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

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 detach…