News Column

Patent Issued for Early Stage Peritonitis Detection Apparatus and Methods

August 26, 2014



By a News Reporter-Staff News Editor at Life Science Weekly -- A patent by the inventors Landherr, Frank J. (Cary, IL); Jensen, Lynn E. (Syracuse, UT); Lan, Jay M. (Thousand Oaks, CA), filed on July 23, 2007, was published online on August 12, 2014, according to news reporting originating from Alexandria, Virginia, by NewsRx correspondents (see also Fresenius Medical Care Holding, Inc.).

Patent number 8801652 is assigned to Fresenius Medical Care Holding, Inc. (Waltham, MA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The invention relates to apparatus and methods for medical diagnostic testing. It has application, inter alia, in detecting the onsite of peritonitis, for example, during continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) procedures.

"Peritoneal dialysis (PD) is a medical procedure for removing toxins from the blood that takes advantage of the semi-permeable membrane surrounding the walls of the abdomen or peritoneal cavity. During a PD procedure, a solution is introduced into the patient's abdomen, where it remains for up to several hours, removing blood toxins via osmotic transfer through that membrane. At completion of the procedure, the solution is drained from the body along with the toxins. CAPD is the manual form of this procedure, requiring that the patient manually drain fresh PD solution into, and spent PD solution out from, the peritoneum. In APD, the entire procedure is handled by automated equipment.

"Peritonitis is a common complication of both CAPD and APD. Often caused by introduction of bacteria (e.g., from the tubing, connectors and other apparatus that make up the PD transfer set) to the peritoneum during dialysis, this swelling of the peritoneum can cause vomiting, abdominal tenderness and a host of other symptoms. Although responsive to antibiotics, peritonitis can end a patient's ability to stay on APD and CAPD therapies. In extreme cases, it can be fatal.

"Standard tests for peritonitis, usually conducted on occurrence of acute clinical symptoms, include the Gram stain procedure, performing a cell count on the peritoneal fluid, culturing that fluid, and/or performing a blood culture. Largely, these tests can only be done in the lab, after a patient has presented with symptoms. By that time, the peritonitis may well have set in, resulting in undue patient distress and potentially necessitating more extensive treatment.

"More recently, reagent test strips have become available, making it possible for physicians or patient's themselves to perform more immediate diagnosis. However, test strips have a limited time window of utility and have generally not been successful in early stage detection.

"CAPD and APD patients are typically counseled to maintain a keen eye for another symptom of peritonitis: a turbid or cloudy effluent bag. This can be late-developing, unfortunately, and is further compounded if the PD solution remains in the body for a long period before expulsion (as is the case, for example, during daytime dwells of APD patients). Detection of turbid effluent is further complicated in APD equipment with long drain lines, since patients may only see the effluent lines and not the effluent bag (where the turbidity is more readily apparent). Moreover, patients who are blind or have poor eyesight must rely on friends, family and/or caregivers to inspect the spent PD fluid for turbidity.

"The prior art suggests that such cloudiness might be detected automatically, e.g., within APD equipment, by detecting the overall amount of non-coherent, polychromatic light that passes through a vessel of PD effluent by use of a source of such light positioned on one side of the vessel and a detector positioned at an opposing side. Implementations of this technique have generally not proven reliable because of poor signal-to-noise.

"An object of the invention is to provide improved methods and apparatus for medical diagnosis, testing and/or treatment in the home or lab.

"A further object of the invention is to provide improved methods and apparatus for PD therapy.

"A still further object of the invention is to provide improved methods and apparatus for detecting the onset of peritonitis, e.g., in connection with peritoneal dialysis.

"Yet a still further object of the invention is to provide such methods and apparatus as can be implemented at reasonable cost, yet, produce efficacious results."

In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventors' summary information for this patent: "The foregoing are among the objects attained by the invention which provides, in one aspect, automated medical testing methods and apparatus that detect the onset of peritonitis from optical characteristics of PD effluent resolved at cellular scales in the flow path.

"For example, according to one aspect of the invention, an APD machine includes, in an effluent flow path, apparatus for early stage peritonitis detection comprising an illumination source and a detector. The source is arranged to illuminate peritoneal effluent in a chamber that forms part of the flow path, and the detector is arranged to detect illuminant scattered by the effluent. The detector detects that scattered illuminant at a cellular scale of resolution, e.g., on a scale such that separate cellular-sized biological (or other) components in the effluent can be distinguished from one another based on scattering events detected by the detector.

"Related aspects of the invention provide apparatus as described above in which the detector is arranged such that separate white blood cells (WBCs) in the effluent can be distinguished from one another based on reflection and scattering (collectively, 'scattering') of illuminant. Apparatus with a detector so arranged can, by way of example, count such WBCs from scattering and can, further, signal the onset of peritonitis if those counts change over time and/or vary from a baseline.

"Further related aspects of the invention provide apparatus as described above in which the detector is arranged such that cellular-sized biological (or other) components of different types in the effluent can be distinguished based on illuminant scattered by them. Related aspects of the invention provide such apparatus in which the detector is so arranged as to permit WBCs in the effluent to be distinguished based on scattering from red blood cells (RBCs), fibrin and/or other components.

"Other aspects of the invention provide apparatus as described above which signal the onset of peritonitis based on variance, e.g., over time and/or from a baseline, in counts of selected biological components in the effluent. Related aspects of the invention provide such apparatus as compute a trend of variance of those counts, e.g., with respect to WBCs in the effluent. Further related aspects of the invention provide such apparatus which compute that trend as a slope of a curve of those counts with respect to time and that signals the onset of peritonitis when that slope exceeds a selected amount.

"Other related aspects of the invention provide such apparatus in which the detector counts scattering events--i.e., events in which illuminant is reflected and scattered from the effluent to the detector--based on intensity and/or location of the scattering event. In one such aspect of the invention, the detector comprises a pin diode that is configured to count scattering events, e.g., based on the intensity of illuminant detected from the effluent. An apparatus according to this aspect of the invention can, for example, signal the onset of peritonitis when the number of counts of a certain intensity (or range of intensities, e.g., which are based on cell size) varies, e.g., from a baseline and/or among drains of spent PD solution from the patient, and/or when a trend of that variance over time exceeds a selected amount.

"In other such aspects, the detector comprises a charge-coupled device (CCD) that is arranged to image the chamber--that is, to record scattering events based on both location and (cumulative) intensity. Further related aspects of the invention provide such apparatus in which the detector generates a histogram of one or more such images, counting scattering events (e.g., based on intensity). Still further related aspects of the invention provide such apparatus which generates a histogram from multiple images taken, for example, during a drain of spent PD solution from the patient. As above, apparatus according to these aspects of the invention can, for example, signal the onset of peritonitis when the number of counts of a certain intensity (or range of intensities) varies over time, e.g., from a baseline and/or among successive drains of PD effluent from the patient.

"Other related aspects of the invention provide such apparatus which the histograms are performed only with respect to selected scattering events recorded in the images, e.g., scattering events of selected intensities and/or lengths. Apparatus accord to these aspects of the invention can, for example, signal the onset of peritonitis when the number of counts from scattering events likely caused by WBCs (and not, for example, RBCs or fibrin) vary over time from a baseline and/or among successive drains of PD effluent from the patient.

"Further aspects of the invention provide such apparatus in which the illumination source is a laser diode (or other source of coherent illuminant).

"Related aspects of the invention provide such apparatus in which the detector is arranged to detect side-scattering events, e.g., events detectable within a field of view perpendicular to a ray of illuminant sourced by the laser diode.

"Further related aspects of the invention provide such apparatus in which illuminant sourced by the laser diode comprises a beam disposed--and, specifically, for example, centered--within a portion of the flow path from which scattering events are counted by the detector.

"Still further related aspects of the invention provide such apparatus in which illuminant sourced by the laser has a beam width selected based on size characteristics of the biological (or other) components from which scattering events are to be counted. Further related aspects of the invention provide such methods in which the beam width has a diameter of about 1.5 times a size of components, e.g., WBCs. Yet still other aspects of the invention provide such apparatus in which the beam width has any of a circular and gaussian cross-section, or other beam size and/or shape.

"Further aspects of the invention provide such apparatus in which the detector comprises a lens arranged to resolve illuminant scattered from components of the effluent at a cellular scale of distances. Related aspects of the invention provide such apparatus in which the lens is arranged to provide a depth of field encompassing a substantive portion of the flow path within the detector field of view, e.g., a depth of field that encompasses a flow chamber from which scattering events are detected.

"Other aspects of the invention provide apparatus as described above for use in connection with CAPD procedures.

"Still other aspects of the invention provide such apparatus for use in detecting the on-set of peritonitis in fluid flows established independent of APD and/or CAPD equipment in which the PD fluid is collected. Such apparatus has application, for example, in testing bags (or other collections) of spent PD effluent, e.g., as they are being emptied for disposal or for further testing.

"Yet still other aspects of the invention provide PD kits that include, in addition to conventional components (such as tubing, clamps, sterilization wipes, and so forth), a test apparatus as described above.

"Still yet other aspects of the invention provide methods of testing PD effluent for the onset of peritonitis paralleling the operations described above.

"Yet still other aspects of the invention provide apparatus and methods as described above for use in detecting, in a PD effluent flow, blood (RBCs), bubbles and other undesirable byproducts of CAPD, APD and so forth. A related aspect of the invention is to provide such apparatus and methods for use in hemodialysis and other medical procedures

BRIEF DESCRIPTION OF THE DRAWINGS

"A more complete understanding of the invention may be attained by reference to the drawings, in which:

"FIGS. 1A-1E depict an automated peritoneal dialysis (APD) treatment system according to one practice of the invention and of the type with which the invention can be practiced;

"FIGS. 2A-2C depict a continuous ambulatory peritoneal dialysis (CAPD) treatment system according to one practice of the invention and of the type with which the invention can be practiced;

"FIGS. 3A-3B depict apparatus for testing PD effluent according to one practice of the invention;

"FIG. 4 depicts an image of the type generated by a charge coupled device in an apparatus according to one practice of the invention; and

"FIGS. 5A-5C depict histograms of the type generated from images generated by charge coupled devices used in practice of the invention;"

URL and more information on this patent, see: Landherr, Frank J.; Jensen, Lynn E.; Lan, Jay M.. Early Stage Peritonitis Detection Apparatus and Methods. U.S. Patent Number 8801652, filed July 23, 2007, and published online on August 12, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8801652.PN.&OS=PN/8801652RS=PN/8801652

Keywords for this news article include: Electronics, Laser Diodes, Fresenius Medical Care Holding Inc..

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Life Science Weekly


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