A device for monitoring the blood occlusion rate using an aortic clamping balloon.

Abstract

The present invention provides a device for monitoring blood flow when the blood flow is stopped using an aortic blockage balloon to prevent complete blockage of the blood flow and prevent development of a complication.　This balloon catheter device comprises a balloon catheter having a catheter tube and an aortic blockage balloon provided at the distal end part of the catheter tube, one or a plurality of optical fibers housed in the catheter tube, one or a plurality of light-emitting devices that are disposed in the balloon and that are connected to the optical fibers and one or a plurality of light detection parts for detecting backscattered light of the emitted light, and one or a plurality of light sources for generating the light to be emitted, the balloon catheter device: emitting, from the aortic blockage balloon into the aorta, light having a wavelength that can be absorbed by a substance present in the blood; detecting backscattered light from inside the blood vessel; and monitoring, over time, the state of blood flow between the aortic blockage balloon and the vascular wall from the intensity of the detected light.

Description

[Technical Field]

[0001] The present invention relates to a device for monitoring the blood occlusion rate using an aortic clamping balloon, and a monitoring method using the device. [Background technology]

[0002] While open thoracoaortic cross ramp (RTACC) and open abdominal aortic compression were used as methods for aortic occlusion in cases of trauma, excessive invasiveness was a concern.

[0003] To address the problem of excessive invasiveness, a method called Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) was developed, which involves blocking blood flow in the aorta using an aortic occlusion balloon. In this method, a balloon catheter is inserted percutaneously through the femoral artery, and blood flow in the aorta is blocked by expanding the balloon. This method is a minimally invasive hemostatic method and also prevents hypothermia.

[0004] In REBOA, by adjusting the balloon diameter through the amount of fluid injected into the balloon, the aortic occlusion area was partially reduced (partial-REBOA), and peripheral blood flow was maintained, thereby preventing complications due to limb ischemia.

[0005] However, the diameter of arteries can easily change depending on the volume of blood vessels, and even without a change in balloon volume, blood flow can be completely blocked (over-inflation), leading to complications (see Non-Patent Literature 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Jonker FH et al., Eur J Vasc Endovasc Surg 2010; 40: 564-71 [Overview of the project] [Problems that the invention aims to solve]

[0007] Traditionally, aortic clamping balloons have been used to stop bleeding from trauma, but because the diameter of the aorta is prone to change, blood flow can be completely blocked (over-inflation), sometimes leading to complications.

[0008] The present invention aims to provide a device that prevents complete occlusion of blood flow and thus prevents the onset of complications by monitoring blood flow when blood flow is stopped using an aortic occlusion balloon. [Means for solving the problem]

[0009] The inventors have discovered that by irradiating a balloon with light of a wavelength absorbed by substances present in the blood vessel into the blood vessel, and detecting the backscattered light from within the blood vessel, it is possible to monitor the presence or absence of blood flow between the blood vessel and the balloon using the backscattered light, thereby detecting unexpected over-inflation and preventing complications.

[0010] Furthermore, we discovered that by using light of multiple wavelengths with different penetration lengths as the light source, it becomes possible to predict blood flow.

[0011] In this invention, in REBOA, blood flow obstruction (over-inflation) is detected by monitoring blood flow between the blood vessel and the balloon using backscattered light. As a result, complications can be prevented. In other words, this invention can solve the problems associated with REBOA.

[0012] The present invention is as follows: [1] A catheter tube and a balloon catheter having a balloon provided at the tip of the catheter tube, The optical fiber housed inside the catheter tube, A light irradiation area and a light detection area for detecting irradiated light, which are arranged inside the balloon and connected to the optical fiber, A light source that generates the light to be emitted. A balloon catheter equipped with, A balloon catheter emits light from a balloon at wavelengths that can be absorbed by substances present in the blood. By detecting scattered light from within the blood vessel and analyzing the intensity of the detected light, it becomes possible to monitor the blood flow between the balloon and the blood vessel wall over time. [2] The balloon catheter of [1], comprising a calculation unit that determines the presence or absence of blood flow based on the intensity of scattered light. [3] A balloon catheter of [2], having a display unit for displaying the blood flow status analyzed by the calculation unit. [4] A balloon catheter of any of the following types [1] to [3], wherein the wavelength of the light emitted is 400 to 500 nm. [5] A balloon catheter according to any of [1] to [4], wherein the balloon emits light of multiple wavelengths with different penetration lengths that can be absorbed by substances present in the blood, the scattered light from within the blood vessel of each wavelength is detected, and the blood flow between the balloon and the blood vessel wall is monitored from the intensity of the scattered light of each wavelength. [6] Define a function represented by equation (1) or (2) below, and fit it using data on the elapsed time from the start of balloon expansion and the backscattered light intensity when backscattered light is detected, and determine the coefficient of determination α. TIFF0007913774000001.tif61149

[0013] or TIFF0007913774000002.tif54149

[0014] Using the calculated coefficient of determination, the elapsed time after the start of expansion is calculated by substituting the backscatter light intensity detected by irradiating with light of wavelength 560 nm (green) or light of wavelength 650 nm into equation (1) or (2) above. The balloon diameter is estimated from the time obtained after the start of expansion. The balloon catheter according to [5], wherein the blood layer thickness is calculated by the following formula: [blood layer thickness = blood vessel diameter (inner diameter) - balloon diameter]. [7] The balloon catheter according to [5] or [6], wherein the lights having different light penetration depths are 2, 3, 4, 5 or 6 kinds of wavelength lights selected from near-infrared light, infrared light, light with a wavelength of 380 to 430 nm (violet), light with a wavelength of 430 to 490 nm (blue), light with a wavelength of 490 to 550 nm (green), light with a wavelength of 550 to 590 nm (yellow), light with a wavelength of 590 to 640 nm (orange), and light with a wavelength of 640 to 770 nm (red). [8] The balloon catheter according to [5] or [6], wherein the lights having different light penetration depths are at least two kinds selected from light with a wavelength of 475 nm, light with a wavelength of 542 nm, and light with a wavelength of 438 nm. [9] The balloon catheter according to [5] or [6], wherein the lights having different light penetration depths are two kinds of green light and red light.

[10] The balloon catheter according to [5] or [6], wherein the lights having different light penetration depths are two kinds of green light with a wavelength of 560 nm and red light with a wavelength of 650 nm.

[11] The balloon catheter according to any one of [1] to

[10] , wherein scattered light is detected at the rear side.

[12] The balloon catheter according to any one of [1] to

[11] , wherein the catheter is a blood vessel occlusion or aortic occlusion catheter.

[0015] The present specification includes the disclosure content of Japanese Patent Application No. 2022-64939 which is the basis of the priority of the present application. [Effects of the Invention]

[0016] By using the balloon catheter of the present invention, the presence or absence of blood flow between the balloon and the blood vessel wall or the blood flow volume during aortic occlusion by the balloon can be monitored, and the onset of complications caused by complete occlusion of the aorta can be prevented by adjusting the balloon diameter using the blood flow volume as an index. [Brief Description of Drawings]

[0017] [Figure 1]This diagram shows the structure of a balloon catheter used in a device for monitoring the blood occlusion rate using an aortic clamping balloon. [Figure 2] This diagram shows the structure of a device for monitoring the blood occlusion rate using an aortic clamping balloon. [Figure 3] This figure shows the backscattered light intensity in a device that monitors the blood occlusion rate using an aortic occlusion balloon. Figure 3A shows the backscattered light intensity at each wavelength in 5 and 10 (v / v)% Intralipid solutions of an expanded balloon (n=3), and Figure 3B shows the time from the start of expansion to the maximum differential of backscattered light intensity due to differences in photopenetration length (ex vivo, mean ± SD, n=4). [Figure 4] This figure shows the change in backscattered light intensity associated with the expansion and contraction of the REBOA balloon in vivo. [Figure 5] This figure shows the intensity of backscattered light (unit: Arbitrary Unit) and balloon diameter for each wavelength of light, over time (horizontal axis) from the start of inflation, when using 560nm light (green) and 650nm light (red). [Figure 6] This figure shows the intensity of backscattered light (unit AU: Arbitrary Unit) and balloon diameter for each wavelength of light, over time (horizontal axis) from the start of inflation, when using 395 nm light (purple) and 560 nm light (green) (Figure 6). [Figure 7] This figure shows whether the backscattered light measured using 395nm light (purple), 560nm light (green), and 650nm light (red) exceeded the threshold (indicated by "○") or did not exceed the threshold (indicated by "×") when the blood layer thickness was large to small. [Figure 8] This diagram shows an overview of a method for measuring blood flow velocity using light. [Figure 9] This figure shows a cross-section of a blood vessel into which a balloon has been inserted, as well as the balloon diameter and blood layer thickness. [Figure 10] This figure shows the changes in backscatter intensity of red and green light within the aorta of a pig in vivo. [Modes for carrying out the invention]

[0018] The present invention will be described in detail below. 1. Device for monitoring the blood occlusion rate using a vascular occlusion balloon. The present invention relates to a device and a monitoring method using a balloon catheter for monitoring blood flow between a blood vessel and a balloon by irradiating the blood vessel wall with light of a wavelength absorbed by substances present in the blood vessel from the balloon, and detecting the backscattered light from within the blood vessel. Monitoring blood flow between the blood vessel and the balloon can also be described as monitoring the blood occlusion rate by the balloon.

[0019] The apparatus used in the present invention is A catheter tube and a balloon catheter having a vascular occlusion balloon provided at the tip of the catheter tube, One or more optical fibers housed within the catheter tube, One or more light irradiation sites arranged inside the balloon and connected to the optical fiber, and one or more light detection sites for detecting backscattered light of the irradiated light, It comprises one or more light sources (light-generating parts) that generate the light to be emitted.

[0020] The device of the present invention is also simply called a balloon catheter.

[0021] When light with a wavelength absorbed by substances present in the blood vessel is shone from a balloon into the blood vessel, if blood is present between the balloon and the vessel wall, the shone light is partially absorbed, and the intensity of the backscattered light decreases. The intensity of the backscattered light is measured to monitor the presence and flow rate of blood in the blood vessel.

[0022] Using the aforementioned device, light of a wavelength that can be absorbed by substances present in the blood is irradiated from the vascular occlusion balloon into the blood vessel, backscattered light from inside the blood vessel is detected, and the presence or absence of blood flow between the vascular occlusion balloon and the blood vessel wall can be monitored over time based on the intensity of the detected light.

[0023] "Blood vessel" includes any blood vessel into which a balloon catheter can be inserted, preferably the aorta.

[0024] A "catheter" refers to a thin tube that can be inserted into a blood vessel. The balloon catheter of the present invention can use a balloon catheter that is normally used in intravascular endoscopes, etc., and its diameter is not limited. It is used to block blood flow by pressing against the wall of a blood vessel such as the aorta with appropriate pressure during bleeding. The balloon catheter has a catheter tube balloon, also called a shaft. The means for expanding the balloon is not particularly limited, but it can be achieved by supplying an appropriate liquid or gas into the balloon. The device of the present invention has a means for supplying and deflating the balloon of the balloon catheter. The means for supplying and deflating the balloon is provided as a lumen in the catheter tube. The balloon is attached near the distal end of the catheter. The catheter tube may have a double structure with an outer tube and an inner tube, in which case a lumen is formed between the two tubes. The pressure when the balloon presses against the blood vessel wall during expansion is 0.2 to 1 kg / cm². 2 The interval between these two is preferable.

[0025] Balloons that can be used to block blood flow are also called occlusion balloons, block balloons, or occlusion balloons.

[0026] The balloon material can be nylon (registered trademark), polyvinyl chloride, polyethylene, polyurethane, polyether block amide copolymer, polyethylene terephthalate, polypropylene, or other olefin polymers, or copolymers consisting of combinations thereof. Silicone rubber and latex rubber can also be used. The balloon size is preferably an expanded diameter of about 10 to 50 mm and a vertical length of about 5 to 100 mm.

[0027] The catheter tip of the present invention may have a structure that allows it to be freely bent. For example, a tension wire can be placed inside the catheter, and the tip can be bent by pulling the tension wire. Furthermore, the tip may be pre-bent to conform to the shape of the treatment site. The device of the present invention may include a guide sheath and a guide wire for inserting and advancing the catheter into the target site. The size of the catheter is preferably 6 to 10 Fr. The catheter can be inserted into the body through the femoral artery or brachial artery by conventional methods. Examples of materials for the catheter tube include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, polyvinyl chloride, polyamide, polyimide, polyethylene terephthalate, polyamide elastomer, polyester, polyester elastomer, and polyurethane.

[0028] Means for transmitting light to the light-irradiating site within the balloon include a light-irradiating site located near the distal end of the catheter and an optical fiber that transmits light from the light source to the light-irradiating site. In this specification, "near the distal end" means the part close to the end opposite to the end connected to the high-intensity pulsed light generation site (proximal end), and refers to the distal end and the part approximately several tens of centimeters from the distal end.

[0029] Furthermore, the apparatus of the present invention includes a light source (light generating part). The light source can generate light of any wavelength, and the generated light is transmitted through an optical fiber connected to the light source, irradiating the blood vessel from the light irradiation part inside the balloon toward the blood vessel wall. The apparatus of the present invention may have one or more light irradiation parts so that light of multiple wavelengths can be irradiated simultaneously. The light irradiation part is not limited, but examples include an LED generating part.

[0030] The optical fiber is housed in a catheter tube and connected to a light source at one end. A suitable laser light irradiation device, such as a lens, may be provided at the tip of the optical fiber. The optical fiber used in this invention can be of a wide range of diameters, from extremely thin ones with a diameter of about 0.05 to 0.6 mm to those with a visible diameter.

[0031] The apparatus of the present invention further includes a photodetection site for detecting backscattered light that is irradiated from the light irradiation site into the blood vessel and reflected and scattered within the blood vessel. The apparatus of the present invention may have one or more photodetection sites so as to be able to detect light of multiple wavelengths simultaneously.

[0032] The present invention provides a device for monitoring the blood blockage rate, which further includes a calculation unit that determines the presence or absence of blood flow based on the intensity of a device that detects backscattered light, and a display unit for displaying the presence or absence of blood flow analyzed by the calculation unit.

[0033] Hemoglobin is a substance found in blood vessels. Hemoglobin absorbs light with a wavelength of 400-500 nm. Therefore, the wavelength of light emitted from the light source is 400-500 nm.

[0034] Furthermore, by irradiating with light of multiple wavelengths with different penetration depths and detecting the backscattered light from within the blood vessels for each wavelength, the blood flow between the vascular occlusion balloon and the blood vessel wall can be monitored from the intensity of the backscattered light for each wavelength. Examples of multiple wavelengths of light include 475 nm light (cyan), 542 nm light (green), and 438 nm light (blue). In this case, the apparatus of the present invention may include multiple optical fibers, multiple light irradiation sites, and multiple light detection sites (receiving sites) for transmitting, irradiating, and receiving light of multiple wavelengths. 2. Backscattered light detection method using a device for monitoring the blood occlusion rate by a vascular occlusion balloon A monitoring light with a wavelength absorbed by substances present in the blood vessel is shone from a light irradiation site placed inside the balloon, and the backscattered light of the irradiated light is detected. Here, backscattered light refers to the light that is absorbed and scattered within the blood vessel after being shone from a light irradiation site near the distal end of the optical fiber, and returns to the fiber. If blood flow is present in the blood vessel, the returning backscattered light is weak, and if there is no blood flow, the returning backscattered light is strong. As mentioned above, substances present in the blood vessel include substances in the blood, and hemoglobin is particularly preferred. Hemoglobin is a pigment protein that absorbs light of a specific wavelength. Therefore, since the light absorption and scattering characteristics differ depending on the amount of hemoglobin present in the blood vessel, it is possible to determine whether or not blood flow is present at the irradiated site by detecting the backscattered light.

[0035] For monitoring, light with a wavelength of 400 nm to 500 nm can be used. The maximum wavelength of light absorbed by hemoglobin is around 400 and 550 nm, but even if it falls outside this range, it can still be absorbed by hemoglobin, a pigment protein, and can therefore be used as monitoring light in the apparatus of the present invention. The light intensity can be low; weak light with an output of 0.01 mW to 1 mW is sufficient. The monitoring light is generated by an external light source, transmitted through a monitoring light transmission fiber, and irradiated from the tip of the fiber. The backscattered light is re-entered into the transmission fiber that was irradiated with the monitoring light, travels backward through the fiber, and returns. To detect the backscattered light, a detector (light detection unit) for monitoring the backscattered light should be connected to the fiber into which the backscattered light enters and returns. By providing a beam splitter in the middle of the fiber, the path of the light returning through the optical fiber can be changed, and further, by passing it through an appropriate bandpass filter, only the light of the desired wavelength can be selected and guided to the scattered light detector. The scattered light detector is not limited to any device that can detect light, but for example, a silicon photodiode can be used.

[0036] Furthermore, by irradiating with light of multiple wavelengths with different penetration depths as monitoring light and detecting the backscattered light from within the blood vessels for each wavelength, the blood flow between the vascular occlusion balloon and the blood vessel wall can be monitored from the intensity of the backscattered light for each wavelength. As multiple wavelengths of light, for example, multiple wavelengths of light from 380-430 nm (violet), 430-490 nm (blue), 490-550 nm (green), 550-590 nm (yellow), 590-640 nm (orange), and 640-770 nm (red) can be used, for example, two, three, four, five, or six types of wavelengths. Examples of light combinations to use include cyan, green, and blue light, or violet, green, and red light, or green and red light. When specifying wavelengths, examples of light combinations to use include near-infrared light, infrared light, or light of wavelengths close to these. For example, light of 475 nm (cyan), 542 nm (green), and 438 nm (blue), or light of 395 nm (violet), 560 nm (green), and 650 nm (red), or light of 560 nm (green) and 650 nm (red). These multiple wavelengths of light can be transmitted, irradiated, and received. As described below, the blood layer thickness can be estimated, the blood flow velocity measured, and then the blood flow rate measured. (1) Estimation of blood layer thickness The absorption coefficient of blood differs depending on the wavelength of light used, resulting in differences in light penetration depth. Hemoglobin in blood has an absorption coefficient peak at blue to green wavelengths and a low absorption coefficient at red wavelengths. Light with a low absorption coefficient is less absorbed by hemoglobin in the blood, resulting in a longer light penetration depth in the blood. When a balloon is inflated in the blood and monitoring light is shone from the light irradiation site inside the balloon, light with a low absorption coefficient is less absorbed by substances in the blood, resulting in a longer light penetration depth and a higher backscatter light intensity. Conversely, light with a high absorption coefficient is more easily absorbed by substances in the blood, resulting in a shorter light penetration depth and a lower backscatter light intensity.

[0037] A vascular occlusion balloon is inflated in a blood vessel, and the backscattered light intensity is measured using light of each wavelength during the inflation process. A threshold of 60-80%, preferably 65-75%, and more preferably 70% of the maximum backscattered light intensity for each wavelength is used, and it is determined whether the measured value using light of each wavelength exceeds the threshold. The blood layer thickness can then be estimated from the pattern of the threshold determination. The blood layer thickness can be estimated as, for example, greater than x1 mm (> x1 mm), x2-x1 mm (greater than x2 mm and less than or equal to x1 mm), x3-x2 mm (greater than x3 mm and less than or equal to x2 mm), and less than or equal to x3 mm (< 0.1 mm). Here, x1, x2, x3, and x4 are any values ​​between 0.05 and 10 mm, preferably between 0.05 and 5 mm, and more preferably between 0.1 and 1 mm.

[0038] For example, the blood layer thickness can be estimated as shown in Example 2 and Figure 7 below. Figure 7 shows whether the backscattered light measured using 395nm light (purple), 560nm light (green), and 650nm light (red) exceeded the threshold (indicated by "○") or did not exceed the threshold (indicated by "×") when the blood layer thickness ranged from large to small. From the threshold determination pattern, the blood layer thickness can be estimated as >1mm, 0.3~1mm, 0.1~0.3mm, or <0.1mm.

[0039] Furthermore, the blood layer thickness can be estimated, for example, by the method shown in Example 3 below. That is, a function represented by the following equation (1) or (2) is defined, and the coefficient of determination α is determined by fitting it using data on the elapsed time from the start of balloon expansion and the backscattered light intensity when backscattered light is detected. TIFF0007913774000003.tif62155

[0040] or TIFF0007913774000004.tif57154

[0041] Using the calculated coefficient of determination, the elapsed time after the start of expansion can be calculated by substituting the backscattered light intensity detected after irradiating with light of a wavelength of 560 nm (green) or light of a wavelength of 650 nm into equation (1) or (2) above. From the obtained elapsed time after the start of expansion, the balloon diameter can be determined, and the blood layer thickness can be calculated using the following equation [blood layer thickness = blood vessel diameter (inner diameter) - balloon diameter]. Note that the balloon diameter can be determined from the time after the start of expansion based on measured values. Equations (1) and (2) above are just examples, and other equations can also be used. (2) Measurement of blood flow velocity Blood flow velocity can be measured in various ways, for example, using light. Figure 8 shows a measurement method using light. When measuring blood flow velocity using light, the balloon has a lumen structure that allows saline solution to be flushed from its tip (Figure 8A). Even if saline solution is flushed without changing the balloon's expansion state, the blood around the balloon is temporarily removed, and the backscattered light intensity changes (Figure 8B). Depending on the blood flow velocity, the time required for the saline solution around the balloon to be flushed away and for the backscattered light to return to its original value will differ. The blood flow velocity (m / s) can be estimated from the return speed of the backscattered light (Figure 8C). (3) Measurement of blood volume The amount of blood flowing through the blood vessels per unit time can be calculated from the values ​​estimated and measured in (1) and (2). For example, it can be calculated using the following formula. Blood flow [m 3 / s]=blood layer cross-sectional area [m 2 ]×Blood velocity [m / s] Blood layer cross-sectional area={(dB / 2+d) 2 -(dB / 2) 2}π [m 2 ] dB[m]: Balloon diameter (calculated from the amount of liquid injected into the balloon) d[m]: Estimated blood layer thickness 3. Method of using the apparatus of the present invention Figure 2 shows an example of the configuration of the device of the present invention, and Figure 1 shows an example of the configuration of the balloon catheter of the present invention.

[0042] The method of using the device of the present invention will be explained with reference to Figure 2. The fiber portion of the device of the present invention is inserted through a sheath inserted into a blood vessel for inserting a balloon catheter, and is brought to the blood vessel whose blood flow is to be monitored. A weak monitoring light is generated from the light source in Figure 2, and this light is transmitted through the fiber and irradiated from the tip of the fiber. The monitoring light is absorbed and scattered by the blood in the irradiated area, and the scattered light enters the fiber again as backscattered light and returns. The path of the returned light is changed by a beam splitter and guided through an appropriate filter to a photodetector (silicon photodiode), and the intensity of the light is measured.

[0043] As described above, by using multiple wavelengths in this process, it is possible not only to monitor the presence or absence of blood flow, but also to quantify blood flow. [Examples]

[0044] The present invention will be specifically described by the following examples, but the present invention is not limited to these examples. In the examples, an aortic occlusion balloon was used as an example. Example 1: Establishment of a trans-balloon backscatter light intensity measurement system. method Figure 2 shows an overview of the trans-balloon backscatter light intensity measurement system constructed. An aortic occlusion balloon (Rescue Balloon, maximum diameter: 40 mmΦ, balloon length: 60 mm, Tokai Medical Products) was inserted into the lumen of a pig aorta, and the balloon was inflated with a syringe. An LED was focused onto one of the fibers of a bifurcated bundle fiber (core diameter: 100 μmΦ, NA: 0.22, SI multimode, Ocean Optics), and two plastic diffuse optical fibers (diffusion length: 70 mm, core diameter: 250 μmΦ) connected to the tip of the LED were inserted into the central lumen of the balloon. Light was irradiated from one end, and the backscattered light was received from the other end, and a silicon photodiode (S2281, receiving area: 100 mm²) was used to measure the light intensity. 2The detection was performed using Hamamatsu Photonics. (i) The measurement accuracy of the experimental system using a scattering agent (Intralipid solution) and pig blood was investigated, (ii) measurements and accuracy investigations were performed using blood samples and pig aorta, and (iii) blood flow detection performance in an in vivo pig model was evaluated. result Figure 3A shows the backscattered light intensity at various wavelengths in 5, 10 (v / v)% Intralipid solutions in an expanded balloon. "〇" (white circle) represents red light, "▲" (black triangle) represents green light, "■" (black square) represents cyan light, and "●" (black circle) represents blue light. Figure 3B shows the photopenetration depth dependence of the time from the start of expansion to the maximum differential value of backscattered light intensity during ex vivo balloon expansion. It was confirmed that the longer the photopenetration depth, the shorter the time from the start of expansion to the maximum differential value. Figure 4 shows an example of the change in backscattered light intensity accompanying the expansion and contraction of a REBOA balloon in vivo. It was confirmed that backscattered light increased after balloon expansion, even under pulsation. Furthermore, it was confirmed that the backscattered light decreased to its pre-expansion intensity when the balloon was deflated. Consideration A change in backscattered light intensity is expected when the light penetration length becomes less than or equal to the blood layer thickness between the blood vessel and the balloon. In Figure 3B, the blood layer thickness between the blood vessel and the balloon decreases as the balloon expands, so it is thought that the shorter the light penetration length, the longer the time from the start of balloon expansion to the change in backscattered light intensity. In Figure 4, an increase in backscattered light from the blood vessel was confirmed in vivo when blood flow between the balloon and the blood vessel was blocked, indicating the possibility of operation under pulsation. From the above, it was shown that it is possible to prevent over-inflation by irradiating light from inside the balloon and detecting backscattered light from the blood vessel. Example 2: Monitoring blood volume using photopenetration depth difference (1) Estimation of blood layer thickness Using the aortic occlusion balloon used in Example 1, blood flow monitoring will be performed using the difference in optical penetration length with 395 nm light (purple), 560 nm light (green), and 650 nm light (red).

[0045] The absorption coefficients of 395 nm light (violet), 560 nm light (green) and 650 nm light (red) are 44.5 mm -1 , 12.5 mm -1 and 0.9 mm -1 , respectively. The smaller the absorption coefficient, the harder the light is absorbed by blood, so the light penetration depth becomes longer.

[0046] Figures 5 and 6 show the intensity of backscattered light of each wavelength (unit: AU, Arbitrary Unit) and the balloon diameter against the time from the start of inflation (horizontal axis) in the case of using 560 nm light (green) and 650 nm light (red) (Figure 5) and in the case of using 395 nm light (violet) and 560 nm light (green) (Figure 6). Measurement is performed until after deflation.

[0047] In each measurement, the difference in the diameter of the balloon when each of the two colors of light in the respective measurement reaches 70% of the maximum backscattered light intensity is, with 560 nm light (green) as a reference, 0.79 mm when 560 nm light (green) and 650 nm light (red) are used (the diameter for red is larger), and -1.2 mm when 395 nm light (violet) and 560 nm light (green) are used (the diameter for violet is smaller). In Figures 5 and 6, the portions enclosed by ellipses include the state where the light intensity reaches 70% of the maximum backscattered light intensity.

[0048] An aortic occlusion balloon in a blood vessel is expanded, the backscattered light intensity when using light of each wavelength is measured during the expansion process, and 70% of the maximum backscattered light intensity of the light of each wavelength is used as a threshold to determine whether the measured value when using light of each wavelength exceeds the threshold.

[0049] Figure 7 shows whether the backscattered light measured using 395nm light (purple), 560nm light (green), and 650nm light (red) exceeded the threshold (indicated by "○") or did not exceed the threshold (indicated by "×") when the blood layer thickness ranged from large to small. The schematic diagram in Figure 7 shows the state in which a balloon is inserted into a blood vessel, with the left side showing a large blood layer thickness and the right side showing a small blood layer thickness. A small blood layer thickness indicates that the balloon is greatly expanded and the blood flow rate is low, while a large blood layer thickness indicates that the balloon is greatly expanded and the blood flow rate is high. In Figure 7, the blood layer thickness is shown in four stages (1 to 4) from large to small. When the blood layer thickness is 1, the backscattered light intensity is small and does not exceed the threshold because all of the 395nm light (purple), 560nm light (green), and 650nm light (red) are easily absorbed by substances in the blood. When the blood layer thickness is 2, 650nm light (red), which has a long penetration length, is not easily absorbed by substances in the blood, so the backscattered light intensity exceeds the threshold. However, 395nm light (violet) and 560nm light (green), which do not have as long a penetration length as 650nm light (red), are easily absorbed by substances in the blood, so the backscattered light intensity is small and does not exceed the threshold. When the blood layer thickness is 3, 650nm light (red) and 560nm light (green), which have long penetration lengths, are not easily absorbed by substances in the blood, so the backscattered light intensity exceeds the threshold. However, 395nm light (purple), which has a penetration length, is easily absorbed by substances in the blood, so the backscattered light intensity is small and exceeds the threshold. When the blood vessel layer thickness is 4, 395nm light (purple), 560nm light (green), and 650nm light (red) are all not easily absorbed by substances in the blood, so the backscattered light intensity is large and exceeds the threshold. In each measurement, the blood layer thickness can be estimated from the threshold determination pattern of whether or not the light of each wavelength exceeded the threshold. When the blood layer thickness is 1, 2, 3, and 4, the blood layer thickness can be estimated to be >1mm, 0.3~1mm, 0.1~0.3mm, and <0.1mm, respectively. (2) Optical measurement of blood flow velocity Figure 8 shows an overview of the method for measuring blood flow velocity using light. When measuring blood flow velocity using light, the balloon has a lumen structure that allows saline solution to be flushed from its tip (Figure 8A). Even if saline solution is flushed without changing the balloon's expansion state, the blood around the balloon is temporarily removed, and the backscattered light intensity changes (Figure 8B). Depending on the blood flow velocity, the time required for the saline solution around the balloon to be flushed away (Figures 8C-1 and 8C-2) and for the backscattered light to return to its original value differs. The blood flow velocity (m / s) can be estimated from the return speed of the backscattered light. Figure 8C-1 shows how saline solution is flushed away when the blood flow is slow, and Figure 8C-2 shows how saline solution is flushed away when the blood flow is fast. (3) Measurement of blood flow Blood flow can be calculated using the following formula. Blood flow [m 3 / s]=blood layer cross-sectional area [m 2 ]×Blood velocity [m / s] Blood layer cross-sectional area={(dB / 2+d) 2 -(dB / 2) 2}π [m 2 ] dB[m]: Balloon diameter (calculated from the amount of liquid injected into the balloon) d[m]: Estimated blood layer thickness Figure 9 shows a cross-sectional view of a blood vessel with a balloon inserted, as well as the balloon and the thickness of the blood layer. Example 3: Investigation of an algorithm for estimating blood layer thickness from backscattered light intensity (1) Changes in backscattered light intensity in the aorta of a pig in vivo Similar to Example 1, the backscattered light was measured using a trans-balloon backscattered light intensity measurement system when irradiated with light at a wavelength of 560 nm (green) and light at a wavelength of 650 nm (red). The balloon was expanded at a constant speed.

[0050] The results are shown in Figure 10. As shown in Figure 10, the backscattered light intensity changes with balloon expansion, and differences in the timing of the large change were observed depending on the wavelength. (2) Examination of an algorithm for estimating blood layer thickness from backscattered light intensity We investigated the construction of an algorithm to estimate the blood layer thickness from the backscatter light intensity data obtained from the measurement in (1). By expanding the balloon at a constant speed, the balloon diameter (blood layer thickness) can be calculated from the time after the start of expansion.

[0051] A function represented by the equation below was defined, and the coefficient α was optimized by fitting it using data on the elapsed time from the start of balloon expansion when backscattered light was detected and the backscattered light intensity. TIFF0007913774000005.tif63111

[0052] (a) Fitting in the range of backscatter light intensity 0 to 0.5 Using the data shown in Figure 10, fitting was performed in the range of backscatter light intensity from 0 to 0.5. The coefficient of determination was 0.98 for light with a wavelength of 650 nm (red) and 0.92 for light with a wavelength of 560 nm (green).

[0053] Using the data shown in Figure 10, fitting was performed in the range of backscatter light intensity from 0 to 1.0. The coefficient of determination was 0.79 for light with a wavelength of 650 nm (red) and 0.91 for light with a wavelength of 560 nm (green).

[0054] The coefficient of determination is a value that indicates the accuracy of the fitting, and the closer it is to 1, the higher the accuracy. The results in (a) and (b) above indicate that it is preferable to estimate the blood layer thickness based on data obtained mainly using light with a wavelength of 560 nm (green), and that in the range of backscatter light intensity of 0 to 0.5, the blood layer thickness can be estimated with higher accuracy by using data obtained using light with a wavelength of 650 nm (red) in combination.

[0055] Using the coefficients obtained through optimization, the elapsed time after the start of expansion can be calculated by substituting the backscatter light intensity obtained by irradiating with light of wavelength 560 nm (green) or light of wavelength 650 nm into equation (1) above. From the obtained elapsed time after the start of expansion, the balloon diameter can be determined, and the blood layer thickness can be calculated using the following equation [blood layer thickness = blood vessel diameter (inner diameter) - balloon diameter]. Note that the balloon diameter can be determined from the time after the start of expansion based on measured values. [Industrial applicability]

[0056] By using the device including the balloon catheter of the present invention, blood flow during aortic occlusion can be monitored.

[0057] All publications, patents, and patent applications cited herein shall be incorporated herein by direct reference. [Explanation of Symbols]

[0058] 1 Balloon 2 Catheter 3. Pig aorta 4 Scattered light 5 Syringes 6 Fiber optic port 7. Diffuse optical fiber (diffuser length: 70 mm, core diameter: 250 μmΦ) 8 irradiation 9 Light Reception 10 LED 11 Plano-convex lens 12 Fiber Folders 13. 2-branch bundled fiber (core diameter: 100 μmΦ each) 14. Silicon photodiode 15 AD converters 16. For measuring incident light 17 Blood exclusion part 18 blood 19 Lumen Structure 20 Physiological saline 21 Blood flow 22 Blood layer thickness 23 Blood vessel wall

Claims

1. A catheter tube and a balloon catheter having a balloon provided at the tip of the catheter tube, The optical fiber housed inside the catheter tube, A light irradiation area and a light detection area for detecting irradiated light, which are arranged inside the balloon and connected to the optical fiber, The light source that generates the light to be irradiated, A balloon catheter equipped with, By irradiating a balloon with light of a wavelength absorbable by substances present in the blood, detecting scattered light from within the blood vessel, and monitoring the blood flow between the balloon and the blood vessel wall over time based on the intensity of the detected light, and adjusting the balloon diameter using the monitored blood flow as an indicator, it is possible to prevent obstruction of blood flow. A balloon catheter that calculates the thickness of the blood layer between the balloon and the blood vessel wall from the intensity of the detected light.

2. The balloon catheter according to claim 1, further comprising a calculation unit that determines the presence or absence of blood flow based on the intensity of scattered light.

3. The balloon catheter according to claim 1, further comprising a display unit for displaying the blood flow state analyzed by the calculation unit.

4. The balloon catheter according to claim 1, wherein the wavelength of the light irradiated is 400 to 500 nm.

5. A balloon catheter having a catheter tube and a balloon provided at the tip of the catheter tube, The optical fiber housed inside the catheter tube, A light irradiation area and a light detection area for detecting irradiated light, which are arranged inside the balloon and connected to the optical fiber, The light source that generates the light to be irradiated, Equipped with, A balloon catheter that irradiates a balloon with multiple wavelengths of light having different penetration depths, which are absorbable by substances present in the blood, detects scattered light from within the blood vessels for each wavelength, and monitors the blood flow between the balloon and the blood vessel wall from the intensity of the scattered light for each wavelength, and prevents blood flow obstruction by adjusting the balloon diameter using the monitored blood flow as an indicator.

6. Define a function represented by equation (1) or (2) below, and perform fitting using data on the elapsed time from the start of balloon expansion and the backscattered light intensity when backscattered light is detected, to determine the coefficients. or Using the calculated coefficients, the elapsed time after the start of expansion is calculated by substituting the backscatter light intensity detected after irradiation with light of wavelength 560 nm (green) or light of wavelength 650 nm into equation (1) or (2) above. The balloon diameter is estimated from the time obtained after the start of expansion. The balloon catheter according to claim 5, wherein the blood layer thickness is calculated using the following formula [blood layer thickness = blood vessel diameter (inner diameter) - balloon diameter].

7. The balloon catheter according to claim 5, wherein the light with different light penetration lengths is two, three, four, five, or six types of light with wavelengths of near-infrared light, infrared light, light of 380-430 nm (violet), light of 430-490 nm (blue), light of 490-550 nm (green), light of 550-590 nm (yellow), light of 590-640 nm (orange), and light of 640-770 nm (red).

8. The balloon catheter according to claim 5, wherein the light with different penetration lengths is at least two of the following: light with wavelengths of 475 nm, 542 nm, and 438 nm.

9. The balloon catheter according to claim 5, wherein the light with different penetration lengths is of two types: green light and red light.

10. The balloon catheter according to claim 5, wherein the light with different penetration lengths is of two types: green light with a wavelength of 560 nm and red light with a wavelength of 650 nm.

11. A balloon catheter according to any one of claims 1 to 10, wherein scattered light is detected at the rear.

12. The balloon catheter according to any one of claims 1 to 10, wherein the catheter is a vascular occlusion or aortic occlusion catheter.

13. The balloon catheter according to claim 11, wherein the catheter is a vascular occlusion or aortic occlusion catheter.

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