An endotracheal tube for mechanically ventilating patients is disclosed. The endotracheal tube comprises a distal end for insertion into the patient's airway, past the vocal chords, through the subglottal region, and into the patient's lung; and a proximal end for connection to a mechanical ventilator. The endotracheal tube further comprises a cuff at the distal end of the endotracheal tube to be located in the subglottal region of the patient below the vocal chords, an inflating lumen for inflating the cuff, and a suction lumen having a suction inlet port leading from the outer surface of the endotracheal tube, and to be located in the subglottal region, for evacuating secretions and/or rinsing fluid from the subglottal region during the mechanical ventilation of the patient. The distal end of the endotracheal tube is formed with an outer surface configuration effective to prevent blockage of the suction inlet port by the cuff or by tracheal mucosal tissue of the patient during a negative pressure condition in the suction lumen.