue and time requirements. Theoretical risk that it may increase risk of pneumothorax and heamoptysis. Pari PEP As for Thera PEP. [email protected] or [email protected] As for Thera PEP. Also can be inserted on PARI nebulisers; saves time with combined inhalation and physiotherapy. As for Thera PEP. 170 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

10 IN THE WORLD OF AIRWAYS CLEARANCE 12 Table 1. continued Advantages Disadvantages Advantages Flutter Valve Hand held oral high frequency oscillation device providing vibration and PEP. Provides approximately 10 cmh 2 0 of positive airway pressure while the ball flutters over airway bowl opening at approximately 15 Hz oscillations, depending on device position. Self-administered. Portable. May be used by some young children (aged 5 years). May be performed while seated. Low costs. May enhance treatment adherence among suitable users. Technique-dependent. Unsuitable for children <5 yrs. Requires adequate cognitive function: Ability and motivation to concentrate. Ability to master breathing techniques. Requires specific physical attributes: Ability to inhale and exhale adequately. Good motor control. Adequate bulbar and facial muscle function. No incompatible facial deformities. Adverse effects may include discomfort, fatigue and shortness of breath, possibly reducing compliance. Theoretical risk of increasing risk of pneumothorax and haemoptysis. RC Cornet Curved tube that contains within its plastic casing a flexible inner tube. During expiration through the device there is a slight positive expiratory pressure and oscillation of the air within the airways. Self-administered. May be used by some young children (aged 5 years). May be performed while seated. Direct costs low. May enhance treatment adherence among suitable users. Portable. sputum is high enough to be easily expectorated [53, 55 57]. High-pressure PEP is similar to lowpressure PEP, but creates a higher expiratory pressure ( cmh 2 O) [58]. This is achieved by performing a forced expiration against the resistor. As with low-pressure PEP, the resistor can be adjusted to produce the greatest airway distension, therefore preventing airway closure on expiration. Oscillating PEP is most commonly performed through either a flutter, cornet or acapella device, although there are other similar devices on the market. All work by causing a vibratory obstruction to airflow, creating both airflow and pressure oscillation during expiration. The oscillation frequency can be altered in all devices and in all devices the patients expiratory effort determines the pressure achieved. Techniques differ, but general advice is to incorporate elements of the active cycle of breathing technique such as the FET and breathing control, along with several cycles of breaths through the PEP device [59 65]. Bubble PEP. Positive expiratory pressure can by achieved by blowing through tubing into water. This is especially useful for encouraging airway clearance in young children. With a little creativity the technique can be incorporated into a game, making it into an enjoyable activity. Altering the depth of water blown through can change the pressure achieved. Intrapulmonary percussive ventilation Intrapulmonary percussive ventilation is very similar to oscillating PEP. The pressure and frequency of the oscillations can be varied, but generally the frequency is 6 12 Hz, with pressures from cmh 2 O [66 68]. Unlike oscillatory PEP, the oscillatory pressures are continuous throughout inhalation and expiration. THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 171

11 12 IN THE WORLD OF AIRWAYS CLEARANCE High-frequency chest wall compression (HFCC) Various devices have been developed in recent years to provide oscillation to the external chest [69, 70]. This usually entails wearing a jacket that is inflated with air to provide external pressure. Airflow is then pulsated into the jacket to provide oscillatory chest compression. Both pressure and oscillation frequency can be altered to provide optimal treatment ensuring optimal comfort. Exercise Various investigators have studied the effects of exercise and exercise programmes in CF [71 73]. It is generally thought that exercise can help improve mucus clearance. However, advice is that it is not superior to routine airway clearance and should only be used as a supplementary therapy. The reduced deterioration of lung function related to exercise is seen only when combined with routine airway clearance. Noninvasive ventilation Although the evidence is limited, some research suggests that noninvasive ventilation (NIV; most commonly biphasic positive airways pressure) may have a role in enhancing airway clearance [74 76]. Medications to aid sputum clearance Mucolytics Mucolytics are sometimes prescribed to facilitate expectoration by reducing sputum viscosity. Regular use of oral mucolytics may be of some benefit in patients who have poor compliance with nebulisation. Oral mucolytics include carbocisteine and mecysteine hydrochloride. Dornase Alfa (DNase) is a genetically engineered version of a naturally Table 1. continued Technique Advantages Disadvantages Technique Advantages Disadvantages Cough Cough Assist Portable electrical device that alternatively applies positive and rapid negative pressure to patient s airway to assist in stimulating cough and secretion clearance via facemask, mouthpiece or tracheotomy /endotracheal tube. Self-administered by some users. Used where weak cough function is the sole impediment to normal secretion clearance. May replace oral / nasopharyngeal suctioning in some patients. Technique-dependent. Requires motivation and cooperation by caregiver. Not a complete airway clearance method except where weak cough is the only defect of the mucociliary clearance mechanism. Intrapulmonary percussive ventilation (IPV) Percussionaire The patient breathes through mouthpiece delivering high-flow mini-bursts at >150 Hz. Continuous airway pressure is maintained while pulsatile percussive airway pressure increases. Aerosolised medications can be delivered under pressure with oscillations vibrating chest. PercussiveTech; PercussiveNeb The PercussiveNEB is a High-frequency intrapulmonary percussive nebuliser (previously known as the PercussiveTech HF), and incorporates a nebuliser to deliver aerosolised medication. It oscillates during exhalation and inhalation at frequencies of Hz. A pressure dial permits adjustment of pressure amplitude and oscillation frequency for individual comfort. May be self-administered by some users. Can be performed in any position. May be suitable for children aged 5 years. Technique-dependent. Requires adequate cognitive function unless patient has artificial airway or is on a ventilator: Ability and motivation to concentrate. Ability to master breathing techniques. Requires specific physical attributes: No incompatible facial deformities. Home use of IPV devices sparsely researched. Adverse effects may include discomfort and shortness of breath, possibly reducing compliance THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

12 IN THE WORLD OF AIRWAYS CLEARANCE 12 Table 1. continued Comment Technique Advantages Disadvantages Hydro-Acoustic Therapy (HAT) Sound waves are generated under water in a special bath to create a percussive effect using frequencies between Hz. The advantages and disadvantages of this new technique are unclear. Pilot study looks promising. Ventilation Noninvasive ventilation (NIV) that interfaces with the patient via a mouthpiece or nasal mask connected to a bi-level pressure generator that sets inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP). The system provides support to the inspiratory and expiratory muscles. Technique-independent. May be self-administered depending on age. Portable. Allows simultaneous involvement in other activities e.g. reading, computer games. May enhance treatment adherence among suitable users. Suitable for children and adults. Can be used either by nasal mask, nasal-oral mask or via tracheostomy. Wide range of interfaces to deal with most facial abnormalities. May be used during acute exacerbations. Requires no postural positioning. Can be used in conjunction with other therapies, including aerosol treatments. Can be used as a bridge for lung transplantation. Can be used to treat type 2 respiratory failure. Requires motivation and cooperation by caregiver where necessary. May result in interface problems. Compliance may be adversely affected by inability to tolerate tight-fitting face mask. Ability to manage mechanical components of the device. Unsuitable for uncooperative individuals. Requires equipment and electricity although can be run off a battery. Risk of causing a pneumothorax with high pressures. occurring human enzyme, which cleaves extra cellular DNA. It is administered by inhalation via a jet nebuliser, and has best effect at least an hour post-nebulisation [77, 78]. Saline and hypertonic saline have been used to rehydrate airways. Hypertonic saline has been shown to have a favourable effect on mucus rheology. It has been suggested that hypertonic saline breaks the ionic bonds within the mucin gel, thereby reducing the effective degree of cross-linking and entanglements and lowering the viscosity and elasticity. Hypertonic saline also works by increasing the ionic concentration of the airway surface fluid, causing water to be drawn into the airway lumen along its osmotic gradient, thereby rehydrating the airway surface fluid [79 81]. Manitol is another osmotic agent thought to yield similar results [79]. Bronchodilators Coughing, the FET and general airway clearance techniques can sometimes cause bronchoconstriction in sensitive and reactive airways (especially in those with asthma and allergic bronchopulmonary aspergillosis) [82 85]. Therefore the administration of steroids and bronchodilator therapy can be of great benefit in maintaining relaxed and open airways [86 89]. Pain relief and antiemetics For those experiencing pain and nausea on coughing and deep breathing, administration of pain relief and antiemetics may have a very favourable effect on compliance and effectiveness of treatment [90, 91]. Numerous companies provide NIV equipment. See chapter 8. Other important considerations Posture and musculoskeletal disorders In those with moderate-to-severe lung disease, it has been THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 173

13 12 IN THE WORLD OF AIRWAYS CLEARANCE recognised that patients can develop significant postural and ribcage disorders. Typically, those with severe disease develop a hyperinflated chest, with a poorly compliant ribcage and tight/shortened accessory muscles [92, 93]. By addressing some of these problems and improving mobility of the ribcage, it is thought that more effective airway clearance can be achieved [94]. Daily routine and environment It is often helpful, when choosing an appropriate airway clearance technique, to take a look at the patient s lifestyle, home environment and employment, before trying to find a technique that has minimal burden on daily life and therefore hopefully increased compliance. Even with those with minimal sputum, it is important to emphasise the importance of establishing daily airway clearance as a tool to assess for sputum retention. For those who find airway clearance and expectoration embarrassing, it is helpful to explore and create an environment where they are happy to participate in effective airway clearance treatment. Hydration General dehydration has an effect on sputum by increasing its viscosity. Good hydration is encouraged, especially during exacerbations when sputum is often thick and tenacious [31]. Do airway clearance techniques work in reality? Cochrane Reviews The range of techniques has recently been evaluated in four Cochrane reviews [95 97], which have recently been summarised [99]. Other non-cochrane reviews appear to come to similar findings [100]. Studies were included if they were of randomised or quasi-randomised clinical trials. For each Cochrane review, comparison had to be made between the device and any other form of physiotherapy [97], no physiotherapy [95] or with other airway clearance techniques [96]. In terms of applying airway clearance techniques [95], there was an increase in the volume of sputum and the mucus transport rate when compared with no airway clearance or spontaneous coughing. Three of the studies observed increased sputum production [ ], with at least a doubling from control of sputum production, whilst four studies [ ] found varying degrees of increased mucus transport using radioactive tracer clearance techniques as compared to control. This review excluded 118 other studies predominately (n=105) because of No control group without chest physiotherapy. Despite not meeting the relevant criteria, a number of the studies excluded showed similar findings to those included. In comparing conventional CPT to other airway techniques [96], there is again a general lack of good-quality studies, although 24 out of 78 studies were included in this review. Overall, regardless of the techniques used, there was little advantage of conventional chest therapy over any of these other techniques. There was little or no improvement in the primary outcome measures of the onesecond forced expiratory volume (FEV1), forced vital capacity or maximal mid-expiratory flows, including in studies undertaken for 6 months or longer. Apart from limited data on patient preference, none of the many secondary outcome measures showed any real improvement between conventional physiotherapy and airway clearance devices. The author s final conclusion was that in general there is a paucity of welldesigned, adequately-powered, longterm trials [96]. Patient preference may be important in determining successful outcome, as CF patients may need to undertake airways clearance themselves. Patients tended to prefer PEP [ ], HFCC/MP [101, 102], and AD [111, 112] to conventional CPT. Only one study reported adherence [109], which was little different between conventional CPT and PEP. In comparing PEP with other forms of airway clearance, 25 out of 40 studies were included [97]. PEP was compared with postural drainage, percussion and vibration (PDPV), HFCC, pursed-lipped breathing, NIV, AD, flutter and controlled/ spontaneous coughing. The included studies were on adults only, children only or a mixed group and covered normal to severe airway disease and over a range of time. FEV1 was the most frequently measured outcome, but regardless of the length of the study, there is no clear evidence that FEV1 significantly improves when comparing PEP and other methods of airway clearance. Patient preference was reported in nine studies [101, , ] and in general was for PEP compared to other techniques. Adherence was no better between PEP and PDPV and flutter [109, 114]. The authors concluded that there was no clear evidence that PEP was a more or less effective intervention overall than other forms of physiotherapy. There was limited evidence that PEP was preferred by participants to other techniques, but this finding is from studies of low quality. In the fourth Cochrane review [99], NIV was compared with airway clearance with no NIV where PEP or active cycle of breathing/fet was used as the control. Three studies were included [113, 116, 117]. There was no difference for post-treatment FEV1, and most patients (n=62) preferred NIV to PEP or active cycle of 174 THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

14 IN THE WORLD OF AIRWAYS CLEARANCE 12 breathing/fet. The physiotherapists also found NIV easier to use [117]. The conclusions from the four Cochrane reviews are that: 1. Airway clearance is important in the short term for patients with CF, but the long-term effect of no airway clearance is unknown. 2. Conventional chest physiotherapy is as effective as other forms of airway clearance. 3. Patients like their independence, and therefore any technique they can use unaided is preferred. 4. NIV appears to help patients clear sputum more easily than other airway clearance techniques. 5. There is a lack of really highquality research in this area with the need to ensure data is collected appropriately and the primary and secondary outcome measures are available to fully understand the effects of any intervention. These findings are confirmed, more or less, in the review of MCCOOL and ROSEN [100], where much of the level of evidence for airway clearance devices is fair to low and the benefits were intermediate to conflicting. No single technique appeared to be superior; suggesting that appropriate and effective techniques need to be chosen on an individual basis. A consistent theme running through these studies is that, regardless of the device used or the way in which the trial was conducted, there appears to be little change in the observed primary and in many cases secondary outcome measures. However, what makes all of these studies difficult to compare is the lack of commonality between recruitment methodology, primary and secondary outcome measures, CASE REPORT A 34-year-old man with significant lung disease secondary to CF This case report gives you a brief insight into the thought process and problem-solving approach when trying to help this young man maintain a clear chest, as well as exposing some of the difficulties and problems encountered. The aim is to highlight that techniques should regularly be assessed and adapted according to needs of the patient and effectiveness of treatment. History of present condition Over the past few years, his health had been deteriorating rapidly. Chief among his problems were severe respiratory exacerbations resulting in several courses of i.v. antibiotics. His main problems are moderate lung disease with an FEV1 of 62% predicted, daily production of 3 4 tablespoons of thick green sputum and allergic bronchopulmonary aspergillosis (which makes him prone to becoming wheezy with significant airway obstruction). Social history He works full time, in a sedentary but busy job. He lives with his partner, who spends quite a lot of time working away. Once a week, he plays football. Nebulised medications He takes DnASE once daily (A trial of hypertonic saline was undertaken but he was unable to tolerate the treatment as it made him very wheezy.) He gets good reversibility from bronchodilators. Physiotherapy When he was a child, his parents practised daily CPT, which was an effective clearance technique. As he got older and became more independent he stopped doing CPT, and became quite noncompliant. In his early 20s, his chest started to deteriorate quite dramatically and he developed allergic bronchopulmonary aspergillosis. CPT was commenced. However, percussion and vibrations had a tendency to induce further bronchoconstriction in the airways. CPT continued to be performed but one-handed. Very slow percussion was needed to clear secretions without inducing bronchoconstriction. After a while he found this difficult to administer to himself, and his girlfriend was working increasingly away from home. He also found it increasingly ineffective. Next we explored the use of AD, as it is an independent technique as well as being gentle. Unfortunately it also had a tendency to induce bronchospasm, and he found it difficult to clear sputum easily. Because of the hyperreaction of his airways, we tried PEP, aiming to maintain relaxed and open airways throughout expiration. We decided on using the acapella, as this device has an adaptation in which it is possible to entrain a nebuliser. This enabled him to nebulise a bronchodilator during physiotherapy. This combination worked well, and allowed effective airway clearance for the time being. At present he only needs to entrain a bronchodilator during physiotherapy at times of pulmonary exacerbation. For the most part, the acapella alone is sufficient in aiding clearance of sputum. This technique needs to be assessed regularly for effectiveness and altered/modified if it fails to do its job, or if a new problem develops that prevents its continued use. THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS 175

15 12 IN THE WORLD OF AIRWAYS CLEARANCE severity of disease etc. This makes setting evidence-based practice guidelines interesting and limited in their conclusiveness [100]. Which technique? Parents of children and adult patients want treatments that will help them achieve optimal health and quality-of-life goals. Useful decision-making criteria may include: 1) what the patient and medical team want to achieve; 2) the clinical effectiveness of the technique; 3) medical contraindications; 4) the ease of teaching/learning the technique by the patients and/or by the carer; 5) the likely acceptability of and hence adherence to the technique; 6) the likely effort/work required by the technique compared to the likely benefit of the technique; 7) the patient s age, motivation, cognitive ability, concentration level and caregiver situation; and 8) the degree of independence that a given technique gives the patient from the carer or the medical teams. Some of the advantages and disadvantages of airways clearance techniques are outlined in the tables. The future Physiological measurements are important in guiding us with regards to the course of disease; however, they do not present the whole picture. Techniques that give the patient greater independence in the management of their own disease may well improve adherence to treatment and therapies, but despite this, few studies have investigated health-related quality-of-life measures, the number of exacerbations or hospital days per year, the costs or harm associated with intervention, or mortality rates. These need to be included along with the appropriate physiological measurements in any randomised controlled trial of airway clearance techniques to ensure that we fully understand how these techniques benefit patients with lung disease. Doubtless new techniques, or modifications of current techniques will be developed in the next few years, which will, with properly controlled randomised trials and sensible and carefully selected primary and secondary outcomes that present the whole picture, provide the much needed evidencebased information needed to understand and apply these techniques. Acknowledgements The author would like to thank J. Hudson and A. Martin for their valuable input. REFERENCES 01. Yankaskas JR, Marshall BC, Sufian B, Simon RH, Rodman D. Cystic fibrosis adult care: consensus conference report. Chest 2004; 125: Annesi I, Kauffmann F. Is respiratory mucus hypersecretion really an innocent disorder? A 22-year mortality survey of 1,061 working men. Am Rev Respir Dis 1986; 134: Lange P, Nyboe J, Appleyard M, Jensen G, Schnohr P. Relation of ventilatory impairment and of chronic mucus hypersecretion to mortality from obstructive lung disease and from all causes Thorax 1990; 45: Vestbo J, Prescott E, Lange P. Association of chronic mucus hypersecretion with FEV1 decline and chronic obstructive pulmonary disease morbidity. Copenhagen City Heart Study Group. Am J Respir Crit Care Med 1996; 153: Braverman JM. Treatment adherence: airway clearance therapy in cystic fibrosis Laube DM, Yim S, Ryan LK, Kisich KO, Diamond G. Antimicrobial peptides in the airway. Curr Top Microbiol Immunol. 2006; 306: Tiddens HAWM, Koopman LP, Lambert RK, et al. Cartilaginous airway wall dimensions and airway resistance in cystic fibrosis. Eur Respir J 2000; 15: Houtmeyers E, Gosselink R, Gayan-Ramirez G, Decramer M. Regulation of mucociliary clearance in health and disease. Eur Respir J 1999; 13: Wanner A, Salathé M, O Riordan TG. Mucociliary clearance in the airways. Am J Respir Crit Care Med 1996; King M, Zidulka A, Phillips DM, Wight D, Gross D, Chang HK. Tracheal mucus clearance in high-frequency oscillation: effect of peak flow rate bias. Eur Respir J 1990; 3: Leith DE. Cough. In: Brain JD, Proctor DF, R ilid LM, eds. Respiratory Defence Mechanisms; Part II. New York, Marcel Dekker, Ross BB, Gramiak R, Rahn H. Physical dynamics of the Cough mechanism. J Appl Physiol 1955; 8: Bennett WD, Foster WM, Chapman WF. Cough-enhanced mucus clearance in the normal lung. J Appl Physiol 1990; 69: Bennett, WD, Zeman KL. Effect of enhanced supra-maximal flows on cough clearance. J Appl Physiol 1994; 77: Clarke S, Jones JG, Oliver DR. Resistance to two-phase gas-liquid flow in airways. J Appl Physiol 1970; 29: Kim CS, Iglesias AJ, Sackner MA. Mucus clearance by two-phase gas-liquid flow mechanism: asymmetric periodic flow model. J Appl Physiol 1967; 62: Scherer PW. Mucus transport by cough. Chest 1981; 805: Kim CS, Brown LK, Lewars GG, Sackner MA. Deposition of aerosol particles and flow resistance in mathematical and experimental airway models. J Appl Physiol 1983; 55: THE BUYERS GUIDE TO RESPIRATORY CARE PRODUCTS

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