Numerous studies have described the difficulties patients experience in using metered dose inhalers (MDIs), including a recent article in the Journal of General Internal Medicine (JGIM) that found 86% of hospitalized patients enrolled in a study unable to properly complete at least 75% of the steps necessary for effective use of an MDI. As with many such articles, the authors conclude that training programs should be instituted in order to ensure proper MDI use.
A recent article in the Primary Care Respiratory Journal (PCRJ), however, claims that not only are patients unable to use their MDIs without proper training, most of them cannot use MDIs properly after training either. Titled "Technique training does not improve the ability of most patients to use pressurised metered-dose inhalers (pMDIs),” the article suggests that clinicians should be prepared to prescribe another type of medication, even a much more expensive medication, unless patients can prove their ability to use an MDI.
Instead of relying on visual observation of inhaler technique, the PCRJ study used the Vitalograph Aerosol Inhalation Monitor (AIM) to measure each patient’s inspiratory and ongoing flow rates, as well as the length of time of the breath hold at the end of inspiration. Proper technique, as indicated by the AIM, was defined as a flow rate of between 10 and 50 L/min initially, with maintenance of flow in that range for at least half of a 3-second inhalation period, and a breath hold of 5 seconds or greater. According to Bernard Garbe of Vitalograph, those criteria “were developed many years ago in conjunction with Prof. Steve Newman” and “have proved to be remarkably good criteria.”
Of the 1275 patients who took part in the testing prior to instruction, almost 1100 failed to meet the AIM criteria on their first attempt, the same 86% failure rate found in the JGIM article. After instruction, 946 out of 1207 patients retested failed to meet the criteria, a rate of 78%. On a third test, 347 patients failed to use their MDIs properly.
The article states that “the most common error found in this study was the inspiratory flow generated by the patients” but provides no data indicating the magnitudes of those errors or whether any of the patients failed to generate the minimum 10 L/min. According to study’s lead author, Dr. Mark Levy of the University of Edinbugh, “the AIM simply indicates that the flow is incorrect. From my experience patients and practitioners usually inhale too quickly.” As Vitalograph’s Garbe notes, the AIM was used in the study only to determine the correctness of the patient’s technique, not to provide instruction; in other studies, he says, AIM training has improved inhaler use.
Despite the pessimistic tone of the article’s title, Dr. Levy believes that “a feedback system to indicate to patients when their technique is correct/incorrect” on the MDI itself could be useful, although he cautions that he is “not sure if the added expense can be justified.” Levy also points to a December 2010 article in the PCRJ by members of the ADMIT Working Group that reviews a number of training systems currently available.
ADMIT (the Aerosol Drug Management Improvement Team) owes its existence in large part to the misuse of inhalers and states as its aim: “we strive to improve the success of therapy for airway obstructive pulmonary diseases such as asthma or COPD through optimal use of the devices already existing and through selection of the right devices for the right patient.” The organization’s web site includes training materials for both MDIs and DPIs.
In the December article, the ADMIT Working Group members suggest that “Ideally, an inhalation training apparatus would provide visual feedback representing the actual distribution of inhaled aerosol in the lungs and show with reasonable accuracy the amount of aerosol delivered to the receptor sites. Such feedback would convey a conceptual understanding of the proper inhalation process, and thereby increase the likelihood that the patient would retain the correct technique.”
While Levy’s article concludes that doctors should assess patient ability to use an MDI, which “should be followed by appropriate action which could include prescription of a different device” and cautions that “cost alone should not determine recommendations for prescribing.” Despite those warnings, however, he says that he does not mean to suggest that pharma companies should abandon MDIs: “pMDIs are a lot cheaper – and fine for those who can use them (about 30-40% of patients), spacers can be added to the pMDIs with good effect, and they are more cost effective than DPIs.”
