An Investigation into the Factors Associated with Incorrect Use of a Pressurized Metered-Dose Inhaler in Japanese Patients.

Abstract

Rationale: Inhalation of the correct dose of a short-acting beta 2 agonist (SABA) from a pressurized metered-dose inhaler (pMDI) is essential for the relief of symptoms in patients with asthma and/or chronic obstructive pulmonary disease. The aim of this study was to evaluate the prevalence and factors associated with the incorrect use of a pMDI. Methods: This study retrospectively assessed the electronic medical records of 161 patients with various respiratory diseases. The patients had never used a pMDI and underwent training by pharmacists educated in the use of a pMDI followed by bronchodilator reversibility testing at our hospital. The patients' characteristics and various lung capacity parameters were evaluated for association with the incorrect use of a pMDI. Results: Thirty-nine of the 161 (24.2%) patients, including 46% of 28 patients older than 80 years, used the pMDI incorrectly, mainly because of incoordination between activation of the device and inhalation (n = 11), inadequate strength to manipulate the device (n = 9), too short duration of inhalation (n = 6), and difficulty in breath holding (n = 3). Advanced age; lower height; and decreased lung volumes, including vital capacity (VC), inspiratory capacity, inspiratory reserve volume (IRV), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow rate, were associated with the incorrect use of a pMDI. Neither the body weight, tidal volume, expiratory reserve volume, %FVC predicted, %FEV1 predicted, nor FEV1% was associated with the incorrect use of a pMDI. Multivariate binomial logistic regression analysis identified decreased IRV as the only independent predictor associated with the incorrect use of a pMDI. Conclusions: Physicians should be aware that elderly patients or patients with decreased IRV might be unable to obtain the correct SABA dose from a pMDI. A large-scale prospective study is required to confirm these findings from our retrospective study with a small group of patients.