Proportional solenoid valve respirator for better assistance in patient ventilation

Mechanical ventilatory support is normally required in patients suffering from respiratory diseases. The present conventional ventilation systems in the hospitals will supply either a preset amount of air or a given air pressure to the patients. They do not take into consideration the patient’s breathing patterns and varying requirements during each inspiration. Proportional Assist Ventilation (PAV) has recently been proposed as a mode of synchronized partial ventilatory support, by applying airway pressure in proportion to inspired volume and flow to overcome higher respiratory system elastance and resistance respectively as a consequence of pulmonary diseases. During supported ventilation, the total pressure applied to the respiratory system is the sum of positive airway pressure and the pressure generated by the respiratory muscles. A Macedonian engineering company has been testing the PAV system and managed to develop a prototype of a smart respirator using a so-called proportional solenoid valve to control air delivery from a pressurized air source. To verify whether the breathing simulator does mimic the human respiratory system, a group of spontaneous tests was conducted to determine the response of tidal volume to different values of resistance, elastance, and effort. These tidal volumes would be used as the normal breathing consequences in support of subsequent PAV performance tests. To determine the influence of the airway resistance to spontaneous breathing, the response of the tidal volume to different resistances was tested under a given elastance and patient effort combination. In these tests, various elastance and patient effort combinations were used. The test results on the breathing simulator demonstrated that the proportional solenoid valve is suitable for air pressure and flow control in a PAV system. When PAV is switched on, flow patterns of patients with abnormal resistance and weak effort could be normalized by selecting suitable values for the system’s technical characteristics. Pressure ‘run-away’ can be prevented by incorporating a back-up safety mechanism in the control program, thus, ensuring the safe operation of the PAV system. The prototype also places the bag valve mask (or Ambu bag), commonly used manually, into a hermetic box in which air comes under pressure. The pressure is then distributed evenly on the surface of the Ambu bag and by controlling the existing pressure and flow, directly affects the extruded air inside the bag. The company has produced several prototypes to be field tested in the hospitals and ambulance vehicles at the national market. Efforts are also placed on securing necessary certification of the product as a medical device, to be done abroad due to the lack of authorized body in the country. The company is looking for technological partners interested in further development of the product and its joint placement on the international market. The potential partners will be able to benefit from the unique propositions of the respirator, whereas the Macedonian engineering company will secure necessary support for the product development and market placement processes.