Sensor for transcutaneous measurement of vascular access blood flow

• US 6,725,072 B2
• Filed: 12/29/2000
• Issued: 04/20/2004
• Est. Priority Date: 10/06/1990
• Status: Expired due to Fees

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: HEMA Metrics Incorporated
• Inventors: Miller, David R., Bell, David A., Steuer, Robert R.
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): McCrosky, David J.
• Application Number:
  US09/750,076
• Publication Number:
  US 20010003793A1
• Time in Patent Office: 1,208 Days
• Field of Search: 600/316, 600/322, 600/323, 600/344, 600/437-454, 600/504, 356/39-42
• US Class Current: 600/310
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61M 1/361 before treatment
• CPC Class Codes: A61M 1/3612 after treatment
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/3663 Flow rate transducers; Flow integrators
• CPC Class Codes: G01N 2021/036 transformable, modifiable
• CPC Class Codes: G01N 21/0303 Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment G01N21/031 - G01N21/15 take precedence

Abstract

An optical sensor includes photoemitter and photodetector elements at multiple spacings (d₁, d₂) for the purpose of measuring the bulk absorptivity (α) of an area immediately surrounding and including a hemodialysis access site, and the absorptivity (α_o) of the tissue itself. At least one photoemitter element and at least one photodetector element are provided, the total number of photoemitter and photodetector elements being at least three. The photoemitter and photodetector elements are collinear and alternatingly arranged, thereby allowing the direct transcutaneous determination of vascular access blood flow.

Claims

1. A sensor for the transaction measurement of vascualr access blood for flow comprising:

a substrate having an axis and an access placement line perpendicular to the axis;

an inboard emitter and an inboard detector positioned on the substrate on either side of and spaced the same distance from the access placement line; and

at least one of an outboard emitter and an outboard detector spaced a distance from the inboard detector and the inboard emitter, respectively.

2. The sensor of claim 1, wherein all of the emitters and detectors are collinear and are alternatingly arranged.

3. The sensor of claim 2, wherein the inboard emitter is the only emitter and wherein there is an inboard detector and an outboard detector on either side of the inboard emitter.

4. The sensor of claim 2, wherein the inboard detector is the only detector and wherein there is an inboard emitter and an outboard emitter on either side of the inboard detector.

5. The sensor of claim 2, wherein there is at least one outboard emitter and at least one outboard detector.

6. The sensor of claim 1, wherein all of the emitters are photoemitters that emit light of the same wavelength.

7. A sensor of the transcutaneous measurement of vascular access blood flow, the sensor having an access placement line and comprising:

a first emitter and a first detector positioned on either side of and space the same distance δ

from the access placement line; and

a second emitter and a second detector positioned on either side of and spaced the same distance δ

from the access placement line, the first and second emitters being arranged along a first diagonal line having a point of intersection and forming an angle with the access placement line and the first and second detectors being arranged along a second line at an angle to the first line at the point of intersection with the access placement line.

8. The sensor of claim 7, where the second line is perpendicular to the first line.

9. The sensor of claim 8, wherein the first and second detectors are equidistant from the point of intersection.

10. The sensor of claim 7, wherein all of the emitters are photoemitters that emit light of the same wavelength.

11. A sensor for the transcutaneous measurement of vascular access blood flow, the sensor having an access placement line and comprising:

a first emitter and a first detector positioned on either side of and spaced the same distance δ

from the access placement line; and

a plurality of additional detectors arranged in alignment along a line defined by the first emitter and the first detector.

12. The sensor of claim 11, wherein one of the additional detectors lies on the access placement line.

13. Apparatus for non-invasively measurement one or more blood parameters associated with a vascular access site, comprising:

means for optically measuring a blood parameter in a volume of tissue parallel to and excluding the access site; and

means for optically measuring the blood parameter in a volume of tissue perpendicular to and including at least a portion of the access site.