PEEP providing circuit for anesthesia systems

Claim 2

A breathing circuit for providing positive end-expiratory pressure for a medical patient, said circuit comprising in combination: inspiratory conduit means for conducting flow of gas to a patient when the patient inhales, said inspiratory conduit means having inlet and outlet end portions adapted for connection to a source of positive pressure and a patient, respectively; first unidirectional valve means disposed between said end portions of said inspiratory conduit means for precluding reverse flow of gas in said inspiratory means upstream of said first valve means when a patient exhales; unidirectional expiratory valve means disposed between said first valve means and said outlet end portion for discharging reverse flow of gas through said expiratory valve means when a patient exhales; said expiratory valve means being biased for providing fixed predetermined positive pressure resistance above that of the positive pressure source against reverse flow of gas downstream of said first unidirectional valve means thereby providing said positive end-expiratory pressure; and said circuit includes expiratory conduit means having inlet and outlet end portions, said expiratory inlet end portion being interconnected with said expiratory outlet end portion being interconnected with said inlet end portion of said inspiratory conduit means to provide a common opening whereby reverse flow of gas is conducted from said expiratory valve means to said common opening.

Claim 3

The breathing circuit as defined in claim 1 wherein said expiratory valve means is biased by the effect of gravity.

Claim 4

The breathing circuit as defined in claim 1 wherein said expiratory valve means is biased by the effect of gravity and is disposed substantially vertically.

Claim 5

A breathing circuit as defined in claim 1 wherein said circuit includes third unidirectional valve means disposed between said expiratory valve means and said inlet end portion of said expiratory conduit means for preventing gas flow other than said reverse flow of gas from passing through said expiratory conduit means.

Claim 6

The breathing circuit as defined in claim 4 wherein said expiratory valve means is biased by the effect of gravity and is disposed substantially vertically.

Claim 7

The breathing cirucit as defined in claim 1 wherein said expiratory valve means is biased by the effect of gravity and is disposed substantially vertically.

Claim 8

In a system for ventilating a medical patient including means for transferring gas to and from a patient, ventilating means for producing positive pressure for ventilating the patient, conduit means for interconnecting said gas transferring means and said ventilating means, and a reservoir bag communicating with said conduit means; an improvement to said system of a breathing circuit for providing positive end-expiratory pressure for the medical patient comprising in combination: inspiratory conduit means having inlet and outlet end portions disposed between said ventilating means and said conduit means, said inlet end portion being interconnected with said ventilating means and said outlet end portion being interconnected with said conduit means, said inspiratory conduit means conducting gas flow from said ventilating means to said conduit means when the patient inhales; first unidirectional valve means disposed between said end portions of said inspiratory conduit means for precluding reverse gas flow through said inspiratory conduit means upstream of said first valve means when the patient exhales; unidirectional expiratory valve means disposed between said first valve means and said outlet end portion for discharging reverse gas flow through said expiratory valve means when the patient exhales; said expiratory valve means being biased for providing fixed predetermined positive pressure resistance above that of said ventilating apparatus against reverse gas flow downstream of said first unidirectional means thereby providing said positive end-expiratory pressure; and expiratory conduit means having one end thereof in communication with said expiratory valve means and the other end thereof in communication with said inlet portion thereby to conduct reverse gas flow therethrough from said expiratory valve means toward said ventilating means.

Claim 9

In a system for ventilating a medical patient including means for transferring gas to and from a patient, ventilating means for producing positive pressure for ventilating the patient, conduit means for interconnecting said gas transferring means and said ventilating means, and a reservoir bag communicating with said conduit means; an improvement to said system of a breathing circuit for providing positive end-expiratory pressure for the medical patient comprising in combination: inspiratory conduit means having inlet and outlet end portions disposed between said ventilating means and said conduit means, said inlet end portion being interconnected with said ventilating means and said outlet end portion being interconnected with said conduit means, said inspiratory conduit means conducting gas flow from said ventilating means to said conduit means when the patient inhales; first unidirectional valve means disposed between said end portions of said inspiratory conduit means for precluding reverse gas flow through said inspiratory conduit means upstream of said first valve means when the patient exhales; unidirectional expiratory valve means disposed between said first valve means and said outlet end portion for discharging reverse gas flow through said expiratory valve means when the patient exhales; said expiratory valve means being biased for providing fixed predetermined positive pressure resistance above that of said ventilating apparatus against reverse gas flow downstream of said first unidirectional means thereby providing said positive end-expiratory pressure; and expiratory conduit means having one end thereof in communication with said expiratory valve means and the other end thereof in communication with said inlet portion thereby to conduct reverse gas flow therethrough from said expiratory valve means toward said ventilating means.

Claim 10

A system for ventilating a medical patient as defined in claim 7 wherein said inlet end portion of said inspiratory conduit and said other end of said expiratory conduit are interconnected to provide a common opening which is in communication with said ventilating means.

Claim 11

A system as defined in claim 8 wherein said expiratory conduit includes second unidirectional valve means disposed between said one end and said other end thereof for preventing said gas flow from preceding therethrough.

Claim 12

A system as defined in claim 7 wherein said expiratory valve means is biased by the effect of gravity.

Claim 13

A system as defined in claim 10 wherein expiratory valve means is disposed in substantially vertical position.

Claim 14

In a rebreathing anesthetic system of the Bain type which comprises a Bain attachment consisting of a length of light weight flexible tubing having one end adapted for patient connection by means of a mask angle or the like, an opposite end adapted to be connected to a reservoir bag, and fresh gas inflow conduit means extending into said flexible tubing and extending essentially coaxially therein for delivering fresh gas to the patient, and a reservoir bag connected to said opposite end of the tubing, the improvement which comprises a breathing circuit for providing positive end-expiratory pressure for a patient, said circuit including: inspiratory conduit means disposed between said reservoir bag and said opposite end of the flexible tubing for conducting flow therethrough from said reservoir bag to said flexible tubing when the patient inhales, said inspiratory conduit means having inlet and outlet end portions, said inlet end portion being interconnected with said reservoir bag and said outlet end portion being interconnected with said flexible tubing; unidirectional valve means disposed within said inspiratory conduit means for precluding reverse gas flow through said inspiratory conduit means when the patient exhales; unidirectional expiratory valve means disposed between said unidirectional valve means and said outlet end portion of said inspiratory conduit means for conducting reverse flow therethrough, said expiratory valve means being biased to provide fixed predetermined positive pressure resistance against said reverse gas flow; and expiratory conduit means for conducting reverse flow therethrough from the patient to said reservoir bag, said expiratory conduit means having inlet and outlet end portions, said inlet end portion being interconnected with said expiratory valve means and said outlet end portion being interconnected with said inlet end portion of said inspiratory conduit.

Claim 15

In a rebreathing anesthetic system of the Bain type which comprises a Bain attachment consisting of a length of light weight flexible tubing having one end adapted for patient connection by means of a mask angle or the like, an opposite end adapted to be connected to a reservoir bag, and fresh gas inflow conduit means extending into said flexible tubing and extending essentially coaxially therein for delivering fresh gas to the patient, and a reservoir bag connected to said opposite end of the tubing, the improvement which comprises a breathing circuit for providing positive end-expiratory pressure for a patient, said circuit including: inspiratory conduit means disposed between said reservoir bag and said opposite end of the flexible tubing for conducting flow therethrough from said reservoir bag to said flexible tubing when the patient inhales, said inspiratory conduit means having inlet and outlet end portions, said inlet end portion being interconnected with said reservoir bag and said outlet end portion being interconnected with said flexible tubing; unidirectional valve means disposed within said inspiratory conduit means for precluding reverse gas flow through said inspiratory conduit means when the patient exhales; unidirectional expiratory valve means disposed between said unidirectional valve means and said outlet end portion of said inspiratory conduit means for conducting reverse flow therethrough, said expiratory valve means being biased to provide fixed predetermined positive pressure resistance against said reverse gas flow; and expiratory conduit means for conducting reverse flow therethrough from the patient to said reservoir bag, said expiratory conduit means having inlet and outlet end portions, said inlet end portion being interconnected with said expiratory valve means and said outlet end portion being interconnected with said inlet end portion of said inspiratory conduit.

Claim 16

The breathing system as defined in claim 12 wherein said expiratory valve means is gravity biased and disposed substantially vertically between said expiratory conduit means and said inspiratory conduit means.