Respiratory and Peripheral Muscle Strength as Predictors of Inhaler Treatment Response in Asthma: A Comparison of DPI and MDI Devices

Respiratory and Peripheral Muscle Strength as Predictors of Inhaler Treatment Response in Asthma: A Randomized Comparison of Dry Powder and Metered Dose Inhalers

Asthma is a chronic respiratory disease characterized by variable airway obstruction. Inhaled therapies are the cornerstone of asthma management, and selecting the appropriate inhaler device is essential for effective treatment. Among available devices, metered dose inhalers (MDIs) and dry powder inhalers (DPIs) are commonly used; however, their effectiveness depends not only on the medication but also on the patient's physiological capacity and inhalation technique.

This prospective randomized study aimed to evaluate the factors influencing inhaler treatment response in newly diagnosed asthma patients. A total of 80 patients with at least a high school education, who demonstrated perfect inhaler technique and adherence, were randomly assigned to MDI or DPI groups (n = 40 each). Baseline and one-month follow-up assessments included pulmonary function tests (PFTs), inspiratory and expiratory muscle strength measurements (MIP, MEP), Asthma Control Test (ACT), and handgrip strength (HGS).

The study investigated how respiratory and peripheral muscle strength, inspiratory capacity, coordination skills, and clinical status affect treatment outcomes with MDI and DPI. Findings from this research may help guide inhaler selection based on patient-specific physiological characteristics to optimize treatment effectiveness.

Inclusion Criteria:

Adults aged ≥ 18 years Newly diagnosed asthma according to GINA guidelines Education level of at least high school Ability to use inhaler devices correctly after standardized training Provided written informed consent to participate

Exclusion Criteria:

Presence of other chronic lung diseases (e.g., COPD, interstitial lung disease) Acute asthma exacerbation at the time of enrollment Severe neurological or cognitive impairment affecting inhaler use

Pregnancy or breastfeeding

Refusal or inability to provide informed consent