Digital inhaler captures changes in physiologic metrics before COPD exacerbation

Between 14 days and 1 day out from an acute exacerbation of COPD, a digital inhaler measured significant drops in inhalation volume, inhalation duration and time to peak, according to study findings.

This research was published in Chronic Obstructive Pulmonary Diseases: Journal of the COPD Foundation.

"This study demonstrates that digital inhalers can provide real-time physiologic and medication use data that may allow clinicians to identify acute exacerbations of COPD (AECOPDs) earlier, potentially improving outcomes through earlier intervention," M. Bradley Drummond, MD, MHS, professor of medicine in the division of pulmonary diseases and critical care medicine at the University of North Carolina, Chapel Hill School of Medicine, told Healio. "For busy clinicians, this has the potential to offer a tool to remotely monitor high-risk COPD patients."

"Importantly, it suggests a shift toward using objective digital markers (like inhalation volume or time to peak) alongside traditional symptom reporting to guide management decisions and preempt exacerbations," Drummond continued.

Study Design

In an open-label, phase 4 pilot study, Drummond and colleagues analyzed 40 current smokers (mean age, 62.5 years; 48% women; 83% white; mean FEV1, 46.1% predicted) with ambulatory COPD using the ProAir Digihaler (Teva Pharmaceutical Industries) for primary rescue medication to uncover what physiologic and inhaler use metrics change before a patient experiences an AECOPD.

"The study was prompted by the clinical need for better early detection of AECOPD, which are common, serious events that accelerate lung function decline, reduce quality of life and increase mortality," Drummond told Healio.

Patients used the ProAir Digihaler for at least 30 days to up to 3 months, resulting in a total of 9,649 inhalations, according to the study. Over this time period, the inhaler captured five metrics:

1. Peak inspiratory flow

2. Inhalation volume

3. Inhalation duration

4. Time to peak inhalation

5. Inhaler use

"While wearable devices can track heart or respiratory rate, they don't capture early lung function changes directly," Drummond said. "Previous studies showed potential for digital inhalers to track medication use and technique, but their utility in predicting COPD exacerbations had not been fully explored."

In addition to collecting digital inhaler metrics, researchers noted that included patients completed the COPD Assessment Test, reported average albuterol/short-acting beta2-agonist use and reported AECOPD events that resulted in receipt of "treatment with antibiotics and/or steroids or hospitalization" over the phone at the 1-month mark. Most patients also did this at the 2-month and 3-month marks.

Results

In the assessed population, 23 AECOPD events were reported by 15 patients.

Compared with the average values recorded for each metric on the 14th day before an AECOPD, Drummond said three metrics changed significantly (P < .02) on the day before an AECOPD:

• Inhalation volume: Dropped from 1.45 L (14 days before) to 1.08 L (day before)

• Inhalation duration: Decreased from 1,876 msec to 1,492.1 msec

• Time to peak: Fell from 500 msec to 376.27 msec

Notably, researchers reported that SABA use steadily rose from 2.7 to 4.2 inhalations/day between the 14th and fifth day before an AECOPD, fell to 3.5 inhalations/day on the fourth day before and three inhalations/day on the third day before, and went back up in the 2 days before the AECOPD (2 days before, 4.1 inhalations/day; day before, 3.7 inhalations/day).

"These physiologic changes occurred before the sharp rise in rescue inhaler use, suggesting patients may perceive symptoms after physiologic changes begin," Drummond told Healio.

The remaining two metrics — peak inspiratory flow and daily number of inhalations — did not significantly differ when assessing the averages on the 14th day before vs. the day before an AECOPD, according to the study.

Between self-reported SABA use and ProAir Digihaler-recorded SABA use, Drummond said there was "strong correlation ... which contrasts with prior literature that often shows poor agreement between subjective and objective adherence data."

"This may have been influenced by participants' awareness that their inhaler use was being tracked," Drummond told Healio.

Future Research

Looking ahead, Drummond told Healio there are five items that future studies can address, one of which is a more inclusive study population.

"Future studies will likely include larger, more diverse populations, given this pilot was limited to current smokers and lacked racial diversity," Drummond said.

Other potential topics to focus on moving forward are algorithm development and use of the digital inhaler in combination with other digital health tools, Drummond told Healio.

"[Studies may] focus on algorithm development that combines physiologic data and medication use to predict AECOPDs more accurately and earlier," he said. "[They also could] evaluate integration with other digital health tools, such as wearables or environmental sensors, to provide a fuller picture of exacerbation risk."

Lastly, Drummond told Healio future studies can assess how clinicians interact with the data and how patients react when alerted about changes.

"Studies will likely incorporate real-time clinician access to data dashboards, enabling proactive clinical interventions, [and] explore interventional trials, where alerts based on digital data trigger specific treatment strategies, to test impact on patient outcomes."

Sources/Disclosures

Source:
Drummond MB, et al. Chronic Obstr Pulm Dis. 2025;doi:10.15326/jcopdf.2024.0555.

Disclosures:
Drummond reports receiving grants paid to his institution from the American Lung Association, Boehringer-Ingelheim, Midmark, the NIH, the Patient-Centered Outcomes Research Institute and Vertex, and receiving consulting fees from AstraZeneca, Becker Pharma, Boehringer Ingelheim, GlaxoSmithKline, Strados, Takeda and Verona, all unrelated to this work. This work was supported by a grant from Teva, paid to Drummond's institution. Please see the study for all other authors' relevant financial disclosures.

Topics: COPD, COPD exacerbation, inhaler, ambulatory COPD, technology