Monocentric, prospective, observational and descriptive study on the evaluation of risk factors for alteration of the alveoarterial gradient of CO2 in pre-hospital patients, intubated and then ventilated in an invasive manner; and their impact on intra-arterial fatehospital.

Inclusion Criteria:

• 18 years of age,
• Endotracheal intubation in pre-hospital and mechanical ventilation,
• Monitoring of Etco2 in pre-hospital settings

Exclusion Criteria:

• Identification of a chest wound blowing during pre-hospital care,
• No technical possibility for performing or analysing arterial sampling,
• Death during pre-hospital care,
• A person who has objected to the processing of his data for research at minimal risk and constraints (category 2) or for research on data, as well as persons subject to legal protection measures.

The patients included are the major patients, intubated and ventilated in pre-hospital, transferred by the medical team to the University Hospital of Angers.

The ventilation settings are left to the caregiver's discretion, as is the purpose of Etco2.