Sensor for transcutaneous measurement of vascular access blood flow

• US 6,937,882 B2
• Filed: 12/09/2003
• Issued: 08/30/2005
• Est. Priority Date: 12/29/2000
• Status: Expired due to Fees

• Current Assignee: HEMA Metrics Incorporated
• Original Assignee: HEMA Metrics Incorporated
• Inventors: Miller, David R., Bell, David A., Steuer, Robert R.
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): Kremer, Matthew J
• Application Number:
  US10/730,005
• Publication Number:
  US 20040116790A1
• Time in Patent Office: 630 Days
• Field of Search: 600/331, 600/310, 600/322, 600/344, 600/373, 600/384
• US Class Current: 600/331
• 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 medical device to be secured to the skin of a patient to measure a physical parameter comprising:

a substrate having a skin surface and an exterior surface;

a flexible circuit board mounted on the exterior surface;

conductive paint deposited on the circuit board to define a circuit that operates to allow calibration of the medical device when the circuit is complete and prevents calibration of the medical device when a portion of the conductive paint is removed from the circuit board;

an aperture formed through the substrate to provide a passage from the skin surface to the conductive path;

a plug positioned within the aperture to adhere to the conductive paint; and

a removable protective layer covering the skin surface of the substrate and secured to the plug so that when the protective layer is removed the plug remains secured to the protective layer resulting in removal of a portion of the conductive paint to prevent calibration of the medical device.

2. The medical device of claim 1, further comprising an exterior cover positioned on the exterior surface of the substrate to define an interior portion of the substrate;

and a plurality of sensing elements housed in the interior portion of the substrate and secured to the circuit board.