Liquid flow sensing apparatus

• US 4,309,993 A
• Filed: 03/06/1980
• Issued: 01/12/1982
• Est. Priority Date: 03/06/1980
• Status: Expired due to Term

• Current Assignee: Baxter Travenol Laboratories Incorporated (Baxter International Inc.)
• Original Assignee: Baxter Travenol Laboratories Incorporated (Baxter International Inc.)
• Inventors: Brown, Richard I.
• Primary Examiner(s): Mancene, Gene
• Assistant Examiner(s): Foycik, Michael J.
• Application Number:
  US06/127,554
• Time in Patent Office: 677 Days
• Field of Search: 361/180, 335/100, 340/608, 338/32 R, 128/214 E, 128/1 D, 200/81.9 R, 200/83 R, 200/81 R, 417/43, 417/45, 73/728
• US Class Current: 604/28
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor

Abstract

Liquid flow sensing apparatus which in the illustrative embodiment is used to sense an occluded vein (cessation of blood flow). A flexible pressure pillow is connected in the blood flow line and is inserted into a housing in contact with a metallic leaf spring. The position of the leaf spring is adjusted relative to an eddy current proximity sensor so that the sensing apparatus is calibrated to a no-alarm position during proper blood flow. If blood flow ceases, the flexible pressure pillow contracts thereby moving the leaf spring away from the eddy current proximity sensor and an alarm condition is thereby detected.

Claims

1. Liquid flow sensing apparatus which utilizes a flexible pressure pillow which expands and contracts in response to liquid flow and cessation of liquid flow respectively, said apparatus comprising:

a base member;

an eddy current proximity sensor carried by said base member;

a flexible metallic spring member carried by said base member for movement toward and away from said eddy current proximity sensor, said spring member being normally biased away from said eddy current proximity sensor;

a housing pivotally mounted on said base and including means for supporting the pressure pillow with one side of the pillow in contact with said flexible spring member, said support means including platen means contacting the opposite side of the pressure pillow for exerting a measurable force against the opposite pillow side in opposition to the biasing force of said flexible spring member so that, in response to the expansion and contraction of the pressure pillow, only said flexible spring member moves relative to said eddy current proximity sensor; and

calibration means controlling the pivotal movement of said housing relative to said base for adjusting the magnitude of said measurable force exerted by said platen means against the pressure pillow.

2. Liquid flow sensing apparatus as described in claim 1

wherein said base member includes a pair of opposed side members and a pivot pin carried by said side members;

wherein said housing includes a pair of side plates coupled to said pivot pin; and

wherein said platen means includes a rigid plate extending between said side plates and facing said flexible spring member.

3. Liquid flow sensing apparatus as described in claim 1 or 2 wherein said calibration means includes a spring biased screw coupling said housing to said base member.

4. Liquid flow sensing apparatus as described in claim 3, and further including a non-metallic spacer interposed between said eddy current proximity sensor and said metallic spring member.

5. An occluded vein sensor which comprises:

a base member;

an eddy current proximity sensor carried by said base member;

a flexible pressure pillow which expands and contracts in response to blood flow and cessation of blood flow, respectively, said flexible pressure pillow comprising a generally pillow-shaped plastic device having a blood inlet end and a blood outlet end, and an additional saline inlet connected to said plastic device and extending generally perpendicular to said blood inlet;

a flexible metallic spring member carried by said base member for movement toward and away from said eddy current proximity sensor, said spring member being normally biased away from said eddy current proximity sensor;

a housing pivotally mounted on said base and including means for supporting said pressure pillow with one side of said pillow in contact with said flexible spring member, said support means including platen means contacting the opposite side of said pressure pillow for exerting a measurable force against said opposite pillow side in opposition to the biasing force of said flexible spring member so that, in response to the expansion and contraction of said pressure pillow, only said flexible spring member moves relative to said eddy current proximity sensor;

calibration means controlling the pivotal movement of said housing relative to said base for adjusting the magnitude of said measurable force exerted by said platen means against said pressure pillow.

6. An occluded vein sensor as described in claim 5,

wherein said base member includes a pair of opposed side members and a pivot pin carried by said side members;

wherein said housing includes a pair of side plates coupled to said pivot pin; and

wherein said platen means includes a rigid plate extending between said side plates and facing said flexible spring member.

7. An occluded vein sensor as described in claim 5 or 6, wherein said calibration means includes a spring biased screw coupling said housing to said base member.

8. An occluded vein sensor as described in claim 7 and further including a non-metallic spacer interposed between said eddy current proximity sensor and said metallic spring member.

9. A method for sensing an occluded vein utilizing an eddy current proximity sensor, which method comprises the steps of:

connecting flexible tubing to a vein;

providing a flexible pressure pillow along said tubing;

positioning said pillow between a rigid platen and a flexible metallic member which is normally biased at a position spaced from the proximity sensor;

calibrating the sensing by moving the rigid platen toward the flexible metallic member to move the pillow and said metallic member against the biasing force of the flexible member toward a position closer to the eddy current proximity sensor than the normally biased position; and

thereafter detecting movement of said metallic member toward its normally biased position away from said eddy current proximity sensor in response to contracting of the pressure pillow thereby signifying an occluded vein situation.