Abstract: A pressure regulator includes a container defining a variable volume chamber having a least one first orifice to be connected to an auxiliary hose such that, in use, the variable volume chamber of the pressure regulator and a sealing cuff are in communication. The regulator includes a pressure means acting on the container for exerting a certain force by means of a weight that can move along an articulated rod for adjusting the air pressure contained in the variable volume chamber. A system for locking the weight is provided for preventing unexpected movement of the weight. The invention is applicable to endotracheal tubes, tracheotomy tube or similar instruments for the ventilation of a patient.