JP5147700B2 - System for automatic measurement of skin perfusion pressure - Google Patents

Description

(Field of Invention)
The present invention relates to a system for automated measurement of skin perfusion pressure at a local site or region of a human body. In particular, the present invention measures measuring means for measuring capillary blood flow, attaching means for ensuring reproducibility, pressure means for applying pressure to a tissue site having capillary blood flow, and measuring applied pressure. And a system including means for detecting and eliminating motion artifacts and determining a relationship between them indicative of an SPP value.

(Description of related technology)
Measurements of skin perfusion pressure are used to determine whether local blood flow, or capillary perfusion, at the local site or area of the ulcer or wound is sufficient to assist wound healing. It has been. For this reason, accurately measuring this parameter is significant for physicians who heal patients suffering from open skin wounds due to complications such as diabetes, pressure ulcers, burns and accidents.

  Conventionally, for measuring skin perfusion pressure or surface perfusion pressure, a surface perfusion pressure monitoring device or a skin perfusion pressure monitoring device connected to a laser Doppler type or other type of optical sensor has been used. For example, Patent Document 1 granted to Borgos et al. Discloses a surface perfusion pressure instrument used in conjunction with a laser Doppler probe that measures the “volume” of flowing blood as a tissue hematocrit value included in the observed amount of microvessels. It is disclosed. This measured value is determined as a function of the applied pressure. The laser Doppler optical probe defines the amount of observation on the skin near the patient's body surface, and the pressure cuff is used to manually apply pressure to the limb near the optical probe.

  Such laser Doppler sensors are placed against the skin under an air cuff that is secured to the affected limb (ie, toe, ankle, arm, leg, etc.). The user using the expansion pump inflates the air cuff by hand. The inflation pressure must be high enough to stop local blood flow at some part of the optical probe. A display device is usually connected to the optical probe via a fiber optic cable, and this display device is also connected to an expansion pump via a tube. When contraction is initiated, the probe monitors the number of flowing red blood cells in and out of the observed volume, regardless of speed. The number of flowing red blood cells detected within the controlled variable is expressed in percent and displayed on the display monitor. This value is shown both as a numerical value and as a bar graph on the Y axis. The instrument also measures the cuff internal pressure and displays the applied cuff pressure in millimeters as the height of the mercury column on the X axis of the display. A bar graph that varies along the X-axis indicates to the operator which cuff pressure is being measured at that time. As the pressure is gradually released by hand, an index of blood flow recovery is output in the form of a bar graph. While the technician is performing the examination, the doctor interprets the data displayed on the display monitor.

  Thus, one of the major problems in using the skin perfusion pressure device described by Borgos et al. Is that the reproducible and reliable measurements are a measurement of operator / engineer skills and surface perfusion pressure. There is a strong point that depends on the skill of the doctor to interpret. Another problem associated with manual contraction is that the method is sensitive to motion artifacts caused by an operator or patient (eg, patient movement, pressure tubing movement or sensor movement). Motion artifacts may also result from patient movement, unconscious muscle movement, operator intervention, and other causes that affect skin perfusion pressure readings. When a patient moves a limb with a sensor / air cuff attached, it is very likely that a physician who determines the pressure at which flow will recover will misread “motion artifact” as a measure of surface perfusion pressure. When performing a skin perfusion pressure test on a sick patient, the physician assumes that the surface perfusion pressure measurement is low. For this reason, if a “motion artifact” occurs, there is a possibility that the doctor interprets this artificially higher than the measured value of the skin perfusion pressure as the reading value of the skin perfusion pressure.

  For example, FIG. 2A shows a display on a prior art monitor. As is apparent from the figure, the perfusion percentage value measured increases as the cuff pressure decreases. A physician performing a skin perfusion test may record a skin perfusion pressure value of 45 millimeters of mercury. FIG. 2B also shows a display with a prior art monitor in which the percentage of perfusion measurement increases as cuff pressure decreases. However, here the motion artifact is displayed as 45 millimeters of mercury. Physicians performing skin perfusion tests may mistakenly record skin perfusion pressure values as 45 millimeters of mercury.

  A further problem with conventional devices is the lack of reproducibility because laser doppler optical probes cannot always be applied to the same site when repeated measurements are required. As a result, the sensors are typically placed at different sites through which different microcirculations flow, so the surface perfusion pressure measurement may change. For example, a fiber optic probe is placed directly on the patient's tissue surface under a pressure cuff. If repeated measurements are required, the fiber optic probe or sensor will not be placed in the same location for subsequent measurements.

  In addition, the use of fiber optic probes on multiple patients creates the risk of nosocomial infections and other infections that occur in hospitals or medical settings. Infection problems may be addressed through the use of disposable probes or sensors. However, disposable probes are more expensive than non-disposable or reusable probes and take longer to remove and replace. Periodic removal and replacement of the probe also results in instrument errors, affecting calibration failures, general system malfunction, and most likely reproducibility.

  Another problem with conventional systems is that the laser Doppler probe or sensor can be placed under or outside the pressure cuff for measurement. A laser Doppler sensor measures the amount of light transmitted, so it would be ideal if it could be provided to a device that is useful for removing ambient light from a measurement site.

  Therefore, there is a need for a device that can be used with a probe without having to disconnect the probe from the monitoring system to replace it with a new probe, and that addresses reproducibility and ambient light issues.

In view of the above-mentioned problems with conventional systems, (i) eliminate the cutting of the probe from the surface perfusion pressure measuring instrument to measure an alternative site or measure another patient; (ii) repeat measurement Providing a sensor placement device that ensures reproducibility and reduces ambient light; and (iii) a system that corrects or eliminates artifacts induced by movement of critical care monitor instruments worn by the patient is needed. is there. In addition, there is a need for a system that increases reliability and reproducibility by eliminating user-created errors, such as variable dilation and deflation, and / or variable outcome determination. A new and improved skin perfusion system that automatically expands and contracts pressure cuffs, controls expansion and contraction, detects and eliminates motion artifacts, and automatically determines SPP values, Needed.
US Pat. No. 6,178,342

  Accordingly, it is an object of the present invention to solve the problems and disadvantages of prior art surface perfusion pressure devices. Thus, one object of the present invention is to automate the measurement of skin perfusion pressure and generate SPP values.

  It is a further object of the present invention to provide a skin perfusion pressure system that automatically expands and contracts to control the inflation pressure and the cuff pressure contraction rate.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that automatically detects and eliminates motion artifacts.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that uses perfusion sensitivity tolerances that gradually adjust the sensitivity threshold when perfusion is restored.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that actively controls the cuff contraction rate.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that determines when movement has become so great as to affect the accurate determination of cuff contraction rate or SPP value.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that does not record the SPP value if it is determined that the movement is too great or the resulting SPP waveform does not have a recognizable perfusion characteristic. It is in.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that evaluates the duration of perfusion fluctuations.

  It is a further object of the present invention to provide a skin perfusion pressure monitoring system that evaluates perfusion variation profiles.

  Further objectives of the present invention are to improve reproducibility when multiple measurements are required, reduce the risk of nosocomial infection, reduce the need for disposable sensors, and reduce the likelihood that ambient light will affect the measurement results. Another object of the present invention is to provide a reliable means for fixing the SPP sensor to the tissue measurement site in order to reliably maintain the connection between the automation system and the sensor.

(Outline of the Invention)
In a first embodiment of the present invention, a system for capillary blood flow measuring means in communication with a tissue site with capillary blood flow and for applying a controllable pressure to the capillary blood flow measuring means and tissue simultaneously. Pressurizing means comprising: (i) driving capillary blood flow in the tissue and (ii) returning the capillary blood flow while controllably releasing the pressure, and responding to an automatic sequence; Measuring means for measuring an applied controllable pressure, and display means for displaying a relationship between the applied controllable pressure and capillary blood flow, the capillary blood flow measuring means and the application Display means in communication with the controllable pressurizing means.

  In a further embodiment of the invention, a sensor placement device is provided for securing the capillary blood flow means to the tissue site.

  In another embodiment of the present invention, a skin perfusion pressure monitoring system is disclosed that automatically calculates SPP values from perfusion measurements. This monitoring system controls and measures the cuff pressure and strictly controls the cuff contraction rate during the critical systole of the skin perfusion pressure test cycle.

  In another embodiment of the invention, the monitoring system utilizes a perfusion sensitivity tolerance that gradually adjusts the sensitivity threshold as the perfusion returns. This makes it possible to measure perfusion over a wide dynamic range while suppressing sensitivity to transient motion.

  In another embodiment of the present invention, the monitoring system actively controls the cuff contraction rate to determine when the motion has become so great as to affect this rate. The test ends when it is determined that the movement is too great.

  In another embodiment of the invention, the monitoring system monitors the duration of perfusion variation. When the microcirculation is restored, a perfusion signal that changes from the baseline flow is generated. On the other hand, a motion artifact produces a perfusion signal with a larger vibration component.

  In another embodiment of the invention, the monitoring system monitors the profile of perfusion variation. When normal flow in both the general and microcirculation is resumed, a change occurs in the perfusion signal with a recognizable and distinguishable pattern. On the other hand, in the case of motion artifacts, in general, a perfusion signal that is random and lasts only for a short time and has many vibration components is generated. Therefore, changes that do not follow the perfusion recovery characteristic are ignored in the monitoring system of the present invention. There is also a well-known perfusion recovery characteristic that does not have characteristics suitable for automatic quantification of SPP values, and the data is displayed so that it can be interpreted by a physician. For example, one of the circulatory conditions in which such a known perfusion pattern occurs is non-reactive hyperemia.

  The above and other objects and advantages of the present invention will become apparent through the following detailed description and appended claims. The invention may best be understood with reference to the accompanying drawings, in which exemplary embodiments are shown.

(Detailed description of the invention)
Before disclosing and describing the devices and methods of the present invention, it is to be understood that certain terminology is used in describing the present invention, but may vary in different contexts. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

  Unless the context clearly dictates otherwise, the singular forms “a”, “an”, and “the” used in the specification and claims are intended to include the plural forms as well. You have to be careful.

  The term “appropriate perfusion” refers to the perfusion criteria used to continue the cuff inflation sequence. This criterion ensures that the probe and the patient's skin are in proper contact. Perfusion is generally greater than 0.1%.

  The term “no flow” refers to a perfusion criterion that cuff contraction begins and is less than approximately 0.1%.

  The term “baseline flow” means a flow between a flow determined to be “no flow” and a modified SPP value.

  The term “motion artifact” refers to a characteristic perfusion that includes the effects of the caregiver, operator or environment, such as patient movement, conscious and unconscious muscle contraction, unwanted noise, caregiver and operator conflicts. Means there is no pattern to return.

  The term “perfusion measurement” is a calculated value proportional to the AC / DC ratio of the signal obtained by the perfusion sensor, measured at the applied cuff pressure.

  The term “perfusion rate” refers to a quantitative measure of capillary blood flow compared to maximally perfused tissue.

  The term “pressurized cuff” or “cuff” and similar source terms means an air cuff or any device that applies pressure in the form of, for example, from above, in contact with the site, wrapped around, or the like.

The term “P ₀ ” is the perfusion measurement value that is the subject of the evaluation or determination of the SPP value.

  The term “re-inflow” means resuming normal microcirculation flow.

  The term “skin perfusion pressure value” or “SPP value” means the cuff pressure that returns the microcirculatory flow back to the observed amount of tissue upon cuff contraction of the test.

(Surface perfusion pressure system)
Referring to FIG. 1, a schematic diagram illustrating an exemplary but non-limiting perfusion pressure monitoring system 10 is illustrated. The skin perfusion pressure monitoring system 10 mainly includes an optical probe or sensor 12, a pressure cuff 14, and a skin perfusion pressure device 22 with a display monitor 30. The optical probe 12 is disposed on the inner surface side of the pressure cuff 14 in the vicinity of the skin of the limb 18 of the patient. Alternatively, the optical probe 12 may be disposed outside the cuff 14 or in the cuff air bladder 14. In other embodiments, the cuff 14 may include a transparent window for viewing the optical probe 12. This skin perfusion pressure device inflates the pressure cuff 14 through the tube 26. The size of the pressure cuff 14 varies depending on whether the target limb is an arm, a toe, a leg, an ankle, or the like, but the local blood flow can be stopped at the site of the optical probe 12 in the tissue 20 to be observed. It must only be able to maintain a high enough pressure (higher than systolic blood pressure). The observed amount of tissue 20 is at the same location as the applied pressure, near the applied pressure, or distal to the applied pressure, in which case, for example, the flow rate is measured with a toe and the pressure is applied at the ankle. The skin perfusion pressure device 22 is connected to the optical probe 12 via the optical fiber cable 24 and is also connected to the pressure cuff 14.

  The optical probe 12 monitors the microcirculation flow in the observed amount of tissue 20. The microcirculation detected in the observed amount of tissue 20 is expressed as a percentage and displayed on the Y axis of the perfusion pressure display device. As best seen in FIG. 5C, this percentage value is generally shown as a number from 0% to 10% and is also shown as a bar graph on the Y-axis of the instrument display 30. The skin perfusion pressure device 22 measures the pressure in the cuff 14 and displays the applied pressure of the cuff on the display X axis in units of millimeters in units of millimeters of mercury. As best seen in FIGS. 5A and 5B, line 15 moves along the X axis and indicates to the operator the cuff pressure being measured at that time.

  The optical probe 12 shown in FIG. 1 includes a fiber 32 that is at least a laser transmitter and a photodiode 34 that is at least one receiver. In other embodiments, a laser or photodiode or both are installed on the probe 12 without the need for fiber optic elements. In operation, coherent light supplied from a solid state laser device or other laser device in the perfusion pressure display apparatus 22 is directed through a bladder of the pressurized cuff 14 to a fiber transmitter 32 that contacts the patient's skin. Photons emitted from the transmitting fiber 32 are scattered by the patient's tissue. Only a fraction (less than 5%) of the emitted photons are collected by the receiver fiber 34. The space between the fiber and the optical aperture of the fiber determines the amount of tissue to be monitored. In general, one transmitter fiber is used with a pair of receiver fibers. The nominal diameter of the fiber core is approximately 50 to 100 microns and is used for observations of about 1 to 2 cubic millimeters. An example of a suitable optical probe is disclosed in US Pat. No. 5,654,539 to Borgos, which is incorporated herein in its entirety.

Nevertheless, those skilled in the art will appreciate that there are many ways to determine the point at which the microcirculatory flow returns to a particular observation. For example, visual observations such as changes in the color of the observation site; ultrasound; optical plethysmography; measurement of body temperature rise; sound waves, eg microphones for pulsatile flow during macrocirculation; metabolic indicators such as pCO ₂ or lactate And bioimpedance or pulse oximeter or both, each used in conjunction with pulsation and blood pressure measurements.

  Some backscattered photons are frequently shifted by cells moving in the microcirculation. The collected photons are collected by the skin blood pressure device 22 via the cable 24 where they collide with the photodiode. Thus, the photons collide with the photodiode as a result of being scattered from the moving and stationary cells. The photodiode voltage includes both frequency and power information. Whereas the Doppler shift frequency is related to cell velocity, the spectral power information is related to the amount of cells moving at a particular frequency. A DC signal component is obtained from the total number of photons received by the receiving fiber 34. The AC signal component is obtained by mixing frequency-shifted photons and stationary structure photons. As the number of cells that move in the observed volume increases, the magnitude of the AC component increases, but the DC offset remains substantially constant. Since the Doppler shift is further caused by the bounced photons, the AC component is increased. The DC component remains nearly constant because the total number of photons scattered by collisions with stationary cells in the measured amount is reduced by the moving cells. Thus, the perfusion measurement is proportional to the ratio of the AC signal to the DC signal, which is an indicator of the amount of cells that are moving in the observed amount of tissue. This type of measurement is usually calculated using both analog and digital signal processing. For example, it is common to convert an AC signal into an RMS equivalent by analog processing. It is these values that are provided to the A / D converter. In a microprocessor, these digitized values can be squared before obtaining the above ratio. The value of this ratio can be increased or decreased by an experimentally derived magnification that depends on the gain distribution across the signal processing path.

  Referring to FIGS. 1 and 3, the cuff inflation sequence is illustrated. The skin perfusion pressure machine 22 initiates the cuff inflation process and enables the laser of the optical probe 12. The cuff 14 bladder is initially maintained at a low pressure, such as 5 to 10 mm Hg, to ensure that the sensing probe is in contact with the patient's skin so that proper perfusion can be detected and measured. If proper perfusion cannot be measured, interrupt cuff inflation and do not continue with the test. If appropriate perfusion can be measured, pressurization cuff 14 is inflated to systolic blood pressure or a target pressure around it and perfusion is measured. If the target pressure does not result in a “no flow” condition, but does not reach the maximum target pressure, the pressure is gradually increased (eg, increased by 40 mm Hg) and the “no flow” criterion is tested again. If the maximum target pressure has been reached but still does not meet the “no flow” criterion, the cuff inflation is interrupted and the test is not continued.

FIG. 4 shows the cuff reduction sequence. As described above, when the skin perfusion pressure device recognizes a “no flow” signal, the cuff pressure automatically begins to contract at a controlled rate. By controlling the contraction speed, reproducibility between measurements in the same patient and reproducibility between patients can be obtained. If the pressure is not falling at a controlled rate, such as due to severe patient movement, the cuff contraction is interrupted and the examination is not continued. If you are reduced at a rate that the pressure is controlled, to analyze the P ₀ for SPP value. If all the conditions required for the SPP value are met, the SPP value is reported, for example as discussed below. If this condition is not met, the test continues for a period of time, after which perfusion measurements are displayed for interpretation by the physician, but no SPP value is reported for the test. The physician will then use the displayed perfusion data along with other information available to determine whether another test should be performed and, if based on his expertise, the appropriate SPP value Can be judged.

5A-5D show different stages of output data drawn on a display monitor. Referring to FIG. 5A, data recorded during the inspection act is displayed. The movement line 15 rises when the pressure decreases. As is apparent from the figure, points are shown showing proper blood flow 35, no flow 36, baseline flow 37, SPP value 38, and return 39 to normal microcirculation. FIG. 5B shows the same pressure line that rises as the pressure drops, but now shows motion artifact 40. As shown, the skin perfusion pressure monitoring system according to the present invention eliminates motion artifacts as not perfusion measurements and continues the examination as seen by the continuing line 15. Referring to FIG. 5C, skin perfusion pressure monitor according to the present invention, in order to eliminate by detecting motion artifact when the P ₀ and SPP value, to analyze a number of different criteria. If P ₀ is considered an SPP value, a bar graph is superimposed on line 15 and the SPP value 38 is recorded, as best seen in FIG. 5C. As can be understood by those skilled in the art, any graph display may be used for drawing the perfusion measurement data set. The skin perfusion pressure monitoring system 10 considers P ₀ as an SPP value and considers a unique criterion for evaluating whether motion artifacts are present. One skilled in the art will appreciate that many or few criteria may be considered. In addition, other criteria other than those described below can be used. For example, linear regression, gradient intercept, differentiation, weighted average, and other well-known mathematical models can be used in addition to or in place of the criteria described below. Regardless of whether the number of criteria considered is small or large, all criteria are used in combination with the determination of the pressure at which microcirculatory flow returns to the observed or measured volume to eliminate unwanted noise, environmental effects, or movement. Exclude.

  As a preparatory screening step, if motion artifacts are so large that they affect the rate of contraction, i.e. patient movement is large, the instrument will interrupt the test and inform the operator that the sensor / probe cannot make an accurate measurement .

As a first criterion, initially P ₀ must be within the valid range of the system for determining the SPP value. If P ₀ is not in the valid range, for example about 1 mmHg to about 150 mmHg, the system does not indicate that a particular P ₀ is an SPP value.

別の基準は、測定値に比して灌流の増加が十分に大きいか否かである。灌流の増加が十分に大きくないならば、ＳＰＰ値にはならない。「ステップサイズ」（すなわち前の測定値から灌流が十分に大きく増加する）を解釈するにあたり、器具では灌流の戻りとして感度閾値を徐々に調節する灌流の許容誤差を使用する。これは、過渡的な動きに対する感度が低い間、システムが広ダイナミックレンジでＳＰＰ値を定めることを可能にする。例えば、灌流が極めて低いならば、器具ではその灌流許容誤差のためモーションアーチファクトの検出および排除を可能にする。表１を参照すると、好適な灌流増加が記録されている。灌流測定値が０．２０％（すなわち高灌流測定値）より高く、印加したカフ圧が１００ｍｍＨｇ未満であれば、前の測定値に対して、灌流が１０％から５０％、好ましくは２５％増加することが必要である。灌流測定値が０．２０％（すなわち高灌流測定値）より高く、印加したカフ圧が１００ｍｍＨｇ以上であれば、前の測定値に対して、灌流が２０％から約８０％、好ましくは４０％増加することが必要である。灌流測定値が０．１５から０．２０％（すなわち中程度の灌流測定）の間で、印加したカフ圧が有効な圧力のいずれかであれば、前の灌流測定値に対して、灌流が２５％から１００％、好ましくは５０％増加することが必要である。灌流測定値が０．１５％（すなわち低灌流測定値）より低く、印加したカフ圧が有効な圧力のいずれかであれば、前の灌流測定値に対して、灌流が５０％から２００％、好ましくは１００％増加することが必要である。

Another criterion is whether the increase in perfusion is sufficiently large compared to the measured value. If the increase in perfusion is not large enough, there will be no SPP value. In interpreting the “step size” (ie, the perfusion increases sufficiently large from the previous measurement), the instrument uses a perfusion tolerance that gradually adjusts the sensitivity threshold as a perfusion return. This allows the system to define SPP values with a wide dynamic range while insensitive to transient motion. For example, if the perfusion is very low, the instrument allows detection and elimination of motion artifacts due to its perfusion tolerance. Referring to Table 1, suitable perfusion increases are recorded. If the perfusion measurement is higher than 0.20% (ie high perfusion measurement) and the applied cuff pressure is less than 100 mmHg, the perfusion will increase by 10% to 50%, preferably 25% over the previous measurement It is necessary to. If the perfusion measurement is higher than 0.20% (ie high perfusion measurement) and the applied cuff pressure is 100 mmHg or more, the perfusion is 20% to about 80%, preferably 40% relative to the previous measurement. It is necessary to increase. If the perfusion measurement is between 0.15 and 0.20% (ie, moderate perfusion measurement) and the applied cuff pressure is one of the effective pressures, the perfusion will be compared to the previous perfusion measurement. It is necessary to increase by 25% to 100%, preferably 50%. If the perfusion measurement is lower than 0.15% (ie low perfusion measurement) and the applied cuff pressure is one of the effective pressures, the perfusion is 50% to 200% relative to the previous perfusion measurement, Preferably it is necessary to increase by 100%.

  Those skilled in the art need not limit the following criteria to high, medium and low perfusion measurements, several points independent of applied cuff pressure, ie pressures above and below 100 mmHg. You will understand that. These may be expressed as a continuous function of perfusion measurements or applied cuff pressure, or both.

Another criterion is whether the blood flow measurement under evaluation, P _0, is sufficiently large, ie whether the flow is above the baseline. Perfusion preferably between 0.05 and 0.2% at the point P _0, and should be more preferably at least 0.10%, is not recorded skin perfusion pressure otherwise.

Another criterion determines whether the “next stage”, ie the stage following point P ₀ is increasing or decreasing. The next stage should not be reduced because it is not a typical signature feature that indicates the return of microcirculation to the observed volume of decreasing pressure. This fourth criterion focuses on the time when the change in perfusion is increasing. As the microcirculation flow returns, a perfusion signal is generated that increases and retains the trace pattern. Motion artifacts generate perfusion signals that are more prone to decrease due to more vibration components.

印加カフ圧が低い、すなわち好ましくは約０から２０ｍｍＨｇ、一層好ましくは１５ｍｍＨｇ未満である場合、次のステップが増加または減少しているかどうかを判断する際に分析される次のステップの数は１である。印加カフ圧が中程度、例えば約１０から５０ｍｍＨｇ、一層好ましくは１５から２０ｍｍＨＧの時、次のステップが増加または減少しているかどうかを判断する際に分析される次のステップの数は２である。印加カフ圧が高く、例えば約４０から１２０ｍｍＨｇ、一層好ましくは５０ｍｍＨｇより高いが１００ｍｍＨｇ未満の時、次のステップが増加または減少しているかどうかを判断する際に分析される次のステップの数は３である。圧力が極めて高く、好ましくは８０から１５０ｍｍＨｇ、最も好ましくは１００ｍｍＨｇより高い時、次のステップが増加または減少しているかどうかを判断する際に分析される次のステップの数は５である。分析対象となる次のステップの数すなわちＮがさらに多い場合、システムがＳＰＰ値を定めた信頼性がさらに高くなる。

If the applied cuff pressure is low, ie preferably about 0 to 20 mmHg, more preferably less than 15 mmHg, the number of next steps analyzed in determining whether the next step is increasing or decreasing is 1. is there. When the applied cuff pressure is moderate, eg about 10 to 50 mmHg, more preferably 15 to 20 mmHG, the number of next steps analyzed in determining whether the next step is increasing or decreasing is two . When the applied cuff pressure is high, for example about 40 to 120 mmHg, more preferably above 50 mmHg but below 100 mmHg, the number of next steps analyzed in determining whether the next step is increasing or decreasing is 3 It is. When the pressure is very high, preferably 80 to 150 mmHg, most preferably above 100 mmHg, the number of next steps analyzed in determining whether the next step is increasing or decreasing is five. When the number of next steps to be analyzed, that is, N is larger, the reliability with which the system determines the SPP value is further increased.

Another criterion for detecting and eliminating motion artifacts is the profile of perfusion changes. The microcirculation generates a perfusion signal that increases in steps, whereas the motion generates a perfusion signal with more vibrational components than the microcirculation. Changes that do not follow the perfusion return signature are ignored. Referring to Table II again, the profile reference perfusion variation for detecting a motion artifact elimination is that a certain number of steps following P ₁ is either at least perfusion values of P _1, greater than this. These steps must not be reduced. In other words, _{P N} from _{P 2} must exceed all _{P 1.} Since such signals do not last long, this criterion is particularly effective in eliminating motion.

Once all the criteria are met, skin perfusion pressure system to the P ₀ and SPP value 38.

  FIG. 5D shows a model that would be seen when the patient has unresponsive hyperemia. In this case, the skin perfusion pressure system recognizes such a pattern as a pattern having no characteristics of a normal perfusion measurement value, and no SPP value is generated. In such cases, perfusion data is reported, and the physician determines the SPP value for that test.

(Sensor or probe installation device)
Conveniently, a surface perfusion pressure system according to the present invention includes a sensor or probe placement device to ensure reproducible data, either as a kit or provided alone, as described above. It may be.

  Referring to FIG. 6, one embodiment of a sensor placement device 100 according to the present invention is shown. The sensor placement device 100 includes a disposable sheath 130 sized to fit an exemplary probe 120 for use in microcirculatory blood flow measurements. One skilled in the art will appreciate that the sensor placement device 100 can be used to secure the covers of various shapes and sizes of probes, electrodes and other monitoring devices.

  According to a first embodiment of the sensor placement device 100, two wings 140 provided on both sides of the proximal end 150 are provided. Wings 140 are wrapped around the patient's limbs to secure the probe 120 thereon. The wings 140 can be of various sizes to accommodate different sizes of limbs.

  The sensor placement device 100 also includes two subject position indicators 160 at the proximal end 150. The position indicator 160 is shaped so that the health care provider can mark the installation location of the sensor placement device 100. If further measurements are required, the sensor placement device 100 and the probe 120 can be placed at the same location on the surface of the tissue, thereby ensuring reproducible data.

  The sensor placement device 100 includes a measurement guide 180 located on at least one side of the sheath 130. The measurement guide 180 is used to determine an accurate installation position. The measurement guide 180 can be sized according to the perforation 200 and can be used in combination. For example, the unit of measurement can begin at the proximal end 150 and increase toward the distal end 170. According to this method, the measurement guide 180 is useful for measuring the installation location after the perforated portion near the distal end 170 is removed.

  The distal end 170 of the sheath 130 includes means for securing the probe to receiving openings 220 located on either side of the sheath 130. The receiving opening 220 is sized and positioned to receive the probe fixing means 290. Receiving openings 220 are placed on either side of the cable end of the probe 120 so that the distal end of the sheath 130 is completely parallel to the sheathing 280. According to this method, the sensor placement device 100 is firmly fixed to the probe 120. The receiving opening 220 shown in FIGS. 6 and 7 is arcuate. One skilled in the art will recognize that the receiving opening can be sized and shaped to accept any means or shape securing means 290 of the probe.

  In one embodiment, the distal end 170 of the sheath 130 is adjacent to the cable clamp 240. Since the cable fixture 240 is adhesive and removable on the back side, it can be detached from the sensor placement device 100 and used to fix the cable 260 extending between the probe 120 and the monitoring system toward a suitable surface.

  The surface of the sensor placement device 100 that comes into contact with the patient's tissue is adhesive coated. Adhesive coatings that do not interfere with the monitoring of physiological parameters include pressure sensitive adhesives that can be repositioned anywhere. The adhesive coating is inherently tacky and is an elastomeric, solvent dispersible, solvent insoluble pressure sensitive adhesive. In one embodiment, the adhesive coating is alkyl acrylate, ester alkyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, sulfoethyl methacrylate, and sodium metacrylate, ammonium acrylate, acrylic acid. Sodium, trimethylamine P-vinylbenzoic acid imide, 4,4,9-trimethyl-4-azonia-7-oxo-8-oxa-9-ene-1-sulfone, N, N-dimethyl-N- (beta- Methacryloxyethyloxy-ethyl) ammonium propionate betaine, trimethylamine methacrylamide, and 1,1-dimethyl-1- (2,3-dihydroxypropyl) methacrylimidoamine A blend of monomeric or polymeric. In another embodiment, the adhesive coating comprises microspheres selected from the group consisting of acrylate-based, alkyl acrylic acid and alkyl acrylate ester monomers alone or in combination with vinyl monomers. The adhesive coating is covered with removable film paper that is used to preserve the tackiness of the adhesive coating under storage, shipping and other non-use conditions.

  The size and shape of the sensor placement device 100 can vary. A logo or other art design can be embossed anywhere on the sensor placement device 100. The color of the sensor placement device 100 can also vary and include various patterns.

  In use, the sensor placement device 100 is implemented at any convenient location, such as an operating room, intensive care unit, examination room or patient room, nursing area, doctor's work place, basically because of its low cost. The probe 120 is used to measure physiological parameters everywhere. The medical personnel can move the sensor placement device 100 from the dispenser device, box or other equipment bin to fit the probe 120 into the distal end 170 of the sheath 130. The opening 220 adjusts the probe fixing method 290. As shown in FIG. 7, the sheath 130 fits the probe 120 with the sheath distal end 170 adjacent to the sheathing 280. If the sensor placement device 100 is too long for the measurement site, parts of the sensor placement device 100 can be cut with the intended perforation 200. After the sensor placement device 100 is mounted on the probe 120, if applicable, the peelable film paper (not shown) is peeled off and the measurement guide 180 accurately places the sensor placement device 100 on the intended portion of the patient's tissue. Can be used to install on. The wing 140 is wrapped around the patient's limb such as a toe or foot to secure the sensor placement device 100 thereon. The cable fixing member 240 can be cut between the distal end 170 of the sheath 130 along the perforation at the position of the perforation. The cable fixing bracket 240 is used for fixing the cable 260 for a suitable support such as a different part of the patient's body or a hospital bed.

  Once positioned, the cable fixture 240 can be disconnected and the probe 120 can be removed from the sensor placement device 100 without being obstructed by the position of the sensor placement device 100. A different probe 120 is then inserted into the sensor placement device 100 without being disturbed by the position of the sensor placement device 100 again. According to this method, the probe 120 can be replaced without requiring a new sensor placement device 100 or a sensor placement device 100 to be reinstalled. If a new sensor placement device 100 is needed, the position indicator 160 marks the replacement sensor placement device 100 to be in the same position as where the sensor placement device 100 was previously placed. In this case, interruptions and errors are minimized during the monitoring of physiological parameters.

  Once monitoring is complete, the medical personnel simply removes the sensor placement device 100 from the patient's tissue and discards it. In this case, the sensor placement device 100 prevents infection while providing precise positioning, repositioning, and fixation of the probe to the patient's tissue.

  Referring to FIG. 8, another embodiment of a sensor placement device 300 is shown. As shown in FIG. 8, the sensor placement device 300 is used to measure a larger limb without using an adhesive and remains at the patient's measurement site until all measurements are completed. The sensor placement device 300 is composed of one sheet or a plurality of parts. The sensor placement device 300 comprises an elastic bandage that includes a laminate of non-woven fabric material and longitudinally woven elastic fibers to provide elasticity. The fabric of the sensor placement device 300 is a water vapor permeable, non-woven polyester fabric, or elastane containing a string of polyester urethane that is twisted vertically. The cloth is coated with an adhesive material that has the ability to stick to itself, not to the skin or clothing. Elastane fiber gives the bandage a certain elasticity, ensuring a coating that is too sticky to be replaced once applied. The fabric is sold under the trade name Coban ™ and St. Available from 3M Company, Paul, Minn.

  Although the sensor placement device 300 is shown as being made from a plurality of parts, those skilled in the art will understand that a single appropriately sized sheet may be used. A transparent plastic window 310 with first and second ends 312, 314 is located on one side of the sheet and is fixed. Window 310 remains open at ends 312 and 314 for easy insertion and removal of a probe (not shown). One skilled in the art will appreciate that only one end of window 310 needs to be open to achieve the purpose of sensor placement. If multiple parts are used, the window 310 joins the various sites 316 by heating or chemical sealing of the elastic bandage.

  In operation, the sensor placement device 300 is, for example, partially wrapped around a leg exposed from the window 310. A probe (not shown) is located in the window 310, while the sensor placement device is further wrapped around the limb on the probe and the window is secured with the probe while taking measurements.

  One skilled in the art will appreciate that the sensor placement device shown in FIG.

  While details of the preferred embodiment have been presented, it is believed that various modifications have been made, including those described above, without departing from the spirit of the invention. Accordingly, the embodiments are not intended to be limiting, modifications may be made without departing from the spirit thereof, and it is desirable to refer to the appended claims rather than the foregoing description showing the scope of the invention.

FIG. 1 is a schematic view of a perfusion pressure monitor used for a patient. FIG. 2A is a schematic diagram of a prior art display monitor showing a normal inspection process as a bar graph. FIG. 2B is a schematic diagram of a prior art display monitor showing motion artifacts as part of a rapidly rising bar. FIG. 3 is a flowchart showing the operation of the perfusion pressure monitor during expansion. FIG. 4 is a flowchart showing an operation in contraction of the perfusion pressure monitor. FIG. 5A is a schematic diagram showing an output display of a pressure line of a skin perfusion pressure monitoring system according to the present invention. FIG. 5B is a schematic diagram showing the output display of the pressure line of the skin perfusion pressure monitoring system according to the present invention as a portion of a rapidly rising bar showing motion artifacts. FIG. 5C is a schematic diagram showing the output display of the pressure line of the skin perfusion pressure monitoring system according to the present invention, along with a rapidly rising bar segment showing motion artifacts, a bar graph, and a true reading of surface perfusion pressure. is there. FIG. 5D is a schematic diagram showing an output display of the pressure line in a circulatory condition known as non-reactive hyperemia. FIG. 6 is a top view of a sensor fixture according to the present invention. FIG. 7 is a perspective view of the installation of a sensor attachment incorporating the SPP sensor according to the present invention. FIG. 8 is a top plan view of another embodiment of a sensor fixture.

Claims (34)

With an inflatable cuff,
At least one blood flow sensor in communication with the cuff , comprising at least one blood flow sensor including an optical probe ;
At least one pressure sensor in communication with the cuff for reading the pressure level of the cuff;
A pressure device operably coupled to the optical probe by a fiber optic cable, the pressure device being in fluid communication with the cuff for expansion and contraction of the cuff A perfusion pressure measuring device,
The pressurizing device is
A pressurized air source;
A conduit connected to the pressurized air source and the cuff to place the pressurized air source in fluid communication with the cuff;
A microprocessor arranged to receive input from the at least one blood flow sensor and the at least one pressure sensor, comprising: a pressurized air flow to the cuff and a pressurized air flow from the cuff. A microprocessor that is controllable;
A computer program executable by the microprocessor;
When the computer program is executed,
Initiating an automatic inflation sequence that results in no flow;
Starting an autoshrink sequence;
During the contraction sequence, causing the microprocessor to automatically consider perfusion measurements as SPP values when all of a predetermined set of conditions are met ;
The predetermined conditions are:
(A) whether the perfusion measurement is from 1 mmHg to about 150 mmHg;
(B) if the perfusion measurement is less than 0.20% and the cuff pressure is less than 100 mmHg, a perfusion increase of 10% to 50% relative to the previous perfusion measurement;
(C) if the perfusion measurement is above 0.02% and the cuff pressure is 100 mmHg or greater, the perfusion increase from about 20% to about 80%;
(D) if the perfusion measurement is from 0.15% to about 0.20% and the cuff pressure is any valid cuff pressure, an increase in perfusion from about 25% to about 100%;
(E) if the perfusion measurement is less than 0.15% and the cuff pressure is from 1 mmHg to about 150 mmHg, an increase in perfusion of about 50% to about 200%;
(F) whether the perfusion measurement is from about 0.05% to about 0.2%;
(G) whether the stage following the perfusion measurement value to be examined for the SPP value is reduced,
(I) when the cuff pressure is low, the number of stages analyzed following the perfusion measurement to be examined for SPP value is one;
(Ii) when the cuff pressure is in a medium range, the number of stages analyzed following the perfusion measurement to be examined for SPP values is two;
(Iii) if the cuff pressure is high, the number of stages analyzed following the perfusion measurement being examined for SPP values is three;
(Iv) if the cuff pressure is very high, the number of stages analyzed following the perfusion measurement being examined for SPP values is five;
And
(H) whether or not the number of stages following the perfusion measurement value to be examined for SPP value is increased,
(I) when the cuff pressure is low, the number of stages analyzed following the perfusion measurement to be examined for SPP value is one;
(Ii) when the cuff pressure is in a medium range, the number of stages analyzed following the perfusion measurement to be examined for SPP values is two;
(Iii) if the cuff pressure is high, the number of stages analyzed following the perfusion measurement being examined for SPP values is three;
(Iv) if the cuff pressure is very high, the number of stages analyzed following the perfusion measurement to be examined for SPP values is 5.
And
An automatic skin perfusion pressure measuring device.   The automatic skin perfusion pressure measurement device according to claim 1, wherein the at least one blood flow sensor is disposed under the cuff.   The automatic skin perfusion pressure measurement apparatus according to claim 1, wherein the at least one blood flow sensor is disposed outside the cuff.   The automatic skin blood pressure measuring device according to claim 1, wherein the at least one blood flow sensor is arranged inside an air bag in the cuff.   The automatic skin perfusion pressure according to claim 1, wherein the at least one blood flow sensor is selected from the group consisting of optical probe means, pulse oximeter means, optical pulse wave recording means, motion detection means, and laser Doppler means. measuring device.   6. The automatic skin perfusion pressure measuring device according to claim 5, wherein the optical probe means includes a laser transmitter fiber and a receiver photodiode.   6. The automatic skin perfusion pressure measuring device according to claim 5, wherein the optical probe means includes a laser transmitter.   8. The automatic skin perfusion pressure measuring device according to claim 7, wherein the optical probe means further includes a photodiode of a receiver.   The automatic skin perfusion pressure measurement device of claim 1, further comprising a display monitor operably connected to the pressurization instrument and capable of displaying data. The automatic skin perfusion pressure measurement device according to claim 9 , wherein the display monitor is capable of displaying data relating to microcirculation in an observed amount of tissue. The automatic skin perfusion pressure measurement apparatus according to claim 9 , wherein the display monitor can further display data related to cuff pressure. The automatic skin perfusion pressure measurement device according to claim 11 , wherein the display monitor can further graphically display an observed amount of cuff pressure versus microcirculation within the tissue.   The automatic skin perfusion pressure measurement apparatus according to claim 1, wherein the cuff includes a transparent window that can be used for observation of the perfusion sensor. A device for measuring the skin perfusion pressure of a patient,
Comprises an inflatable cuff, the cuff have a perfusion detecting means for detecting the perfusion in the cuff communication with, perfusion detecting means includes an optical probe, a cuff,
Means for automatically inflating the cuff to a pressure that creates a no-flow condition according to an automatic expansion sequence;
Means for automatically deflating the cuff according to an automatic deflation sequence;
By automatically and continuously examining a series of perfusion measurements against a predetermined set of criteria, motion artifacts are eliminated and all conditions of the predetermined set of criteria are met. automatically look contains and means for regarding the SPP value of one of the perfusion measurements during the,
Means for automatically inflating the cuff and means for automatically deflating the cuff are operably coupled to the optical probe by a fiber optic cable;
The predetermined conditions are:
(A) whether the perfusion measurement is from 1 mmHg to about 150 mmHg;
(B) whether the increase in perfusion from the previous measurement value exceeds a predetermined minimum increase value,
(I) If the perfusion measurement is above 0.20% when the cuff pressure is less than 100 mmHg, the increase in perfusion is from 10% to 50%,
(Ii) If the perfusion measurement exceeds 0.20% when the cuff pressure is 100 mmHg or more, the increase in perfusion is from 20% to 80%,
(Iii) if the perfusion measurement is 0.15% to 0.20% when the cuff pressure is any valid cuff pressure, then the perfusion increase is 25% to 100%;
(Iv) if the perfusion measurement is less than 0.15% when the cuff pressure is any valid cuff pressure, the increase in perfusion is from 50% to 200%.
And
(C) whether the perfusion measurement is from about 0.05% to about 0.2%;
(D) whether the stage following the perfusion measurement being tested for SPP values is increasing or decreasing,
(I) when the cuff pressure is from 0 to 20 mmHg, one subsequent perfusion measurement is increased,
(Ii) when the cuff pressure is between 10 and 50 mmHg, the two subsequent perfusion measurements have increased,
(Iii) When the cuff pressure is 40 to 120 mmHg, the three subsequent perfusion measurements are increased,
(Iv) If the cuff pressure is above 80 mmHg, the 5 next perfusion measurements are increased,
And
(E) whether the perfusion measurement is one of a series of perfusion measurements that fit the perfusion variation profile, wherein the perfusion variation profile is:
(I) If the cuff pressure is between 0 and 20 mmHg, the next perfusion measurement has not decreased,
(Ii) If the cuff pressure is between 10 and 50 mmHg, the next two perfusion measurements are not decreasing,
(Iii) If the cuff pressure is 40 to 120 mmHg, the next three perfusion measurements are not decreasing,
(Iv) If the cuff pressure is above 80 mmHg, the next five perfusion measurements are not decreasing,
A profile in which the measured perfusion measurement meets a criterion selected from the group consisting of:
Including the device. The automatic expansion sequence is:
Inflating the cuff to a first pressure;
Confirming that the perfusion detection means is detecting and measuring perfusion;
Inflating the cuff to a second pressure;
Confirming that no flow was achieved,
Increasing the cuff pressure by a predetermined increment until a no-flow condition is achieved;
15. The apparatus of claim 14 , comprising interrupting the expansion sequence if the cuff pressure reaches a predetermined maximum value before a no flow condition is achieved. The apparatus of claim 14 , wherein the automatic expansion sequence expands the cuff to a first pressure of 5 mmHg to 10 mmHg. 15. The device of claim 14 , wherein the automatic inflation sequence inflates the cuff to the patient's systolic blood pressure. 15. The apparatus of claim 14 , wherein the automatic expansion sequence increases the cuff pressure by a predetermined increment of about 40 mmHg until a no flow condition is achieved. The autoshrink sequence is
(A) releasing pressure from the cuff at a desired controlled rate;
(B) monitoring the contraction rate;
(C) interrupting the contraction sequence if the contraction speed is not substantially equal to the desired controlled speed;
(D) analyzing whether the perfusion measurement is regarded as an SPP value using the means to be examined;
(E) determining whether at least one automatic stop criterion is satisfied;
(F) repeating steps (a)-(e) until at least one automatic stop criterion is met;
15. The apparatus of claim 14 , comprising: (g) reporting the SPP value if there is the SPP value obtained in step (d). The autoshrink sequence is
(H) repeating steps (a) to (e) a predetermined number of times in the absence of an acceptable SPP value, and then continuing to repeat steps (a) to (e) for a predetermined time. When,
20. The apparatus of claim 19 , further comprising: (i) displaying perfusion measurements on a display for interpretation by a physician. 20. The apparatus of claim 19 , wherein analyzing whether a perfusion measurement can be considered an acceptable SPP value comprises identifying that the measured perfusion pressure is not due to motion artifacts. Determining whether the increase in perfusion from the previous measurement exceeds a predetermined minimum increase is determined by the following criteria:
With a cuff pressure of less than 100 mmHg, the perfusion measurement is above 0.20% and the increase in perfusion is 25%;
The perfusion measurement exceeds 0.20% at a cuff pressure of 100 mmHg or more, and the increase in perfusion is 40%;
A perfusion measurement equal to 0.15% to 0.20% and a perfusion increase of 50% at any valid cuff pressure;
The perfusion measurement is less than 0.15% at any effective cuff pressure and the increase in perfusion is 100%;
15. The apparatus of claim 14 , comprising determining whether one of the conditions is satisfied. Considering the perfusion measurement as an SPP value is that (i) the cuff pressure is less than 15 mmHg and one subsequent perfusion measurement is increased, (ii) the cuff pressure is 15 to 20 mmHg, Perfusion measurements are increasing, (iii) Cuff pressure is 50 to 100 mmHg, 3 subsequent perfusion measurements are increasing, (iv) Cuff pressure is 100 mmHg to 150 mmHg, 5 subsequent perfusion measurements 15. The apparatus of claim 14 , comprising considering the perfusion measurement as an SPP value if a criterion selected from the group consisting of increasing values is met. Defining a profile of perfusion variation is that the measured perfusion measurement is (i) if the cuff pressure is less than 15 mmHg, the next perfusion measurement is not reduced, (ii) the cuff pressure is 15 to 20 mmHg If the next two perfusion measurements are not reduced, (iii) If the cuff pressure is 50 to 100 mmHg, then the next three perfusion measurements are not reduced, (iv) the cuff pressure is from 100 mmHg 15. The apparatus of claim 14 , comprising defining a profile that meets a criterion selected from the group consisting of the next five perfusion measurements not decreasing at 150 mm Hg. The automatic skin perfusion pressure measuring device according to claim 1 or 14 , further comprising an installation device for fixing the blood flow measuring means in place at one time or more. 26. The installation device of claim 25 , wherein the device is disposable. 26. The placement device of claim 25 , further comprising a removable sheath configured to secure the blood flow measurement means to a patient. 28. The installation device of claim 27 , further comprising at least two wings disposed on opposite sides of the proximal end of the sheath and receiving openings disposed on opposite sides of the distal end of the sheath. 28. The sensor placement device of claim 27 , further comprising a measurement guide extending along at least one longitudinal side of the sheath. And further including a perforated portion, wherein the first perforated portion is adjacent to the distal end of the sheath, and the second perforated portion includes the first perforated portion and the sheath. 28. The sensor placement device of claim 27 , wherein the sensor placement device is between a third perforated portion that is closer to the proximal end of the device. And further comprising a cable clamp, the cable clamp being adjacent to the distal end of the sheath and configured to be removed from the sensor placement device, over the cable extending between the probe and the monitoring system. 28. The sensor installation device according to claim 27 , which is arranged. 29. The sensor placement device of claim 28 , wherein the wing includes at least one position indicator. 28. The sensor placement device of claim 27 , wherein the sheath includes an adhesive coating on a surface of the sheath configured to secure the sensor placement device to a patient's tissue. 26. The blood flow measurement means installation device according to claim 25 , wherein the installation device includes a self-adhesive cloth including a window for inserting the blood flow measurement means.

Images