System and method for measuring blood urea nitrogen, blood osmolarity, plasma free hemoglobin and tissue water content
AssigneeHema Metrics, Inc.
InventorsRobert R. Steuer, David R. Miller
Life of this patent
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Abstract
Systems and methods are provided for noninvasively measuring the levels of urea, blood osmolarity (or Na+), plasma free hemoglobin and tissue water content in a patient's blood or tissue. Light of selected wavelengths is passed through blood or body tissue and the transmitted or reflected light is detected and the detected signals can be electronically compared and manipulated to provide the non-invasive, continuous and quantitative display of a patient's blood urea, blood osmolarity (or Na+), plasma free hemoglobin and tissue water content.
Claims13
A system for determining a plurality of different constituents of the blood or tissue of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- a plurality of determining means each receiving said first radiation from said first detecting means for determining a respective constituent, said plurality of determining means being equal to the plurality of constituents.
A method for determining a plurality of different blood or tissue constituents of the blood or tissue of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to examination in the extracorporeal passageway, in the body part or the extracorporeal passageway defining a blood conduit, the method comprising the steps of:
- flowing the blood of a patient through a blood conduit;
- placing a first emitter emitting a first radiation wavelength on the blood conduit;
- directing the first radiation wavelength through the blood on the blood conduit;
- directing the first radiation wavelength through the blood in the blood conduit;
- detecting the amount of first radiation after passing through the blood in the blood conduit, the detected amount of first radiation having at least one extinction characteristic;
- and
- determining a plurality of blood constituents based on the detected amount of first radiation.
A system for determining tissue water content of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining tissue water content by solving the equation [(Xwi/Xwt)−1]×100, where, Xwi equals the initial volume of water per volume of tissue at time 0 and Xwt equals the volume of water per volume of tissue at time t.
A system for determining BUN of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining BUN by solving the equation [E2190/E1300][Circlesolid][F[log (I/Io)8/log (I/Io)13]], where E2190 equals the extinction coefficent at 2190 nm wavelength, E1300 equals the extinction coefficient at 1300 nm wavelength, F equals a function of hematocrit, I equals the transmittal intensity of source radiation, Io equals the intensity of incident source radiation;
- log (I/Io)8 is the log value at 810 nm wavelength and log (I/Io)13 is the log value at 1300 nm wavelength.
A system for determining sodium content of the blood of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining sodium content by solving the equation [log (8)][Circlesolid]F[log (8)/log (13)], where F is a function of hematocrit. to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first-radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining plasma free hemoglobin by solving the equation A[log(8)[Circlesolid]F(log (8)/log (13)]+B, where A equals slope and B equals offset.
A system for determining osmolarity of the blood of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining osmolarity by solving the equation g [log (8)][Circlesolid]F[log (8)/log (13)]+b, where g equals slope and b equals offset.
A system for determining plasma free hemoglobin of the blood of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:
- blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;
- a first emitter positioned on said conduit receiving means for emitting a first-radiation wavelength;
- directing means for directing the first radiation wavelength into the flowing blood in the blood conduit;
- first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;
- and
- determining means receiving said first radiation from said first detecting means for determining plasma free hemoglobin by solving the equation A[log(8)[Circlesolid]F(log (8)/log (13)]+B, where A equals slope and B equals offset.
Dependencies are inferred from the claim text.