RU2797635C2 - Virtual epidural anesthesia and spinal puncture simulator - Google Patents

Abstract

FIELD: medicine and veterinary medicine.

SUBSTANCE: invention can be used to teach and improve the practical skills of performing manipulations of epidural and spinal punctures. A virtual epidural simulator consisting of a haptic device with a syringe rigidly attached to it, connected to a pneumatic system that can control the pressure in the syringe to simulate the effect of entering the epidural space, and a display for visualizing a virtual scene created and controlled by a personal computer, the haptic device is made according to the kinematic scheme of a delta mechanism, with a movable platform using a fastening device with an imitation of the pavilion of a Tuohy needle, a syringe is rigidly fixed, connected to a pneumatic system with the ability to create and control a given pressure in it, while the display is equipped with a touchscreen for changing the position of the virtual patient in the virtual scene and is located above the haptic device, completely covering it.

EFFECT: obtaining virtual epidural anesthesia and spinal puncture simulator.

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Description

The invention relates to medicine and veterinary medicine and can be used to teach and improve the practical skill of manipulating epidural and spinal punctures.

Epidural anesthesia, also known as “epidural”, is one of the methods of regional anesthesia, in which drugs are injected into the epidural space of the spine through a catheter. The injection results in loss of pain sensation (analgesia), loss of general sensation (anesthesia), or muscle relaxation (muscle relaxation). Spinal puncture (lumbar puncture, lumbar puncture, lumbar puncture) - the introduction of a needle into the subarachnoid space of the spinal cord at the lumbar level. It is carried out for the purpose of diagnosing the composition of the cerebrospinal fluid, as well as for therapeutic or anesthetic purposes. Thus, both manipulations are similar in terms of the method of their implementation - the needle passes through various layers of the soft tissues of the back, then it must fall into the gap between the vertebrae, tightened with a yellow ligament (ligamentum flava), after which an anesthetic is injected into the epidural space, or in the case of spinal puncture, they are pierced membranes of the spinal cord in order to obtain cerebrospinal fluid or perform spinal anesthesia. These procedures are very serious and, if performed incorrectly, can lead to the development of dangerous complications [Kopacz DJ, Neal JM, Pollock JE. The regional anesthesia "learning curve". What is the minimum number of epidural and spinal blocks to reach consistency? Reg Anesth. 1996 May-Jun;21(3):182-90].

Various types of devices are known - simulators designed to train the skill of the procedure of epidural anesthesia and spinal puncture. As a rule, such devices consist of a model of the patient's back and various interchangeable blocks, which are an imitation of soft tissue layers of the back, placed in the simulator above an imitation of the spinal column, made of a solid material that prevents the passage of the needle [Duggan JE. An epidural simulator device for training practitioners in the anaesthetic technique of epidural injection. GB Patent GB 2369714; 2000; Simulab Corporation, Washington, USA. Medical training models, 2011]. The main property for such a simulator is the creation of fairly realistic tactile sensations that occur during the passage of layers of soft tissues and then the passage of the yellow ligament, and also allow you to simulate any of the methods for identifying the epidural space [Daykin AP, Bacon RJ. An epidural injection simulator. Anaesthesia. 1990;45:235-6; Paw HG. A trainer for identification of the epidural space. Anaesthesia. 1995;50:914]. The needle enters the epidural space as soon as its end passes through the yellow ligament, pushing back the dura mater. The resulting negative pressure confirms the view that the epidural space is only a potentially existing channel. Accurate identification of when the needle enters the epidural space reduces the risk of damage to the dura mater. Methods for identifying the epidural space fall into two main categories: the "loss of resistance" technique and the "hanging drop" technique.

The "loss of resistance" technique is the most common way to identify the epidural space. Passing the needle through the skin into the interspinous ligament is felt as significant resistance. When the end of the needle enters the thickness of the interspinous ligament, the mandrin is removed and a syringe filled with air or isotonic sodium chloride solution is attached to the needle. If an attempt to introduce a solution encounters significant resistance or is impossible, then the end of the needle is indeed in the thickness of the interspinous ligament and it can be advanced forward.

There are two ways to control the advancement of the needle. One is that the needle with the syringe connected is slowly continuously advanced forward with the left hand, while the right hand constantly exerts pressure on the plunger of the syringe. When the end of the needle enters the epidural space, the resistance decreases sharply and the piston suddenly moves forward easily. The second method is that the needle is advanced in translational movements, at a time feeding it forward a few millimeters, after which they stop and gently press on the plunger of the syringe, trying to determine by sensation whether the needle is still in the thickness of the ligaments, or the resistance has already been lost and she got into the epidural space. The second method is faster and more practical, but requires some experience to stop in time and avoid perforation of the dura mater.

Using the "loss of resistance" technique, isotonic sodium chloride or air can be administered, depending on the preference of the anesthetist. There are reports that air bubbles can cause incomplete or mosaic blockade, but this is only possible with the introduction of large volumes of air. Isotonic sodium chloride solution is easily confused with cerebrospinal fluid, which makes it difficult to suspect inadvertent puncture of the dura mater.

Hanging drop technique. The needle (preferably with a shield) is inserted deep into the interspinous ligament, after which the mandrin is removed. A drop of liquid is suspended from the pavilion of the needle - most often an isotonic solution of sodium chloride. As long as the needle advances through tight ligaments, the drop does not move. After puncture of the ligamentum flavum and the end of the needle enters the epidural space, the “hanging drop” disappears in the lumen of the needle under the influence of negative pressure. However, if the needle becomes obturated, the drop will not be drawn from the pavilion into the lumen of the needle and will be advanced until the cerebrospinal fluid leak indicates a perforation of the dura mater. It should be noted that only very experienced anesthesiologists use the hanging drop technique. This technique is also used for near-medial access.

It should also be borne in mind that epidural puncture can be performed at the level of all four parts of the spine: cervical, thoracic, lumbar, sacral.

The described simulation models have good realism, but they also have significant drawbacks. Thus, it is difficult to get an idea of the various anatomical variants of the structure of the back (for example, in the case of severe scoliosis), and the ongoing need for consumables causes the high cost of their use in the educational and accreditation processes. These shortcomings force the developers of simulation equipment to turn to the creation of virtual simulators of the epidural anesthesia procedure.

Typically, devices for simulating epidural anesthesia consist of a device that creates tactile feedback (haptic device), which allows you to create certain forces on the student’s hand and a screen that creates an image of the back and the puncture needle [Vaughan, Neil & Dubey, Venketesh & Wee, Michael & Isaacs , Richard. (2013). A review of epidural simulators: Where are we today? // Medical engineering & physics. 35.10.1016/j.medengphy.2013.03.003]. A number of such simulators use haptic devices with one degree of freedom (1-DOF). For such devices, forces are created in one direction, as a rule, specially designed devices are used for this purpose. They provide an exceptionally accurate picture of the tactile sensations as layers of back tissue pass into the epidural space, perhaps even more accurate than many of the models [Isaacs, R & Wee, Myk & Parker, B & Dubey, VN & Vaughan, Neil. (2014). Measurement of epidural insertion pressures in laboring women of varying body mass indices and imaging of the lumbar spine to develop a high-fidelity epidural simulator for training. Anaesthesia. 69. 84-84]. However, when using such devices, the choice of the place of entry into the back (entry point), as well as the angle of entry, is either set initially, or determined by selecting from predefined ones, or selected from any input device (mouse, keyboard, touchscreen). Virtual simulators also often use a syringe connected to a haptic device, which is connected to a pneumatic or hydraulic system with a pressure sensor that allows you to create negative pressure effects in the epidural space and imitates for the student certain ways of identifying the epidural space or obtaining cerebrospinal fluid during spinal puncture.

Some virtual epidural and lumbar puncture simulators use haptic devices with several degrees of freedom, which allows not only to create the sensation of passing through layers of soft tissues, but also to select the site of the epidural procedure (entry point) and tilt the needle. For example, haptic devices such as Sensable (Geomagic) Phantom are widely used for this purpose [Glassenberg R, Glassenberg S. Development of a Tactile Feedback Simulator for Placement of an Epidural or Spinal Needle. Anesthesiology. 2004; 101:A1358; Coles TR, John NW. The effectiveness of commercial haptic devices for use in virtual needle insertion training simulations. In Advances in Computer-Human Interaction, Third International Conference 2010;148-153; Magill JC, Byl MF, Hinds MF, Agassounon W, Pratt SD, Hess PE. A novel actuator for simulation of epidural anesthesia and other needle insertion procedures. Simul Healthc 2010;5(3):179-84]. However, Sensable Phantom, being a device with 6 degrees of freedom (6 DOF) has the ability to create haptic feedback on only 3 of them (motorized 3 DOF + free 3 DOF). Thus, it is not possible to fix the angle of passage of the needle through the tissues of the back, set at the entry point, which the authors of such simulators try to solve in various ways, which generally solve this issue in the virtual reality scene, but at the same time do not help with fixing the angle set at the entry point. corner on the device itself. There is a Mediseus device (US patent WO 2007/068050 A1), which includes a Sensable Phantom haptic device, installed inside the back mold, while the needle passes through the entry point in this model and is attached to the handle of the haptic device, thus, the indicated drawback - the absence in this haptic device of the required number of degrees of freedom with the creation of tactile force is eliminated. But virtual simulators of epidural anesthesia and spinal puncture, built on the basis of the Sensable Phantom digital pen, also suffer from the shortcomings inherent in the kinematic scheme of this haptic device, which is a sequential lever mechanism, which imposes significant restrictions on the forces of tactile feedback generated by it and, accordingly, on the realism of the sensations it creates when passing through various layers of soft tissues.

In addition, the realism of such devices is also affected by the location of the screen of the device on which the virtual scene is rendered. In most cases, the screen is located separately from the feedback device and does not imply a stereoscopic image, which greatly reduces the effect of using such a simulator [Ravali, G., & Manivannan, M. (2017). Haptic feedback in needle insertion modeling and simulation. IEEE reviews in biomedical engineering, 10, 63-77; Gourishetti, R., & Manivannan, M. (2019). Improved force JND in immersive virtual reality needle insertion simulation. Virtual Reality, 23(2), 133-142].

The closest device for a virtual simulator of epidural anesthesia and spinal puncture is the device described above, containing a haptic device with a syringe mounted on it, connected to a pneumatic system, without a mechanically fixed entry point and a screen for visualizing a virtual scene. The most significant disadvantage of such devices is the lack of a mechanical limitation of the angle of passage of tissues by the puncture needle and adequate visualization of the virtual scene.

For the first time, we propose an epidural anesthesia and spinal puncture simulator containing a haptic device for creating tactile feedback in the form of a delta mechanism with a syringe rigidly placed on its movable platform connected to a pneumatic system to create and maintain a given pressure in it, as well as a screen for visualization of a virtual scene placed above the haptic device.

The optical scheme of the virtual epidural simulator is shown in Fig. 1 where:

1 - touchscreen display

2 - haptic device (delta mechanism)

3 - mobile platform of the haptic device (delta mechanism)

4 - attachment of a syringe with imitation of a puncture needle

5 - syringe

6 - pneumatic system hoses

7 - pump

8 - air pressure sensor

9 - control device (personal computer)

The virtual epidural simulator consists of a display with a touchscreen 1 installed above the haptic device 2, the kinematic scheme of which is a parallel device or a delta mechanism. On the movable platform 3 of the haptic device 2, a syringe 5 is rigidly fixed by fastening a syringe with an imitation of a puncture needle 4. The syringe 5 is connected by means of pneumatic system hoses 6 to a pump 7 and an air pressure sensor 8. It creates, controls a virtual scene and visualizes it on the display with touchscreen 1 control device (personal computer) 9.

Working with a virtual epidural simulator is performed as follows: the student controls the simulator by holding syringe 5 in his hand, rigidly fixed on the movable platform 3 of the haptic device 2. By moving the syringe 5 and, accordingly, the movable platform 3 of the haptic device 2, the student sets the position of the syringe and the puncture needle in scene that is displayed on display 1. Using the touchscreen of display 1, the student can change the position of the patient's body in the virtual scene within certain limits, which sets the angle of entry of the needle in the virtual scene. The location of the display with touchscreen 1 above the haptic device 2 leads to the fact that the student observes the movements of not his hands, but

manipulations carried out by him with the help of a haptic device in a virtual scene, creating the effect of his presence in this scene. The haptic device 2, after the introduction of a virtual needle into the virtual model of the back placed on the stage by the trainee, creates the forces necessary to create tactile sensations accompanying the passage of the puncture needle through all layers of the soft tissues of the human back during the epidural procedure. The control device (personal computer) 9 controls the haptic device 2 and controls the behavior of objects in the virtual scene. After entering the epidural space, the control device (personal computer) controls the pump 7 by changing the pressure in the pneumatic system connected to the syringe 5, simulating a change in pressure in syringe into the epidural space. The control device (personal computer) 9 controls the change in pressure in the pneumatic system using an air pressure sensor 8.

Thus, the use of the kinematic scheme of the parallel device (delta mechanism) in the haptic device 2 causes its greater spatial stability and the possibility of creating significant forces required to simulate the passage of the soft tissues of the back and, especially, the yellow ligament. The rigid connection of the syringe 5 with the movable platform 3 of the haptic device (delta mechanism) 2 also contributes to this. The location of the display with touchscreen 1 above the device leads to the observation by the students of an exclusively virtual scene and their manipulations in it, which contributes to the creation of realistic visual sensations during these manipulations (especially this effect is manifested when a stereoscopic image is created on the display in one way or another).

Due to the use of the kinematic scheme of the parallel device (delta mechanism) in the haptic device, significant spatial stability, high effort when creating tactile feedback and realistic tactile sensations are provided, the location of the display above the haptic device provides the effect of direct participation and the presence of the student in the virtual scene, allowing also interactively set the angle of entry into the soft tissues of the back, and the pneumatic system makes it possible to simulate high-quality effects for accurate identification of the epidural space in a virtual scene.

Claims (1)

A virtual simulator of epidural anesthesia and spinal puncture, consisting of a haptic device with a syringe rigidly attached to it, connected to a pneumatic system that has the ability to control the pressure in the syringe to simulate the effect of entering the epidural space, and a display for visualizing a virtual scene that is created and is controlled by a personal computer, characterized in that the haptic device is made according to the kinematic scheme of the delta mechanism, with the movable platform of which, using a fastening device with an imitation of the Tuohy needle pavilion, a syringe is rigidly fixed, connected to a pneumatic system with the possibility of creating and controlling a given pressure in it, while the display is equipped with a touchscreen to change the position of the virtual patient in the virtual scene and is located above the haptic device, completely covering it.

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