The ratio of the venous-arterial carbon dioxide partial pressure difference to the arteriovenous oxygen content difference (Pv-aCO₂/Ca-vO₂) may be a marker of anaerobic metabolism in patients with acute circulatory failure. This study aims to assess the prognostic value of the PvCO2-PaCO2/CaO2-CvO2 in the early phase of septic shock.

The ratio of the venous-arterial carbon dioxide partial pressure difference to the arteriovenous oxygen content difference (Pv-aCO₂/Ca-vO₂) may be a marker of anaerobic metabolism in patients with acute circulatory failure. This study aims to compare the kinetics of the PvCO2-PaCO2/CaO2-CvO2 ratio with a classic marker of anaerobic metabolism (arterial lactate) in the early phase of septic shock.

Inclusion Criteria:

Patients aged over 18 years presenting with septic shock, defined as sepsis with persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) ≥ 65 mmHg and lactatemia > 2 mmol/L despite adequate fluid resuscitation. Sepsis is defined by the presence of a suspected or confirmed infectious source associated with organ dysfunction (neurological, respiratory, renal, hepatic, or hematological). [Sepsis 3 criteria]

Exclusion Criteria:

• Absence of central venous access.
• Central venous access not positioned in the superior vena cava (e.g., femoral access).

Patients aged over 18 years presenting with septic shock, defined as sepsis with persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) ≥ 65 mmHg and lactatemia > 2 mmol/L despite adequate fluid resuscitation. Sepsis is defined by the presence of a suspected or confirmed infectious source associated with organ dysfunction (neurological, respiratory, renal, hepatic, or hematological). [Sepsis 3 criteria]

Biological, hemodynamic and outcome data.

For 2 years after study completion.