Proof-of-concept Study on Dyspnea Analysis Via GapCO2

Inclusion Criteria: * Age ≥ 18 years * Patient presenting with acute dyspnea defined by a sensation of respiratory discomfort with at least one of the following criteria: RR ≥ 22 and/or SpO2 \< 95% * Arterial blood gas sampling performed as part of care * Inclusion less than 1 hour after arrival time to the emergency department * Non-opposition to participation in the study Exclusion Criteria: * Temperature greater than or equal to 37.5°C * Patient who has already received a diuretic or vasodilator treatment in the emergency department or by a prehospital medical team * Systolic blood pressure less than or equal to 100 mmHg and/or signs of peripheral hypoperfusion * Inability to express refusal to participate in the study