Disclosed is a device for respiratory assistance and a measurement system that includes the device. The device includes a tube, which forms a main channel, and at least one auxiliary channel connected to a source of respiratory gas. The device further includes a unit by which vitiated gas, exhaled by a patient, is removed from the patient between a distal end of the auxiliary channel, which opens into the main channel, and a distal end of the main channel, and which is configured to capture and remove the exhaled gas, undiluted by insufflated fresh respiratory gas.
