WO2022254064A1 - Device for monitoring the perfusion status of skin flaps - Google Patents

Device for monitoring the perfusion status of skin flaps Download PDF

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Publication number
WO2022254064A1
WO2022254064A1 PCT/ES2022/070324 ES2022070324W WO2022254064A1 WO 2022254064 A1 WO2022254064 A1 WO 2022254064A1 ES 2022070324 W ES2022070324 W ES 2022070324W WO 2022254064 A1 WO2022254064 A1 WO 2022254064A1
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WIPO (PCT)
Prior art keywords
light sources
tissue
light
detector
interest
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PCT/ES2022/070324
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Spanish (es)
French (fr)
Inventor
Pedro MARTÍN MATEOS
Pablo Acedo Gallardo
José Luis JORCANO NOVAL
Luis DÍAZ OJEDA
Jorge BONASTRE JULIÁ
José Ramón MARTÍNEZ MÉNDEZ
Carlota Largo Aramburu
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Universidad Carlos Iii De Madrid
Fundación Para La Investigación Biomédica Del Hospital Universitario La Paz
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Publication of WO2022254064A1 publication Critical patent/WO2022254064A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/0265—Measuring blood flow using electromagnetic means, e.g. electromagnetic flowmeter
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/40—Grinding-materials

Definitions

  • Free flaps are complex surgical tools that are the last reconstructive step for many defects after cancer or trauma.
  • Vascular failure is the most frequent and serious complication, and it can lead to total loss of the flap.
  • the diagnosis of this failure is sometimes complex or is performed too late, preventing surgery to save the flap.
  • the device for monitoring the state of perfusion of skin flaps makes it possible to quantitatively determine the perfusion of a tissue of interest, particularly a flap, in both absolute and relative terms (when compared to tissue from the same patient) regardless of oxygen saturation and in a safe manner.
  • the device is based on the absorption of light in Diffuse Reflectance Spectroscopy (DRS), that is, on the analysis of light that is not specularly reflected, but has penetrated the tissue and, therefore, has information about it.
  • DRS Diffuse Reflectance Spectroscopy
  • the device of the invention uses a narrow-bandwidth, multi-source approach.
  • the device comprises a set of light sources, preferably three LEDs (light emitting diodes), with wavelengths in the visible range (approximately 400 to 700 nm).
  • the light sources can be laser, white filtered source or others.
  • the device also achieves good results when two light sources are used, one of which works as a reference.
  • the light from the LEDs is coupled to an optical fiber and led to a collimator to illuminate the tissue surface of interest.
  • Tissue illumination can be carried out with the device at a certain distance (non-contact operation), or with the device directly attached to the tissue (contact operation).
  • a detector captures light (diffuse reflectance) escaping from the tissue for analysis.
  • the device comprises, when it operates without contact, crossed polarizers, which filter the light that escapes from the tissue. Its bottom is to filter the direct reflection on the tissue, in this way, the light that reaches the detector does not come from the first layers, but has traveled through the interior of the tissue of interest.
  • crossed polarizers are positioned just after the collimator and before the detector.
  • the device works without fiber optics and without a collimator.
  • the device comprises two or more light sources intended to illuminate the tissue of interest, using a certain predetermined wavelength, in the visible range.
  • the device also includes a detector, associated with the light sources, and intended to capture diffuse light reflected by tissue. interest, the detector comprising demodulators tuned to the light sources.
  • the device comprises a control module connected to the light sources and the detector.
  • each light source is modulated at a certain frequency (in the visible spectrum) so that it is possible, with a single detector, to measure all of them simultaneously using several amplitude demodulators, arranged in the detector, and synchronized with said sources. modulation frequencies. Likewise, it is possible to multiplex the lighting times of the light sources, so that the emission is carried out sequentially.
  • simultaneous spectral interrogation is allowed through the use of frequency modulation, or time modulation, multiplexing, and phase sensitive detection.
  • the intensity detected for each wavelength is subsequently recovered and used in the calculations used to estimate the perfusion state of the tissue of interest analyzed.
  • the device and particularly the collimator and detector, can be arranged to both contact up to several centimeters from the tissue of interest.
  • the emission of light and analysis can be carried out both in very short times (one second of emission is more than enough), and in continuous measurements over time, to perform tissue monitoring.
  • This device which is based on optical spectroscopy, would, for the first time, make available to clinical staff a device specifically designed for flap analysis, which would be capable of providing an absolute or relative measure of their perfusion status, their viability, and potential problems.
  • Figure 1. Shows a schematic view of the device for monitoring the state of perfusion of skin flaps in a fiber optic embodiment.
  • Figure 2. Shows two graphs with the experimental results obtained when a vein is obstructed.
  • Figure 3. Shows a graph with the spectral responses of the tissue to different problems with the flap.
  • Figure 4.- Shows a schematic view of the device for monitoring the state of perfusion of skin flaps in an embodiment without fiber optics.
  • the device which is shown in a first embodiment in a schematic representation in figure 1, comprises a control module (6) to which a set of LED sources (1) is connected, specifically four in figure 1, which emit a Light at a preset wavelength, in the visible spectrum.
  • a control module (6) to which a set of LED sources (1) is connected, specifically four in figure 1, which emit a Light at a preset wavelength, in the visible spectrum.
  • current sources (5) are arranged between each of the LEDs (1) and the control module (6), configured to control the current. .
  • the light from the LEDs (1) is coupled to an optical fiber (9) and is taken to a collimator (3) in which a beam of light is generated to illuminate a surface area of approximately 30mm z of tissue (2). of interest.
  • the device, and more specifically the collimator (3) can be attached to the tissue (2) or a few centimeters from it, thus making it possible to operate the device both remotely and with contact.
  • a diffused light beam escapes from the tissue (2), which is collected in a large-area silicon or germanium detector (4) for analysis.
  • the diffused light beam collected in the detector (4) is taken to a transimpedance amplifier (7), which in turn is connected to the control module (6).
  • the control module (6) itself can comprise a microcontroller configured to carry out the analysis and interpretation of the data collected, thus being the device completely autonomous, and/or may be intended to be connected to an external device (8), to which the data is sent.
  • the device in the event that the device is operated without contact, it comprises a set of two crossed polarizers (not represented in figure 1 ), which are positioned just after the emitter and before the detector. In the event that the device is operated with contact, these polarizers are not necessary.
  • the device comprises light sources (1), in which each light source (1) is configured to emit at a length of different wave in the visible range, a detector (4) associated with the light sources (1) and intended to capture diffuse light reflected by the tissue of interest (2), the detector (4) comprising demodulators tuned to the sources light (1), and a control module (6) connected to the light sources (1) and the detector (4).
  • any of the two embodiments of the invention described above can use two or more light sources (1), the preferred embodiment of the invention being the one in which the device comprises three light sources (1).
  • the light sources (1) use certain wavelengths for identification. Thus, it is possible to identify obstructions either in the artery or in the vein that connect the flap with the patient's circulatory system, thus determining the viability of the graft.
  • Figure 3 shows the results of a test in which a spectrometer and a white light source (covering the entire visible range) were used to illuminate a certain area of the flap.
  • Figure 3 reflects the most relevant results, showing the absorption spectrum of the tissue normalized to an initial state in which the flap had normal blood flow. In this way, and as long as the flap maintains normal blood circulation, the spectrum remains the same, so that normalization would give rise to values that would be around 1. However, an obstruction in the vein causes the blood level to increase and the oxygenation of the blood to drop. This translates into an increase in the total absorption level that reduces the signal obtained in the spectrum (dashed line trace clearly below 1). In addition, the greater amount of hemoglobin causes the characteristic ripples to appear between 400 and 470 nm.
  • a blockage of the artery produces a decrease in the blood level, which reduces absorption and therefore increases the signal level (continuous line trace above 1) and an increase in deoxygenated hemoglobin that produces , again, the ripple in the spectrum between 400 and 470 nm.
  • light sources (1) operating in the wavelength ranges of 425-460 nm (preferably 440 nm), 450-490 nm (preferably 470nm) and 630-690nm (preferably 660 nm). , the latter being used as a reference, since it does not vary when veins or arteries are blocked.
  • a first one, used as a reference would work in the 630-690nm range, and a second would work in either of the two 425-460nm or 450-490 ranges. .
  • each of them works in one of the indicated ranges.
  • at least one must work in the reference range of 630-690 nm and the rest can work in any of the other two ranges.
  • the processing of the collected data in its simplest implementation, can consist of calculating the ratio between the optical intensities detected at the 400 nm and 600 nm wavelengths. Said ratio (or ratios) will see its value increased in the event of an arterial obstruction appearing or decreased in the event of an obstruction appearing in a vein.
  • the use of spectral classification techniques contributes to improve the performance of the device.
  • the device comprises three LEDs (1), which work at wavelengths in the visible range, the optimum being those around 440, 470 and 660 nm.
  • the optimum being those around 440, 470 and 660 nm.
  • an animal model is used, in which vein and artery obstructions are simulated while their spectrum is measured throughout the visible range. The intensity reflected at these specific wavelengths is the one that best allows monitoring of tissue perfusion status (2).

Abstract

An optical diagnostic device enabling the non-invasive monitoring of the perfusion status of skin flaps, comprising for this purpose: an optical fibre (9); three or more light sources (1), each light source (1) being configured to emit at a different wavelength in the visible range, the light sources (1) being coupled to the optical fibre (9); a collimator (3) coupled to the optical fibre (9) at an opposite end to the light sources (1), intended to illuminate the surface of a tissue of interest (2); a detector (4) associated with the collimator (3) and intended to capture a light reflected by the tissue of interest (2), said detector comprising one demodulator for each light source (1); and a control module (6) connected to the light sources (1).

Description

DISPOSITIVO DE MONITORIZACIÓN DEL ESTADO DE PERFUSIÓN DE COLGAJOS DE PIEL DEVICE FOR MONITORING THE PERFUSION STATUS OF SKIN FLAPS
DESCRIPCIÓNDESCRIPTION
OBJETO DE LA INVENCIÓN OBJECT OF THE INVENTION
Se trata de un dispositivo de diagnóstico óptico que permite monitorizar el estado de la perfusión en colgajos de piel de forma no invasiva. It is an optical diagnostic device that allows non-invasive monitoring of the state of perfusion in skin flaps.
ANTECEDENTES DE LA INVENCIÓN BACKGROUND OF THE INVENTION
Los colgajos libres son herramientas quirúrgicas complejas que constituyen el último paso reconstructivo para muchos defectos tras un cáncer o un traumatismo. El fallo vascular es la complicación más frecuente y grave, y puede llevar a la pérdida total del colgajo. El diagnóstico de este fallo es a veces complejo o se realiza demasiado tarde, impidiendo una cirugía que permita salvar el colgajo. Free flaps are complex surgical tools that are the last reconstructive step for many defects after cancer or trauma. Vascular failure is the most frequent and serious complication, and it can lead to total loss of the flap. The diagnosis of this failure is sometimes complex or is performed too late, preventing surgery to save the flap.
Por lo tanto, un conocimiento preciso en tiempo real del estado de perfusión (paso de un fluido, a través del sistema circulatorio o el sistema linfático, a un órgano o un tejido, normalmente refiriéndose al traspaso capilar de sangre a los tejidos) de los colgajos libres, tanto durante la cirugía como en el período postoperatorio, es de suma importancia para garantizar la viabilidad de los colgajos. Therefore, a precise knowledge in real time of the state of perfusion (passage of a fluid, through the circulatory system or the lymphatic system, to an organ or a tissue, normally referring to the capillary transfer of blood to the tissues) of the free flaps, both during surgery and in the postoperative period, is of paramount importance to guarantee the viability of the flaps.
A día de hoy no existe ningún sistema específico que permita la medida del estado real de perfusión de colgajos de manera precisa, cómoda y eficaz. To date, there is no specific system that allows the measurement of the actual state of flap perfusion in a precise, comfortable, and efficient manner.
DESCRIPCIÓN DE LA INVENCIÓN DESCRIPTION OF THE INVENTION
El dispositivo de monitorización del estado de perfusión de colgajos de la piel, objeto de la presente invención, permite determinar de forma cuantitativa la perfusión de un tejido de interés, particularmente un colgajo, en términos tanto absolutos como relativos (cuando se compara con el tejido sano de un mismo paciente) con independencia de la saturación de oxígeno y de forma inocua. The device for monitoring the state of perfusion of skin flaps, object of the present invention, makes it possible to quantitatively determine the perfusion of a tissue of interest, particularly a flap, in both absolute and relative terms (when compared to tissue from the same patient) regardless of oxygen saturation and in a safe manner.
El dispositivo se basa en la absorción de luz en Espectroscopia de Reflectancia Difusa (DRS, Diffuse Reflectance Spectroscopy), es decir, en el análisis de la luz que no es reflejada especularmente, sino que ha penetrado en el tejido y, por lo tanto, posee informadón del mismo. The device is based on the absorption of light in Diffuse Reflectance Spectroscopy (DRS), that is, on the analysis of light that is not specularly reflected, but has penetrated the tissue and, therefore, has information about it.
Cuando se inyecta luz en el tejido, los fotones, al interactuar con los componentes del medio, no sólo sufren eventos de dispersión, sino que también son absorbidos. Muchos de los analitos de interés en los tejidos comunes, como es el caso de la hemoglobina, presentan respuestas espectrales muy específicas en su interacción con la luz. Por lo tanto, esto permite la estimación de la concentración de estos analitos a través del análisis de la luz que emerge del tejido. When light is injected into the tissue, the photons, when interacting with the components of the medium, not only undergo scattering events, but are also absorbed. Many of the analytes of interest in common tissues, such as hemoglobin, exhibit highly specific spectral responses when interacting with light. Therefore, this allows the estimation of the concentration of these analytes through the analysis of the light emerging from the tissue.
Aunque se pueden emplear varias estrategias de interrogadón espectral, el dispositivo de la invendón utiliza un enfoque de fuentes múltiples de ancho de banda estrecho. Particularmente, el dispositivo comprende un conjunto de foentes de luz, preferentemente tres LEDs (diodos emisores de luz), con unas longitudes de onda en el rango visible (aproximadamente entre 400 hasta 700 nm). Alternativamente, las foentes de luz pueden ser láser, foente blanca con filtro u otras. El dispositivo también obtiene buenos resultados cuando se utilizan dos foentes de luz, en la que una trabaja como referenda. Although various spectral interrogation strategies can be employed, the device of the invention uses a narrow-bandwidth, multi-source approach. Particularly, the device comprises a set of light sources, preferably three LEDs (light emitting diodes), with wavelengths in the visible range (approximately 400 to 700 nm). Alternatively, the light sources can be laser, white filtered source or others. The device also achieves good results when two light sources are used, one of which works as a reference.
En un primer aspecto de la invendón, la luz de los LED se acopla a una fibra óptica y se lleva a un colimador para ¡luminar la superfide del tejido de interés. La iluminadón del tejido se puede llevar a cabo con el dispositivo a una certa distanda (operadón sin contacto), o con el dispositivo directamente pegado al tejido (operación con contacto). Un detector capta la luz (reflectanda difusa) que escapa del tejido para su análisis. In a first aspect of the invention, the light from the LEDs is coupled to an optical fiber and led to a collimator to illuminate the tissue surface of interest. Tissue illumination can be carried out with the device at a certain distance (non-contact operation), or with the device directly attached to the tissue (contact operation). A detector captures light (diffuse reflectance) escaping from the tissue for analysis.
Además de esto, y para minimizar la contribución de la alta reflectanda en las primeras capas del tejido, en un aspecto de la invendón el dispositivo comprende, cuando opera sin contacto, unos polarizadores cruzados, que filtran la luz que escapa del tejido. Su fondón es filtrar la reflexión directa sobre el tejido, de esta forma, la luz que llega al detector no proviene de las primeras capas, sino que ha viajado por el interior del tejido de interés. Los polarizadores se posidonan justo después del colimador y antes del detector. In addition to this, and in order to minimize the contribution of the high reflectance in the first layers of the tissue, in one aspect of the invention the device comprises, when it operates without contact, crossed polarizers, which filter the light that escapes from the tissue. Its bottom is to filter the direct reflection on the tissue, in this way, the light that reaches the detector does not come from the first layers, but has traveled through the interior of the tissue of interest. The polarizers are positioned just after the collimator and before the detector.
Alternativamente, en un segundo aspecto de la invendón, el dispositivo trabaja sin fibra óptica y sin colimador. Es dedr, el dispositivo comprende unas foentes de luz, dos o más, destinadas a iluminar el tejido de interés, empleando una derla longitud de onda predeterminada, en el rango visible. El dispositivo comprende además un detector, asodado a las fuentes de luz, y destinado a captar una luz difosa reflejada por el tejido de interés, comprendiendo el detector unos demoduladores sintonizados con las fuentes de luz. Finalmente, el dispositivo comprende un módulo de control conectado a las fuentes de luz y al detector. Alternatively, in a second aspect of the invention, the device works without fiber optics and without a collimator. In other words, the device comprises two or more light sources intended to illuminate the tissue of interest, using a certain predetermined wavelength, in the visible range. The device also includes a detector, associated with the light sources, and intended to capture diffuse light reflected by tissue. interest, the detector comprising demodulators tuned to the light sources. Finally, the device comprises a control module connected to the light sources and the detector.
La intensidad de cada fuente de luz está modulada a una cierta frecuencia (en el espectro visible) de forma que se puede, con un único detector, medirlas todas de forma simultánea utilizando varios demoduladores de amplitud, dispuestos en el detector, y sincronizados con dichas frecuencias de modulación. Así mismo, es posible multiplexer los tiempos de encendido de las fuentes de luz, de manera que la emisión se realiza de forma secuencial. The intensity of each light source is modulated at a certain frequency (in the visible spectrum) so that it is possible, with a single detector, to measure all of them simultaneously using several amplitude demodulators, arranged in the detector, and synchronized with said sources. modulation frequencies. Likewise, it is possible to multiplex the lighting times of the light sources, so that the emission is carried out sequentially.
Así, se permite la interrogación espectral simultánea mediante el uso de la multiplexación por modulación de frecuencia, o de tiempo, y detección sensible a la fase. La intensidad detectada para cada longitud de onda es, posteriormente, recuperada y se emplea en los cálculos que se utilizan para estimar el estado de perfusión del tejido de interés analizado. Thus, simultaneous spectral interrogation is allowed through the use of frequency modulation, or time modulation, multiplexing, and phase sensitive detection. The intensity detected for each wavelength is subsequently recovered and used in the calculations used to estimate the perfusion state of the tissue of interest analyzed.
El dispositivo, y particularmente el colimador y el detector, pueden disponerse tanto en contacto hasta a varios centímetros del tejido de interés. Además, se puede realizar la emisión de luz y análisis tanto en tiempos muy cortos (un segundo de emisión es más que suficiente), como en medidas continuadas en el tiempo, para realizar una monitorizadón del tejido. The device, and particularly the collimator and detector, can be arranged to both contact up to several centimeters from the tissue of interest. In addition, the emission of light and analysis can be carried out both in very short times (one second of emission is more than enough), and in continuous measurements over time, to perform tissue monitoring.
Este dispositivo, que está basado en espectroscopia óptica pondría, por primera vez, a disposición del personal clínico un aparato específicamente diseñado para el análisis de colgajos, que sería capaz de proporcionar una medida absoluta o relativa del estado de la perfusión los mismos, de su vialidad, y de potenciales problemas. This device, which is based on optical spectroscopy, would, for the first time, make available to clinical staff a device specifically designed for flap analysis, which would be capable of providing an absolute or relative measure of their perfusion status, their viability, and potential problems.
DESCRIPCIÓN DE LOS DIBUJOS DESCRIPTION OF THE DRAWINGS
Para complementar la descripción que se está realizando y con objeto de ayudar a una mejor comprensión de las características de la invención, de acuerdo con un ejemplo preferente de realización práctica de la misma, se acompaña como parte integrante de dicha descripción, un juego de dibujos en donde con carácter ilustrativo y no limitativo, se ha representado lo siguiente: Figura 1.- Muestra una vista esquemática del dispositivo de monitorizadón del estado de perfusión de colgajos de piel en una realizadón con fibra óptica. To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of its practical embodiment, a set of drawings is attached as an integral part of said description. where, with an illustrative and non-limiting nature, the following has been represented: Figure 1.- Shows a schematic view of the device for monitoring the state of perfusion of skin flaps in a fiber optic embodiment.
Figura 2.- Muestra dos gráficos con los resultados experimentales obtenidos cuando se obstruye una vena. Figure 2.- Shows two graphs with the experimental results obtained when a vein is obstructed.
Figura 3.- Muestra un gráfico con las respuestas espectrales del tejido ante distintos problemas con el colgajo. Figure 3.- Shows a graph with the spectral responses of the tissue to different problems with the flap.
Figura 4.- Muestra una vista esquemática del dispositivo de monitorizadón del estado de perfusión de colgajos de piel en una realizadón sin fibra óptica. Figure 4.- Shows a schematic view of the device for monitoring the state of perfusion of skin flaps in an embodiment without fiber optics.
REALIZACIÓN PREFERENTE DE LA INVENCIÓN PREFERRED EMBODIMENT OF THE INVENTION
Se describe a continuación, con ayuda de las figuras 1 a 4, una realizadón preferente del dispositivo de monitorizadón del estado de perfusión de colgajos de piel. A preferred embodiment of the device for monitoring the state of perfusion of skin flaps is described below with the help of figures 1 to 4.
El dispositivo, que se muestra en una primera realizadón en una representadón esquemática en la figura 1, comprende un módulo de control (6) al que se conecta un conjunto de fuentes LED (1), concretamente cuatro en la figura 1, que emiten una luz a una longitud de onda preestabledda, en el espectro visible. Con el objetivo de modular la intensidad que llega a los LEDs (1) se disponen unas fuentes de corriente (5) entre cada uno de los LEDs (1) y el módulo de control (6), configurado para realizar el control de la corriente. The device, which is shown in a first embodiment in a schematic representation in figure 1, comprises a control module (6) to which a set of LED sources (1) is connected, specifically four in figure 1, which emit a Light at a preset wavelength, in the visible spectrum. In order to modulate the intensity that reaches the LEDs (1), current sources (5) are arranged between each of the LEDs (1) and the control module (6), configured to control the current. .
La luz de los LED (1) se acopla a una fibra óptica (9) y se lleva a un colimador (3) en el que se genera un haz de luz destinado a iluminar una superfide de aproximadamente 30mmzdel un tejido (2) de interés. El dispositivo, y más concretamente el colimador (3), puede estar pegado al tejido (2) o unos centímetros de este, pudiéndose por tanto operar el dispositivo tanto a distanda como con contacto. The light from the LEDs (1) is coupled to an optical fiber (9) and is taken to a collimator (3) in which a beam of light is generated to illuminate a surface area of approximately 30mm z of tissue (2). of interest. The device, and more specifically the collimator (3), can be attached to the tissue (2) or a few centimeters from it, thus making it possible to operate the device both remotely and with contact.
Como se muestra en la figura 1, del tejido (2) escapa un haz de luz difusa, que es recogido en un detector (4) de silicio o germanio de gran superficie para su análisis. El haz de luz difusa recogida en el detector (4) se lleva a un amplificador de transimpedanda (7), y que a su vez está conectado con el módulo de control (6). El propio módulo de control (6) puede comprender un microcontrolador configurado para llevar a cabo el análisis e interpretación de los datos recogidos, siendo así el dispositivo completamente autónomo, y/o puede estar destinado a conectarse a un dispositivo extemo (8), al que se envían los datos. As shown in Figure 1, a diffused light beam escapes from the tissue (2), which is collected in a large-area silicon or germanium detector (4) for analysis. The diffused light beam collected in the detector (4) is taken to a transimpedance amplifier (7), which in turn is connected to the control module (6). The control module (6) itself can comprise a microcontroller configured to carry out the analysis and interpretation of the data collected, thus being the device completely autonomous, and/or may be intended to be connected to an external device (8), to which the data is sent.
Además de esto, y para minimizar la contribución de la alta reflectancia en las primeras capas del tejido (2), en el caso de que el dispositivo se opere sin contacto, este comprende un conjunto de dos polarizadores cruzados (no representados en la figura 1), que se posidonan justo después del emisor y antes del detector. En el caso de que el dispositivo se opere con contacto, estos polarizadores no son necesarios. In addition to this, and to minimize the contribution of the high reflectance in the first layers of the fabric (2), in the event that the device is operated without contact, it comprises a set of two crossed polarizers (not represented in figure 1 ), which are positioned just after the emitter and before the detector. In the event that the device is operated with contact, these polarizers are not necessary.
En una segunda realización de la invención, mostrada en la figura 4 y más sencilla que la primera realización, el dispositivo comprende unas fuentes de luz (1), en el que cada fuente de luz (1) está configurada para emitir a una longitud de onda diferente en el rango visible, un detector (4) asociado a las fuentes de luz (1) y destinado a captar una luz difusa reflejada por el tejido de interés (2), comprendiendo el detector (4) unos demoduladores sintonizados con las fuentes de luz (1), y un módulo de control (6) conectado a las fuentes de luz (1) y al detector (4). In a second embodiment of the invention, shown in figure 4 and simpler than the first embodiment, the device comprises light sources (1), in which each light source (1) is configured to emit at a length of different wave in the visible range, a detector (4) associated with the light sources (1) and intended to capture diffuse light reflected by the tissue of interest (2), the detector (4) comprising demodulators tuned to the sources light (1), and a control module (6) connected to the light sources (1) and the detector (4).
Cualquiera de las dos realizaciones de la invención descritas anteriormente puede emplear dos o más fuentes de luz (1), siendo la realización preferente de la invención aquella en la que el dispositivo comprende tres fuentes de luz (1). Any of the two embodiments of the invention described above can use two or more light sources (1), the preferred embodiment of the invention being the one in which the device comprises three light sources (1).
En el dispositivo de la presente invención, las fuentes de luz (1) utilizan unas ciertas longitudes de onda para la identificación. Así, se logran identificar obstrucciones bien en la arteria o bien en la vena que conectan el colgajo con el sistema circulatorio del paciente, determinando así la viabilidad del injerto. In the device of the present invention, the light sources (1) use certain wavelengths for identification. Thus, it is possible to identify obstructions either in the artery or in the vein that connect the flap with the patient's circulatory system, thus determining the viability of the graft.
En la figura 3 se muestran los resultados de una prueba en la que se utilizó un espectrómetro y una fuente de luz blanca (cubriendo en todo el rango visible) iluminando una cierta área del colgajo. Así, cuando se forzó una obstrucción en la vena, mediante pinzamiento, y en la arteria, pudieron medirse cambios en las respuestas espectrales del tejido asociados a cada condición. Figure 3 shows the results of a test in which a spectrometer and a white light source (covering the entire visible range) were used to illuminate a certain area of the flap. Thus, when an obstruction was forced in the vein, by clamping, and in the artery, changes in the spectral responses of the tissue associated with each condition could be measured.
La figura 3 refleja los resultados más relevantes, que muestran el espectro de absorción del tejido normalizado a un estado inicial en el que el colgajo tenía un flujo sanguíneo normal. De esta forma, y siempre que el colgajo mantenga una circulación sanguínea normal, el espectro se mantiene igual, por lo que la normalización daría lugar a valores que se situarían alrededor de 1. Sin embargo, una obstrucción en la vena produce que el nivel de sangre aumente y que la oxigenación de esta baje. Esto se traduce en un incremento del nivel total de absorción que reduce la señal obtenida en el espectro (traza en línea discontinua por debajo claramente de 1). Además, la mayor cantidad de hemoglobina hace que aparezcan los rizados característicos entre 400 y 470 nm. Figure 3 reflects the most relevant results, showing the absorption spectrum of the tissue normalized to an initial state in which the flap had normal blood flow. In this way, and as long as the flap maintains normal blood circulation, the spectrum remains the same, so that normalization would give rise to values that would be around 1. However, an obstruction in the vein causes the blood level to increase and the oxygenation of the blood to drop. This translates into an increase in the total absorption level that reduces the signal obtained in the spectrum (dashed line trace clearly below 1). In addition, the greater amount of hemoglobin causes the characteristic ripples to appear between 400 and 470 nm.
De igual manera, un bloqueo de la arteria produce un decremento del nivel de sangre, que reduce la absorción e incrementa, por lo tanto, el nivel de señal (traza en línea continua por encima de 1) y un incremento de hemoglobina desoxigenada que produce, de nuevo, el rizado en el espectro entre 400 y 470 nm. Estos dos efectos pueden medirse claramente con las fuentes de luz (1) que operan en franjas de longitud de onda de 425-460 nm (preferentemente 440 nm), 450-490 nm (preferentemente 470nm) y 630-690nm (preferentemente 660 nm), siendo este último utilizado como referencia, ya que no varía ante bloqueos de venas o arterias. Similarly, a blockage of the artery produces a decrease in the blood level, which reduces absorption and therefore increases the signal level (continuous line trace above 1) and an increase in deoxygenated hemoglobin that produces , again, the ripple in the spectrum between 400 and 470 nm. These two effects can be clearly measured with light sources (1) operating in the wavelength ranges of 425-460 nm (preferably 440 nm), 450-490 nm (preferably 470nm) and 630-690nm (preferably 660 nm). , the latter being used as a reference, since it does not vary when veins or arteries are blocked.
Por lo tanto, en el caso de utilizar dos fuentes de luz (1), una primera, empleada como referencia, trabajaría en el rango de 630-690nm, y una segunda trabajaría en cualquiera de los dos rangos 425-460nm o 450-490. Alternativamente, en el caso de que se utilicen tres fuentes de luz (1), cada una de ellas trabaja en uno de los rangos indicados. En el caso de que se utilicen más fuentes de luz (1), al menos una debe trabajar en el rango de referencia de 630-690 nm y el resto puede hacerlo en cualquiera de los otros dos rangos. Therefore, in the case of using two light sources (1), a first one, used as a reference, would work in the 630-690nm range, and a second would work in either of the two 425-460nm or 450-490 ranges. . Alternatively, in the event that three light sources (1) are used, each of them works in one of the indicated ranges. In the event that more light sources (1) are used, at least one must work in the reference range of 630-690 nm and the rest can work in any of the other two ranges.
A la vista de lo anterior, el procesamiento de los datos recogidos, en su implementación más sencilla, puede consistir en el cálculo del ratio entre las intensidades ópticas detectadas a las longitudes de onda de 400 nm y a la de 600 nm. Dicho ratio (o ratios) verá su valor incrementado en el caso de aparecer una obstrucción arterial o decrementado en el caso de aparecer una obstrucción en una vena. La utilización de técnicas de clasificación espectral contribuye a mejorar las prestaciones del dispositivo. In view of the above, the processing of the collected data, in its simplest implementation, can consist of calculating the ratio between the optical intensities detected at the 400 nm and 600 nm wavelengths. Said ratio (or ratios) will see its value increased in the event of an arterial obstruction appearing or decreased in the event of an obstruction appearing in a vein. The use of spectral classification techniques contributes to improve the performance of the device.
En una realización preferente de la invención, el dispositivo comprende tres LEDs (1), que trabajan a unas longitudes de onda en el rango visible, siendo las óptimas las que están en el entorno de 440, 470 y 660 nm. Para la obtención de las longitudes de onda óptimas se utiliza un modelo animal, en el que se simulan obstrucciones de vena y arteria mientras que se mide su espectro en todo el rango visible. La intensidad reflejada a estas longitudes de onda concretas es la que mejor permite monitorizar el estado de perfusión del tejido (2). In a preferred embodiment of the invention, the device comprises three LEDs (1), which work at wavelengths in the visible range, the optimum being those around 440, 470 and 660 nm. To obtain optimal wavelengths, an animal model is used, in which vein and artery obstructions are simulated while their spectrum is measured throughout the visible range. The intensity reflected at these specific wavelengths is the one that best allows monitoring of tissue perfusion status (2).
Para validar experimentalmente el dispositivo presentado en la figura 1, se han realizado un conjunto de experimentos. En un ensayo preliminar, se utilizó una rata (jattus norvegicus) como modelo experimental. Se amputó el miembro posterior de la rata dejándola en continuidad a través de los vasos femorales (sólo arteria y vena femoral). Esto ha permitido reproducirlo que ocurre cuando falla la anastomosis arterial o venosa para evaluar el rendimiento del sensor. To experimentally validate the device presented in figure 1, a set of experiments have been carried out. In a preliminary test, a rat (jattus norvegicus) was used as an experimental model. The hindlimb of the rat was amputated, leaving it in continuity through the femoral vessels (only femoral artery and vein). This has made it possible to reproduce what happens when the arterial or venous anastomosis fails to evaluate the performance of the sensor.
Con una pinza vascular, se realiza una oclusión de inicio y fin conocidos de forma secuencia!. Del mismo modo, se realizaron ensayos de diferentes duraciones se realizaron ocluyendo la arteria, la vena y ambas al mismo tiempo. With a vascular clamp, an occlusion of known start and end is performed sequentially!. Similarly, trials of different durations were performed by occluding the artery, the vein, and both at the same time.
Los resultados de algunos de estos experimentos, en los que en particular se ocluye una vena, se muestran en la figura 2. Los dos marcadores mostrados en esta figura se han calculado directamente como la relación entre las intensidades óptica sostenidas a diferentes longitudes de onda. Mientras que el primer marcador está relacionado con la concentración de sangre en la zona de medición, el segundo proporciona una indicación de la saturación de oxígeno. The results of some of these experiments, in which a particular vein is occluded, are shown in Figure 2. The two markers shown in this figure have been calculated directly as the ratio of the sustained optical intensities at different wavelengths. While the first marker is related to the blood concentration in the measurement zone, the second provides an indication of oxygen saturation.
Estos resultados proporcionan una clara indicación del estado de perfusión de la extremidad posterior de la rata, ya que un aumento de la concentración sanguínea y una disminución de la saturación de oxígeno siguen a la oclusión de la vena. These results provide a clear indication of the perfusion status of the rat hindlimb, as an increase in blood concentration and a decrease in oxygen saturation follow vein occlusion.
De la misma manera, se produce una disminución repentina tanto de la concentración de sangre como de la saturación de oxígeno por el sistema cuando se aplica la pinza vascular a la arteria femoral. Similarly, a sudden decrease in both blood concentration and oxygen saturation throughout the system occurs when the vascular clamp is applied to the femoral artery.

Claims

REIVINDICACIONES
1.-Dispositivo de monitorizadón del estado de perfusión de colgajos de la piel, que comprende: 1.- Device for monitoring the perfusion status of skin flaps, comprising:
- dos o más fuentes de luz (1) destinadas a iluminar superficialmente un tejido de interés (2), en el que cada fuente de luz (1) está configurada para emitir a una longitud de onda diferente en el rango visible, - two or more light sources (1) intended to superficially illuminate a tissue of interest (2), in which each light source (1) is configured to emit a different wavelength in the visible range,
- un detector (4) asodado a las fuentes de luz (1), destinado a captar unas intensidades ópticas de una luz difusa reflejada por el tejido de interés (2), comprendiendo el detector (4) unos demoduladores sintonizados con las fuentes de luz (1), y - a detector (4) associated with the light sources (1), intended to capture optical intensities of diffuse light reflected by the tissue of interest (2), the detector (4) comprising demodulators tuned to the light sources (1), and
- un módulo de control (6) conectado a las fuentes de luz (1) y al detector (4), configurado para calcular un ratio entre las intensidades ópticas detectadas a las longitudes de onda emitidas por las fuentes de luz (1). - A control module (6) connected to the light sources (1) and to the detector (4), configured to calculate a ratio between the detected optical intensities at the wavelengths emitted by the light sources (1).
2.- El dispositivo de la reivindicación 1, que comprende adicionalmente: 2. The device of claim 1, further comprising:
- una fibra óptica (9), estando las dos o más fuentes de luz (1) acopladas a la fibra óptica (9), - an optical fiber (9), the two or more light sources (1) being coupled to the optical fiber (9),
- un colimador (3) acoplado a la fibra óptica (9) en un extremo opuesto a las fuentes de luz (1), destinado a iluminar superficialmente un tejido de interés (2), y estando el detector (4) asociado al colimador (3). - A collimator (3) coupled to the optical fiber (9) at one end opposite the light sources (1), intended to superficially illuminate a tissue of interest (2), and the detector (4) being associated with the collimator ( 3).
3.- El dispositivo de la reivindicación 1, que comprende tres o más fuentes de luz (1) destinadas a iluminar superficialmente un tejido de interés (2), en el que cada fuente de luz (1) está configurada para emitir a una longitud de onda diferente en el rango visible. 3. The device of claim 1, comprising three or more light sources (1) intended to superficially illuminate a tissue of interest (2), wherein each light source (1) is configured to emit at a length different wave in the visible range.
4.- El dispositivo de la reivindicación 2, que comprende tres o más fuentes de luz (1) destinadas a iluminar superficialmente un tejido de interés (2), en el que cada fuente de luz (1) está configurada para emitir a una longitud de onda diferente en el rango visible. 4. The device of claim 2, comprising three or more light sources (1) intended to superficially illuminate a tissue of interest (2), wherein each light source (1) is configured to emit at a length different wave in the visible range.
5.- El dispositivo de las reivindicaciones 3 o 4, que comprende tres fuentes de luz (1). 5. The device of claims 3 or 4, comprising three light sources (1).
6.- El dispositivo cualquiera de las reivindicaciones anteriores, en el que las fuentes de luz (1) se seleccionan entre LEDs (diodos emisores de luz) y fuente blanca con filtro. 6. The device of any of the preceding claims, in which the light sources (1) are selected between LEDs (light emitting diodes) and a white source with a filter.
7.- El dispositivo de las reivindicaciones 1 o 2, en el que una primera fuente de luz (1) emite a una longitud de onda en el rango de 630-690 nm, y una segunda fuente de luz (1) emite a una longitud de onda seleccionada entre 425-460 nm y 450-490 nm. 7. The device of claims 1 or 2, wherein a first light source (1) emits at a wavelength in the range of 630-690 nm, and a second light source (1) emits at a wavelength selected between 425-460 nm and 450-490 nm.
8.- El dispositivo de las reivindicaciones 3, 4, o 5, en el que las fuentes de luz (1) emiten a unas longitudes de onda comprendidas en unos rangos de 425-460 nm, 450- 490 nm y 630-690 nm. 8. The device of claims 3, 4, or 5, in which the light sources (1) emit at wavelengths in the ranges of 425-460 nm, 450-490 nm and 630-690 nm .
9.- El dispositivo de las reivindicaciones 1 o 2, en el que una primera fuente de luz (1) emite a una longitud de onda en tomo a 660 nm, y una segunda fuente de luz (1) emite a una longitud de onda seleccionada entre 440 nm y 470 nm. 9. The device of claims 1 or 2, in which a first light source (1) emits at a wavelength of around 660 nm, and a second light source (1) emits at a wavelength selected between 440 nm and 470 nm.
10.- El dispositivo de las reivindicaciones 3, 4 o 5, en el que las fuentes de luz (1) emiten a unas longitudes de onda en tomo a 440 nm, 470 nm y 660 nm. 10. The device of claims 3, 4 or 5, in which the light sources (1) emit at wavelengths around 440 nm, 470 nm and 660 nm.
11.- El dispositivo de la reivindicación 2, 4 o 5, que comprende adicionalmente unos polarizadores cruzados, vinculados al detector (4) y destinados a filtran la luz difusa reflejada en el tejido de interés (2). 11. The device of claim 2, 4 or 5, which additionally comprises crossed polarizers, linked to the detector (4) and intended to filter the diffuse light reflected in the tissue of interest (2).
12.- El dispositivo de la reivindicación 2, 4 o 5, que comprende adicionalmente unas fuentes de comente (5) conectados entre cada una de las fuentes de luz (1) y el módulo de control (6). 12. The device of claim 2, 4 or 5, further comprising current sources (5) connected between each of the light sources (1) and the control module (6).
13.- El dispositivo de la reivindicación 2, 4 o 5, que comprende adicionalmente un amplificador de transimpedancia (7), conectado entre el detector (4) y el módulo de control (6). 13. The device of claim 2, 4 or 5, further comprising a transimpedance amplifier (7), connected between the detector (4) and the control module (6).
PCT/ES2022/070324 2021-05-31 2022-05-27 Device for monitoring the perfusion status of skin flaps WO2022254064A1 (en)

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