Review: pressurised metered dose inhalers are as effective as other hand held inhalers for delivering β2 agonist bronchodilators in stable asthma
QUESTION: In patients with stable asthma, is the standard chlorofluorocarbon containing pressurised metered dose inhaler (PMDI) as effective as other hand held inhaler devices, including chlorofluorocarbon-free PMDIs, for delivering short acting β2 agonist bronchodilators?
Studies published from 1966 to December 2000 were identified by searching the Cochrane Airways Group trials database, Medline, EMBASE/Excerpta Medica, CINAHL, and 17 online respiratory websites. Bibliographies of relevant studies were reviewed, and pharmaceutical companies that manufacture inhaled asthma drug were contacted for further studies.
Studies in any language were selected if they were laboratory, hospital, or community based randomised controlled trials of children or adults with stable asthma that compared delivery of short acting β2 agonist bronchodilators by standard PMDI (with or without a spacer device) with any other hand held inhaler. Trials comparing different doses of inhaled drugs and those that used challenge testing were also included.
2 reviewers independently extracted data on study design, patient characteristics, details of the intervention, study duration, outcomes, and quality. Outcomes included lung function, quality of life measures, symptom scores, drugs for additional relief, steroid requirement, nocturnal awakening, acute exacerbation, days off work or school, treatment failure, patient compliance, patient preference, adverse effects, bronchial hyper-reactivity, and systemic bioavailability.
89 articles describing 84 studies met the selection criteria. 71 trials involved adults and 13 involved children. Most trials involved patients with mild to moderate asthma (baseline forced expiratory volume in 1 second [FEV1] >50% of predicted). Meta-analyses were done using a fixed effects model as long as statistical heterogeneity did not exist. In both adults and children, standard PMDIs did not differ from any of the other 10 hand held inhaler devices (Turbohaler, Diskhaler, hydrofluoroalkane PMDI, Rotahaler, Spiros, Easyhaler, multidose powder inhaler, Clickhaler, Gentlehaler, and Autohaler) for FEV1, forced vital capacity, peak expiratory flow rate, area under the curve for FEV1, blood pressure, symptoms, brochial hyper-reactivity, systemic bioavailability, inhaled steroid requirement, serum potassium concentration, or use of additional relief brochodilators.
In patients with stable asthma, the standard chlorofluorocarbon containing pressurised metered dose inhaler is as effective as other hand held inhalers, including chlorofluorocarbon free pressurised metered dose inhalers, for delivering short acting β2 agonist bronchodilators.
- Lisa Cicutto, RN, ACNP, CAE, PhD
- Assistant Professor, Faculty of Nursing, University of Toronto Acute Care Nurse Practitioner-Respirology, Toronto Western Hospital, University Health Network Ontario Ministry of Health Career Scientist Toronto, Ontario, Canada
The 2 systematic reviews by Brocklebank et al and Ram et al assess an important, and perhaps overlooked, area of asthma care — the effectiveness of various inhaler devices for delivering short acting bronchodilators and corticosteroids. These papers are based on reviews found in the Cochrane Library; given that the mandate of the Cochrane Collaboration is the conduct of high quality systematic reviews of healthcare interventions, we can be confident about the methodological rigour of these reviews. It is unlikely that studies were missed because the authors conducted thorough searches for published and unpublished studies reported in any language. Studies were identified through electronic databases (Medline, CINAHL, EMBASE/Excerpta medica), online respiratory websites, manual searches of pertinent journals, review of references of retrieved articles, and review of proceedings of respiratory societies. The investigators also contacted pharmaceutical companies to identify additional studies. Studies included in the reviews involved children and adults with mild to moderate asthma who were followed up in a broad range of practice settings. Unfortunately, many of the studies could not be included in the meta-analyses because of inconsistencies across studies in the type of outcomes measured, the methods used to measure various outcomes, and because of lack of extractable data.
The results of the 2 reviews are applicable to nurses working with patients who have asthma and their families. The reviews highlight the importance of considering the characteristics of inhaler devices for delivering asthma medications. The reviews compared CFC containing PMDIs to other hand held inhaler devices for delivering short acting β2 agonists and corticosteroids, and concluded that CFC PMDIs are as effective as alternative types of inhalers. The reviews did not identify a superior inhaled delivery device for asthma medications.
Much global attention is focused on the use of CFCs because of their ozone depleting nature. As a result of the recognition of CFCs as an ozone depleting substance, the Montreal Protocol was signed by Canada, the UK, the USA, and several other countries to develop a national transition strategy to phase out the use of CFCs used in PMDIs. In Canada, the first step of the phase out schedule became effective January 1, 2002.
As a result of the Montreal Protocol and the international recognition of CFCs as an ozone depleting substance, our attention must focus on determining the effectiveness of non-CFC containing inhaler delivery devices for individuals with asthma. We need to ensure that safe, effective, easy to use, desirable, and suitable alternatives exist for patients with asthma. In most countries, non-CFC containing inhaler delivery devices have existed for several years. Some of these alternative inhalers were included in the studies reviewed by Brocklebank et al and Ram et al. Examples include the Turbohaler, Diskhaler, and hydrofluoroalkane based PMDIs. It is expected that as a result of the phase out of CFC containing PMDIs, several new inhaler devices will be developed and marketed. It is important for nurses to be familiar with the schedule of phase out for CFC PMDIs in their countries, to inform patients of the phase out schedule and how it will affect them, and to work with patients to identify a suitable replacement. If a replacement inhaler is required, nurses need to ensure that the patients are aware of the appropriate dosing and timing of medication, that they are able to accurately provide a return demonstration of the replacement device, and that they are knowledgable about the care of the inhaler and whether a spacing device is needed.
In summary, the clock is ticking towards the phase out of CFC based PMDI devices. Several viable replacements are currently available and more will be forthcoming. These devices are not bioequivalent and it is the responsibility of nurses and other healthcare providers to assist individuals with asthma in their choices of replacement devices and to provide instructions for their proper use.
Sources of funding: NHS Research and Development Health Technology Assessment Programme.
For correspondence: Dr J Wright, Bradford Hospitals NHS Trust, Bradford Royal Infirmary, Bradford UK.
A modified version of this abstract appears in ACP Journal Club.