Patent ID: 8066003

Claim:
A method for improving tidal volume detection precision which is used in medical devices for affecting the breathing system of patient, characterized in that it includes the following steps: a) a processing unit ( 1 ), through the driving of a valve, drives an airway system to alternatively enter an inspiration period and an expiration period so as to operate the airway system, and controls an opening position of an inspiratory valve ( 3 ) during the inspiration period; b) at an end phase of the expiration period, depending on the airway pressure transmitted in real-time by an airway pressure sensor within a respiratory period, the processing unit ( 1 ) calculates peak pressure and PEEP value, and at the same time calculates the value of ΔV, the variation of tidal volume, depending on the flow rate values transmitted in real-time by flow rate sensors ( 7 and 8 ); and c) the processing unit ( 1 ) calculates the tidal volume V T actually obtained at the patient terminal during a current respiratory period, using the formula V T =ΔV×(C−Ctube)/C, wherein C is system compliance, Ctube is the compliance C of a line, and calculates the tidal volume V T ′ which the airway is intended to reach for the next expiration period, using the formula V T ′=ΔV T +ΔV T ×K, wherein K is a scaling factor for control and adjustment, ΔV T =V T set−V T , V T set is the presetted tidal volume, and the processing unit accordingly controls the opening position of the inspiratory valve ( 3 ) during a next inspiration period.