Blood leak detector for extracorporeal treatment system

• US 6,947,131 B2
• Filed: 02/19/2003
• Issued: 09/20/2005
• Est. Priority Date: 05/07/2002
• Status: Active Grant

• Current Assignee: Gambro Lundia AB (Baxter International Inc.)
• Original Assignee: CHF Solutions, Inc.
• Inventors: Merrick, Edwin B., O'Mahony, John J., Behan, Sonny
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): Nguyen, Sang H.
• Application Number:
  US10/367,875
• Publication Number:
  US 20030210390A1
• Time in Patent Office: 944 Days
• Field of Search: 356213-218, 356432-436, 356317-320, 356 39- 41, 128/633, 128664-665, 250/343, 250/341, 600/322, 600/336, 210/96.M, 210/96.2, 210/118, 210/188
• US Class Current: 356/218
• CPC Class Codes: A61M 1/1692 Detection of blood traces in dialysate
• CPC Class Codes: A61M 2205/331 used as turbidity change detectors, e.g. for priming-blood or plasma-hemoglubine-interface detection

Abstract

A blood leak detector is disclosed having a light source projecting a beam along an optical path, wherein the beam has a wavelength in a range of about 800 nm to 930 nm; a light detector receiving the beam; a housing with a slot to receive a transparent tube between the light source and light detector and aligned with the optical path.

Claims

1. A blood leak detector comprising:

a light source projecting a beam along an optical path through an aperture having a diameter in a range of 30 to 60 thousands of an inch, wherein the beam has a wavelength in a range of about 800 to 930 nm;

a light detector receiving the beam through an aperture having a diameter in a range of 30 to 60 thousands of an inch;

a housing to receive a tubular liquid passage between the light source and light detector, said mount housing having a slot transverse to the optical path to receive the tubular liquid passage, wherein said slot has a width narrower than the tubular liquid passage when uncompressed; and

wherein the housing further comprises side walls of the slot, and said side walls each having a recess for the light source and light detector respectively, wherein said recess is an open region in said side wall having a first end flush with the side wall and a second end aligned with the aperture.

2. A blood leak detector comprising:

a housing body having an upper surface with a slot to receive a liquid transport tube and a bottom surface with a cavity;

a module fitted into the cavity of the housing body, and said module further comprising a light source mounted in a first block of the module and a light detector mounted in a second block of the module, wherein a slot between the first block and the second block aligns with the slot of the housing body, and an optical path extends from said light source through the slot and to the light detector;

said first block includes a first transparent bore aligned with the optical path and between the light source and the slot, wherein said first transparent bore has a diameter of in a range of 30 to 60 thousands of an inch;

said second block includes a second transparent bore aligned with the optical path and between the light detector and the slot; and

wherein said first block further comprises a first opaque casing for said light source, and said first opaque casing having said first transparent bore, and said second block further comprising a second opaque casing for said light detector and said second opaque casing having said second transparent bore.

3. A blood leak detector as in claim 2 wherein the first and second opaque casings are each opaque cylinders having an end aperture with a transparent plug forming the transparent bore.

4. A blood leak detector comprising:

a housing body having an upper surface with a slot to receive a liquid transport tube and a bottom surface with a cavity;

a module fitted into the cavity of the housing body, and said module further comprising a light source mounted in a first block of the module and a light detector mounted in a second block of the module, wherein a slot between the first block and the second block aligns with the slot of the housing body, and an optical path extends from said light source through the slot and to the light detector;

said first block includes a first transparent bore aligned with the optical path and between the light source and the slot, wherein said first transparent bore has a diameter of in a range of 30 to 60 thousands of an inch;

said second block includes a second transparent bore aligned with the optical path and between the light detector and the slot; and

wherein the first block and second block each further comprise a side wall of the slot, and each of said side walls has a recess for the first and second transparent pores respectively, wherein each recess is an open region in the corresponding side wall having a first end flush with the side all and a second end aligned with an end of one of the transparent bores.

5. A blood leak detector as in claim 4 wherein the second end of the recess is adjacent a window portion of the side wall transparent to light emitted by said light source.

6. A blood lead detector as in claim 5 wherein said window portion of the side wall is aligned with the optical path.

7. A blood leak detector comprising:

a housing having a slot to receive a transparent tubing;

a light source projecting a beam along an optical path through an aperture of about 30 to 60 thousands of an inch, wherein the beam has a wavelength in a range of about 800 to 930 nm;

a light detector receiving the beam through an aperture of about 30 to 60 thousands of an inch, and

a retractable vane aligned with the slot and having an extended position extending into the slot to block the beam upstream of the light detector and a retracted position unblocking the beam, wherein said vane is biased to the extended position and is displaced to the retracted position by tubing inserted in the slot.

8. A blood leak detector as in claim 7 wherein the light detector is responsive substantially only to the wavelength of the beam from the light source.

9. A blood leak detector as in claim 7 wherein the light beam is cyclically turned on and off at a defined rate, and, during each cycle, said light detector generates a first signal when the light beam is on and a second signal when the light source is off.

10. A blood leak detector as in claim 7 wherein the vane further comprises a spring biasing said vane in the extended position.

11. A blood leak detector as in claim 7 wherein the vane is biased towards the extended position by gravity.

12. A blood leak detector as in claim 7 wherein the vane is moved to a retracted position by a filtrate tube inserted in the detector.

13. A blood leak detector as in claim 7 wherein the vane is opaque to the light beam.

14. A method for detecting low blood concentrations in a liquid carrying tube using a blood leak detector having a light source, an optical path, a housing with a slot to receive the liquid carrying tube and a light sensor, said method comprising:

a. inserting the tube into the slot of the housing wherein the slot is substantially narrower than the tube when uncompressed, such that the tube is pressed flat against side walls the slot;

b. protecting optical surfaces of the light source and light sensor recesses in the side walls separating said optical surfaces from the tube wherein the optical surfaces are each a transparent aperture for each of the light source and light sensor;

c. shielding the light sensor from ambient light by forming the side walls substantially taller than a width of said slot;

d. projecting a light beam from the light source, through the aperture for the light source, the tube, the aperture for the light sensor and to the light sensor;

e. cyclically reading magnitudes of light received by the light sensor when the light source is projecting the beam and when the beam is not projected, and

f. determining an occurrence of a blood leak if a difference between the reading of the magnitude of light when the beam is projected and not projected falls below a threshold level.

15. A method to compensate for ambient light in an optical blood leak detector having a modulated light source, a light detector, a liquid path imposed between the light source and light detector, and a light detector circuit with a synchronous demodulator, said method comprising:

a. driving the light source to emit light at a certain modulation frequency along the liquid path and toward the light detector;

b. receiving the emitted light at the light detector and the light detector generating a signal indicative of the receive light;

c. demodulating with the synchronous demodulator the signal generated by the light detector to isolate a portion of the signal corresponding to light detected at the certain modulation frequency;

d. sensing blood in the light path based on the isolated portion of the signal;

e. calibrating the light detector by;

e(1). establishing as a first optical reference a signal value from the light detector while detecting the modulated light passing through the liquid carrying tube without blood, and

e(2). establishing as a second optical reference a signal value from the light detector while detecting the modulated light passing through a filter in the light path, wherein the filter has a transmittance value equal to a liquid carrying tube with a threshold blood level.