PATIENT VENTILATION SYSTEM WITH A GAS IDENTIFICATION UNIT (As Amended)

• US 20110041847A1
• Filed: 06/24/2008
• Published: 02/24/2011
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: Maquet Critical Care AB (Getinge AB)
• Original Assignee: Maquet Critical Care AB (Getinge AB)
• Inventors: Cosic, Nebojsa
• Granted Patent: US 8,701,659 B2
• Time in Patent Office: Days
• US Class Current: 128/203.14
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit
• CPC Class Codes: A61M 2016/102 Measuring a parameter of the content of the delivered gas
• CPC Class Codes: A61M 2202/025 Helium
• CPC Class Codes: A61M 2205/702 automatically during use
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01F 1/68 by using thermal effects
• CPC Class Codes: G01F 25/10 of flowmeters
• CPC Class Codes: G01N 2291/0215 Mixtures of three or more gases, e.g. air
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects

Abstract

A patient ventilation system has a flow regulating and gas mixing assembly for providing oxygen to a first gas inlet and at least a second gas to a second gas inlet. The first and second gas inlets are connected to an inspiratory channel for conveying a delivered gas mixture including the oxygen and the at least second gas to a proximal tubing. The proximal tubing in turn is connected to an expiratory channel and connectable to a patient. The patient ventilation system further has a gas identification unit with which the at least second gas can be identified. The gas identification unit is arranged to measure actively a first value which is dependent on the characteristics of the at least second gas and attempt to identify the at least second gas based on said first value. The flow regulating and gas mixing assembly changes, at least temporarily, the concentration of the at least second gas in the delivered gas mixture if the gas identification attempt fails. The gas identification unit is further arranged to, subsequent to such a change in concentration, actively measure a second value which is dependent on the characteristics, and identify the at least second gas based on the second value alone or in combination with the first value.

Claims

1-13. -13. (canceled)

14. A patient ventilation system comprising:

a breathing circuit comprising an inspiration channel and an expiration channel adapted for connection to a patient;

a flow regulating and gas mixing arrangement connected to said breathing circuit that delivers a gas mixture comprising oxygen and at least a second gas to the patient via the expiratory channel;

a control unit configured to control operation of said flow regulating and gas mixing arrangement;

a gas identification unit configured to initiate an attempt to identify said second gas by actively measuring a first value dependent on a characteristic of said second gas;

said control unit being configured to monitor said attempt by said gas identification unit to identify said second gas and, if said attempt fails to identify said second gas, to cause said flow regulating and gas mixing arrangement to, at least temporarily, change a concentration of said second gas in said gas mixture; and

said gas identification unit being configured, after said change in concentration, initiate a subsequent attempt to identify said second gas by actively measuring a second value dependent on a characteristic of said second gas and to identify said second gas from said second value alone or in combination with said first value.

15. A patient ventilation system as claimed in claim 14 wherein said control unit is configured to cause said flow regulating and gas mixing arrangement to change said concentration of said second gas in said gas mixture by causing said second value to be outside of a value range that encompasses all values corresponding to more than one predetermined type of gas or gas mixture, and wherein said gas identification unit is configured to identify said second gas, in said subsequent attempt, dependent on said second gas value alone.

16. A patient ventilation system as claimed in claim 14 wherein said gas identification unit is configured to identify said second gas based on a difference between said first value and said second value caused by said change in concentration of said second gas in said gas mixture.

17. A patient ventilation system as claimed in claim 14 wherein said gas identification unit is located in said inspiration channel.

18. A patient ventilation system as claimed in claim 14 comprising proximal tubing adapted to connect said expiration channel to said patient, and wherein said gas identification unit is located in said proximal tubing or in said expiration channel.

19. A patient ventilation system as claimed in claim 14 wherein said control unit is configured to cause said flow regulating and gas mixing arrangement to at least temporarily change said concentration of said second gas in said gas mixture by at least temporarily increasing a flow of said second gas in said flow regulating and gas mixing arrangement.

20. A patient ventilation system as claimed in claim 14 wherein said control unit is configured to cause said flow regulating and gas mixing arrangement, after said change in said concentration of said second gas in said gas mixture, to compensate for said change by adjusting at least one of a flow of oxygen or a flow of said second gas to cause an average volume fraction of oxygen in said gas mixture over time to be substantially equally to a predetermined reference value.

21. A method for operating a patient ventilation system, comprising the steps of:

connecting a breathing circuit comprising an inspiration channel and an expiration channel to a patient;

through a flow regulating and gas mixing arrangement connected to said breathing circuit, delivering a gas mixture comprising oxygen and at least a second gas to the patient via the expiratory channel;

with a computerized control unit, controlling operation of said flow regulating and gas mixing arrangement;

with a gas identification unit, initiating an attempt to identify said second gas by actively measuring a first value dependent on a characteristic of said second gas;

in said control unit, monitoring said attempt by said gas identification unit to identify said second gas and, if said attempt fails to identify said second gas, automatically causing said flow regulating and gas mixing arrangement to, at least temporarily, change a concentration of said second gas in said gas mixture; and

in said gas identification unit, after said change in concentration, initiating a subsequent attempt to identify said second gas by actively measuring a second value dependent on a characteristic of said second gas and identifying said second gas from said second value alone or in combination with said first value.

22. A method as claimed in claim 21 comprising, from said control unit, causing said flow regulating and gas mixing arrangement to change said concentration of said second gas in said gas mixture by causing said second value to be outside of a value range that encompasses all values corresponding to more than one predetermined type of gas or gas mixture and, in said gas identification unit, identifying said second gas, in said subsequent attempt, dependent on said second gas value alone.

24. A method as claimed in claim 21 comprising, in said gas identification unit, identifying said second gas based on a difference between said first value and said second value caused by said change in concentration of said second gas in said gas mixture.

25. A method as claimed in claim 21 comprising connecting said expiration channel to said patient via proximal tubing, and locating said gas identification unit in said proximal tubing or in said expiration channel.

26. A method as claimed in claim 21 comprising, from said control unit, causing said flow regulating and gas mixing arrangement to at least temporarily change said concentration of said second gas in said gas mixture by at least temporarily increasing a flow of said second gas in said flow regulating and gas mixing arrangement.

27. A method as claimed in claim 21 comprising, from said control unit, causing said flow regulating and gas mixing arrangement, after said change in said concentration of said second gas in said gas mixture, to compensate for said change by adjusting at least one of a flow of oxygen or a flow of said second gas to cause an average volume fraction of oxygen in said gas mixture over time to be substantially equally to a predetermined reference value.

28. A method as claimed in claim 21 wherein said patient ventilation system comprises at least one flow meter, and comprising the additional step of calibrating said at least one flow meter dependent on the identity of said gas.

24-1. A method as claimed in claim 21 comprising locating said gas identification unit in said inspiration channel.