A device for sampling exhaled air of a patient is provided. The device comprises an endotracheal tube and a sampling probe for sampling exhaled air of a patient. The endotracheal tube comprises a ventilation passageway, a proximal end to be connected to a connection hub and a distal end to be placed inside a patient oropharyngeal cavity. The sampling probe comprises a sampling conduit and is mounted within the endotracheal tube. The sampling probe comprises a proximal end adapted to be connected to a fluid analyser and a distal end adapted to receive samples of the exhaled air, such that the probe is adapted to convey the samples to the fluid analyser and wherein such distal end is placed at or near the distal end of the endotracheal tube. The distal end of the sampling probe is arranged separate from the inner wall of the endotracheal tube and wherein the internal diameter of the sampling conduit is equal to or less than 3 millimeters. Systems and methods for sampling exhaled air of a patient are also provided.