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

Use of Central Venous-arterial Carbon Dioxide Tension Difference to Diagnose Low Cardiac Output in Patients With Septic Shock Undergoing Hyperbaric Oxygen Therapy

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.

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

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

Exclusion Criteria:

• - 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