Recognition of Early Pulmonary Structural Changes by Using Real-time High Fidelity Expiratory CO2 Analysis

January 19, 2026 updated by: Medical University of Graz
In this study the investigators aim to detect and characterize structural airway and lung vessel changes due to COPD or ILD as assessed by real-time high fidelity expiratory CO2 analysis. The long-term goal is to detect pulmonary structural changes in a stage, when variables of currently used standard methods (e.g. pulmonary function test) are not yet altered.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide and is responsible for over 6% of all-cause mortality. Due to aging societies and exposure to risk factors, increasing prevalence is expected in the following years. Cigarette smoking is the most important risk factor for COPD, but also non-smokers may develop the disease. Although COPD is primarily seen as obstructive airway disease, it may also affect the lung parenchyma, the lung vessels, the systemic vessels, the heart and other organs. Therefore, COPD may be seen as a "pulmonary component of a systemic disease ". According to recent evidence patients with COPD and relevant lung vessel disease are at a higher risk to develop exacerbations and have worse prognosis. Usually, COPD patients suffer from a mild pulmonary hypertension, however some of them may present with a "pulmonal vascular phenotype" (PVP). Patients with PVP usually suffer from a relatively mild airway obstruction and are characterized by pathological changes in the small lung vessels, strongly elevated pulmonary vascular resistance, severely reduced diffusion capacity, normo- or hypocapnia, circulatory limitation of exercise capacity and a progressive right heart failure. Early recognition and therapy of COPD may stop further progression of the disease and the development of complications including changes in the small lung vessel.

Interstitial lung diseases (ILD) are characterized by structural changes in the lungs with fibrotic destruction and loss of alveolar tissue. Male gender and smoke exposure are frequent risk factors. At the time of diagnosis, patients are usually in an impaired physical condition suffering from severe symptoms and advanced functional limitation. In a subgroup of patients, a severe lung vessel disease is present further worsening prognosis. Although in the past few years major improvements in the therapy of some forms of ILD have been achieved, the available drugs are not curative. Their aim remains to slow down disease progression. Therefore, an early detection of ILDs may help to initiate targeted treatment on time and improve the prognosis of patients.

Structural pulmonary changes both due to COPD or ILD result in a loss of small airways and small lung vessels, which are not detectable with standard pulmonary function tests until 50% of the small airways disappeared. Although these changes may also take place due to physiological lung-aging, in smokers this effect is clearly accelerated. Diffusion capacity (DLCO) and the so-called Krogh factor (KCO) are sensible markers of early pulmonary structural changes. In addition, lung density as assessed by high-resolution CT-scan and analyzed by specific software represents a sensitive tool. Pulmonary vascular resistance (PVR) and pulmonary vascular compliance are sensitive parameters for the detection of pulmonary vascular changes.

Similar to DLCO, high fidelity analysis of expiratory CO2-flow measurement may allow a sensitive detection of structural pulmonary changes. The method has the advantage that no extrinsic gas is needed. The aim of this explorative pilot study is to investigate if high fidelity expiratory CO2-analysis is able to detect early pulmonary structural changes, even before it can be assessed by pulmonary function testing (e.g. FEV1 or vital capacity).

Study Type

Interventional

Enrollment (Actual)

40

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
    • Styria
      • Graz, Styria, Austria, 8036
        • Department of Internal Medicine, Pulmonology

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • all male and female patients older than 18 years who have COPD, ILD or are smokers and non smokers without pulmonary diseases.
  • right heart catheterization performed due to to suspected pulmonary hypertension and further clinical investigation like echocardiography, lung function testing, 6-minute walk test, laboratory testing and blood gas analysis.
  • written informed consent

Exclusion Criteria:

  • contraindication for lung function testing
  • acute life-threatening disease (including acute myocardiac infarction, pulmonary embolism, large aortic aneurysma, pneumothorax, opthalmic, brain, abdominal or thoracic surgery within the last 4 weeks, hemoptysis).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: COPD patients
Diagnostic test: single high-fidelity expiratory CO2 analysis
in addition to regular pulmonary function testing a real-time high-fidelity assessment of expiratory CO2 will be performed
Other: ILD patients
Diagnostic test: single high-fidelity expiratory CO2 analysis
in addition to regular pulmonary function testing a real-time high-fidelity assessment of expiratory CO2 will be performed
Other: non-smoker controls
Diagnostic test: single high-fidelity expiratory CO2 analysis
in addition to regular pulmonary function testing a real-time high-fidelity assessment of expiratory CO2 will be performed
Other: smoker controls
Diagnostic test: single high-fidelity expiratory CO2 analysis
in addition to regular pulmonary function testing a real-time high-fidelity assessment of expiratory CO2 will be performed

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
change in partial pressure of CO2 (in mmHg) during expiration
Time Frame: 1 day
the change in real-time high-fidelity partial pressures of CO2 (in mmHg) during expiration will be compared among groups
1 day

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of Graz

Investigators

  • Principal Investigator: Horst Olschewski, Prof., Devision of Pulmonology, Medical University Hospital of Graz, Austria

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 1, 2020

Primary Completion (Actual)

March 1, 2025

Study Completion (Actual)

March 1, 2025

Study Registration Dates

First Submitted

August 4, 2021

First Submitted That Met QC Criteria

October 11, 2021

First Posted (Actual)

October 25, 2021

Study Record Updates

Last Update Posted (Actual)

January 21, 2026

Last Update Submitted That Met QC Criteria

January 19, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ID 7684

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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