Oxygen and anesthesia delivery and monitoring device

• US 4,127,121 A
• Filed: 09/17/1976
• Issued: 11/28/1978
• Est. Priority Date: 09/17/1976
• Status: Expired due to Term

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah (State of Utah)
• Inventors: Westenskow, Dwayne R., Johnson, Curtis C.
• Primary Examiner(s): Recla, Henry J.
• Application Number:
  US05/724,194
• Time in Patent Office: 802 Days
• Field of Search: 128/142 R, 128/142.2, 128/142.3, 128/145.5, 128/145.6, 128/145.8, 128/188, 128/209, 128/210, 128/DIG. 17, 128/2.08, 128/191 R, 128/191 A, 137/93
• US Class Current: 128/203.14
• CPC Class Codes: A61M 16/104 specially adapted for anaesthetics A61M16/18 takes precedence
• CPC Class Codes: A61M 2016/1025 the O2 concentration

Abstract

A device for continuously monitoring oxygen consumption and anesthesia gas uptake of surgical patients, having servo-controlled replenishment mechanisms to automatically maintain preset levels of oxygen and anesthesia gas for inhalation. A closed, recirculating delivery circuit is utilized to adminster an appropriate volume of oxygen and anesthesia gas to a surgical patient. An oxygen sensor monitors decreases in oxygen concentration within the recirculatory system and triggers restoration to the preset concentration by means of feedback comparator circuitry. With the oxygen held at the desired level, any volume changes in the system are caused by uptake of anesthesia gas, which is monitored by detecting variations in the expansion of a respirator bellows. The desired amount of anesthesia gas is preset and maintained by a potentiometric monitoring device which produces a voltage proportional to the peak expansion of the bellows. Variations from the preset level of anesthesia gas drive a servo-mechanism for replenishing the anesthesia gas to the preset value. Data relating to oxygen consumption and anesthesia gas uptake are displayed by means of conventional instrumentation.

Claims

1. A closed, recirculating oxygen and anesthesia delivery circuit for monitoring and controlling rates of addition of oxygen and anesthesia gas in response to rates of oxygen consumption and anesthesia uptake, comprising:

a. a closed circuit having at least one inlet means for addition of oxygen and at least one inlet means for addition of anesthesia gas to said circuit and outlet means for connecting said circuit to a patient, said system being operable to preserve a closed system environment between said circuit and the patient'"'"'s lungs;

b. first sensing means for detecting concentrations of oxygen within the closed circuit;

c. flow controlling means for maintaining a single direction of gas flow across said oxygen concentration sensing means;

d. first feedback means for comparing the detected oxygen concentration with a preset oxygen concentration indicator;

e. first servo means including a motor-speed regulated pump responsive to said first feedback means and operable to maintain oxygen concentrations at a safe value relative to the preset oxygen concentration by regulating addition of oxygen through one or more of said oxygen inlet means, said motor-speed regulated pump being coupled at said oxygen inlet means for controlling oxygen feed into said closed circuit;

f. second sensing means for detecting the concentration of the applied anesthesia gas within the closed system;

g. second feedback means for comparing the detected anesthesia gas concentration with a preset anesthesia concentration indicator;

h. second servo means including a motor-speed regulated pump responsive to said first feedback means and operable to maintain anesthesia concentrations at a safe value relative to the preset anesthesia concentration by regulating addition of anesthesia through one or more of said anesthesia inlet means, said motor-speed regulated pump being coupled at said anesthesia inlet means for controlling anesthesia feed into said closed circuit;

i. means for reducing and maintaining CO₂ concentrations at safe levels within the closed system.

6. A closed, recirculating oxygen and anesthesia delivery circuit as defined in claim 1, wherein said second sensing means includes a bellows connected within said circuit, said bellows defining a volume which varies in response to variations in anesthesia gas concentration within said circuit and having a sensing means attached at said bellows for detecting peak volume variations thereof.

7. A closed, recirculating oxygen and anesthesia delivery circuit as defined in claim 6, wherein said sensing means attached at said bellows includes a potentiometric sensor which responds to changes in peak volume of said bellows with corresponding change in voltage, thereby providing a signal to the second feedback means representing circuit volume changes.

2. A closed, recirculating oxygen and anesthesia delivery circuit for monitoring and controlling rates of addition of oxygen and anesthesia gas in response to rates of oxygen consumption and anesthesia uptake, comprising:

a. a closed circuit having at least inlet means for addition of oxygen and at least one inlet means for addition of anesthesia gas to said circuit and outlet means for connecting said circuit to a patient, said system being operable to preserve a closed system environment between said circuit and the patient'"'"'s lungs;

b. first sensing means for detecting concentrations of oxygen within the closed circuit;

c. flow controlling means for maintaining a single direction of gas flow across said oxygen concentration sensing means;

d. first feedback means for comparing the detected oxygen concentration with a preset oxygen concentration indicator;

e. first servo means responsive to said first feedback means and operable to maintain oxygen concentrations at a safe value relative to the preset oxygen concentration by regulating addition of oxygen through one or more of said oxygen inlet means;

f. second sensing means for detecting the concentration of the applied anesthesia gas within the closed system;

g. second feedback means for comparing the detected anesthesia gas concentration with a preset anesthesia concentration indicator;

h. second servo means responsive to said second feedback means and operable to maintain anesthesia gas concentration by regulating addition of said anesthesia gas through one or more of said anesthesia inlet means;

i. circulating means spacially located between said oxygen inlet means and said first sensing means, said circulating means being operable to improve diffusion of replenished oxygen prior to contact therewith by said first sensing means; and

j. means for reducing and maintaining CO₂ concentration at safe levels within the closed sensor.

3. A closed, recirculating oxygen and anesthesia delivery circuit as defined in claim 2, wherein said second sensing means includes a bellows connected within said circuit, said bellows defining a volume which varies in response to variations in anesthesia gas concentration within said circuit and having a sensing means attached at said bellows for detecting peak volume variations thereof.

4. A closed, recirculating oxygen and anesthesia delivery circuit for monitoring and controlling rates of addition of oxygen and anesthesia gas in response to rates of oxygen consumption and anesthesia uptake, comprising:

a. a closed circuit having at least one inlet means for addition of oxygen and at least one inlet means for addition of anesthesia gas to said circuit and outlet means for connecting said circuit to a patient, said system being operable to preserve a closed system environment between said circuit and the patient'"'"'s lungs;

b. first sensing means for detecting concentrations of oxygen within the closed circuit;

c. flow controlling means for maintaining a single direction of gas flow across said oxygen concentration sensing means;

d. first feedback means for comparing the detected oxygen concentration with a preset oxygen concentration indicator;

e. first servo means responsive to said first feedback means and operable to maintain oxygen concentrations at a safe value relative to the preset oxygen concentration by regulating addition of oxygen through one or more of said oxygen inlet means;

f. second sensing means comprising a bellows connected within said circuit, said bellows defining a volume which varies in response to variations in anesthesia gas concentration within said circuit and having a sensing means attached to said bellows for detecting peak volume variation thereof;

g. second feedback means coupled to the output of said second sensing means for comparing the detected anesthesia gas concentration with a preset reference concentration;

h. second servo means responsive to said second feedback means and operable to maintain anesthesia gas concentration by regulating addition of said anesthesia gas through one or more of said anesthesia inlet means; and

i. means for reducing and maintaining CO₂ concentration at safe levels within the closed system.

5. A closed, recirculating oxygen and anesthesia delivery circuit as defined in claim 4, wherein said sensing means attached at said bellows includes a potentiometric sensor which responds to changes in peak volume of said bellows with a corresponding change in voltage, thereby providing a signal to the second feedback means representing circuit volume changes.