Non-invasive Monitoring of Mixed Venous Oxygen Saturation Using the Capnodynamic Method in Adults

Inclusion Criteria: * Age \> 18 years * Not participating in any other interventional study at the time of the study. * Patients under controlled mechanical ventilation in passive conditions. * Situations where the responsible physician deems that, for the benefit of clinical management and therapeutic decision-making, the patient would benefit from the placement of a pulmonary artery catheter (Swan-Ganz) and/or monitoring of central or mixed venous saturation. * Obtaining informed consent. Exclusion Criteria: * Failure to obtain informed consent. * No need for invasive mechanical ventilation.