Abstract: A reversibly operable motor is mechanically connected to automatically position the piston of an air syringe that is pneumatically connected to the inflatable/deflatable seal ring or cuff of a laryngeal mask airway device (LMA) that is installed in a patient, who is being ventilated and/or anaesthetized via the airway of the LMA device. Ideally, (i) the air at the head end of the syringe, plus (ii) the air contained in the inflatable cuff of the LMA, plus (iii) the air contained in their interconnection, is a “substantially constant” volume which is shared at these three locations but which is automatically shifted by piston displacement, such that air pressure in the substantially constant volume is caused to correct as necessary for conformance to a predetermined level of set-point pressure.