Validation of the Use of the Arteriovenous Tension Difference in CO2 Under Hyperbaric Conditions

NCT07492030 | Not Yet Recruiting

• 2 other identifiers: 2025_0047IDRCB
• Study Type: observational
• Target: 74
• Locations: 1 country
• Sites: 1

Brief Summary

The central venous-arterial carbon dioxide tension difference is used daily in intensive care to establish peripheral tissue hypoperfusion, mainly mediated by a low cardiac index. The partial pressures of gases (oxygen, carbon dioxide) increase in the blood of patients breathing 100% oxygen in hyperbaric conditions. Thus, the validity of this biomarker in situations of acute circulatory failure during a hyperbaric oxygen therapy session has not been established. The objective of the study is therefore to establish the diagnostic performance of the central venous-arterial carbon dioxide tension difference in the diagnosis of a low cardiac index in patients with septic shock undergoing hyperbaric oxygen therapy for necrotizing fasciitis.

Conditions

Necrotizing Fascitis; Cellulitis; Septic Shock

Keywords

HBO; gapCO2; necrotizing fascitis; cellulitis; cardiac index

Outcome Measures

Primary Outcomes (1)

• Area under the receiver operating characteristic (ROC) curve constructed from central venous-arterial carbon dioxide tension difference measurements

  used to define low cardiac output measured as a cardiac index \< 2.2 L/min/m² by cardiac echocardiography under hyperbaric oxygenation conditions after 15 min at the maximum treatment pressure of 2.5 ATA under FIO2 at 1 (T1) Maximum treatment pressure i.e., 2.5 ATA under FIO2 at 1

  After 15 minutes at maximum treatment pressure (T1)

Secondary Outcomes (4)

• Evaluate the concordance at different time points (T0, T1, T2, and T3) between the definition of low cardiac output by cardiac index <2.2 L/min/m² (gold standard) and the Pvc-aCO2 value according to the threshold of 6 mmHg.

  After 15 minutes at ambiant pressure in the hyperbaric chamber (T0), after 15 minutes at 2.5 ATA under FIO2 at 1 (T1), after 75 minutes following the start of the session (T2), and 15 minutes after the end of HBOT session (T3)

• Compare cardiac index values measured at T0, T1, T2, and T3 according to three pre-specified groups classified according to Pvc-aCO2 values established by Ospina-Tasco´n et al.: < 6 mmHg; (2) 6.0-9.9 mmHg; (3) ≥ 10 mmHg.

  After 15 minutes at ambiant pressure in the hyperbaric chamber (T0), after 15 minutes at 2.5 ATA under FIO2 at 1 (T1), after 75 minutes following the start of the session (T2), and 15 minutes after the end of HBOT session (T3)

• Evaluate the performance of transcutaneous oximetry variations from the subclavian reference electrode after passive leg raising, a non-invasive procedure, as a diagnostic tool for preload dependence.

  After 15 minutes at maximum treatment pressure (T1)

• Describe clinical parameters related to blood pressures, echocardiographic data and respiratory mechanics changes induced in patients admitted for necrotizing fasciitis complicated by septic shock under hyperbaric oxygen therapy.

  After 15 minutes at ambiant pressure in the hyperbaric chamber (T0), after 15 minutes at 2.5 ATA under FIO2 at 1 (T1), after 75 minutes following the start of the session (T2), and 15 minutes after the end of HBOT session (T3)

Study Arms (1)

Adult patients diagnosed with necrotizing fasciitis and receiving OHB

Adult patients diagnosed with necrotizing fasciitis and receiving OHB treatment for the first time will be offered participation in the study if they meet the following inclusion criteria: * Diagnosis of necrotizing fasciitis complicated by septic shock as defined by the Surviving Sepsis Campaign * Indication for HBOT according to the criteria of the 2016 European Consensus Conference * Patient intubated and ventilated prior to the HBOT session, receiving intravenous sedation at doses sufficient to be in a passive ventilation state * Patient equipped with a central venous line in the superior vena cava allowing central venous blood gas analysis * Patient with an arterial catheter allowing arterial blood gas analysis

Other: Echography

Interventions

Echography OTHER

Cardiac output is estimated by taking three measurements of the time-velocity integral using pulsed Doppler at the level of the left ventricular outflow tract, known as the subaortic time-velocity integral (TVI). The systolic ejection volume is calculated by multiplying the subaortic TVI by the area of the aortic outflow tract diameter. Cardiac output is calculated by multiplying this systolic ejection volume by the patient's heart rate. The cardiac index is calculated by dividing cardiac output by the patient's calculated body surface area. Blood gas sampled from central arterial and venous catheters at the four stages of the experimental plan Cardiac output and blood gases will be measured: * After 15 minutes of ventilation on a hyperbaric ventilator at ambient pressure in the chamber with FIO2 equivalent to that of the intensive care unit (T0). * After 15 minutes at maximum treatment pressure, i.e., 2.5 ATA under FIO2 at 1 (T1) * After 75 minutes at the plateau following the star

Adult patients diagnosed with necrotizing fasciitis and receiving OHB

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult patients diagnosed with necrotizing dermo-hypodermitis who are receiving OHB treatment for the first time at the Regional Hyperbaric Oxygen Therapy Center at Lille University Hospital, a tertiary referral center where complementary hyperbaric oxygen therapy treatment for necrotizing dermo-hypodermitis in the Hauts-de-France region is centralized.

You may qualify if:

• Diagnosis of necrotizing fasciitis complicated by septic shock as defined by the Surviving Sepsis Campaign
• Indication for HBOT according to the criteria of the 2016 European Consensus Conference
• Patient intubated and ventilated prior to the HBOT session, receiving intravenous sedation at doses sufficient to be in a passive ventilation state
• Patient equipped with a central venous line in the superior vena cava allowing central venous blood gas analysis
• Patient with an arterial catheter allowing arterial blood gas analysis

You may not qualify if:

• \- Minors
• Pregnant women
• Persons deprived of their liberty (prisoners, persons under guardianship or trusteeship)
• Persons not affiliated with or not covered by a social security system
• Patients on spontaneous ventilation
• Patients without an echocardiographic assessment window (anechoic)
• Severe ARDS according to the Berlin classification
• Technical impossibility of sampling central arterial or venous blood
• Absolute contraindication to hyperbaric oxygen therapy (undrained pneumothorax, unstable angina or acute myocardial infarction, severe asthma attack)
• Relative contraindication to hyperbaric oxygen therapy
• Respiratory: Chronic respiratory failure, severe pulmonary emphysema
• Circulatory: Rhythm or conduction disorders
• Neurological: uncontrolled epilepsy
• ENT: sinusitis, otitis, chronic rhinitis; laryngocele; acute otitis media; osteospongiosis
• Ophthalmic: retinal detachment

Sponsors & Collaborators

• University Hospital, Lille: lead
• Santelys Association: collaborator
• HyperbaricCare: collaborator

Study Sites (1)

Centre d'Oxygénothérapie Hyperbare du CHU de Lille

Lille, 59037, France

Location

Biospecimen

Retention: SAMPLES WITHOUT DNA

Whole blood samples taken from arterial and central venous catheters during four experimental phases.

MeSH Terms

Conditions

Fasciitis, Necrotizing; Cellulitis; Shock, Septic

Interventions

High-Energy Shock Waves

Condition Hierarchy (Ancestors)

Fasciitis; Musculoskeletal Diseases; Skin Diseases, Infectious; Infections; Suppuration; Connective Tissue Diseases; Skin and Connective Tissue Diseases; Inflammation; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Sepsis; Systemic Inflammatory Response Syndrome; Shock

Intervention Hierarchy (Ancestors)

Ultrasonic Waves; Sound; Radiation, Nonionizing; Radiation; Physical Phenomena

Central Study Contacts

Nicolas DOGNON, Doctor

CONTACT

33 3 20 44 55 50; nicolas.dognon@chu-lille.fr

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 10, 2026
• First Posted: March 25, 2026
• Study Start: June 15, 2026
• Primary Completion (Estimated): September 15, 2027
• Study Completion (Estimated): March 15, 2028
• Last Updated: May 14, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

FR (1)