Detector for air in blood dialysis systems

• US 3,989,625 A
• Filed: 02/25/1975
• Issued: 11/02/1976
• Est. Priority Date: 02/25/1975
• Status: Expired due to Term

• Current Assignee: MA SPA (CLN Coils Lamiere Nastri SPA)
• Original Assignee: MA SPA (CLN Coils Lamiere Nastri SPA)
• Inventors: Mason, Barry D.
• Primary Examiner(s): Spear, Jr., Frank A.
• Application Number:
  US05/552,984
• Time in Patent Office: 616 Days
• Field of Search: 128/214 E, 210/321 K, 210/94, 210/96, 210/85, 340/239, 340/237, 250/573, 250/574, 250/575
• US Class Current: 210/94
• CPC Class Codes: A61M 1/3624 Level detectors; Level control

Abstract

A sensor system for detecting the absence of substantially air-free blood in a blood chamber of an artificial kidney dialysis system. The system includes a first and a second radiation source and sensor means responsive to said radiation. The sensor means is aligned with and intersects the axis of the first source, and is not aligned with and does not intersect the axis of the second source. Perception of sufficient radiation from the first source indicates absence of blood in the chamber. Perception of sufficient radiation from the second source indicates foam in the blood chamber. The sensor system can control valve means, and preferably can selectively be by-passed, and automatically be adjusted for sensitivity.

Claims

1. A sensor system for detecting the absence of substantially air-free blood from a blood chamber, said blood chamber including a wall with a transparent portion, said sensor system comprising:

a first radiation source, a second radiation source, each having a respective axis; and

sensor means responsive to said radiation, said sensor means being aligned with and intersecting the axis of the first source, and on the other side of the blood chamber therefrom, and being out of alignment with, and not intersecting, the axis of the second source, the radiation from the first source being substantially focused on the sensor means, and the radiation from the second source illuminating a substantial area of said transparent portion lying transverse to its own axis, the sources and sensor means all lying outside of and being directed toward said transparent portion, whereby radiation from the first source is directly perceived by the sensor means when only air lies within the blood chamber between the first source and the sensor means, and not perceived by it when there is blood between the first source and the sensor means, and whereby radiation from the second source is perceived by the sensor means when there is reflection from blood foam in the blood chamber in the path of reflection between the parts of the transparent portion visible to the second source and to the sensor means, and perceived less when there is either foam-free blood, or no blood in the said path of reflection.

2. A sensor system according to claim 1 in which the sensor means has an active condition and a passive condition, one of said conditions being assumed as the consequence of reception of radiation from one of the sources, and in which control means is responsive to the said one condition of the sensor means to terminate the flow of fluid through the blood chamber.

3. A sensor system according to claim 2 in which a pump is driven by a motor to supply fluid to the blood chamber, and in which the control means is adapted and connected to said motor to permit or to prevent its operation to supply fluid.

4. A sensor system according to claim 2 in which a valve is provided at the outlet of the blood chamber selectively to permit or to prevent flow of fluid from the blood chamber, and in which the control means is adapted and connected to determine the flow condition of the valve.

5. A sensor system according to claim 4 in which the valve comprises a clamp adapted to pinch closed a conduit connected to the outlet of the blood chamber to prevent said flow.

6. A sensor system according to claim 2 in which an alarm is provided to notify of the absence of substantially foam-free blood in the blood chamber, and in which the sensor means is adapted and connected to the alarm to activate the alarm in said absence.

7. A sensor system according to claim 2 in which the control means has a sensitivity level, and in which adjustment means is provided to adjust said sensitivity level.

8. A sensor system according to claim 7 in which the said adjustment means initially adjusts to an alarm condition relative to the conditions in the blood chamber, and then automatically decreases the sensitivity to a level which will indicate an alarm condition only upon a deterioration of the condition in the blood chamber by a predetermined increment.

9. A sensor system according to claim 2 in which the control means includes means for setting the sensitivity of the control to a level below that which would activate the control means whereby the control means is activated to terminate the flow of fluid through the blood chamber when the sensor means produces an output responsive to said level.

10. In combination:

a sensor system according to claim 9; and

an electrical pump motor for pumping the fluid, said motor being powered from a source of power separate from the control means, whereby the motor can be operated when the control means is disabled.

11. A combination according to claim 10 in which an override-reset circuit is provided to disable the control means even when conditions in the blood chamber would activate the same for operating the pump motor independently of the control means.

12. In combination:

a sensor system according to claim 2; and

an electrical pump motor for pumping the fluid, said motor being powered from a source of power separate from the control means, whereby the motor can be operated when the control means is disabled.

13. A combination according to claim 12 in which an override-reset circuit is provided to disable the control means even when conditions in the blood chamber would activate the same for operating the pump motor independently of the control means.

14. A sensor system according to claim 1 in which said radiation is infra-red radiation.

15. A sensor system according to claim 1 in which the sensor comprises a pair of sensors, and in which each sensor is individually responsive to radiation only from a different and respective one of said sources, radiation from one being perceived directly, and the other by reflection from blood foam.

16. A sensor system according to claim 1 in which the sources are light-emitting diodes.

17. A sensor system according to claim 16 in which said radiation is infra-red radiation.

18. A sensor system according to claim 1 in which said sources are electrically connected in series connection with one another, whereby neither source is actuable in the absence of actual emission of radiation by the other.

19. A sensor system according to claim 1 further including clamp means adapted to clamp onto the outside of the blood chamber, said clamp means including a pair of arms having faces facing toward the blood chamber, the sensor means being carried by said arms and in said faces.

20. A sensor system according to claim 19 in which spring means is provided to hold the clamp means to the blood chamber.