Use and Misuse of Metered-dose Inhalers by Patients with Chronic Lung Disease: A Controlled, Randomized Trial of Two Instruction Methods

著者: Patricia de Blaquiere, Dale B. Christensen, William B. Carter, Thomas R. Martin - American Review of Respiratory Disease 1989 被引用: 185

Abstract Metered-dose inhalers are often used incorrectly by patients with chronic airflow obstruction, and there is a lack of controlled studies designed to evaluate methods to teach the correct use of these devices. Therefore, we screened 100 consecutive stable outpatients for correct or incorrect inhaler use and then conducted a randomized trial of two methods to teach correct use. Patients were classified as correct or incorrect users with a modified metered-dose inhaler containing a thermistor that detected inspiration, inhaler activation, and the duration of breathholding. Patients were classified as incorrect users if they failed to: (1) activate the inhaler once during inspiration, and/or (2) hold their breath at the end of inspiration. There were 38 correct users and 62 incorrect users. Incorrect users were randomized to one of two teaching protocols: (1) standardized verbal instruction alone, or (2) standardized verbal instruction plus an automatic visual signal during inspiration. Incorrect users were restudied 6 to 10 wk later to reassess technique. Both treatment protocols were equally effective in converting incorrect to correct users. However, the verbal instruction alone required significantly less time than the instruction with the mechanical aid. for all subjects, the proportion using correct technique declined over time, particularly for incorrect users. We also examined a series of patient characteristics, obtained by questionnaire and spirometry, to determine whether they could be used in the clinical setting to identify incorrect users. By discriminant analysis, a group of four variables predicted correct metered-dose inhaler use: bron-chodilator responsiveness, a history of additional instruction about proper technique, verbal knowledge of the correct inhaler maneuvers, and the patient's perception of whether it is important to use an inhaler. Responsiveness to inhaled bronchodilators was the single best predictor of correct inhaler use. This study indicates that verbal instruction alone is as effective as verbal instruction supplemented with a visual aid in teaching the correct use of metered-dose inhalers. Patient characteristics can be used to identify those patients who are likely to use metered-dose inhalers incorrectly, so that teaching efforts can be concentrated on these patients.