Transcutaneous CO₂ Therapy in Recurrent Hard-to-Heal Diabetic Foot Ulcers

February 22, 2026 updated by: Igor Frangez, University Medical Centre Ljubljana
Recurrent and hard-to-heal diabetic foot ulcers (DFUs) represent a clinically challenging subgroup with delayed closure and frequent non-response to standard of care (SOC). Impaired local perfusion and superficial tissue hypoxia, commonly attributed to microcirculatory dysfunction, are proposed contributors to impaired wound-bed progression and prolonged healing trajectories in diabetes. Transcutaneous gaseous carbon dioxide (CO₂) therapy is a non-invasive adjunct intervention with a mechanistic rationale to modulate local microcirculation and tissue oxygenation; however, controlled clinical evidence in recurrent, hard-to-heal DFUs remains limited. This prospective, randomized, controlled, open-label, parallel-group clinical investigation compares transcutaneous CO₂ therapy plus SOC versus SOC alone over 4 weeks. The primary objective is to determine whether the proportion of completely healed DFUs at Week 4 differs between groups under a predefined healing confirmation procedure. Key secondary objectives include quantifying changes in superficial tissue oxygenation (StO₂) using hyperspectral imaging and assessing pain intensity (NPRS). Supportive outcomes include ulcer area reduction metrics and wound-bed appearance in unhealed.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

  • Slovenia
    • Slovenia
      • Ljubljana, Slovenia, Slovenia, 1000
        • UMC Ljubljana

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • diabetes mellitus type 1 or 2
  • recurrent hard to heal DFU

Exclusion Criteria:

  • KOPD stage IV
  • CKD stage IV
  • malignant diseases
  • pregnancy
  • infected ulcer at baseline
  • inability to comply with visits

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Standard of care + CO2 therapy
Standard of care (3 times weekly) + transcutaneous gaseous CO2 therapy 20 times (every weekday for 50 minutes)
Other: transcutaneous application of gaseous CO2 on lower part of the body
Participants in the intervention group received SOC alongside 20 sessions of CO₂ therapy. These 50-minute sessions were administered once daily on weekdays (Monday-Friday) over a 4-week period. CO₂ therapies were performed using the medical device. The participant's lower body was sealed in a single-use, biocompatible, medical-grade wrap. The wrap was filled with medical-grade CO₂ to a 99.9% concentration for a 50-minute session. After 50 minutes, CO₂ was pumped out and the wrap removed.
No Intervention: Standard of care
Standard of care (3 times weekly)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
complete ulcer healing
Time Frame: 4 weeks
full epitelization without exudate confirmed at 2 consecutive exams
4 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
change in StO2
Time Frame: 4 weeks
StO₂ (%) will be measured using Hyperspectral Imaging (by TIVITA HSI device) at baseline and weeks 1, 2, 3, and 4. The outcome is change from baseline in StO₂ (%). Higher values indicate better tissue oxygenation/perfusion.
4 weeks
change in pain intensity (NPRS)
Time Frame: 4 weeks
Change from baseline in pain intensity assessed by the Numeric Pain Rating Scale (NPRS)Outcome Measure Description: Pain intensity will be self-reported using the Numeric Pain Rating Scale (NPRS), an 11-point scale from 0 = no pain to 10 = worst imaginable pain. The outcome is change from baseline in NPRS score at week 4.
4 weeks

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Medical Centre Ljubljana

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

  • Finzgar, M., Melik, Z., in Cankar, K. (2015). Effect of transcutaneous application of gaseous carbon dioxide on cutaneous microcirculation. Clinical Hemorheology and Microcirculation, 60(4), 423-435. https://doi.org/10.3233/CH-141898
  • Macura, M., Ban Frangež, H., Cankar, K., Finžgar, M., in Frangež, I. (2020). The effect of transcutaneous application of gaseous CO2 on diabetic chronic wound healing-A double-blind randomized clinical trial. International Wound Journal, 17(5), 1182-1190. https://doi.org/10.1111/iwj.13436

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 20, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 30, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 10, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 10, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 18, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 22, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NM-DVS-CO2

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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