Patent ID: 6142150
Filing Date: 2000-11-07
Classification: A61M

Abstract:
A ventilator comprising:a cylinder assembly comprising a cylinder having an outlet and a shiftable piston therein to deliver gas to the outlet;a patient circuit coupled with the cylinder outlet for conveying cylinder-derived gas to a patient during gas-supplemented inhalations;a PEEP assembly operatively coupled with said cylinder assembly for maintaining a constant pressure within said patient circuit during patient exhalation,said cylinder having varying piston starting positions and effective compliances at the beginning of said gas-supplemented inhalations; anda control circuit operatively coupled with said cylinder assembly and including;a cylinder pressure sensor coupled with said cylinder for sensing the gas pressure therein and providing cylinder pressure signals representative thereof;a patient circuit pressure sensor coupled with said patient circuit for sensing gas pressure therein and providing patient circuit pressure signals representative thereof;a signal processor coupled with said sensors and operable for receiving said pressure signals therefrom, said signal processor operable to determine, using said received pressure signals, a predicted compliance of said cylinder at the end of a gas-supplemented inhalation and a compliance-compensated volume of gas to be delivered by said cylinder assembly for said gas-supplemented inhalation, and to generate an output representative of said compliance-compensated volume of gas; anda controller coupled with said signal processor and cylinder assembly in order to receive said output and operate said cylinder assembly to deliver said compliance-compensated volume of gas, so that the patient receives a desired tidal volume of gas from the cylinder assembly notwithstanding the position of said piston within said cylinder and the compliance of said cylinder at the beginning of said inhalation.