# Quantification of smoking-related airway remodelling in COPD, using N-Tidal

## TL;DR

This study shows that capnography can track how smoking affects airway changes in COPD, with a key tipping point around 25 pack years.

## Contribution

The study identifies a non-linear dose-response relationship between smoking and airway remodelling in COPD using capnography.

## Key findings

- Waveform features from capnography correlate strongly with pack year smoking history.
- A non-linear association peaks around 25 pack years, suggesting a critical threshold for lung function decline.
- Capnography can quantify smoking-related airway remodelling in COPD patients.

## Abstract

Tobacco smoking is the primary cause of chronic obstructive pulmonary disease (COPD) globally. Capnography data was collected twice daily for up to 6 months from 147 COPD participants across multiple studies using TidalSense’s N-Tidal device. Waveform features from the alpha angle region of the capnogram showed strong association with pack year history, indicating that capnography can quantify a dose-response relationship between smoking exposure and airway remodelling. This non-linear association reached an inflection around 25 pack years, potentially indicating a ‘tipping point’ beyond which the likelihood of retaining normal lung function significantly diminishes. This provides valuable mechanistic insights and could help estimate disease risk and support early preventative interventions.

Trial registration ClinicalTrials.gov NCT02814253 (registered on 27 June 2016), ClinicalTrials.gov NCT03615365 (registered on 3 August 2018), ClinicalTrials.gov NCT04939558 (registered on 25 June 2021).