Chronic obstructive pulmonary disease (COPD) is a common long-term lung disease that causes breathlessness, cough, and frequent flare-ups. Most patients with COPD use inhaled medications every day. However, many people do not use their inhalers correctly, or they cannot generate the right inspiratory flow for their device. When inhalers are used incorrectly, the medication does not reach the lungs properly, symptoms worsen, and the risk of exacerbations increases.

This pragmatic randomized controlled trial evaluates whether a structured physiotherapist-led inhaler optimization program improves inhaler use in routine outpatient COPD care. The program is delivered by trained physiotherapists over 12 months and includes three in-person sessions. During these sessions, the physiotherapist evaluates the patient's inhaler technique using placebo devices, measures the patient's peak inspiratory flow with the In-Check DIAL® device, and provides individualized "teach-to-goal" education to help patients use their inhalers correctly. If the patient continues to make critical errors or cannot generate the appropriate inspiratory flow for their inhaler, the physiotherapist may recommend adapting the type of inhaler to better match the patient's abilities.

Participants will be randomly assigned to one of two groups. The intervention group will receive the structured program in addition to their usual COPD care. The control group will continue with usual outpatient care without the physiotherapist-led sessions. All participants will complete baseline and 12-month assessments, which include inhaler technique evaluation, inspiratory flow measurement, respiratory questionnaires, and lung function tests. Telephone follow-up calls will be performed at months 2, 5, and 8 to monitor symptoms, inhaler use, and adherence.

The main outcome of the study is the proportion of inhalers used incorrectly at 12 months. Incorrect use is defined as at least one critical inhaler technique error or an inspiratory flow that is too low or too high for the patient's device. Secondary outcomes include changes in respiratory symptoms, health status, adherence to inhaled treatment, patient satisfaction with inhalers, confidence in inhaler use, and the number of COPD exacerbations or hospitalizations during the study.

This research may help improve everyday inhaler use in people with COPD and support more personalized inhaler selection in routine clinical care. Although participants may not benefit directly, the study poses minimal risks and may contribute to future improvements in COPD management.

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Most patients rely on inhaled medications to control symptoms and reduce the risk of exacerbations. However, many patients do not use their inhalers correctly. Critical errors-such as incorrect preparation of the device, improper inhalation technique, or an inspiratory flow that is not appropriate for the device-are common and can lead to reduced drug delivery, poorer symptom control, and more frequent exacerbations. Previous studies conducted at the study site have shown that nearly 70% of hospitalized COPD patients used at least one inhaler incorrectly. In addition, peak inspiratory flow (PIF) varies between individuals, and many patients are unable to generate the flow required for certain dry powder inhalers. Despite this, regular assessment of inhaler technique and inspiratory flow is not systematically implemented in outpatient practice.

This randomized controlled trial evaluates whether a structured, physiotherapist-led inhaler-optimization program can reduce incorrect inhaler use among outpatients with COPD. The intervention includes three face-to-face visits over 12 months. During these sessions, physiotherapists trained in inhaler technique assessment use device-specific placebo inhalers and standardized checklists to identify critical errors. They also measure PIF with the In-Check DIAL® device, adjusted to the resistance of each patient's inhaler. The physiotherapist then provides individualized "teach-to-goal" education, with demonstration, correction, and repeated practice until mastery of the inhaler technique is achieved. When persistent errors or suboptimal PIF are identified, the physiotherapist informs the treating physician to consider adapting the type of inhaler.

Participants are randomly assigned (1:1) to the intervention group or the usual-care group. Usual care consists of regular management by the treating physician, which may include inhaler review at the physician's discretion, but without the structured physiotherapist-led sessions. Both groups undergo baseline and 12-month assessments that include inhaler technique evaluation using placebo devices, PIF measurement, respiratory questionnaires, and pulmonary function testing. Participants in both groups also receive telephone follow-up calls at months 2, 5, and 8 to assess symptoms, inhaler use, adherence, and confidence in inhaler use.

The primary endpoint is the proportion of misused inhalers at 12 months. An inhaler is considered misused if the patient demonstrates at least one critical technique error or if their measured PIF is outside the recommended range for their specific device. This composite outcome captures both aspects of inhaler adequacy: correct handling of the device and physiological ability to use it effectively. Because participants may use more than one inhaler device, the primary outcome is assessed at the inhaler level while accounting for clustering within participants. Secondary endpoints include changes in health status measured by validated respiratory questionnaires (CAT and CCQ), treatment adherence using the TAI questionnaire, satisfaction with inhalers, confidence in inhaler use, pulmonary function parameters, and the number of COPD exacerbations and hospitalizations over the 12-month follow-up.

The trial uses a pragmatic design to reflect real-world outpatient care. The inhaler-optimization program is intended to be simple, scalable, and easily integrated into routine COPD management. The educational approach is based on individualized instruction and repeated reinforcement, which patients in prior studies have reported as highly valuable. Outcome assessment at 12 months is performed by assessors who are not involved in delivering the intervention and are instructed to remain blinded to group allocation.

The study is minimal-risk and non-invasive. Potential risks include temporary fatigue or coughing during repeated inspiratory maneuvers and the time required for study visits and follow-up calls. The intervention does not involve investigational products or exposure to radiation. Data are collected according to Swiss data protection regulations using coded identifiers and secure REDCap databases.

By evaluating inhaler technique and inspiratory flow in a structured, standardized manner, this study aims to provide new evidence on how to improve inhaler use in COPD. Results may support more personalized device selection, enhance patient education practices, and reduce COPD exacerbations and associated healthcare burden. The findings may be applicable to a wide range of outpatient settings and could inform future guidelines on inhaler optimization in chronic respiratory diseases.

Inclusion Criteria:

1. Age ≥18 years
2. COPD confirmed by spirometry (FEV1/FVC <0.7)
3. Current use of at least one maintenance inhaler
4. Follow-up at the outpatient pneumology clinic of HFR Fribourg
5. Ability to provide written informed consent

Exclusion Criteria:

1. Inability to provide informed consent (e.g. severe cognitive impairment, advanced psychiatric disorder, unresolved language barrier)
2. Life expectancy <12 months
3. Predominant other chronic lung disease (e.g. asthma, fibrosis)
4. Any condition preventing completion of study procedures
5. Ongoing participation in another interventional trial on inhaler technique

De-identified individual participant data underlying the published results will be made available upon reasonable request after publication of the primary study results. The study protocol, informed consent form, statistical analysis plan, and analytic code will also be available upon reasonable request. Requests should be directed to the corresponding investigator and will be reviewed in accordance with institutional policies and applicable Swiss data protection regulations.

De-identified individual participant data and supporting documents will be available beginning 6 months after publication of the primary study results and will remain available for at least 5 years thereafter upon reasonable request.

Access to de-identified individual participant data and supporting documents (study protocol, statistical analysis plan, informed consent form, and analytic code) will be granted to qualified researchers whose proposed use of the data is methodologically sound and consistent with the aims of the study. Requests should be directed to the corresponding investigator and will be reviewed by the study team in accordance with institutional policies and applicable Swiss data protection regulations. Data will be shared in a de-identified format after approval of a data access request and, if required, after signature of a data sharing agreement.