Use of Assist Devices to Actuate Pressurized Metered-Dose Inhalers in Elderly Patients with Asthma

Introduction: Some elderly patients experience difficulty when attempting to use pressurized metered-dose inhalers (pMDIs) due to reduced finger muscle strength. However, no studies have investigated the finger muscle strength required for pMDI actuation. Therefore, we created a modified pMDI pinch gauge and examined the finger muscle strength in elderly asthmatic patients with and without the use of a pMDI assist device to push the canister. Methods: We measured the finger muscle strength (N) required to spray pMDI formulations (Adoair^®, Alvesco^®, Flutiform^®, and Breztri^®) using one hand in healthy individuals. We then similarly measured the finger muscle strength when using the modified pinch gauge in older adults aged 65 years or older with bronchial asthma who used pMDI formulations. Results: The finger muscle strength required to actuate these devices was 29.4 N or more in healthy individuals. In the older patients with asthma, the finger muscle strength was 38.45 ± 5.80 N in men and 31.34 ± 9.94 N in women. The finger muscle strength was ≤ 29.4 N in 6.6% of men and 40.0% of women. Conclusions: Finger muscle strength should be considered when selecting a device for older patients with asthma, and the use of a pMDI assist device to push the canister is recommended in patients with weaker finger muscles.