An endotracheal tube includes a flexible hollow tube having a constant outer diameter and a distal inflatable cuff configured to extend across a patient's vocal cords. The cuff defines a reduced-diameter central portion positioned at the vocal cords and enlarged proximal and distal portions that seal above and below the vocal cords, accommodating varying tracheal anatomies. The tube includes a ventilation passageway and a separate inflatable cuff lumen extending within the tube and fluidly isolated from the ventilation passageway. The cuff lumen communicates with the cuff through a distal aperture to enable controlled inflation. The configuration improves cuff sealing, reduces trauma to the vocal cords, and facilitates use of a single tube size across a range of patients.