In the palliative care of many advanced respiratory diseases, clearance of airway secretions is an important aspect of treatment. This is particularly the case in patients with chronic suppurative lung diseases such as cystic fibrosis, diffuse bronchiectasis, and in some patients with advanced chronic obstructive pulmonary disease (COPD), where large volumes of sputum may overwhelm the mucociliary clearance mechanisms. Patients with ineffective cough due to neuromuscular diseases, such as motor neurone disease or muscular dystrophy, are particularly vulnerable to retained ­airway secretions and pneumonia. Cough suppressants are not usually appropriate in these patients, although they may be used at night in the palliative phases of the disease if cough is disturbing sleep.

In patients with copious sputum production and an effective cough, the initial approach is to reverse or ameliorate the cause by use of specific treatments. In patients with cystic fibrosis or diffuse bronchiectasis, a prolonged course of high-dose intravenous antibiotics is often the most effective measure in relieving symptoms even in end stage disease, and may remain an appropriate treatment even in patients approaching death [15,16]. A number of mucolytic or mucokinetic drugs are used in specific diseases [17]. Nebulized 0.9 % sodium chloride is sometimes used in patients with COPD or other lung diseases in an attempt to improve expectoration, although its effect is modest. Hypertonic 6–7 % sodium chloride has been shown to be effective in patients with cystic fibrosis and diffuse bronchiectasis of other causes [17,18]. It improves hydration of the airway surface liquid and enhances sputum clearance but it can provoke coughing which may be distressing and exhausting for patients with advanced disease. Hypertonic sodium chloride sometimes provokes bronchospasm so that patients may benefit from prior use of a bronchodilator drug such as salbutamol or terbutaline. Inhaled mannitol also seems to improve mucociliary clearance in patients with bronchiectasis or cystic fibrosis [19]. It acts as an osmotic agent, drawing water into the airway mucosa. Dornase alfa (rhDNase) is widely used in all stages of cystic fibrosis but is not effective in bronchiectasis of other causes. The sputum of patients with cystic fibrosis is very viscous as a result of a high content of DNA derived from decaying neutrophils in the airway. DNase is an enzyme which cleaves this DNA thereby reducing the viscosity of the sputum making it easier to expectorate [17]. Stopping smoking improves the symptom of cough in patients with chronic bronchitis and COPD [20]. Carbocisteine is a mucolytic drug which has been shown to reduce the frequency of exacerbations in patients with COPD who have a chronic productive cough [21]. Inhaled anticholinergic drugs such as ipratropium or tiotropium may reduce mucus production although their effect on cough is not consistent.

In patients with suppurative lung disease, clearance of secretions can be enhanced by a variety of specialist physiotherapy techniques and devices [22]. Cough is the natural mechanism for airway clearance. However, in disease states, collapse of the airways may occur during the high intrathoracic pressure phase of coughing, impairing the clearance of secretions. The forced expiratory technique (“huffing”) consists of forced expirations without closure of the glottis, starting from mid-lung to low-lung volumes. It can be particularly effective in patients with bronchiectasis or cystic fibrosis as an alternative to coughing. Patients can be taught the forced expiratory technique to enhance clearance without excessive effort. Physiotherapy is an integral part of the long-term management of these patients. Some techniques such as chest wall percussion and vibration require the assistance of a care giver while other ­techniques can be performed without assistance, giving patients independence in performing their own airway clearance. Autogenic drainage is a technique that uses controlled expiratory airflow during tidal breathing to mobilize secretions from the peripheral airways. The active cycle of breathing technique involves a cycle of breathing control, thoracic expansion exercises, and the forced expiratory technique. A number of mechanical devices can assist in sputum clearance. These include positive expiratory pressure (PEP) masks, and oscillating PEP devices such as flutter, Acapella^®or cornet devices, as well as high-frequency chest wall oscillation vests [22]. The acceptability of airway clearance techniques is crucial and patient preference must be taken into account. The amount of time and effort involved can infringe on daily activities and can add to the overall burden of treatment in patients with advanced lung disease. Specialist physiotherapist input is invaluable in ­devising an airway clearance regimen that suits the individual patient’s needs.

In patients with neuromuscular disease, cough becomes less effective as muscle weakness progresses. An effective cough requires a full inspiration, followed by glottic closure and adequate expiratory muscle strength to generate a high intrathoracic pressure and high peak expiratory flow. Physiotherapy techniques for improving the effectiveness of cough in clearing secretions are crucial in the management of these patients [23]. The inspiratory phase of cough normally fills the lungs to a high lung volume which optimizes the length-tension properties of the expiratory muscles and increases the lung elastic recoil pressure. In neuromuscular disease, a poor inspiratory effort results in only a small volume of air being inhaled.

Patients can be taught a glossopharyngeal breathing technique (“frog breathing”) whereby the glottis sucks in air and then propels it into the lungs. Weakness of the expiratory muscles results in paradoxical outward motion of the abdomen with reduced expiratory flow during coughing. Manual compression of the upper abdomen and lower thorax (“manual thrust”) can enhance cough flow rates and effectiveness. Mechanical means of assisting cough include insufflation-exsufflation devices. These deliver deep positive pressure insufflations followed immediately by application of a negative pressure to the airway opening during exsufflation. This enhances both the inspiratory phase of cough by increased lung inflation, and the expiratory phase by augmenting expiratory flow. Thus both manual and mechanical assisted coughing can enhance clearance of secretions [23].