Nebulisers for chronic obstructive pulmonary disease.

Definition of chronic obstructive generally agreed that the bronchodilation obpulmonary disease tained is largely a reflection of the dose of In this paper the term “chronic obstructive bronchodilator administered rather than the pulmonary disease” (COPD) is used as defined mode of administration. It is therefore unlikely in the forthcoming British Thoracic Society that treatment with either a nebuliser or a guidelines for the management of COPD metered dose inhaler will give superior results (1997) as a chronic slowly progressive disorder for most patients provided similar doses are characterised by airways obstruction (reduced given to the lungs by each device. The question forced expiratory volume in one second (FEV1) therefore becomes one of convenience and cost. and ratio of FEV1 to forced vital capacity For low dose bronchodilator therapy – for ex(FVC)) which does not change markedly over ample, 100–400 lg salbutamol or terbutaline – several months. Most of the lung function imtreatment with a metered dose inhaler is more pairment is fixed, althugh some reversibility convenient whilst a nebuliser can deliver higher can be produced by bronchodilator (or other) doses more easily. A nebuliser has the further therapy. advantage of being independent of effort or The guidelines indicate that, in practice, a breathing pattern when a patient is distressed. diagnosis of COPD requires a history of chronic This means that a patient can begin nebulised progressive symptoms such as cough, wheeze treatment using a mask or a mouthpiece while and/or breathlessness without intervening the medical attendent can continue with other periods of “wellness”, usually a cigarette smoktasks. The use of a metered dose inhaler in this ing history of more than 20 pack years, and situation would require the medical attendant objective evidence of airways obstruction (or respiratory therapist or nurse) to stand by (ideally verified by spirometric testing) that the patient and supervise or administer multiple does not return entirely to normal with treatdoses of treatment, possibly more than 20, at ment. one minute intervals. Breathless patients are less likely to be able to inspire slowly or breath hold for optimum lung deposition from a metered dose inhaler. Acute exacerbations of COPD The optimum dose of bronchodilator treatCurrent clinical practice is based largely on ment (b agonist or anticholinergic) in acute tradition rather than on careful clinical trials. COPD is not known. Mestitz et al showed Although patients with COPD are considered that terbutaline was equally effective given by to have relatively static lung function, most metered dose inhaler or nebuliser and the dose have some reversibility and peak flow will often response was still rising at 40 mg. However, show a modest rise during the first few days in doses of b agonist above 5–10 mg tend to be hospital. For example, Rebuck et al found that, associated with unacceptable side effects such in 51 patients with COPD, the mean peak flow as tremor or palpitations. Gross and colleagues increased from 70 l/min to 95 l/min (36% rise) showed that the optimum response to ipra90 minutes after treatment with a nebulised tropium bromide occurred at 0.4–0.6 mg. A bronchodilator, and a later study reported a review of practice in Britain shows that salrise of 19% in mean peak flow from 113 l/min butamol or terbutaline (5 mg), with or without to 134 l/min in 47 patients with COPD after ipratropium bromide (0.25–0.5 mg), is usually nebulised bronchodilator treatment. These administered to patients with acute airflow obstudies demonstrate that patients with acute struction. This would require 50 inhalations exacerbations of COPD can respond to high of salbutamol followed by 25 inhalations of doses of bronchodilator drugs. ipratropium bromide via a metered dose inSeveral studies have suggested that patients haler. Most doctors mix salbutamol and iprawith acute asthma or COPD may respond tropium bromide respirator solutions in a single better to treatment with a b agonist given by nebuliser chamber and administer it imnebuliser than by metered dose inhaler. Howmediately. It has recently been suggested that ever, other authors have suggested that treatthe Turbohaler dry powder device may be used ment with a metered dose inhaler (given effectively by patients with severe airflow through a spacer device) may be as effective as obstruction. 13 This would allow the adnebulised treatment in the acute situation. It Hope Hospital, ministration of 5 mg (10 puffs) or 10 mg (20 is difficult to compare these results directly as Salford, puffs) of terbutaline almost as conveniently as Lancashire the patient groups and inhaler devices were M6 8HD, UK with a nebuliser. different and most studies have contained relB R O’Driscoll Nebulised treatment might have a further atively small numbers of patients, making it