APPARATUS, METHOD, SYSTEM AND COMPUTER PROGRAM FOR LEAKAGE COMPENSATION FOR A VENTILATOR

• US 20100024819A1
• Filed: 06/20/2006
• Published: 02/04/2010
• Est. Priority Date: 06/21/2005
• Status: Abandoned Application

• Current Assignee: Breas Medical Ab (Shanghai Fosun Pharmaceutical (Group) Co., Ltd.)
• Original Assignee: Breas Medical Ab (Shanghai Fosun Pharmaceutical (Group) Co., Ltd.)
• Inventors: Tiedje, Mikael
• Application Number:
  US11/993,148
• Publication Number:
  US 20100024819A1
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/10 Electroencephalographic signals

Abstract

A ventilator apparatus, method, system, and computer program for determining leakage in a flow circuit providing pressurized gas to a patient having breathing disorder. The present invention determines the leakage by calculating a ratio between a measured flow of gas and a determined flow of gas related to a standard leakage. The determined standard leak flow may be calculated from a formula derived from Bernoulli'"'"'s theorem. The invention may further be arranged to use a volume difference between inspiration and expiration phases in the compensation process.

Claims

1. A ventilator for supplying pressurized breathing gas, comprising:

a flow generator for producing pressurized breathing gas to be delivered to an interface;

a first interface connected to said flow generator and arranged to receive said pressurized breathing gas from said flow generator and to deliver said pressurized breathing gas to a patient; and

at least one second interface connected to a processing unit and adapted to receive at least one signal indicative of the flow of pressurized breathing gas from the patient and to deliver the signal to said processing unit, said processing unit for controlling the pressure from the ventilator based on the signal indicative of the flow of said pressurized breathing gas received from said second interface, characterized in that wherein said processing unit is arranged to compensate for leakage in said ventilator using a ratio between said measured flow of pressurized breathing gas and a flow related to a reference standard leak.

2. A ventilator according to claim 1, wherein said at least one first interface for receiving at least one signal indicative of the flow of pressurized breathing gas is located in said ventilator.

3. A ventilator according to claim 1, wherein said processing unit further comprises a computational device adapted to calculate said mass flow for a standard leak using a formula derived from Bernoulli'"'"'s equation, said formula being:

$m={\int <br><br>}_{A_c}<br><br>\mathrm{\rho <br><br>}<br><br><br><br>u<br><br>\left(r,x\right)<br><br><br><br><br><br>\mathrm{Ac}$

where m is the mass flow through a pipe, r the volume density of the fluid in the pipe, u(r,x) the velocity profile for the fluid in the pipe and Ac the cross sectional area for the flow, and where said calculated mass flow is divided by pressure for said pressurized breathing gas to obtain a normalized mass flow.

4. A ventilator according to claim 1, wherein said computational device is adapted to retrieve values for said standard reference leak flow from a table of values representing said standard reference leak flow values at a certain pressure for the pressurized breathing gas.

5. A ventilator according to claim 1, wherein said processing unit means additionally comprises a data storage unit for later analysis and inspection of the measured signals indicative of the instantaneous mass flow for the pressurized breathing gas, the physiological state of the patient and said ratio between the measured signal indicative of the instantaneous mass flow for the pressurized breathing gas and a standard reference leak flow.

6. A ventilator according to claim 1, wherein said processing unit additionally comprises a first communication device for communicating with an external sensing device.

7. A ventilator according to claim 1, wherein said processing unit further comprises a second communication device for communication with the ventilator from an external computational device for retrieving data and results for analysis and/or inspection.

8. A ventilator according to claim 7, wherein said first or second communication devices may be a wired or a wireless communication device.

20. A ventilator according to claim 2, wherein said processing unit further comprises a computational device adapted to calculate said mass flow for a standard leak using a formula derived from Bernoulli'"'"'s equation, said formula being:

$m={\int <br><br>}_{A_c}<br><br>\mathrm{\rho <br><br>}<br><br><br><br>u<br><br>\left(r,x\right)<br><br><br><br><br><br>\mathrm{Ac}$

where m is the mass flow through a pipe, r the volume density of the fluid in the pipe, u(r,x) the velocity profile for the fluid in the pipe and Ac the cross sectional area for the flow, and where said calculated mass flow is divided by pressure for said pressurized breathing gas to obtain a normalized mass flow.

21. A ventilator according to claim 20, wherein said computational device is adapted to retrieve values for said standard reference leak flow from a table of values representing said standard reference leak flow values at a certain pressure for the pressurized breathing gas.

22. A ventilator according to claim 21, wherein said processing unit additionally comprises a data storage unit for later analysis and inspection of the measured signals indicative of the instantaneous mass flow for the pressurized breathing gas, the physiological state of the patient and said ratio between the measured signal indicative of the instantaneous mass flow for the pressurized breathing gas and a standard reference leak flow.

23. A ventilator according to claim 6, wherein said first or second communication devices may be a wired or a wireless communication device.

9. A ventilation system comprising

a mechanical ventilator for supplying pressurized breathing gas;

a tubing for guiding said pressurized breathing gas connected to said mechanical ventilator;

a device connected to said tubing for administrating said pressurized breathing gas to a patient;

at least one sensing device arranged to measure at least a signal indicative of the instantaneous flow for said pressurized breathing gas and further arranged to send said signal to said mechanical ventilator; and

a processing unit arranged to receive said signal indicative of flow for controlling the pressure or flow from the mechanical ventilator, wherein said processing unit is arranged to compensate for leakage in said ventilator system using a ratio between said measured flow of pressurized breathing gas and a flow related to a reference standard leak.

10. A ventilation system according to claim 9, wherein said at least one sensing device for measuring a signal indicative of the instantaneous flow for said pressurized breathing gas is located in or nearby said mechanical ventilator or nearby said device for administering said pressurized breathing gas to a patient.

11. A ventilation system according to claim 9, wherein said processing unit further comprises a computational device adapted to calculate said mass flow for a standard leak using a formula derived from Bernoulli'"'"'s equation, said formula being:

$m={\int <br><br>}_{A_c}<br><br>\mathrm{\rho <br><br>}<br><br><br><br>u<br><br>\left(r,x\right)<br><br><br><br><br><br>\mathrm{Ac}$

where m is the mass flow through a pipe, r the volume density of the fluid in the pipe, u(r,x) the velocity profile for the fluid in the pipe and Ac the cross sectional area for the flow, and where said calculated mass flow is divided by pressure for said pressurized breathing gas to obtain a normalized mass flow.

24. A ventilation system according to claim 10, wherein said processing unit further comprises a computational device adapted to calculate said mass flow for a standard leak using a formula derived from Bernoulli'"'"'s equation, said formula being:

$m={\int <br><br>}_{A_c}<br><br>\mathrm{\rho <br><br>}<br><br><br><br>u<br><br>\left(r,x\right)<br><br><br><br><br><br>\mathrm{Ac}$

where m is the mass flow through a pipe, r the volume density of the fluid in the pipe, u(r,x) the velocity profile for the fluid in the pipe and Ac the cross sectional area for the flow, and where said calculated mass flow is divided by pressure for said pressurized breathing gas to obtain a normalized mass flow.

12. A method for determining a leakage in a ventilator, comprising the steps of:

measuring the mass flow through the ventilator;

comparing values from a standard leak calculation for a standard leak in said ventilator;

characterized by

calculating a ratio between said measured mass flow through the ventilator and said values from a standard leak calculation for a standard leak flow in said ventilator; and

determining said leakage from said comparison.

13. A method according to claim 12, wherein based on said calculated ratio between the measured mass flow through the ventilator and said values from a standard leak calculation for a standard leak in said ventilator, a compensation for the difference between the measured mass flow and the calculated standard leak flow is performed.

14. A method according to claim 12, wherein said step of measuring the mass flow through the ventilator further comprises the sub steps of:

sampling instantaneous values for the mass flow through the ventilator; and

calculating a ratio between said each sampled value for the instantaneous mass flow and a corresponding value for the standard leak flow.

15. A method according to claim 12, wherein said sub steps of sampling said instantaneous values for the mass flow through the ventilator and calculation of said ratio further comprises the steps of:

sampling values for the mass flow through the ventilator during one predetermined time period;

calculating a ratio between said sampled mass flow values and corresponding standard leak flow values during said predetermined time period;

calculating a mean value for said ratio by integrating the ratio over the predetermined time period measured and dividing it by the number of flow values sampled; and

calculating mass flow through the ventilator using a known relation between said mean value for the flow ratio and a standard leak flow.

16. A method according to claim 12, wherein said calculation for the standard leak flow in said ventilator is performed from Bernoulli'"'"'s equation.

17. A method according to claim 12, wherein said mass flow for a standard leak is calculated using a formula derived from Bernoulli'"'"'s equation, said formula being:

$m={\int <br><br>}_{A_c}<br><br>\mathrm{\rho <br><br>}<br><br><br><br>u<br><br>\left(r,x\right)<br><br><br><br><br><br>\mathrm{Ac}$

where m is the mass flow through a pipe, r the volume density of the fluid in the pipe, u(r,x) the velocity profile for the fluid in the pipe and Ac the cross sectional area for the flow, and where said calculated mass flow is divided by pressure for said pressurized breathing gas to obtain a normalized mass flow.

18. A method according to claim 12, wherein said step of calculating the mean value for said ratio further includes the sub steps of:

calculating a volume for the inspiration and the expiration phases of a patient;

determining a volume difference between said inspiration and expiration phases;

calculating the actual flow rate based on said volume difference;

calculating a ratio between said actual flow rate based on said volume difference and a standard leak flow; and

adding said ratio between the actual flow rate based on said volume difference and a standard leak flow and said mean value for said ratio.

25. A method according to claim 14, wherein said sub steps of sampling said instantaneous values for the mass flow through the ventilator and calculation of said ratio further comprises the steps of:

sampling values for the mass flow through the ventilator during one predetermined time period;

calculating a ratio between said sampled mass flow values and corresponding standard leak flow values during said predetermined time period;

calculating a mean value for said ratio by integrating the ratio over the predetermined time period measured and dividing it by the number of flow values sampled; and

calculating mass flow through the ventilator using a known relation between said mean value for the flow ratio and a standard leak flow.

19. A computer program for determining a leakage in a ventilator system, comprising instruction sets for:

obtaining data indicative of a first mass flow of breathing gas through the ventilator system;

obtaining a second mass flow for a standard leak flow in said ventilator system;

calculating a ratio between said first mass flow and said second standard leak flow in said ventilator system; and

determining a leakage in said ventilator system from said ratio.