METHOD FOR IMPROVING CONTROL AND DETECTION PRECISION OF TIDAL VOLUME BY A CALCULATION INTRODUCED WITH R VALUE

• US 20090165798A1
• Filed: 12/01/2008
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Beijing Aeonmed Co., Ltd.
• Original Assignee: Beijing Aeonmed Co., Ltd.
• Inventors: CHANG, Fei, CONG, Yumeng, WANG, Wei
• Granted Patent: US 8,066,003 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0866 Passive resistors therefor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit

Abstract

The present invention discloses a method for improving control and detection precision of tidal volume by introducing R value, comprising the steps of: a plateau pressure Pplate is used to calculate a system compliance C with C=ΔV/(Pplate−PEEP); V_T, the tidal volume obtained currently at patient terminal, is calculated with V_T=ΔV×(C−Ctube)/C, wherein ΔV is the variation of tidal volume, PEEP is the positive end expiratory pressure and Ctube is the compliance C of the line. Depending on the calculated V_T, the tidal volume which is actually obtained by the patients during this period, the processing unit calculates the tidal volume V_T′, which the airway is intended to reach during the next expiration period, by V_T′=V_T+ΔV_T×K wherein K is a scaling factor for control and adjustment, V_T is the tidal volume obtained by the patient during the current period, V_Tset is the presetted tidal volume, ΔV_T=V_Tset−V_T. And the processing unit accordingly controls the opening position of the inspiratory valve during the next inspiration period, so as to achieve the purpose of improving control and detection of precision tidal volume.

Claims

1. A method for improving tidal volume detection precision which is used in medical devices for affecting the respiratory system of the patient, characterized in that it includes the following steps:

(a) a plateau pressure Pplate is used to calculate a system compliance C with C=Δ

V/(Pplate−

PEEP);

(b) V_T, the tidal volume obtained actually at the patient terminal is calculated with

V_T=Δ

V×

(C−

Ctube)/C,

Wherein, Δ

V is the variation of the tidal volume, PEEP is the positive end expiratory pressure and Ctube is the compliance C of the line.

2. A method for improving tidal volume detection precision according to claim 1, characterized in that, the plateau pressure Pplate=Ppeak−

R×

L, wherein Ppeak is peak pressure, L is peak flow rate and R is resistance.

3. A method for improving tidal volume detection precision according to claim 1, characterized in that, the medical device is an anesthesia machine or aventilator.

4. 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 a airway system to alternatively enter the inspiration period and the expiration period so as to operate the system, and controls the opening position of a inspiratory valve (3) during the inspiration period;

b) At the end phase of the expiration period, depending on the airway pressure transmitted in real-time by a 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 AV depending on the flow rate values transmitted in real-time by flow rate sensors (7 and 8); and

c) using the method according to claims 1 and 2, the processing unit (1) calculates the tidal volume V_T actually obtained at the patient terminal during the current respiratory period, and calculates the tidal volume V_T′

which the airway is intended to reach for next expiration period, and the processing unit accordingly controls the opening position of the inspiratory valve (3) during the next inspiration period.

5. A method for improving tidal volume detection precision according to claim 4, characterized in that, V_T′

=V_T+Δ

V_T×

K, wherein K is a scaling factor for control and adjustment, V_T is the tidal volume actually obtained by the patient during the current period, V_Tset is the presetted tidal volume, Δ

V_T=V_Tset−

V_T.

6. A method for improving tidal volume detection precision according to claim 5, characterized in that, the medical device includes an anesthesia machine or a ventilator.

7. 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:

Step S101;

an upper computer provides the presetted value VTset of an initial tidal volume;

Step S103;

an processing unit controls the opening position of an inspiratory valve according to the tidal volume;

Step S105;

a plateau pressure Pplate is calculated by Pplate=Ppeak−

R×

L, wherein the resistance R=Δ

P/L=(Ppeak−

Pplate)/L, the peak pressure Ppeak and the peak flow rate L are obtained by the monitoring of the sensor;

Step S107;

a system compliance C is calculated by C=Δ

V/(Pplate−

PEEP) wherein Δ

V is the tidal volume variation and PEEP is the positive end expiratory pressure. Δ

V and PEEP can be obtained through the monitoring of the sensor;

Step S109;

V_T, the tidal volume which is actually obtained by the patients during this period, is calculated by V_T=Δ

V×

(C−

Ctube)/C wherein Ctube is the compliance of the line, which is obtained by self-checking when the machine starts up;

Step S111;

Δ

V_T, the deviation of the tidal volume, is calculated by Δ

V_T=V_Tset−

V_T, wherein V_Tset is the presetted tidal volume, and V_T is the tidal volume actually obtained by the patient during this period;

Step S113;

it is determined whether V_T reaches requirement of precision, wherein if yes, returns to S103, and still operates depending on the tidal volume of the last time, while if no, performs Step S115; and

Step S115;

the tidal volume V_T′

, which the airway is intended to reach for next expiration period, is calculated by V_T′

=V_T+Δ

V_T×

K, wherein K is a scaling factor for control and adjustment, V_T is the tidal volume actually obtained by the patient during the current period, Δ

V_T=V_Tset−

V_T, and returns to Step S103 and the processing unit (1) accordingly controls the opening position of the inspiratory valve (3) during the next inspiration period.

8. A method for improving tidal volume detection precision according to claim 7, characterized in that, the medical device include an anesthesia machine or an ventilator.