Off-Axis Blood Chamber

• US 20120065568A1
• Filed: 09/13/2010
• Published: 03/15/2012
• Est. Priority Date: 09/13/2010
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: Hema Metrics, LLC
• Inventors: Law, Perry N., Barrett, Louis L.
• Granted Patent: US 8,328,748 B2
• Time in Patent Office: Days
• US Class Current: 604/6.15
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/3609 Physical characteristics of the blood, e.g. haematocrit, urea
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2205/3313 used specific wavelengths
• CPC Class Codes: A61M 2230/207 hematocrit

Abstract

An extracorporeal blood chamber for an optical blood monitoring system has a mixing area and viewing area that are offset from the axis of the blood flow path into and out of the blood chamber. The off-axis design provides more leverage for threading the blood chamber onto a dialysis filter. It also eliminates the need for turbulence posts.

Claims

1. A blood chamber for optically monitoring blood flowing through an extracorporeal tube, the blood chamber defining a flow path through an internal blood flow cavity which provides a viewing area for optical monitoring of the blood, the blood chamber comprising:

an internal blood flow cavity comprising two substantially parallel internal flat walls separated by a predetermined distance;

a first port and channel in fluid communication with the internal blood flow cavity;

a second port and channel in fluid communication with the internal blood flow cavity,

the first port and channel and the second port and channel being in axial alignment along a first axis;

a viewing area within the internal blood flow cavity defined by a pair of viewing lenses commensurate with at least a portion of the respective flat walls defining the internal blood flow cavity, the viewing region being offset from the first axis.

2. A blood chamber as recited in claim 1 further comprising:

a pair of flow guides in the internal blood flow cavity, the first flow guide guiding blood flowing into the internal blood flow cavity along the first axis such that the blood flows off the axis and into the viewing region within the internal blood flow cavity and the second flow guide guiding blood exiting from the viewing region such that it flows along the first axis through the second port and channel to exit the blood chamber;

a pair of flow guides that channel the internal blood flow in a circular pattern to encourage formation of one of more eddy current to promote mixing and homogeneity of the blood in the viewing area.

3. A blood chamber as recited in claim 1 wherein the lenses provide a circular viewing region.

4. A blood chamber as recited in claim 2 wherein the shape of the flow guides and the internal blood flow cavity are symmetric with respect to the direction of flow of the blood.

5. A blood chamber as recited in claim 2 further comprising a peripheral wall spanning between the flat parallel walls and defining part of the blood flow cavity, the peripheral wall being arcuate and having a radius greater than the radius of the circular viewing region.

6. A blood chamber as recited in claim 1 wherein the viewing lenses are made of a clear material in order to facilitate the emission and detection of light at predetermined wavelengths passing through the viewing lenses and blood flowing through the viewing region of internal blood flow cavity, and at least a portion of the blood chamber is made of an opaque material, wherein the opaque portion of the blood chamber isolates the viewing lenses from light ducting from one lens to the other lens without passing through blood flowing through the internal blood flow cavity.

7. A blood chamber as recited in claim 6 wherein the blood chamber includes a chamber body made of an opaque material, and a pair of lens bodies each made of a clear material, the lens bodies being sonically welded to the chamber body to form the blood chamber.

8. A blood chamber as recited in claim 7 wherein the lens bodies are molded from clear polycarbonate, and the chamber body is molded from tinted polycarbonate material which does not transmit light energy at or near at least one of 660 nm, 810 nm and 1300 nm.