RU2243002C2 - Method and device for determining needle end position in biological tissues - Google Patents

Abstract

FIELD: medicine; medical engineering.

SUBSTANCE: method involves introducing light guide into needle cavity. Polished distal end of the light guide is matched with the needle end. Reflected radiation is supplied to and taken off from biological tissue. Intensity and spectral characteristics of radiation are measured or structure and color of image reflected from the biological tissues passed by the needle end in succession. The measured characteristics are compared to known ones. The differences are interpreted to identify the biological tissues. The device has optically connected radiation source, beam splitter, optical light guide having distal and proximal ends and photosensor which output is connected to video monitor. The distal end of the light guide is removable. It is mounted in medical needle pavilion. The polished end face of the distal light guide end is combined with needle end.

EFFECT: high accuracy and reliability in identifying needle end position in biological tissue of interest.

5 cl, 3 dwg

Description

The invention relates to medical equipment and is intended to determine the location of the end of the syringe needle in biological tissues, for example, when performing epidural anesthesia, percutaneous puncture of heart cavities, diagnostic manipulations in lung tissues, diagnosis and subsequent treatment of thrombotic diseases of the arteriovenous system, etc.

A known method for the endoscopic detection of cancerous tissue (German Patent (DE) No. 4110228, IPC 5 A 61 B 1/06, H 04 N 7/18, RJ ISM 7-05-94), based on the fluorescence of the marked substance in the cancerous tissue under the action of modulated light supplied by a light guide placed in the endoscopic probe, and observing the image created by the fluorescent radiation removed from the fiber on a television monitor.

The disadvantage of this method for identifying the location of the working end of the probe in biological tissue is the low accuracy of identification due to insufficient determination of the location of the fiber relative to the working end of the probe and tissue, as well as the need to use a marking agent that fluoresces under the influence of light, which for most biological tissues has a neurotoxic effect .

The closest in technical essence and adopted for the prototype is a method for determining the location of the end of the needle in biological tissue located in the epidural space of the spinal canal, described in the manual for doctors: Morgan ml. D.E., Magid S. Michael. Clinical anesthesiology - M. / St. Petersburg., Binom / Nevsky dialect, 1998 (p.303-304).

This method is based on the tactile sensations of the doctor’s fingers against resistance when passing through the biological tissues of the end of the needle and pressure on the syringe plunger (the method of “loss of resistance”) or on fixing the moment of disappearance of a drop of isotonic sodium chloride solution from the needle pavilion under the influence of negative pressure in the epidural space (hanging drop method).

The disadvantage of this method is the subjectivity of the doctor’s sensations, which leads to errors in determining the moment when the end of the syringe needle enters the identifiable tissue, especially when the needle is obstructed (the hole in the needle is clogged), and possible perforation (damage) of the dura mater of the spinal cord, causing danger and complications of epidural blockages (see Svetlov VA, Kozlov SP. Dangers and complications of central segmental blockades. Anesthesiology and intensive care. 2000, No. 5, p. 86).

A device is known that can be used to determine the position of the working end of an endoscopic probe relative to biological tissues (Endoscope with a laser video camera, US patent No. 5172685, 5 A 61 V 1/06, RZH ISM 7-14-94).

The device contains an optical radiation source, a fiber through which optical radiation is supplied and removed, a probe into which a fiber is inserted, a beam splitter installed on the optical path for illuminating biological tissue and directing reflected radiation to a photosensor that generates a signal proportional to the amount of light, a video monitor, whose input is connected to the photosensor.

A disadvantage of the known device is that it does not accurately determine the distance between the desired tissue and the working end of the probe, since the location of the working end of the fiber relative to the working end of the probe and the desired biological tissue is not well defined, and also does not allow the use of standard disposable needles instead of the probe, since the working end of the fiber is stationary mounted in the endoscopic probe.

Also known is a needle for targeted puncture biopsy of the thyroid gland (patent RU 2033758 C1, dated April 30, 1995), which, by the set of essential features, is closest to the invention and is selected as a prototype.

The needle is made in the form of a tube with specially located holes in its side walls and with an oblique cut of the working end installed in its pavilion with a replaceable obturating mandrel made in the form of a cylinder whose diameter corresponds to the inner diameter of the needle and the cut angle of the working end of the mandrel equal to the cut angle of the needle containing a device for fixing the position of the mandrel, an ultrasound apparatus, on the screen of which the location of the working end of the needle relative to biological tissue is visualized.

A disadvantage of the known device is the low accuracy of determining the moment of entry of the end of the needle into the desired fabric due to the fact that the holes in the side walls of the needle to create ultrasonic sensors for the position of the working end of the needle are located at a certain distance from its working section, ambiguity and variability of the connections between the measured density and type of biological tissue, as well as the inability to use standard disposable needles, medical needles and the refusal to use tissue-marking substances.

The technical result provided by the invention is to increase the accuracy and simplify the determination of the position of the end of the needle in biological tissues due to the uniqueness of determining the moment of entry of the end of the needle into the tissue, the use of standard disposable medical needles and the rejection of the use of a tissue-marking substance.

The specified problem in the inventive method for determining the location of the end of the needle in biological tissues is solved as follows.

The working end of the fiber is placed in the pavilion of the medical needle with the possibility of its subsequent removal, the polished end of the working end of the fiber is combined with the working cut by the end of the needle, the needle is inserted into the tissue, the tissue is irradiated with optical radiation using the fiber, the optical signal reflected from the fabric is converted into an electrical signal, register radiation reflected from the biological tissues sequentially passed by the needle end, observe a signal in the form of a graph on a video monitor, analyze the characteristics of counter radiation, comparing the nature of the change in the measured values with the known nature of the changes in reflected radiation from various tissues, and the position of the tip of the needle is determined by the nature of the changes in these values, and the intensity values of the reflected radiation or its spectral characteristics, or the structure and color of the generated image are analyzed.

A device for determining the position of the end of the needle in biological tissues, characterized in that it contains optically connected optical radiation source, a beam splitter, an optical fiber and a photo sensor, the output of which is connected to a video monitor, the end of the fiber being installed in the pavilion of the medical needle with the possibility of removal from it, and polished The end of the fiber end is aligned with the end of the needle.

Since different biological tissues have different absorption, reflection, and other spectral characteristics of optical radiation for certain wavelengths, the intensity and spectral composition of reflected radiation will be different for different biological tissues (see, for example, Khayrullina A.Ya. et al. " Databank on the optical and biophysical properties of blood, biological tissues and biofluids in the visible and near infrared spectral regions ", Optical Journal, No. 3, 1997). Images created by radiation reflected from various biological tissues also have a different structure and color.

The change in the intensity and spectral composition of radiation from biological tissues during their successive passage by the tip of the needle is recorded using a photosensor (photodetector (s)), converted into an electrical signal and displayed as a graph or image of an object of observation on a video monitor or computer monitor.

Based on the conducted practical experiments, the relative change in a similar graph or structure and color of the image is known when the needle passes through various tissues, for example, during epidural anesthesia of skin tissue, adipose tissue, muscle tissue, intervertebral (interspinous) ligament tissue, yellow ligament tissue, epidural tissue, dura mater and spinal cord tissue. The combination of the polished working end of the fiber with the end of the needle allows you to get a signal on the video monitor corresponding to the optical radiation reflected from the biological tissue, through which at the given moment the end of the needle passes through the fiber, which unambiguously determines the moment the needle enters the identified tissue and thereby increases the accuracy of identification biological tissue.

After identification of the fabric, the working end of the fiber is removed (pulled out) from the needle pavilion, which allows the use of standard disposable needles.

The essence of the proposed inventions is illustrated in Fig. 1, where, as an example, experimental graphs of the relative changes in the electrical signal from the photosensor during sequential passage of the biological tissue of the animal through the tip of the needle, obtained for three radiation wavelengths: red - a, yellow - b, blue - c (here for example, adipose tissue is located in the range of the end of the needle at a depth of 10-20 mm, the tissue of the yellow ligament is in the range of 40-50 mm, the tissue of the epidural space is in the range of 52-58 mm), as well as figure 2 and 3, where from razheny schematic circuit device for implementing the proposed method.

The device (figure 2) contains a needle 1 with a working end of a fiber 2 inserted into its cavity and a device 3 for combining and fixing the position of the polished end of the working end of the fiber with the end of the needle. The end face of the working end of the optical fiber 2, combined with the end of the needle 1, can have a bevel made at an angle no more than the angle determined by the numerical aperture of the optical fiber, which allows one to receive reflected radiation from the fabric, and the second end of the optical fiber 2 is placed in the housing 4, where optically connected a beam splitter 5, a light source 6, a photosensor 7, the output of which is connected to a video monitor of a computer 8.

The device 3 for combining and fixing the position of the polished end of the working end of the optical fiber with the end of the needle can be made in the form of a collet clamp or a removable ring having a slot for clamping with a screw (see the Designer Handbook of Precision Instrumentation. / Ed. Litvin F.L., M -L, Mechanical Engineering, 1964, pp. 414-416). The beam splitter 5 can be made in the form of a translucent mirror, and the radiation source 6 can be controlled LEDs with different wavelengths or wide-range light sources — an incandescent lamp, a “white” LED. The photosensor 7 can be made in the form of an optical radiation receiver such as a photodiode or a CCD matrix if a tissue image is transmitted to the monitor. To improve the conversion of the beam of rays reflected from the biological tissue into an electrical signal, a lens 9 can be used that transmits radiation from the second end of the fiber end to the photodetector. When using an incandescent lamp or a “white” LED as a light source, the filter (s) 10 can be used to operate in the most sensitive wavelength range of light.

The signal from the photodetector enters the controller (computer) 11, where it is processed and transmitted in the form of a graph to the monitor (display) 8. The controller can also control the switching of the LEDs.

After determining the position of the end of the needle in the desired tissue (for example, tissue of the epidural space), the light guide is removed (pulled out) from the needle pavilion in order to connect a syringe to the needle or to install a catheter, etc. This allows the use of disposable needles. The light guide 2 can also be disposable.

The device (Fig. 3) comprises a needle 1, a light guide 2 inserted by the working end into a needle, the polished end of which is aligned with the end of the needle and fixed with the help of device 3. The second end of the light guide 2 is located in the housing 4, where the beam splitter 5 is made, made a splitter into two bundles, one of which is illuminated from a radiation source of a wide range of light wavelengths 6, and the other, reflected radiation enters the photosensor 7, made in the form of a spectrophotometer, where, for example, radiation spectra are determined , absorption or other spectral characteristics of radiation reflected from biological tissues adjacent to the end of the needle and the working end of the fiber combined with it. The results of spectral analysis are processed using a computer program and are sent to the display of computer 8. The photosensor 7 can also be made in the form of a video camera, which converts the tissue image from the second end of the fiber into an electrical signal, followed by its transmission to a video monitor.

After determining the location of the end of the needle in the desired fabric, the optical fiber bundle is pulled out of the needle pavilion.

The proposed method is implemented using the inventive device (figure 2) as follows.

Insert the working end of the light guide 2 into the cavity of the standard needle 1, combine its polished working end with the end of the needle and fix them relative to each other with the device 3. Turn on the radiation source 6, insert the needle into the patient’s skin tissue and begin to sequentially advance it in the tissues, measuring with the receiver 7, the intensity of the reflected radiation, the measurement results of which are observed in the form of a graph on the monitor 8. Comparing the nature of the change in the measured values with the known nature of the changes in the intensity of the reflected of radiation from various tissues, identify the location of the end of the needle into the tissue and, in particular, into the epidural space fabric. For a more accurate and reliable identification, the source of radiation can be switched LEDs with different wavelengths (for example, visible and near infrared), or different filters are installed in front of the switched radiation receiver. If a CCD array is used as a receiver, then the image of the tissue is observed on the video monitor and the position of the end of the needle is identified by its structure and color, since the fabric adjacent to the end of the needle and the polished end of the working end of the fiber combined with it are transferred by the fiber to the end the second end of the fiber.

According to a variant of the device of FIG. 3, the proposed method is implemented as follows.

Insert the working end of the light guide 2 into the cavity of the needle 1, combine its polished working end with the end of the needle and fix their relative position with the device 3. Turn on the radiation source 6, insert the needle into the patient’s skin tissue and begin to sequentially advance it in the tissues, measuring spectral spectrophotometer 7 radiation reflected from tissue transmitted to a computer monitor 8. Since the absorption, reflection, and other spectral characteristics of each substance are different, they identify bio logical fabric. If the photosensor 7 is made in the form of a video camera, then while advancing the needle, images of tissues adjacent to its end are observed on the monitor and the desired fabric is identified by their known structure and color.

The proposed method and device for determining the position of the end of the needle in biological tissues allows you to move from methods that currently exist in practice, based on the subjective tactile and visual sensations of the doctor to objective measurements based on the well-known law on various emission spectra and absorption of optical radiation by various substances, or directly observe the tissue, which increases the accuracy of determining the moment of entry of the end of the needle into the identified tissue.

Compared with the known methods and prototype, the accuracy of determining the position of the needle is increased, since the working end of the needle is combined with the polished end of the working end of the fiber, which is in contact with the desired biological tissue that reflects optical radiation and carries information about the type of tissue, there is also no need to use a tissue-marking substance. The unambiguous determination of the moment of entry of the end of the needle with the light guide, for example, into the tissue of the epidural space reduces (excludes) the likelihood of puncture of the dura mater of the spinal cord, causing dangers and complications in epidural blockages, which improves the quality of treatment. The ability to remove the fiber from the needle pavilion after identification of biological tissue allows the use of disposable standard medical needles, in particular, during epidural anesthesia, which simplifies identification, eliminates possible infection and also improves the quality of treatment.

Claims (5)

1. The method of determining the position of the end of the needle in biological tissues, characterized in that the distal end of the fiber is placed in the pavilion of the medical needle with the possibility of its subsequent removal, the polished end of the distal end of the fiber is combined with the end of the needle, the needle is inserted into the fabric, the tissue is irradiated with optical radiation when using the light guide, they convert the optical signal reflected from the tissue into an electrical signal, register the radiation reflected from the tissues sequentially passed by the end of the needle, observe it a video monitor, analyze the characteristics of the reflected radiation, by comparing the variation of the measured values with the known nature of the reflected radiation changes from various tissues, and the nature of change of these values determine the position of the needle end. 2. The method according to claim 1, characterized in that they analyze the values of the intensity of the reflected radiation. 3. The method according to claim 1, characterized in that they analyze the spectral characteristics of the reflected radiation. 4. The method according to claim 1, characterized in that the structure and color of the image generated by the reflected radiation are analyzed. 5. A device for determining the position of the end of the needle in biological tissues, characterized in that it contains optically connected optical radiation source, a beam splitter, an optical fiber and a photosensor, the output of which is connected to a video monitor, and the distal end of the fiber is installed in the pavilion of the medical needle with the possibility of removal from it and the polished end face of the distal end of the fiber is aligned with the end of the needle.

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