Breathing circuit having improved water vapor removal

• US 6,523,538 B1
• Filed: 01/05/2000
• Issued: 02/25/2003
• Est. Priority Date: 01/05/2000
• Status: Expired due to Term

• Current Assignee: Vyaire Medical Consumables LLC
• Original Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Inventors: Wikefeldt, Per
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): MITCHELL, TEENA KAY
• Application Number:
  US09/478,169
• Time in Patent Office: 1,147 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.22, 128/204.23, 128/205-2-2, 128/204.14, 128/204.15, 128/204.16, 128/204.17, 128/205.28, 128/911, 128/912
• US Class Current: 128/204.18
• CPC Class Codes: A61M 16/01 specially adapted for anaesthetising A61M16/104, A61M16/18 take precedence
• CPC Class Codes: A61M 16/0808 Condensation traps
• CPC Class Codes: A61M 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/1045 Devices for humidifying or heating the inspired gas by using recovered moisture or heat from the expired gas
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 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 2205/3606 cooled
• CPC Class Codes: A61M 2205/7536 allowing gas passage, but preventing liquid passage, e.g. liquophobic, hydrophobic, water-repellent membranes

Abstract

A breathing circuit of the closed circuit type has improved means for removing water vapor to prevent condensation within the circuit. A dryer is placed in the breathing circuit, downstream of the CO₂ absorber, for removing water vapor from the breathing gases, including that entrained in the breathing gases during passage through the CO₂ absorber. The dryer may utilize a thermoelectric cooling element or a water vapor permeable membrane.

Claims

1. An improved breathing circuit for a subject, said breathing circuit comprising:

an inspiration limb providing breathing gases for supply to the subject;

an expiration limb receiving breathing gases containing water vapor from the subject;

means for circulating breathing gases in the breathing circuit to supply breathing gases to the subject and to receive breathing gases from the subject;

a CO2 absorber interposed in said breathing circuit for removing CO2 from the breathing gases provided in said inspiration limb to the subject; and

dryer means in said breathing circuit, downstream of said CO2 absorber, for removing water vapor from the breathing gases provided in the inspiration limb to the subject to prevent moisture condensation, said dryer means having means for cooling breathing gases received from said CO2 absorber to remove water vapor therefrom, said dryer means having heat exchanger means for heating cooled breathing gases from which water vapor has been removed and which are provided in said inspiration limb to the subject.

2. The improved breathing circuit according to claim 1 wherein said dryer means includes thermoelectric means for cooling said breathing gases.

3. The improved breathing circuit according to claim 2 wherein said thermoelectric means also produces heat and wherein said heat exchanger means is coupled to said thermoelectric means and employs the heat from said thermoelectric means to heat the cooled breathing gases from which moisture has been removed.

4. The improved breathing circuit according to claim 3 wherein said thermoelectric element has a fan operative associated therewith for improving the cooling action of said thermoelectric element and wherein said heat exchanger means is coupled to an exhaust of said fan for supplying heat removed from said thermoelectric element by said fan to the cooled breathing gases for heating the cooled breathing gases.

5. The improved breathing circuit according to claim 1 wherein said dryer means is sized to remove water vapor released from said CO₂ absorber into the breathing gases.

6. The improved breathing circuit according to claim 5 wherein said breathing circuit includes a heat and moisture exchanger in a patient limb for the subject for exchanging heat and moisture from the exhaled breathing gases to the inhaled breathing gases and wherein said heat and moisture exchanger removes a portion of the moisture from the exhaled breathing gases and said dryer means is further defined as sized to remove the remaining portion of the moisture from the breathing gases.

7. The improved breathing circuit according to claim 1 wherein said breathing circuit includes a heat and moisture exchanger in a patient limb for the subject for exchanging heat and moisture from the exhaled breathing gases to the inhaled breathing gases.

8. The improved breathing circuit according to claim 1 further defined as comprising a low-flow anaesthesia breathing circuit.

9. The improved breathing circuit according to claim 1 wherein said heat exchanger means of said dryer means comprises a heat exchanger for heating the cooled breathing gases with breathing gases received from said CO2 absorber.

10. An improved breathing circuit for a subject, said breathing circuit comprising:

an inspiration limb providing breathing gases for supply to the subject;

an expiration limb receiving breathing gases containing water vapor from the subject;

means for circulating breathing gases in the breathing circuit to supply breathing gases to the subject and to receive breathing gases from the subject;

a CO2 absorber interposed in said breathing circuit for removing CO2 from the breathing gases provided in said inspiration limb to the subject; and

dryer means in said breathing circuit, downstream of said CO2 absorber, for removing water vapor from the breathing gases provided in the inspiration limb to the subject to prevent moisture condensation, said dryer means comprising a water vapor permeable element having a surface along which the breathing gases received from said CO2 absorber are passed to remove water vapor from the breathing gases.

11. The improved breathing circuit according to claim 10 including means for supplying drying gas to another surface of said water vapor permeable element other than the one along which the breathing gases are passed.

12. The improved breathing circuit according to claim 11 further including means for synchronizing the supply of drying air to said another surface with the breathing cycles of the subject.

13. The improved breathing circuit according to claim 10 wherein said water vapor permeable element comprises a tube formed of water vapor permeable material through which tube the breathing gases pass.

14. The improved breathing circuit according to claim 13 wherein said tube includes means for creating turbulent flow of said breathing gases in said tube.

15. The improved breathing circuit according to claim 13 further including a jacket surrounding said tube along at least a portion of its length for receiving drying gas for removing the water vapor.

16. The improved breathing circuit according to claim 15 further including means for synchronizing the supply of drying air to said jacket with the breathing cycles of the subject.

17. The improved breathing circuit according to claim 10 wherein said dryer is sized to remove water vapor released from said CO2 absorber into the breathing gases.

18. The improved breathing circuit according to claim 17 wherein said breathing circuit includes a heat and moisture exchanger in a patient limb for the subject for exchanging heat and moisture from the exhaled breathing gases to the inhaled breathing gases and wherein said heat and moisture exchanger removes a portion of the moisture from the exhaled breathing gases and said dryer is further defined as sized to remove the remaining portion of the moisture from the breathing gases.

19. The improved breathing circuit according to claim 10 wherein said breathing circuit includes a heat and moisture exchanger in a patient limb for the subject for exchanging heat and moisture from to exhaled breathing gases to the inhaled breathing gases.

20. The improved breathing apparatus according to claim 10 further defined as comprising a low-flow anaesthesia breathing circuit.

21. The improved breathing circuit according to claim 11 further defined as comprising a low-flow anaesthesia breathing circuit.