On-line fault detection and correction in anesthesia delivery system

• US 5,957,129 A
• Filed: 07/30/1997
• Issued: 09/28/1999
• Est. Priority Date: 07/30/1997
• Status: Expired due to Fees

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Ohmeda, Inc. (Linde Plc)
• Inventors: Tham, Robert Q., Keitel, Todd
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): ANDERSON, CHARLES WENDELL
• Application Number:
  US08/902,886
• Time in Patent Office: 790 Days
• Field of Search: 128/204.28, 128/205.24, 128/204.18, 128/204.22, 128/203.12, 128/203.14, 128/204.26, 128/204.21
• US Class Current: 128/204.28
• CPC Class Codes: A61M 16/104 specially adapted for anaesthetics A61M16/18 takes precedence
• CPC Class Codes: A61M 16/22 Carbon dioxide-absorbing devices ; Other means for removing carbon dioxidecartridges with absorbing substances for respiratory apparatus A62B19/00
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2016/1035 the anaesthetic agent concentration
• CPC Class Codes: A61M 2205/702 automatically during use

Abstract

An anesthesia delivery system having a means of determining the functioning of its gas mixer, vaporizer and analyzers, their accuracies and other characteristics by comparing, at high flow conditions, the input of oxygen concentration and agent concentration set by a clinician and delivered by the system, the input from a feedback respiratory analyzer of the inspired O₂ and agent concentrations and the input of a monitor analyzer that determines the O₂ and agent concentrations in the patient circuit. A CPU compares the three sets of input data to make various determinations since, at high flow conditions, all of the three sets of data should be consistent. Thus the CPU can determine from a comparison, whether one set of data is indicative of a faulty device, can provide a bias adjustment if an analyzer is merely off in its readings or carry out other safety and corrective functions based on comparing the three data inputs.

Claims

1. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient, said anesthesia system comprising:

a patient circuit for administering the breathing gas and anesthetic agent to the patient, said patient circuit having a wye connector for connection to a patient through which inhaled and exhaled gases pass to and from a patient, a fresh gas supply providing a fresh gas to said patient circuit, said fresh gas supply comprising an electronic controlled gas mixer for providing a mixture of gases at a settable proportion and an electronic controlled vaporizer for introducing anesthetic agent vapor to the mixture of gases from said electronic controlled gas mixer, a CPU controlling said electronic controlled vaporizer and said electronic controlled mixer, a mixer setting device operable by a user to input to said CPU the concentration of at least one component of the breathing gas desired to be administered to a patient through said patient circuit, a first gas monitor for analyzing said at least one component at or near said wye connector, a second gas monitor detecting the concentration of said at least one component in the gas circulating within said patient circuit, means to cause a high flow of fresh gas to enter said patient circuit from said fresh gas supply, and said CPU including means to compare the concentration of said at least one component determined by said first gas monitor, said second gas monitor and the concentration of said at least one component inputted by a user with said input device when said high flow of gas is entering said patient circuit.

2. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 1 wherein said at least one component is oxygen.

3. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 2 wherein said CPU determines a fault condition when the oxygen concentration determined from said first gas monitor, said second gas monitor and said oxygen concentration inputted by a user to said mixer setting device and delivered by the system are compared and are not within predetermined limits with respect to each other.

4. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 1 wherein said at least one component is anesthetic agent vapor.

5. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 3 wherein said CPU determines a fault condition when the anesthetic agent vapor concentration determined from said first gas monitor, said second gas monitor and said anesthetic agent concentration inputted by a user to said input device and delivered by the system are compared and are not within predetermined limits with respect each other.

6. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 1 wherein said means to cause a high flow of fresh gas to enter said patient circuit includes a timer that activates said means at predetermined intervals.

7. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 2 wherein said means to cause a high flow of gas to enter said patient circuit comprises a manual activator operable by a user.

8. An anesthesia system for delivering a breathing gas containing a settable anesthetic concentration to a patient as defined in claim 1 wherein said CPU provides a bias signal to correct the reading of at least one of said first and second gas monitors and said bias signal is determined by said CPU comparing said values of oxygen concentration from said first and second gas monitors.

9. An anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient as defined in claim 1 wherein said system provides the breathing gas at a minute ventilation rate and said means to cause a high flow of fresh gas to enter said patient circuit comprises increasing the flow of said fresh gas to be greater than the minute volume.

10. Anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient, said anesthesia system comprising:

a patient circuit for administering the breathing gas and anesthetic agent to the patient, said patient circuit having a wye connector for connection to a patient through which inhaled and exhaled gases pass to and from a patient, a fresh gas supply providing a fresh gas to said patient circuit at a known rate, said fresh gas supply comprising an electronic controlled gas mixer for providing a mixture of gases at a known proportion and an electronic controlled vaporizer for introducing anesthetic agent vapor to the mixture of gases from said electronic controlled gas mixer, a CPU controlling said electronic controlled vaporizer and said electronic controlled mixer, a data input device operable by a user to input to said CPU the concentrations of oxygen and anesthetic agent desired to be administered to a patient through said patient circuit, a first gas monitor for analyzing oxygen and anesthetic agent at or near said wye connector, a second gas monitor detecting the concentration of oxygen and anesthetic agent in the gas circulating within said patient circuit, flow control means to increase the rate of flow of said fresh gas entering said patient circuit from said fresh gas supply, and said CPU including a comparator to compare the concentration of oxygen and anesthetic agent determined by said first gas monitor, said second gas monitor and the concentration of oxygen and anesthetic agent inputted by a user with said data input device when said increased flow of fresh gas is entering said patient circuit, said flow control means returning said rate of flow of said fresh gas entering said patient circuit from said fresh gas supply to said known rate when said comparator has completed comparing the oxygen and anesthetic agent concentrations.

11. An anesthesia system for delivering a breathing gas containing a known anesthetic concentration to a patient as defined in claim 10 wherein said first and second gas monitors are controlled by a bias signal from said CPU and said CPU further modifies said bias signal to one of said first and second gas monitors based on the comparison of said comparator.

12. An anesthesia system for delivering a breathing gas containing a known anesthetic concentration to a patient as defined in claim 10 wherein said comparator provides a signal when one of said first or second gas monitors or said fresh gas supply provides concentrations of oxygen and anesthetic agent outside a predetermined range with respect to the other two concentrations, said anesthesia system further including an alarm operable by said signal notifying the user as to which device providing such concentrations is outside said predetermined limit.