Optics: measuring and testing – Blood analysis – Hemoglobin concentration
Reexamination Certificate
2000-09-07
2003-08-26
Rosenberger, Richard A. (Department: 2877)
Optics: measuring and testing
Blood analysis
Hemoglobin concentration
C600S320000, C600S328000, C436S066000
Reexamination Certificate
active
06611320
ABSTRACT:
The present invention relates to a non-invasive method for determination of blood characteristics including hemoglobin (EVF/haematocrit) in a vessel containing a mixture of liquid and blood cells using the orientation effects of the red blood cells. The present invention also relates to an apparatus for performing the, method.
BACKGROUND TO THE INVENTION
There are different non-invasive methods known for measurement of hemoglobin. These methods make use of absorption of energy at a certain light wavelengih of the red blood cells (RBCs). Carim et al disclose in U.S. Pat. No. 5,755,226 a non-invasive method and apparatus for the dirct non-invasive prediction of hematocrit in mammalian blood using photopletysmography (PPG) techniques and data processing. However, this method only makes use of the ability of the RBCs to absorb energy. This method is also quite complicated regarding the formulas which are to be used when calculating the predicted hematocrit. Thus the method is time consuming. This method has not taken into account the red blood cell orientation and distribution in blood vessels.
Further, a method and an apparatus, are disclosed in WO 97/15229 for determining hemoglobin concentration in blood. The method is used for detecting hemoglobin in the microvascular system beneath the mucosal membranes on the inside of the lip of a human subject by introducing a measuring tip into the mouth of a subject. This means that the measuring tip of the apparatus must have some kind of sterile shell before it may be placed in the mouth. This sterility of the measuring tip means that either the apparatus must be autoclaved before measuring or that a disposable plastic tip has to be used when performing the method. This method further uses the reflection of light for determining the concentration of hemoglobin.
Accordingly, there is a need for new methods for detecting hemoglobin which takes into account the blood cell orientation and thus gives a more accurate detection value. Further, methods which do not involve an extra step of making the apparatus sterile before measuring or disposable tips are desirable. The new methods should also be less sensitive to variations in the blood pressure, e.g. the pulsative, (systolic) pressure.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the present invention there is provided a new non-invasive method for determination of blood characteristics including hemoglobin from a mixture of liquid and blood cells contained in a light pervious vessel comprising:
a) directing at least one light beam against the vessel;
b) detecting the intensity of the light of said light beam transmitted through the vessel;
c) detecting the intensity of the light of said light beam reflected from the vessel;
d) calculating a quotient of said detected intensity of said transmitted light and detected intensity of said reflected light or a quotient of said detected intensity of said reflected light and detected intensity of said transmitted light; and
e) analyzing said quotient to determine the blood characteristics.
In accordance with a second aspect of the present invention there is provided an apparatus for determination of blood characteristics including hemoglobin from a mixture of liquid and blood cells contained in a light pervious vessel comprising:
i) at least one light source for directing a light beam against the vessel;
ii) a first detector for detecting the intensity of the light of said light beam transmitted through the vessel;
iii) a second detector for detecting the intensity of the light of said light beam reflected from the vessel; and
iv) a processor for calculating a quotient of said intensity of said transmitted light detected by said first detector and said intensity of said reflected light detected by said second detector or a quotient of said intensity of said reflected light detected by said second detector and said intensity of said transmitted light detected by said first detector, and for analyzing said quotient to determine the blood characteristics including hemoglobin; and optionally
v) registration means for storing the blood characteristics; and optionally
vi) means for visualization for visualizing the blood characteristics.
Preferably the processor is adapted to convert the quotient to a concentration value of the determined blood characteristics. This adaption may be performed by using a calibration curve.
In accordance with a third aspect of the present invention there is provided use of an apparatus according to the second aspect of the present invention in a dialysis apparatus (or dialysis device).
DETAILED DESCRIPTION OF THE INVENTION
With the expression “blood characteristics” is meant in the present application characteristics of blood such as concentration of blood components, e.g. hemoglobin, total hemoglobin, red blood cells, white blood cells, platelets, cholesterol, albumin, thrombocytes, lymphocytes, drugs and other substances, viscosity, blood pressure, blood flow, blood volume, blood cell illnesses, abnormal blood cell appearances, anaemia, leukemia, lymphoma.
With the expression “hemoglobin” is meant in the. present application oxyhemoglobin, reduced hemoglobin, carboxy hemoglobin, methemoglobin and sulphhemoglobin.
With the expression “red blood cells”, also known as erythrocytes, is meant in the present application whole or partly lysed red blood cells which contain hemoglobin.
With the expression “light pervious vessels” is meant in the present application a blood vessel in an animal, a pipe, a tube or a tubing which is light pervious. The pipe, tube or tubing may be manufactured from acrylonittile butadiene styrene (ABS), polycarbonate or acrylic glass (polymethylmethacrylate; PMMA) which gives a non-flexible material or from polyvinyl chloride (PVC) or silicon rubber, plasticized PVC, e.g. PVC plasticized with dioctylphtalate, diethylhexylphtalate or trioctyltrimellitate, which gives a flexible material. PMMA is the most preferred non-flexible material. The light pervious vessel may be used when performing liquid transfusions or blood transfusions. The elasticity of the material may be varied in a wide range. The animal containing a blood vessel is preferably a mammal, most preferred a human being.
As used herein, “light” refers generally to electromagnetic radiation at any wavelength, which includes the infrared, visible and ultraviolet portions of the spectrum. A particularly preferred-portion of the spectrum is that portion where there is relative transparency of the tissue, such as in the visible and near-infrared wavelengths. It is to be understood that for the present invention, light may be nonpolarized or polarized light, coherent light or incoherent light and illumination may be steady pulses of light, amplitude modulated light or continues light.
Light sources which may be used in the method and the apparatus according to the invention are e.g. light emitting diodes (LEDs), laser diodes or combinations thereof such as VCSEL (vertical cavity surface emitting laser). Preferably less expensive LEDs are used. Today there are also new strong light emitting diodes which may be used in the method and the apparatus according to the invention. Flash lamp light sources are also conceivable for use in the present invention. The light source may further be capable of emitting monochromatic light, i.e. a monochromator. Optical fibres for guiding the light to and from the measured spot and/or quartz halogen lamps or tungsten lamps may also be used as light sources. Optical light fibres and or direct illumination on the measured spot may also be used.
Detectors which may be suitable for use when performing the method according to the present invention, are phototransistors, photodiodes, photomultipliers, photocells, photodetectors, optical power meters, amplifiers, CCD arrays and so on.
According to one preferred embodiment of the method of the present invention, the detected intensity of the light of said light beam transmitted through the vessel, the detected intensity of the light of said light beam refl
Enlund Gunnar
Lindberg Lars-Göran
Vegfors Magnus
Barth Vincent P
OptoQ AB
Rosenberger Richard A.
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