JP2004290641A - Method and apparatus for blood vessel detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus to know if a blood sampling needle has reached a blood vessel or not while the blood sampling needle is led to the blood vessel with exact information on a two dimensional location of the blood vessel under the skin of a subject for blood sampling. <P>SOLUTION: The apparatus monitors an electric potential of the blood sampling needle or an impedance or phase between other electrodes mounted on the blood sampling needle and those on the human body, and know if the blood sampling needle has reached the blood vessel or not based on these changes. This enables blood sampling to be done without fail, and imposes reduced physical strain on the subject for blood sampling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method and an apparatus for detecting whether or not a needle has reached a blood vessel when blood is collected outside the body from a blood vessel under the human skin via a hollow blood collection needle.
[0002]
[Prior art]
Conventionally, blood is collected from blood vessels by the injection method by wrapping an elastic rubber-like cord called a tourniquet around the arm and aiming at blood vessels that have emerged on the skin when blood flow was temporarily restricted. Then, the injection needle was punctured into the blood vessel, and then the blood was drawn into the syringe by negative pressure suction.
[0003]
In recent years, a chip-shaped blood analyzer having a size of several mm to several cm square, which is provided with a fine needle for collecting blood and has a fine groove channel, various analyzers, and analyzers, has been developed. (See, for example, Patent Document 1.) A needle of such a chip-shaped blood analyzer is punctured into the skin of a subject, blood is collected from a subcutaneous blood vessel, and the blood is drawn onto the chip. Analyze the concentration of chemicals (sodium, potassium ions, glucose, urea nitrogen, creatinine, etc.). The chip has been developed for people to use at home and for health management.
[0004]
[Patent Document 1]
JP 2001-258868 A
[Problems to be solved by the invention]
The tourniquet is used during normal blood collection, as described above, with the aim of embossing blood vessels on the skin to make it easier for blood collectors to identify the site to puncture the injection needle. one of. Wrapping and squeezing the tourniquet around the arm is one of the pains to be given to a blood recipient together with the pain when puncturing the injection needle.
[0006]
Further, in the chip-shaped blood analyzer, first, the diameter of the needle is reduced (for example, outer diameter 100 μm, inner diameter 50 μm) in order to suppress pain at the time of puncturing as much as possible, so that rigidity (buckling strength) is reduced. It is very low. In order to effectively mitigate such a decrease in strength, it is desirable to shorten the entire length of the needle, and such a demand is that the amount of blood that remains in the needle at the time of collection and is not used for analysis is reduced. It is important from a viewpoint. When the length of the needle is shortened in this manner, the tip itself comes close to the skin at the time of blood collection, and it is difficult to see blood vessels with the naked eye because the chip assumes that the subject himself collects blood. There was a problem of becoming.
[0007]
Further, as shown in Patent Document 2, when a needle is punctured into the skin, the atmosphere of the skin near the needle is reduced in pressure to relieve pain, the skin is raised, and then the needle is automatically punctured into the skin. In such a case, it is particularly difficult to see the blood vessel, and in some cases, there is a problem that the needle cannot be guided to the blood vessel and blood cannot be collected.
[0008]
[Patent Document 2]
JP 2003-83958 A
As described above, to suppress discomfort due to the tourniquet at the time of blood collection by normal injection, and to ensure that the subject who is a blood collector when using the chip-shaped blood analyzer confirms the blood vessel position while collecting blood. Therefore, the position of the blood vessel must be monitored in some way when the needle is punctured into the skin.
[0010]
For this purpose, several techniques for visualizing blood vessels have been known. In many of these known examples, light is guided from outside the body to the body, and blood vessel information is obtained from reflected light or transmitted light. For example, near-infrared light having a wavelength of 700 to 1200 nm is applied to a finger or a back of a hand having a relatively small thickness, and an image pickup device such as a CCD (Charge Coupled Device) is arranged on the back side of the light to pass through the body. Observe the spatial distribution of light intensity. (Patent Document 3) Such near-infrared light is often used because it has a relatively small absorption coefficient due to hemoglobin or the like in water or blood constituting the human body and is easily transmitted. The light transmitted through the blood vessels is higher in water and hemoglobin concentration in blood than other parts, and the transmitted light is weakened by absorption, so the image becomes darker. Light transmitted through the portion is relatively not absorbed and has a high intensity, so that a bright image can be obtained. Therefore, a blood vessel image is obtained.
[0011]
[Patent Document 3]
JP-A-8-164124
Derivation of a blood vessel image by transmission of near-infrared light as described above can be actually used only in a relatively thin portion such as a finger or the back of a hand due to the limitation of the intensity of a light source. In particular, it is difficult to transmit light of sufficient intensity in the upper arm or forearm portion often used for blood collection. Therefore, a method of irradiating a human body with light, invading the human body once, and then capturing light reflected from the irradiated surface again by an image sensor to obtain a blood vessel image is also known. (Patent Literature 4) When such reflected light is used, the intensity of light directly reflected on the skin surface is strong, and the intensity of light that once enters the human body and is reflected again from the human body is relatively weak. Therefore, in order to catch only light containing blood vessel information (light that has been reflected after entering the human body), in the case of this known example, a liquid is applied to the surface of the skin to be irradiated with light to directly reduce the reflected light. ing. In addition, the skin is irradiated with two types of light having different wavelengths from 400 to 600 nm and from 600 to 800 nm, and the former uses less light components that once enter the body and then reflect again compared to the latter. A method of obtaining a blood vessel image by subtracting the images obtained by both methods is also known. (Patent Document 5)
[0013]
[Patent Document 4]
JP-A-8-164125 [Patent Document 5]
JP-A-8-164123
As described above, when a blood vessel image is obtained using light, there is a problem in that the applicable portion is limited in the transmission method. In addition, when the reflection method is used, complicated work such as applying a liquid to the skin surface is required to suppress light directly reflected from the skin surface, and two types of light sources, a filter, and a dichroic are required. There is a problem that an expensive and complicated device including a mirror and an image analysis mechanism is required.
[0015]
In order to solve such a problem, Japanese Patent Application Laid-Open No. H11-163873 discloses a method of imaging a spatial distribution of reflected light intensity when a light source including a wavelength component of at least about 600 to 1200 nm is irradiated on the skin surface in the vicinity of an observation site using a CCD or the like. It is shown that a blood vessel image can be obtained by capturing with an element. In this known example, light that directly reflects on the skin surface without entering the body and once penetrates into the body but reflects without reaching the blood vessels directly below the skin surface and shields light that is emitted outside the body again It is characterized by using a direct-reflection light shielding device that does not block light coming out of the body after reaching the lower part of the blood vessel just below the skin surface, thereby constituting a blood vessel visualization device at low cost. be able to.
[0016]
[Patent Document 6]
Japanese Patent Application No. 2003-68898
[0017]
However, the blood vessel image obtained by the spatial distribution of the light intensity that guides the light described above into the body and is emitted outside the body again is only a two-dimensional image, and the exact depth direction of the blood vessel is determined. Information is not available. That is, when blood is collected from a blood vessel using such a blood vessel visualization device, the position where the injection needle is punctured can be determined by the blood vessel visualization device. It is not clear whether it will penetrate. Therefore, there is a problem that it is not clear when to introduce blood into the injection cylinder at a negative pressure to introduce blood into the injection cylinder in order to introduce blood into the injection cylinder.
[0018]
The problem to be solved by the present invention is that when the blood collection needle is guided to the blood vessel while accurately grasping the two-dimensional position of the blood vessel existing under the blood collection subject, the blood collection needle is connected to the blood vessel. It is an object to provide a means for detecting arrival.
[0019]
[Means for Solving the Problems]
Hollow needles used for blood collection are usually made of a metal alloy or the like which has rigidity and can be bent but never broken even when a force of a durability limit is applied within a certain range. Generally, materials such as stainless steel having high cost performance are used. The needle may be coated with a biocompatible material, for example, silicon carbide, carbon or an organic polymer, for the reason that the needle is guided into a living body. Since it is often porous, as a result, the property of high electrical conductivity of a metal alloy such as stainless steel as a base material is maintained.
[0020]
The present inventors have noticed that when such a conductive needle is introduced into the body, the needle acts as a kind of electrode in the body, and from this electrical response, the needle is moved into the blood vessel. We thought that it could be used as a sensor to detect whether it was led.
[0021]
That is, first of all, the needle is brought into contact with the skin surface and punctured, and then gradually penetrates into the body (it does not reach the blood vessels). The potential is believed to be different from when the needle penetrated the blood vessel and the needle tip contacted the blood. Therefore, by observing such a difference in potential, it is possible to detect whether the tip of the needle has reached the blood vessel.
[0022]
And secondly, an electrode different from the needle is installed on the skin surface, and the needle is brought into contact with the skin surface while applying an AC voltage between the electrode and the needle to puncture the skin and gradually enter the body. Go. It is considered that the impedance and the phase between the needle and the electrode at this time naturally change depending on the depth of penetration into the body and the medium, that is, whether or not the blood is in contact with the blood in the blood vessel. Therefore, in this case as well, by observing such changes in impedance and phase, it is possible to detect whether or not the needle tip has reached the blood vessel.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an outline of a system having a two-dimensional blood vessel visualization device disclosed in Patent Document 6 and a blood vessel reaching detection mechanism of the present invention. First, the configuration of the blood vessel visualization device is such that a direct reflection light shielding device 104 equipped with an LED (Light Emitting Diode) 102 that emits near-infrared light is placed on a human forearm 101, and is closely fixed by a fixing band 118; An image of the skin surface in the vicinity is observed by an image pickup device such as a CCD camera 105, and a blood vessel image 107 is projected on a monitor 106. At the same time, a blood collection needle 109 attached to an injection tube 108 is also displayed on the monitor 106 to display the blood vessel image 107. The blood collection needle 109 is guided to an appropriate position for blood collection from the positional relationship between the blood collection needle image 111 and the blood collection needle image 111 and punctures the skin. However, such a blood vessel visualization device is not always necessary when a blood vessel is inflated using a tourniquet and a clear visual observation is performed as in the conventional method. At this time, the potential between the electrode 112 fixed to the skin surface and the blood collection needle 109 is measured by the DC voltmeter 115 via the wiring A113 and the wiring B114, respectively, and the result is transferred to the personal computer (PC) 116. Thus, the results are sequentially displayed on the monitor 117 for the personal computer.
[0024]
The potential of the blood collection needle 109 based on the electrode 112 when the blood collection needle 109 is made to penetrate into the body aiming at a blood vessel immediately below the skin is sequentially displayed on the monitor 117 for a personal computer, and the potential of the blood collection needle 109 when passing under the skin is shown. Since the potential and the potential when the blood reaches the blood vessel and comes into contact with the blood in the blood vessel are different from each other, if this is monitored, it is possible to detect whether or not the tip of the blood collection needle 109 has reached the blood vessel. it can. After detecting that the blood collection needle 109 has reached the inside of the blood vessel in this manner, the blood may be drawn into the injection cylinder 108 as a negative pressure in the injection cylinder 108 which is a blood storage container.
[0025]
In general, the potential generated when a metal is immersed in an electrolyte solution differs depending on the composition of the electrolyte even for the same metal. Therefore, it is considered that the potential change inside and outside the blood vessel as described above originates from the difference between the electrolyte component constituting the extravascular skin inside and the electrolyte component constituting the blood inside the blood vessel. This is nothing more than detecting whether the blood collection needle has reached the blood vessel.
[0026]
As a second means, an impedance analyzer is used in place of the DC voltmeter 115 in FIG. 1, an AC voltage is applied between the blood collection needle 109 and the electrode 112, and the impedance, phase, and equivalent The capacitance and resistance of the capacitor obtained from the circuit are obtained, and whether or not the blood collection needle 109 reaches the blood vessel and comes into contact with the blood is detected from these changes. However, at this time, a current flows through the body when the voltage is applied, but in order not to damage the human body, the amount of the current should be 100 μA or less according to the BF type of JIS T 0601, which specifies the leakage current of medical electrical equipment. Is desirable.
[0027]
Also in this case, the electrolyte component constituting the inside of the skin outside the blood vessel and the electrolyte component constituting the blood inside the skin, the composition and concentration of water and the like are different from each other, the impedance and the phase between the blood collection needle 109 and the electrode 112, In addition, it is considered that this has affected the capacitance and resistance of the capacitor obtained from the equivalent circuit, and these changes were observed when the blood collection needle 109 was pierced into the skin and penetrated into the body aiming at the blood vessel. If so, it can be detected whether or not it has reached the blood vessel and has come into contact with the blood. In this way, the blood collection can be completed by allowing the blood collection needle 109 to reach the inside of the blood vessel and then drawing the blood into the injection cylinder with negative pressure inside the injection cylinder.
[0028]
【Example】
[First embodiment]
Using the blood vessel visualization device having the configuration shown in FIG. 1 and the system having the blood vessel reaching detection mechanism of the present invention, blood is guided from a venous blood vessel on the back of the forearm of a human into a syringe with a 22-gauge blood collection needle attached. Tried.
As described above, the blood collection needle 109 is punctured into the skin while confirming the position of the blood vessel with the blood vessel visualization device, and the blood collection needle is guided to the blood vessel. At this time, the elapsed time dependency of the voltage between the blood collection needle 109 and the electrode 112 was as shown in FIG. First, at the point (A) in the figure, a change in voltage due to the puncture of the blood collection needle into the skin is observed. Next, until (B), the elapsed time on the horizontal axis is almost proportional to the depth of penetration of the blood collection needle into the body, so that in this range, the potential is almost constant and is about -25 millivolts, independent of the depth of penetration into the body. It turns out that it becomes. When the point (B) is reached, the potential increases by about 100 millivolts. This is considered to indicate that the blood collection needle has reached the blood vessel. In fact, in (C) in the figure, the blood collection needle is temporarily stopped from entering the body, and then the inside of the syringe cylinder to which the blood collection needle is attached is moved. When negative pressure was applied, it was confirmed that blood was guided into the syringe. Here, before reaching (B) in the figure, it was confirmed that blood could not be guided into the injection cylinder even if the pressure in the injection cylinder was negative. The change in the potential as shown in FIG. 2 is caused by the fact that the electrolyte component constituting the inside of the skin outside the blood vessel, the electrolyte component constituting the blood vessel, and the electrolyte component constituting the blood in the blood vessel are different from each other. It has been shown that from such a change, it is possible to detect whether the blood collection needle has reached the target blood vessel or the inside thereof.
[0029]
[Second embodiment]
In the system shown in FIG. 1, an impedance analyzer was used instead of the DC voltmeter 115, a sine wave AC current was passed between the blood collection needle 109 and the electrode 112, and the impedance and phase between the two were obtained from the response. FIG. 3 shows changes with the lapse of time. The alternating current at this time was a frequency of 100 Hz and the effective value was constant at 50 μA. The elapsed time on the horizontal axis is substantially proportional to the depth of the blood collection needle that has entered the body. Therefore, from this figure, the impedance decreases with the increase of the penetration depth, and after 30 seconds, hardly changes and remains constant. It is considered that such a decrease in impedance is due to an increase in the contact area between the needle and the human body as the penetration depth increases. On the other hand, the phase increases in the negative direction as the penetration depth increases, which means that the electrical resistance and capacitance components at the interface between the blood collection needle and the human body fluctuate. ing. This value also becomes almost constant at about -59 degrees after elapse of 20 seconds, but it can be seen that it increases to the positive side by about 2 to 3 degrees at the point (A) in the figure. By the way, when the skin surface of the arm is made a small wound to cause capillary blood to ooze out to the skin surface, the blood sampling needle is brought into contact with it, and the alternating current under the same conditions is passed, the phase is -38 degrees. Since the increase of the phase to the positive side described above is a direction approaching the value when the blood comes into contact with the needle, it is considered that the result reflects the result of the blood collection needle reaching the blood vessel and coming into contact with the blood. Then, at the time (B) in the figure, the blood collection needle was once stopped from entering the human body, and then the inside of the syringe was subjected to negative pressure, and it was confirmed that blood was guided into the syringe. Therefore, it is considered that the phase change as described above reflects the result of the blood collection needle reaching the blood vessel and coming into contact with the blood, and this is observed by observing such a phase change. Can be detected whether or not has reached the inside of the blood vessel.
[0030]
FIG. 4 shows the dependence of the impedance and phase on the elapsed time when the frequency of the alternating current flowing between the blood collection needle 109 and the electrode 112 is 100 kHz and the effective value is 50 μA. Also at this time, the impedance decreases as the elapsed time increases (substantially proportional to the increase in the penetration depth of the blood collection needle). On the other hand, the phase increases toward the positive side as the elapsed time increases, reaches a maximum at about -9 degrees at the point (A) in the figure, and then begins to decrease and then reverse. By the way, because the phase when the AC current of the same condition is passed by making a minute wound on the skin surface of the arm and exuding capillary blood to the skin surface, contacting a blood collection needle there and flowing -45 degrees, It is considered that the decrease in the phase after (A) in the figure reflects that the blood collection needle reached the blood vessel and came into contact with the blood in the blood vessel. Then, when the pressure inside the syringe was reduced to a negative pressure at the time (B) in the figure, it was confirmed that blood was guided into the syringe. This also indicates that it is possible to determine whether or not the blood collection needle has reached the inside of the blood vessel by observing the phase change.
[0031]
(Third embodiment)
An attempt was made to introduce blood through a painless needle 501 (outer diameter: 100 μm, inner diameter: 60 μm) onto a chip-shaped blood analyzer as shown in FIG. The chip is formed by laminating two polycarbonate substrates, and includes a blood flow path 502, a sensor electrode 503 for electrochemically sensing sodium ions, potassium ions, glucose, and urea nitrogen concentrations in blood; And an electrode pad 504 for outputting an electric signal of a sensor output. The chip size is 2 cm square.
[0032]
Next, as shown in FIG. 6, the tip 602 is placed on the slider 601 and fitted into the holder main body 603 so that the painless needle 501 at the tip of the tip is set in the cylinder 604 integrated with the holder main body. I do. Further, as described in the first embodiment, the direct reflection light shielding device 104 including the LED 102 that emits near-infrared light is installed from the upper arm to the inside of the forearm of the human, and the above-described blood vessel image immediately below the skin and The positional relationship between the tip of the tip set in the holder and the painless needle 501 is captured by the CCD camera 105, and this is confirmed on a monitor (not shown). Based on the positional relationship between the two, the position of the blood collection holder on which the chip is mounted is adjusted, and the painless needle 501 is guided just above the blood vessel to bring the cylinder 604 into contact with the skin surface. Thereafter, the air is exhausted through the in-cylinder exhaust hose 605, and when the pressure in the cylinder 604 is reduced, the skin sticks to the cylinder 604 and bends into the cylinder. Then, the painless needle 501 punctures the skin and automatically enters the body.
[0033]
The painless needle 501 and the electrode 112 adhered to the skin surface are connected to a DC voltmeter 115 via a wiring A113 and a wiring B114, respectively, where the voltage between the painless needle 501 and the electrode 112 is measured. Is transferred to the personal computer 116 and displayed on the monitor 117 in real time. Then, a change in the potential of the painless needle 501 when the electrode 112 is set to the reference potential according to the depth of penetration of the painless needle into the body is monitored. The painless needle pushes the slider 601 toward the skin side, guides the sponge 607 deeper into the body while bending, and reaches the blood vessel. Whether or not the blood vessel has been reached is determined from the potential change of the painless needle as described in [First Embodiment]. When the blood vessel has reached the blood vessel, the in-chip flow path 502 is set to a negative pressure via the blood collection suction hose 606, The blood in the blood vessel is guided through the painless needle to the on-chip flow path having a blood storing action. With such a procedure, about 4 μl of blood could be introduced onto the chip.
[0034]
Also, an impedance analyzer is installed instead of the DC voltmeter 115 in FIG. 6, and the wirings A and B are connected thereto. Then, an alternating current having a frequency of 100 Hz and an effective value of 50 μA was passed between the painless needle 501 and the electrode 112, and the impedance and phase were determined from the response using an impedance analyzer. The painless needle 501 is pierced into the skin in the same procedure as above, and changes in impedance and phase when entering the body aiming at a blood vessel are shown on the monitor 117 in real time. Judged whether or not. Then, when the behavior of the phase change that seems to have reached the blood vessel as shown in FIG. 3 is obtained, the blood in the blood vessel is passed through the painless needle through the suction hose 606 for blood collection and the negative pressure in the channel 502 inside the chip. To a channel on the chip that has a blood containing action. With such a procedure, about 4 μl of blood could be introduced onto the chip.
[0035]
As shown in this embodiment, even in a chip-shaped blood analyzer having a blood collection needle (painless needle), the potential of the painless needle or the impedance and phase between the painless needle and the electrode are observed to determine whether the painless needle has reached the blood vessel. It was found that the judgment could be made by performing
[0036]
(Fourth embodiment)
An automatic blood sampling device having a configuration as shown in FIG. 7 was manufactured, and an attempt was made to collect blood from a vein inside a human forearm. This device will be briefly described. The syringe 108 to which the 22-gauge blood collection needle 109 is attached is attached to the movable arm A703 of the linear actuator A702 via the joint A701. In addition, a syringe 704 for creating a negative pressure in the syringe is attached to a movable arm B707 of a linear actuator B706 via a joint B705. The linear actuators A and B are connected to a personal computer 116 and controlled. The movable arms A and B are movable in the direction of the arrow in the figure. The main body of the linear actuator A is fixed to the column 708. Further, it is connected to one end of the input terminal of the DC voltmeter 115 from the blood collection needle 109 via the wiring A113, and the output value of the voltmeter is sequentially transferred to the personal computer 116.
[0037]
Next, as shown in FIG. 8, the blood collection needle 109 in the device shown in FIG. 7 is placed near the skin surface 802 inside the human forearm 801. The electrode 112, which is in contact with the skin surface, is connected to an input terminal of a DC voltmeter 115 via a wiring B114. Then, as shown in FIG. 9, a target is set at the blood vessel 803 directly below the skin, which is the target, a signal is sent from the personal computer 116 to the linear actuator A 702, the movable arm A 703 is pushed out to the skin surface 802 side, and the blood sampling needle 109 is punctured into the skin. . The change in the voltage between the blood collection needle 109 and the electrode 112 when the blood collection needle is inserted into the body is sequentially transferred to the personal computer via the DC voltmeter 115, and the blood collection needle reaches the blood vessel 803, and the voltage change behavior As shown in FIG. 10, when the movement of the linear actuator A is automatically stopped by the signal from the personal computer and the invasion of the blood collection needle is stopped, as shown in FIG. A signal is also sent to the actuator B 706, and the syringe 704 is pulled in a direction opposite to the skin surface direction to make the inside of the syringe 108 a negative pressure. In this way, about 10 cc of blood 1001 could be drawn into the syringe 108.
[0038]
Further, an alternating current is passed between the blood collection needle 109 and the electrode 112 using an impedance analyzer instead of the DC voltmeter 115 in FIG. 8, and the impedance and phase are obtained from the voltage response at that time, and the penetration depth of these blood collection needles into the body The dependence is monitored, and blood is collected also by controlling and operating the linear actuators A and B with a personal computer in the same manner as described above from the change when the blood vessel reaches the blood vessel as shown in FIGS. Was able to do.
[0039]
【The invention's effect】
As described above, the conventional inexpensive and simple method of visualizing blood vessels directly under the skin using near-infrared light can only obtain two-dimensional positional information of blood vessels. In the case of invasion into the blood vessel, it was not possible to clearly determine whether the blood reached the blood vessel, but the potential and phase of the blood collection needle of the present invention or the impedance and phase between the blood collection needle and other electrodes attached to the living body were monitored. Then, from these changes, it has become possible to determine whether or not the blood collection needle has reached the blood vessel or the inside thereof. As a result, blood collection can be reliably performed, and the physical burden on the blood collection subject can be further reduced.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a conventional blood vessel visualization device and a potential measurement mechanism of a blood collection needle.
FIG. 2 is a diagram showing a change in the potential of the blood collection needle when the blood collection needle is made to enter a human body.
FIG. 3 is a diagram showing changes in impedance and phase between a blood collection needle and an electrode adhered to skin when the blood collection needle is made to enter a human body. (AC current: 100 Hz, 50 μA)
FIG. 4 is a diagram showing changes in impedance and phase between a blood collection needle and an electrode adhered to skin when the blood collection needle is made to enter a human body. (AC current: 100 kHz, 50 μA)
FIG. 5 is a diagram showing a chip-shaped blood analyzer.
6 is a diagram illustrating a procedure for introducing blood into the chip-shaped blood analyzer shown in FIG. 5 by using the method of the present invention for detecting whether or not blood has reached a blood vessel.
FIG. 7 is a diagram illustrating an automatic blood collection device.
FIG. 8 is a diagram illustrating how blood is collected using an automatic blood collection device.
FIG. 9 is a diagram illustrating a state in which blood is collected using an automatic blood collection device.
[Explanation of symbols]
101 Human forearm 102 LED
103 Power supply 104 Direct reflection light blocking device 105 CCD camera 106 Monitor 107 Blood vessel image 108 Injection cylinder 109 Blood sampling needle 110 Injection cylinder image 111 Blood sampling needle image 112 Electrode 113 Wiring A
114 Wiring B
115 DC voltmeter 116 Personal computer 117 Personal computer monitor 118 Fixed band 501 Painless needle 502 Channel 503 Sensor electrode 504 Electrode pad 601 Slider 602 Chip 603 Holder main body 604 Cylinder 605 Cylinder exhaust hose 606 Blood sampling suction hose 607 Sponge 701 Joint A
702 Linear actuator A
703 Movable arm A
704 Syringe 705 Fitting B
706 Linear Actuator B
707 Movable arm B
708 post 801 forearm 802 skin surface 803 blood vessel 1001 blood

Claims (8)

In the process of injecting a needle made of an electrically conductive material into the human body, a voltage between the needle and an electrode in contact with the surface of the human body is monitored, and the needle is used based on a change in the voltage. A blood vessel detection method, which detects that the object has reached a desired blood vessel. A needle for human invasion composed of an electrically conductive material, an electrode in contact with the human body surface, and the needle and the electrode are electrically connected to measure a voltage between the two. Blood vessel detection device composed of the device. In the process of injecting a needle made of an electrically conductive material into the human body, an alternating current is passed between the needle and an electrode in contact with the surface of the human body, and the electrical response is Obtain at least one of the circuit constants such as the impedance between the needle and the electrode, the electrical resistance that can be calculated from the phase or an equivalent circuit assumed based on this, and the capacitance of the capacitor, monitor these, and monitor these changes. A blood vessel detection method comprising detecting that the needle has reached a desired blood vessel. A needle for human invasion composed of an electrically conductive material, an electrode in contact with the surface of the human body, and an electrical current that is electrically connected between the needle and the electrode and an alternating current flows between the two; A device that can determine at least one of circuit constants such as electrical resistance and capacitor capacity that can be calculated from the impedance and phase between the needle and the electrode or an equivalent circuit assumed based on the electrical response from the electrical response. Blood vessel detection device. The blood vessel according to claim 1 or 3, wherein the needle according to claims 1 and 3 is particularly hollow, the needle is made to penetrate the human body, and the tip of the needle reaches a desired blood vessel in the human body. A blood collection method characterized in that when detected by a detection method, blood in a blood vessel is guided to a container capable of accommodating blood connected to an end of the needle which is in contact with the human body and opposite to the end. The blood collection device according to claim 2 or 4, wherein the needle is particularly hollow, and comprises a blood vessel detecting device according to claim 2 or 4, and a container capable of storing blood connected to one end of the needle. apparatus. In claim 5, in particular, when the tip of the needle has reached a desired blood vessel in the human body, the movement of the blood collection needle is stopped, and then the end of the needle is opposite to the end in contact with the human body. A blood collection method, wherein the step of guiding blood in a blood vessel to a connected container capable of containing blood is automatically performed by using an automatic control device. 7. The blood collection device according to claim 6, wherein the device controls movement of the needle back and forth in at least one direction, and draws blood into a container connected to one side of the needle and capable of storing blood. Is automatically operated via an automatic control device in response to an output signal of a blood vessel detection device.

Images