JP2002519088A - Blood system characteristic evaluation device - Google Patents

Abstract

(57) SUMMARY An apparatus and method are provided for detecting and monitoring the properties of blood circulation in a tissue. The method includes transmitting (12) light energy to tissue, detecting (16, 17) light energy after being affected by the tissue, and determining at least one property of the tissue. Including. Determining the at least one property includes determining an attenuation of the light energy, calculating a time from transmission of the light energy to detection, relating the attenuation and travel time to the at least one property; including.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

【Technical field】

The present invention relates to the field of medical diagnostics. In particular, the present invention relates to devices and methods for assessing the physiological characteristics of the circulating blood system of the body.

[0002]

BACKGROUND OF THE INVENTION

Blood pressure is a measurable parameter of the circulatory system and can greatly contribute to knowing the overall physiological state of the body. U.S. Pat. No. 3,980,075 describes a method for constantly monitoring and measuring tissue perfusion of blood. Such perfusion depends on blood pressure and can therefore be used as an indicator of target organ blood circulation.

[0003] There are many physiological aspects of blood pressure, because many factors affect blood pressure and blood circulation is involved in all functions of the body.

Referring to FIG. 1, this is a graph schematically illustrating the cycling relationship between the time and amount of blood present in a particular cross-section of an organ measured by light absorption at the appropriate wavelength. . Graph B represents an organ or tissue that is farther from the heart as compared to the organ of Graph A. Not only is there a small phase difference in the change in rhythm of blood volume, it is clear that the amplitude of the rhythm of the organ measured at the site represented by graph B is different from the amplitude of the rhythm of the organ at site A. .

[0005]

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a detection device for monitoring the characteristics of a circulating blood element of the body. Such a device consists of at least one light sensor unit and comprises at least one transmitter and at least one detector. The transmitter has means for illuminating at least one spectral component of continuous light or pulsed light. The apparatus also includes a controller for managing the light sensor and determining the travel time of the light component.

[0006] It is a further object of the present invention to provide a method for monitoring the properties of the blood circulation of a tissue by measuring the attenuation of light at at least two different parts of the body. According to this method, the following steps are performed. Illuminating the tissue with light energy, detecting a portion of the light energy after being affected by the tissue, determining a decay of the light energy, and determining a travel time of the light energy. Relating attenuation and transit time to at least one property of the tissue.

[0007] Accordingly, according to a preferred embodiment of the present invention, there is provided an apparatus for detecting and monitoring characteristics of a circulating blood element of the body. The apparatus detects at least one spectral component of light, at least one transmitter for transmitting light through tissue containing blood components, and at least a portion of the light transmitted through the tissue. Connected to the at least one detector for controlling the transmitted light and detecting the transit time of the transmitted light; and a controller connected to the at least one detector and the transmitter for detecting the travel time of the transmitted light. A processing unit for processing medical and physiological information about the tissue.

Further, according to a preferred embodiment of the present invention, the transmitter comprises means for emitting at least one pulse of illumination, each of the pulses of illumination having at least one spectral component of light. The pulses may have similar magnitudes in proportion to their corresponding energy levels, or may be equally spaced. The pulses may include direct current (DC) optical components.

Further, according to a preferred embodiment of the present invention, the two detectors are arranged in parallel.

[0010] According to a preferred embodiment of the present invention, there is also provided a method for monitoring the properties of the blood circulation of a tissue. The method includes transmitting light energy to tissue, detecting light energy after being affected by the tissue, and determining at least one property of the tissue.

Further, in accordance with a preferred embodiment of the present invention, determining at least one characteristic comprises: determining a decay of light energy; calculating a time from transmission of light energy to detection; Relating the damping and the transit time to at least one property.

The light energy may be in the form of a burst comprising spaced pulses, each of the spaced pulses having at least one spectral band.

Further, in accordance with a preferred embodiment of the present invention, the determining comprises calibrating the resting blood pressure at at least two predetermined points. At least one of the predetermined points has a static blood pressure value of zero, an equivalent hydrostatic column of zero blood pressure value, or any other value.

Further, according to a preferred embodiment of the present invention, the step of determining includes a step of normalizing, wherein the normalizing comprises processing the received signal at one or more measurement points to obtain a waveform. Determining the time lag of the waveform, thereby determining the group delay and viscosity.

The properties that have been determined include circulatory parameters at the cellular and subcellular levels, systolic pressure, diastolic pressure, blood viscosity, changes in viscosity, cardiac output, oxygen saturation, , A systolic waveform and blood flow.

Alternatively, according to a preferred embodiment of the present invention, the determining comprises measuring blood circulation at different depths.

Further, according to a preferred embodiment of the present invention, the detecting step includes detecting light transmitted through the tissue or reflected by the tissue.

Further, in accordance with a preferred embodiment of the present invention, the detecting step includes detecting a change in the frequency of the received reflected pulse, thereby determining blood viscosity. Also, the detecting step includes a flow characteristic.

Further, according to a preferred embodiment of the present invention, the method further comprises displaying at least one of the characteristics in at least one of a group of formats including a two-dimensional or three-dimensional form.

Further, according to a preferred embodiment of the present invention, the method further comprises biofeedback by altering a physiological state of the body, whereby medical and physiological information about the tissue is sent to the processing unit. Change typing.

Finally, light is transmitted via one of a group of sources including semiconductor light emitting diodes (LEDs) and diode lasers.

DETAILED DESCRIPTION OF THE INVENTION In accordance with a preferred embodiment of the present invention, it is noted that the amount of blood in a particular tissue changes dynamically, and the characteristics of blood circulation and other characteristics of that particular site are recorded. Assess tissue characteristics. As described below, the characteristics of the circulatory system as a whole can be inferred from local measurements. According to the present invention, the intensity of the light beam impinging on the tissue is measured, and the intensity of the light beam after being affected by the tissue is also measured to determine the effect on the tissue at a particular wavelength. Thus, the more blood there is at a particular site, the greater the effect at visible and gold infrared wavelengths.

According to the invention, the sensor unit comprises at least one transmitter of light and one detector. In this simplest form, seen in FIG. 2A, with reference to the transmitter 12 illuminating the tissue. Some light travels through the tissue, some of which are detected by the detector 16 and quantified and processed by the processing unit 24 to extract medical and physiological information. A controller unit 22 is sandwiched between one processor 24 and the other detector 16 and transmitter 12. Alternatively, as indicated by arrow 25, detector 17 can be set to determine the light reflected from the tissue, rather than the transmitted light.

Examples of light sources include any suitable sources such as semiconductor light emitting diodes (LEDs) and diode lasers, and argon, neodymium, synthetic yttrium, Robedi
gaseous lasers such as um and carbon dioxide.

The controller 22 controls the light from the sensor unit and determines the travel time of the transmitted or reflected light. The controller is for biofeedback training, etc.
It can be connected to a display screen to display the result.

Referring now to FIG. 2B, which is a schematic diagram of an alternative sensor according to the present invention, wherein an optical filter 18 is added in front of the transmitter 12 to enhance the spectral band selectivity of the device.

According to the present invention, light pulses can be used. The transmitter 12 can emit a burst of spectrally identical light pulses, as shown in FIG. 3 to which reference is now made. Burst A, Burst B, and Burst C are each 500 microseconds in length and represent the chain of bursts generated by the transmitter, but are sent sequentially by the transmitter at equal intervals. In every burst,
Each light pulse (31, 32, 33, 34, 35, 36, 37, etc.) is typically 50 microseconds long, has the same magnitude in proportion to the energy level, and all pulses are energetically It means that they are the same.

In a different embodiment, illustrated in FIG. 4, to which reference is now made, each burst of light:
For example, the burst D includes pulses such as pulses 51 and 52. Each pulse includes a plurality of different spectral band components 58, 59, 60, each having a magnitude proportional to the energy level in a particular spectral band. The passage of the pulse through the tissue 14 attenuates the energy level of the pulse, as marked by the lower magnitude of the detected pulse 61,62. The spectral components of each pulse, such as components 65, 66, 67, may be attenuated differently. Certain spectral attenuation patterns may be considered to have significance for certain physiological properties.

According to the Doppler effect, the apparent frequency of the light pulse detected by the detector depends on the speed at which the reflected burst is moving. The pulse is directed at the blood flow, and the received frequency is affected by the speed of the blood flow. Thus, by assessing the frequency of the burst light pulses, the radial velocity of the blood is inferred. Fourier transform analysis or wavelet analysis may be applied to the received light to derive the frequencies that make up the overall rhythm of the flow, thereby increasing sensitivity to small differences in frequency, from 1 cm / sec to 50 cm / sec. Low liquid velocities, such as within the range, can be calculated. Using frequency analysis techniques, turbulence can be resolved into constituent frequencies, from which laminar flow components can be derived.

According to Poiseuille's law, the following relationship is obtained.

[0031]

Q = π · Δpr ⁴ / (8ηI) where Q = blood flow, Δp = differential pressure along the pipe, r = radius of the pipe, I = length of the pipe, η = viscosity,

To derive the viscosity η, the variables Q, Δp, r, I for a given length of tube are replaced by measured data or otherwise known data. Blood viscosity is a feature that can be very important for assessing various physiological and medical conditions.

[0033]

[Calibration of measurement for blood pressure]

To establish a function between the parameters measured according to embodiments of the present invention and the blood pressure measured by conventional means, a calibration step must be performed. "Textbook of Medical Physiology", 8th edition, Giton A. C. (Guyton, AC); B. Sonders (WB Saunder
s Company), pages 165, 167, disclose hydrostatic pressure maps at different locations along the venous system. Applicants have recognized that this map can also be used for the arterial system.

Referring to FIG. 5, this is a schematic diagram of the hydrostatic blood pressure of a human body. “Hydrostatic blood pressure” and “static blood pressure” are used interchangeably herein. In FIG. 5, in the neck region 80, the venous pressure is reduced to zero. This is so actively maintained by the physiological feedback mechanism, so that a sensor placed in place to observe venous blood is calibrated at that point to zero hydrostatic (static) pressure. In that regard, arterial blood can be measured separately due to different spectral features,
This is known in the art. Due to the sufficiently high sampling resolution of the measurement system, the cycle characteristics of the blood circulation can be observed.

Thus, at point 80 and at an additional point 82 on the leg where the mean hydrostatic pressure of the blood column can be easily calculated, mean zero or zero and any other constant hydrostatic pressure. To provide a calibration curve. The difference in blood pressure between the point at zero pressure 80 and the point 82 is a function of the weight of the column of blood between these two points, which is the difference in height Δh between the two points. Function. Such a calibration curve provides a function between the hydrostatic (static) pressure of the blood at a particular measurement location and the optical information collected by the sensor unit.

Alternatively, the difference in hydrostatic blood pressure may be measured between any two points, and is not limited to measuring between zero pressure and a second point. The difference in hydrostatic blood pressure is the difference in height between any two points, or the difference in one point by changing the relative height of the points,
Is one of For example, in the latter case, the difference in hydrostatic blood pressure can be measured when moving the leg or arm from one position to another.

Line normalization can be achieved by processing the received signal and establishing the waveform by removing inappropriate variables such as noise and patient motion. This can be achieved, for example, by comparing the measured rhythms at two different measurement sites, thus establishing a common characteristic of the wave, while a transient characteristic common only to one site. Noise or influence can be avoided.

In FIG. 1 to which reference is now made, waves are illustrated at two different points in the body, schematically illustrating the amount of blood then present in each tissue. Although the magnitudes are different and the phases are shifted, the normal waveforms are seen to be similar. The phase shift occurs as a result of a time lag at one site relative to the other site closer to the heart. It is understood that the heart is used for illustrative purposes only, and that other organs such as liver, kidney, brain and eyes can be used as reference points. Wave attenuation is caused by the dissipation of the body's driving energy, which is also affected by the viscosity of the blood. In this way, a waveform can then be established by using the common features of the waves from two different measurements at different locations.

[0039]

[Heart output]

The integration of the waveforms gives the relative cardiac output. By normalizing the diameter of the blood vessel, the absolute value of the cardiac output is obtained.

[0040]

[Optical sharpness, sampling resolution, and system resolution]

In order to degrade the properties of the circulatory system at the cellular or even subcellular level, a narrow light beam is provided by the transmitter so that the resolution of the measurement is appropriate. Typical erythrocytes are 8 microns in diameter, implying that a narrower beam is needed to be able to assess a single cell at a time. To achieve such a high resolution measurement, a short duration of light and subsequent detection is also needed, so that a particular cell can be measured within a particular time frame. This can be achieved by using a laser diode at the measurement site that has a narrow beam, typically about 5 to 100 microns, and the short bursts described above. While it is preferred to assess red blood cells for size, it is understood that it is also possible to assess white blood cells or other blood cells.

[0041] Statistical processing of measurements can be used to define circulatory parameters. For example, a change in blood cell velocity may be caused by a change in blood pressure or blood viscosity, or may be dependent on cardiac output characteristics.

It is understood that the measurements are used for many applications. For example, measurements may indicate the effect of drugs and stimulants. By comparing the vitality of tissues in different areas, information can be used to define the boundaries between dead and living tissue, but this, for example, is common in general and plastic surgery. Useful. In addition, the measurements can be used for biofeedback.

The measurements are also useful to indicate the nature of the blood flow. For example, turbulence or laminar flow is a useful parameter to indicate any restriction of the artery.

[0044]

[Different depth measurement]

The apparatus according to the method of the invention is used to measure the properties of tissue containing blood at different depths. Such a device is shown in FIG. The transmitter 12 sends a pulse of light, which penetrates and interacts with the tissue 54, resulting in a pulse attenuation. Ray 52 comprises a discontinuous pulse, is partially absorbed at the surface,
Partially penetrates tissue 54. Along ray 52, two different points of reflection 66,
58 is shown. Some energy is deflected off of optical path 52 at each of these points, by parallel detectors 16A, 16B corresponding to points 56, 58, respectively. In order to obtain data on blood circulation at different depths, embodiments having different configurations of transmitters and detectors are also contemplated.

Similarly, the diameter of the blood vessel can be determined to normalize cardiac output.

In this way, the increment path or time of the ray of tissue 54 coming from point 58 as compared to point 56 can be calculated. At the same time, the incremental decay of light energy is also calculated by comparing the amount of energy coming from point 58 to the amount of energy coming from point 56. For homogeneous tissue, the attenuation is uniform and constitutes a linear function of travel time or path length in the tissue. However, since the tissue under investigation is likely to be non-uniform or contain non-uniform portions, the pulse attenuation
On the one hand it cannot serve as a clear measure of the depth of penetration and on the other hand it typically represents the tissue optically. To overcome the limitations of such a system, a chain of bursts as shown in FIG. 3 can be adjusted with superimposed sinusoids.

To illustrate the intent of the present invention, reference is made to FIG. 7, which is a schematic diagram of a burst modulated by superimposed energy waves.

Each pulse in a burst can be adjusted for superimposed cycles by comparing to adjacent pulses. Thus, the third burst C
At the beginning of the pulse 71 is recognized by a long gap in time before a new pulse (within burst D) occurs, and burst D is the last burst of a half cycle.

The phase difference of the cycle of the pulse between two points measured simultaneously at two different points depends on the distance between the same two points. In this way, the tissue in such a case can be considered to be homogeneous if the geographical path of the light rays within the tissue is the only factor causing the phase difference. However, if the expected phase difference does not appear, there must be non-uniformity in the tissue that causes a phase difference shift that is different from what is expected from pure geographic considerations. The results are output in any suitable form, including two-dimensional graphs, three-dimensional formats, and by cross-sections.

It is understood by those skilled in the art that the present invention is not limited to medical diagnosis of humans, but is also applicable to livestock and animals, including, for example, chickens, cows, racehorses, rabbits and monkeys. You.

It is also understood by those skilled in the art that the present invention is not limited to what has been particularly shown and described in the foregoing specification. Rather, the scope of the invention is defined by the following claims.

[Brief description of the drawings]

FIG. 1 is a graph showing the amount of blood present in two different tissues along the time axis.

FIG. 2A is a schematic view of a foundation detection unit according to the present invention.

FIG. 2B is a schematic diagram of the unit of FIG. 2A with a spectral filter fitted before the transmitter.

FIG. 3 is a schematic diagram of a burst of pulses emitted from a sensing unit.

FIG. 4 is a schematic diagram of a transmitted burst including a composite pulse.

FIG. 5 is a schematic diagram of two reference points for mean hydrostatic blood pressure of the human body, where the reference point is zero mmHg in the neck region.

FIG. 6 is a schematic diagram of a detector assembly for assessing depth changes in blood characteristics.

FIG. 7 is a schematic diagram of a burst modulated by superimposed energy waves.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (71) Applicant Galgally Haplada Street 16, 46766 Herzelia, Israel

Claims (21)

[Claims] 1. An apparatus for detecting and monitoring a characteristic of a circulating blood element of the body, the apparatus comprising at least one spectral component of light for transmitting light through tissue containing said blood element. One transmitter, at least one detector for detecting at least a portion of the light transmitted through the tissue, and the transmitter connected to the at least one detector and the transmitter. A controller for controlling the transmitted light, detecting the transit time of the transmitted light, and calibrating the resting blood pressure at at least two predetermined points; and a processing unit connected to the controller, wherein: A processing unit for processing medical and physiological information related to the medical device. 2. The apparatus of claim 1, wherein said transmitter includes means for emitting at least one pulse of illumination, wherein each of said at least one pulse of illumination comprises at least one spectral component of light. 3. The apparatus of claim 2, wherein said each of said at least one pulse has a similar magnitude in proportion to its corresponding energy level. 4. The apparatus of claim 2, wherein said each of said at least one pulse is equally spaced. 5. The apparatus of claim 1, wherein said at least one detector comprises at least two detectors arranged in parallel. 6. The apparatus of claim 2, wherein said at least one pulse carries direct current (DC) energy. 7. A method for monitoring a characteristic of a blood circulatory system of a tissue, the method comprising: transmitting light energy to the tissue; and detecting the light energy after being affected by the tissue. A method comprising: determining at least one property of the tissue; and calibrating resting blood pressure at at least two predetermined points. 8. The method of claim 1, wherein determining the at least one characteristic comprises: determining a decay of the light energy; calculating a time from transmission of the light energy to detection; and the decay and travel time. 8. The method of claim 7, comprising: relating to at least one property. 9. The method of claim 7, wherein said light energy is in the form of a burst comprising spaced pulses, each of said spaced pulses having at least one spectral band. 10. The method of claim 7, wherein at least one of said predetermined points has a hydrostatic blood pressure value of zero. 11. The method of claim 7, wherein at least one of said predetermined points has a hydrostatic blood pressure value of zero. 12. The step of determining includes a step of normalizing, wherein the normalizing comprises: processing a received signal at at least one measurement point to obtain a waveform; determining a time lag of the waveform; Determining the group delay and / or viscosity thereby. 13. The at least one characteristic includes circulatory system parameters at the cellular and subcellular levels, systolic pressure, diastolic pressure, blood viscosity, viscosity change, cardiac output and blood flow. The method of claim 7, comprising one of the group comprising: oxygen saturation; and a systolic waveform. 14. The method of claim 7, wherein said determining comprises measuring blood circulation at different depths. 15. The method of claim 7, wherein said detecting step comprises detecting light transmitted through or reflected by the tissue. 16. The method of claim 7, wherein said detecting step comprises detecting a change in frequency of the received reflected pulse, thereby determining blood viscosity. 17. The method of claim 7, wherein said detecting step includes a flow characteristic. 18. The method of claim 7, further comprising displaying at least one of said characteristics in at least one of a group of formats including two-dimensional and three-dimensional features. 19. The method of claim 18, wherein altering a physiological condition of the body, thereby altering input of medical and physiological information about the tissue to the processing unit. 20. The method of claim 7, wherein the light is transmitted via one of a group of sources including a semiconductor light emitting diode (LED) and a diode laser. 21. The system of claim 1, wherein the light is transmitted via one of a group of sources including a semiconductor light emitting diode (LED) and a diode laser.