The research is designed to evaluate influence of transcutaneous application of CO2 (carbon dioxide) on chronic wound healing. Transcutaneous application of CO2 is known to have immediate effect on vasodilatation and elevates oxygen release from Hb via the Bohr effect. After repetition of the therapies neoangiogenesis is induced. Impairment of microcirculation is one of the causes of impared wound healing and improvement in circulation could have positive effect on wound healing, reduction of the wound area and granulation of the wound bed (Falanga score).

Transcutaneous application of gaseous CO2 showed to be a successful adjuvant therapy in treatment of chronic wounds in diabetic patients (PMID: 32633896). In this intervention technique, therapeutic concentrations of medical-grade CO2 are applied to the skin's surface in a safe, non-invasive manner. The main therapeutic mechanism is derived from the human body's natural response to locally increased CO2 concentration. Because vasodilatory capacity is impaired in diabetic foot, these mechanisms enhance local microvascular perfusion, thereby improving tissue oxygenation in patients with DFUs. Furthermore, although the researchers primarily focus on CO2 therapy as an intervention method, its efficacy is also suggested in preventing DFUs. We plan to enrole 120 patients, 80 into the study arm that will recieve CO2 therapy and 40 for a control group wothout CO2 therapy. All 120 patienrs will receive standard wound care. Aditionally, only study group will receive 20 treatments with CO2 (each workday for 4 weeks). Lower part of the body will be inserted into therapeutic wrap that is filled with 99.9% CO2 gas for 50 minutes. In both groups investigator will evaluate wound status (size, Falanga score of the wound bed) before first and after 4 weeks of treatment. Main outcome measure will be ratio of the completely heald wounds, reduction of the wound size in non healed wounds and status of the wound bed in non healed wounds after 4 weeks of treatment. Possible side effects of the CO2 therapy will be monitored.

Inclusion Criteria:

• confirmed diagnosis of DM Type 1 or Type 2,
• confirmed diagnosis of a non-healing DFU without clinical signs of infection,
• being able to provide informed consent for the participation, and

Exclusion Criteria:

• patients with severe comorbidities: deep vein thrombosis, chronic kidney diseases grade III and IV, chronic heart diseases NYHA (New York Heart Association) III and IV, patients with known malignant diseases, patients with progressive infection, signs of systemic infection with elevated inflammatory markers or osteomyelitis