Cardiopulmonary bypass system

• US 3,890,969 A
• Filed: 01/21/1974
• Issued: 06/24/1975
• Est. Priority Date: 01/21/1974
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: Halbert Fischel
• Inventors: Fischel, Halbert
• Primary Examiner(s): Truluck, Dalton L.
• Application Number:
  US05/435,223
• Time in Patent Office: 519 Days
• Field of Search: 128/214R,214B,214E,214F,214.2,230 23/258.5
• US Class Current: 604/6.14
• CPC Class Codes: A61M 1/3603 in the same direction
• CPC Class Codes: A61M 1/3623 Means for actively controlling temperature of blood
• CPC Class Codes: A61M 1/3624 Level detectors; Level control
• CPC Class Codes: A61M 1/3666 Cardiac or cardiopulmonary bypass, e.g. heart-lung machines
• CPC Class Codes: Y10S 128/03 Heart-lung

Abstract

An emergency alertable gravity feed cardiopulmonary bypass system is disclosed in which a blood volume responsive transducer is utilized in returning oxygenated blood to a human circulatory system at a pumping rate corresponding to venous drainage or selected norms. The transducer is coupled to a standpipe and is responsive to a confined gas volume therein related to the blood volume in a first air evacuable, gravity fed, collapsible bag and is coupled to a rate setting control. Blood flow from the first bag is directed by a control responsive oxygenation pump through a membrane oxygenator and heat exchanger and air evacuable collapsible bag and a main pump before return to the patient. The oxygenation pump rate slaved to the main pump is greater than the gravity feed rate, and a pressure relieving conduit recirculates excess blood flow from the second bag to the first bag. Supervisory control of the flow rate of the main pump may be exercised by manual adjustment of the flow rate.

Claims

1. A cardiopulmonary bypass system for receiving a variable rate gravity fed venous blood flow from a human circulatory system, revitalizing the blood and returning the blood to the circulatory system at a flow rate substantially equal to the gravity fed blood flow comprising:

a first collapsible bag disposable below a withdrawal point coupled to receive a gravity fed flow of blood at an inlet, the collapsible bag being at least partially filled with blood and substantially without a blood-gas interface, the collapsIble bag having a sufficient flexibility such that a collapse of the bag resulting from an emptying of blood therein inhibits a suction from occurring at the inlet;

a second collapsible bag;

recirculation path means for communicating blood from the second collapsible bag to the first collapsible bag;

revitalization means coupled between the first and second collapsible bags for continuously oxygenating and warming blood from the first bag and transporting the oxygenated and warmed blood to the second bag;

main pump means coupled to the second bag for delivering a blood flow from the second bag to a human circulatory system at a rate controlled by a control signal applied thereto;

blood volume transducer means coupled to the first bag for providing a signal related to the blood volume in the first bag; and

controller means responsive to the blood volume indication for supplying a control signal to the main pump means to drive the main pump means at a rate which tends to maintain the blood volume of the first bag at a predetermined level such that the return blood flow rate is held substantially equal to the venous blood flow.

2. The invention as set forth in claim 1 and in which the first collapsible bag volume is determined by the blood therein and including gas containment means coupled to said first bag and said transducer means and having nominal blood levels and an interior volume small in comparison with the interior volume of the first collapsible bag, said gas containment means defining a confined gas volume, the pressure within which acts on the transducer means such that blood flow rate changes into the first collapsible bag manifested by blood volume changes of the bag result in fractional changes in the confined gas volume and subsequent pressure changes that are much amplified with respect to the fractional blood volume changes of the bag.

3. The invention as set forth in claim 2 in which said blood volume transducer means is coupled to the first container by a vertically extending standpipe having a small interior volume in comparison with the interior volume of said first container, said standpipe being positioned to prevent blood from the first container from coming into contact with said transducer.

4. The invention as set forth in claim 2 and in which the transducer means, the gas containment means and the collapsible bag define a closed system such that when the gas containment means is exposed to ambient air pressure and the system is brought to a reference level, the closing of the system thereby defines a transducer reference with respect to subsequent blood flow changes.

5. The invention as set forth in claim 1 and further comprising rate setting control means tending to maintain a return blood flow rate equal to a venous feed rate and means for manually overriding the rate setting control.

6. The invention as set forth in claim 1, and in which the revitalization means comprises:

a membrane oxygenator, oxygenator pump and heat exchanger coupled in series fashion, said oxygenator pump including means responsive to the flow rate of the main pump for maintaining the flow rate of the oxygenator pump at a rate greater than that of the main pump, such that a flow is recirculated back from said second bag to said first bag and the main pump does not operate without a blood flow supply.

7. In a cardiopulmonary bypass system of the type having a first container for receiving a blood drainage, a second container for receiving a revitalized blood flow from the first container, blood treatment apparatus and an auxiliary pump coupled between the first and second containers;

a recirculation path for coupling blood from the second container to the first container, and a main pump coupled to the second container for providing a blood flow to a human cardiovascular system, the combination therewith of;

transducer means responsive to a blood volume in the first container;

means coupled between tHe main pump and the auxiliary pump for driving the auxiliary pump at a rate greater than that of the main pump; and

means for driving the main pump at a rate related to blood volume responsive signals received from said transducer means.

8. The invention as set forth in claim 7 and further comprising:

a reservoir for storing a fluid at a level greater than that of a fluid level in the first container;

means coupled between the reservoir and the first container for communicating a flow from the reservoir to a said container; and

valve means for selectively admitting a fluid from the reservoir to the first container.