JP6950947B2 - Medical high frequency device with cooling function - Google Patents

Description

The present invention relates to a medical high frequency device such as an electric knife, and particularly to a medical high frequency device having a cooling function with a physiological saline solution.

When ablation of tissue is performed using an electric knife during surgery, if the overheated electric knife comes into contact with a blood vessel, there is a risk of bleeding, and as the temperature rises sharply, the tissue is charred and the electrode of the charcoal substance is reached. May occur.
Therefore, in order to prevent overheating of the high-frequency device electrode and allow the protein to coagulate and seal the blood vessel without bleeding, a pump is used to supply physiological saline through the small pores formed in the electrode. High-frequency electrodes for irrigation have been developed to cool the electrodes by doing so.

Patent Document 1 describes that a water pipe is installed on a shaft portion to which a tip electrode is attached, and physiological saline is supplied by a pump.
Patent Document 2 describes that a lumen for water injection is provided along the axial direction on the peripheral wall of the heat-resistant tube body into which the electric knife is inserted.

Japanese Unexamined Patent Publication No. 2016-087180 Japanese Unexamined Patent Publication No. 2014-400555

By supplying physiological saline around the electrodes, it becomes possible to prevent overheating of the high-frequency device electrode, prevent carbonization of tissues, and coagulate proteins to seal blood vessels.
However, if the amount of saline supply is insufficient, the original function is impaired, while if the amount of saline supply is excessive, it dissipates to tissues other than the cauterization point via the saline solution, resulting in a sufficient cauterization rate. You won't get it.

Assuming that physiological saline is supplied in accordance with cauterization in order to optimize the supply of physiological saline, a sensor for monitoring the timing of cauterization is required, but the system becomes larger. Not only is it complicated, but there is also a limit to the responsiveness, making it difficult to easily cauterize minute parts.
Therefore, an object of the present invention is to autonomously supply an optimum amount of physiological saline according to the temperature of the high-frequency device electrode without inviting an increase in size of the high-frequency electrode and without requiring a special mechanism such as a pump. Is to enable.

In order to solve the above problems, the present invention utilizes a phenomenon in which the pressure inside a physiological saline container (cylindrical portion) having micropores increases due to the amount of heat generated when a tissue piece is cauterized with an electric knife. Then, the physiological saline solution is discharged from the micropores. As a result, the tissue temperature is maintained above the protein coagulation temperature, and the excised portion is kept below 100 ° C. by the latent heat of vaporization of the physiological saline to prevent carbonization.

According to the present invention, the excised part is autonomously and surely maintained at 100 ° C. or lower by discharging physiological saline using the amount of heat generated when the tissue piece is cauterized with an electric knife. Therefore, it is possible to dramatically improve the safety and reliability of medical high-frequency devices without increasing the size and cost of high-frequency electrodes.

FIG. 1 is a diagram showing the basic principle of the present invention. FIG. 2 is a diagram showing the results of measuring the relationship between the applied pressure (pressure Pa: horizontal axis) and the amount of air leakage (mL / min: vertical axis) inside the physiological saline pipe for each diameter of the small hole. Is. FIG. 3 is a diagram showing the structure of the tubular electrode. FIG. 4 is a diagram showing operation at the time of incision using a medical high frequency device provided with a tubular electrode. FIG. 5 is a diagram showing a rotation mechanism and a linear motion mechanism of an insertion tube that guides a tubular electrode. FIG. 6 is a diagram showing an example of a flowchart when moving the insertion tube.

[Example 1]
FIG. 1 is a diagram showing the basic principle of the present invention.
The cooling mechanism of the present invention is provided inside the tubular electrode 1 from a tubular electrode 1 of a medical high-frequency device such as an electric knife, a small hole 1a formed on the peripheral surface of the bottom surface thereof, and a source of physiological saline. It is composed of a check valve 2 for circulating physiological saline toward the patient.
The tubular electrode 1 is made of stainless steel, which is widely used as a medical high-frequency device, for example, but has a thin wall surface and can sufficiently secure a surface area in contact with physiological saline with respect to the mass. Therefore, the amount of heat generated at the electrodes of the medical high-frequency device locally and instantly heats the physiological saline solution filled inside the tubular electrode 1. Along with this, thermal expansion of the physiological saline occurs, but the check valve 2 prevents the backflow of the physiological saline to the source, and the viscosity of the physiological saline prevents the small holes 1a from flowing back. The internal pressure of the tubular electrode 1 (hereinafter referred to as "in-pipe pressure") rapidly increases locally in the periphery. As a result, physiological saline is discharged from the small holes 1a formed around the tubular electrode 1 and supplied to the periphery of the electrode.

As for the diameter of the small hole 1a, if the pressure inside the pipe of the physiological saline is at the atmospheric pressure level, the physiological saline is not discharged due to the surface tension, viscosity, etc. of the physiological saline, and the pressure inside the pipe is predetermined. It is stipulated that the optimum amount of physiological saline should be discharged only when the pressure rises above the pressure. That is, the diameter, number, and arrangement of the small holes 1a are such that the optimum amount of physiological saline is supplied to the required place at the timing when cooling is required, and the tubular electrode 1 is surely prevented from overheating. The optimum value is selected based on the calorific value of the tubular electrode by experiments and the like.
By selecting the diameter, number, and arrangement of the small holes 1a in this way, the tissue pieces are efficiently cauterized at the moment when a high voltage is applied to the tubular electrode 1, and the ambient temperature and pressure of the small holes 1a are selected. Is raised, and physiological saline is discharged from the small hole 1a, so that overheating can be reliably prevented.

FIG. 2 shows the applied pressure (pressure Pa: horizontal axis) and the amount of air leakage (mL / min: vertical axis) inside the tube when a stainless steel copper tube having an inner diameter of 2 mm and a thickness of 0.012 mm is used as the tubular electrode 1. An example of the result of measuring the relationship of the shaft) for each diameter of the small hole is shown. The area colored in light blue is the area where air leaks more than water droplets when the air is used as physiological saline, and the area colored in pink is the area where air leaks but does not leak when used as physiological saline. Is shown.

In this example, 100 small holes 1a are formed in a range of 1 mm in axial length from the bottom surface of the stainless copper tube, and FIG. 2 shows a case where water discharge cannot be confirmed by observing for 1 hour. In white, the case where the discharge is 0.01 ml / min or less is shown in light color, and the case where the discharge is large is shown in filled.
12.58 μl of water exists in the space from the bottom surface of the tubular electrode 1 to the check valve 2 (hereinafter referred to as “intra-pipe space”), but as is clear from the result of FIG. 2, the diameter of the small hole When the pressure is 1μ or 5μ, the physiological saline is not discharged (0.01 ml / min or less) until the pressure in the pipe reaches 10 kpa (equivalent to a depth of 1 m), and when the pressure in the pipe exceeds 10 kpa, the amount of leakage gradually increases. Will increase to.

On the other hand, when the small pores were 10μ or 15μ, a large amount of discharge occurred when the pressure in the pipe of the physiological saline was 5 kpa (equivalent to a water depth of 50 cm) or more. When the small holes exceeded 25 μm, a large amount of discharge occurred even if the pressure inside the pipe increased slightly.
In this way, the discharge amount of the physiological saline solution with respect to the in-tube pressure can be selected according to the small holes, and the amount of heat generated in the tubular electrode 1 of the medical high-frequency device, the size of the in-tube space, and the medical high-frequency device. The diameter and number of the small holes 1a can be selected in relation to the amount of physiological saline supplied to cool the tubular electrode of the above to a predetermined temperature or lower.
In a general medical high-frequency device, the diameter of the small holes is the diameter when the number of small holes is 100, taking into account the amount of change depending on the wettability of the small hole surface, the hole depth, the viscosity of the liquid, and the like. Appropriate cooling can be achieved by selecting in the range of 1 μm or more and 100 μm or less.

Generally, when a medical high-frequency device is an electrosurgical unit, a high-frequency current of 300 kHz to 5 MHz is applied to a living body, and the heat generated at this time is used to incise and coagulate the tissue. When such a high voltage is applied between the tubular electrodes, a high-frequency current of about 0.5 A is concentrated and flows into the living body from the tip of the tubular electrodes. As a result, intracellular water evaporates rapidly around the tubular electrode of the electrosurgical knife, and the cell membrane and the cell membrane are explosively broken, so that the tissue is incised. The heat generated by the application of the high-frequency current also acts on the surrounding tissues, and this portion is coagulated by the heat, the tissues are contracted, the capillaries and microvessels are occluded, and bleeding is suppressed.

At this time, on the outer peripheral surface of the tubular electrode, which is the tip of the scalpel, a high-frequency current acts as a spark column and flows to the living body, and the resistance of the contact portion becomes a large value of 200 to 1,000 Ω. Here, assuming that the resistance of the contact portion is 200Ω and the flowing current is 0.5A, ^{the amount of heat of I 2} R = 50 [J] is generated per second according to Joule's law.
Assuming that this heat acts on a cylindrical living surface area portion with a diameter of 1 mm and a depth of 1 mm, the volume of this portion is 8 × 10 ^-4 cm ³ , so the amount of heat required to heat to 100 ° C or higher is It will be 0.3J.
On the other hand, the amount of heat required for vaporization is 2263 J / cm ³ , and as a result, when 0.5 A is energized, this part evaporates in 0.04 seconds.
When the pressure in the tube space increases with the vaporization of the physiological saline solution, the physiological saline solution is discharged from the small hole 1a to cool the periphery of the tubular electrode. As a result, when the temperature around the tubular electrode falls below a predetermined temperature, the check valve 2 is opened as the pressure inside the pipe decreases, air bubbles generated inside are discharged from the small hole 1a, and the physiological saline supply source enters the space inside the pipe. Saline is supplemented.

For example, assuming that the above process raises the temperature from room temperature (20 ° C) to 80 ° C in the axial length region of 1 mm, the coefficient of thermal expansion of water is 0.021% / ° C and the coefficient of thermal expansion of copper is 0.021% / ° C. At 0.0051% / ° C, the discharge rate changes due to water, expansion of the pipe, decrease in viscosity of water, expansion of the small pore system due to thermal expansion of the pipe, etc., but only the difference between the volume expansion coefficient of copper and the volume expansion coefficient of water. Assuming that it is discharged, 0.0159% / ° C will be discharged.
That is, assuming that the copper electrode having a diameter of 1 mm and a depth (length in the axial direction) is filled with water, if the temperature rises by 60 ° C, the water will be.
0.5 * 0.5 * 3.14 * 0.021 / 100 * 60 = 0.00091mm ³
That is, it expands by 0.009891 μl.
On the other hand, copper
0.5 * 0.5 * 3.14 * 0.0051 / 100 * 60 = 0.0024021mm ³
That is, it expands by 0.0024021 μl.
Since the difference between the two corresponds to the amount of leakage, the amount of leakage is 0.0074889 μl.
From Fig. 2, 1.7 μl of gas can be discharged per second from one hole with a diameter of 0.001 mm under an applied pressure of 1.0 kPa, and if water is filled at the gas discharge rate, it is possible to discharge water from 100 small holes. The amount of water discharged at 44 μs will be filled.

If the high-frequency power supply is operated in a pulse shape in a 100 μs cycle (10 kHz) that is sufficiently longer than 44 μs, and the inside of the tubular electrode is heated from room temperature to 80 ° C, the total discharge amount will be.
0.0074889 * 10000 = 75 μl / s = 4500 μl / min = 4.5 ml / min.
Since the flow rate of a commercially available irrigation pump is 1 to 30 ml per minute, according to this embodiment, an equivalent physiological saline solution is supplied without using an irrigation pump or a special drive source. It turns out that it is possible.
Furthermore, when a high-frequency scalpel is used at high output, a part of the physiological saline may boil, but in response to this, the discharge amount increases dramatically, so the discharge performance is improved and the amount of heat generated is reduced. It enables commensurate cooling.

On the other hand, when the heat source is small with respect to the size of the tubular electrode, the temperature gradient of the liquid in the tube cannot be ignored. In this case, as the distance from the heating source increases, the temperature of the liquid decreases, so that the amount of expansion decreases. When heated in a shorter time, pressure is generated inside the liquid according to the amount of expansion due to the inertia of the surrounding liquid. When discharged by the reaction force, the discharge amount changes autonomously according to the temperature.

When used in a medical high-frequency device in which a sudden temperature change occurs, the discharge pressure can be obtained by the expansion and evaporation pressure of the liquid and the inertial force of the liquid, so that the physiological saline solution always exceeds the small hole 1a. It is not always necessary to provide a check valve as long as it is filled to maintain the water level.
The physiological saline solution may be replenished from the auxiliary tank by using gravity or surface tension, and of course, it may be replenished by using a simple pump.

FIG. 3 shows the tubular electrode of this embodiment. Small holes 1a are formed on the surface of the tubular electrode 1 filled with physiological saline in the processing progress direction.
FIG. 4 shows the operation at the time of incision using a medical high frequency device including the tubular electrode 1. When the tubular electrode 1 and the tissue come into contact with each other, the temperature of the contact portion is raised by the high frequency and the electrical resistance of the tissue, the water content of the tissue evaporates, and a space is created.
On the other hand, the tubular electrode 1 is heated, and the physiological saline solution is discharged from the small hole 1a due to the thermal expansion pressure of the internal physiological saline solution and the vapor pressure when evaporation is accompanied. By discharging the physiological saline solution, the tissue cooling action works, and the incision is performed in a state close to the coagulation mode of the high-frequency scalpel, which is a conventional medical technique. Since the coagulation mode is used for hemostasis, the incision can be advanced without bleeding by sealing the cut blood vessel. In this way, the tubular electrode 1 is cooled at the same time as the tissue is cooled, and the space inside the pipe is filled with physiological saline equivalent to the discharge amount.

Conventionally, in surgery using a high-frequency scalpel, the doctor intermittently switches between the incision mode and the coagulation mode while checking the condition of the incision, so that the incision is made as quickly as possible while minimizing the amount of bleeding. Highly skilled technology is required to realize.
On the other hand, according to this embodiment, since the incision region of the tubular electrode 1 can be autonomously cooled, the hemostatic function is maintained even if a moving mechanism for moving the tubular electrode 1 by an actuator is added. It is possible to move the electrodes autonomously in the state.
That is, as shown in FIG. 5, the tubular electrode 1 is guided by the electrode guide 2 at the tip of the insertion tube, and can be moved in the rotation direction and the axial direction by the rotation mechanism 3 and the linear motion mechanism 4. At that time, since the temperature around the electrode is appropriately maintained by the discharge of the physiological saline solution described above, the control of the rotation mechanism and the linear motion mechanism can be prioritized.

FIG. 6 shows an example of a flowchart when the insertion tube is moved by the rotation mechanism 3 and the linear motion mechanism 4.
When the current stops flowing to a certain level, the linear motion is repeated again. As a result, damage to the tissue due to excessive current supply can be kept to a minimum.
At that time, the high frequency energy may be output continuously or intermittently.

Since it is desirable to minimize the dissipated current that flows from the tubular electrode 1 to other than the processing point via physiological saline, the tissue is excised by rotating in the direction approaching the designated position in the path to the designated position of the organ. In this case, it is desirable that the current conducts only at the tip in the rotation direction. Therefore, a coating using ceramic or the like for other than the tip, or an electrode in which only the tip is a conductive material and the other is an insulating material may be used.

As described above, according to the medical high-frequency device provided with the cooling structure of the present invention, during tissue ablation, the tissue temperature is autonomously maintained above the protein coagulation temperature, and the excised portion is cut by latent heat of evaporation. Since carbonization can be reliably prevented at a temperature of ℃ or lower, it is expected to be widely adopted as a medical high-frequency device with dramatically improved safety without requiring advanced skill.

1: Tubular electrode 1a: Small hole 2: Electrode guide 3: Rotation mechanism 4: Linear mechanism

Claims (3)

It is a cooling structure for medical high-frequency devices.
Tubular electrodes and
And a saline supply device for filling the saline inside the tubular electrode,
The tubular electrode is formed with a small hole that opens in the direction of incision.
When the tubular electrode Te tissue dissection during odor is heated, if the saline in the interior space of the tubular electrode exceeds a predetermined pressure expands, the physiological through the small holes by an increase in the pressure and discharging brine cooling the tubular electrode,
The cooling structure in which the diameter of the small hole is set so that the physiological saline solution in the internal space of the tubular electrode is not discharged through the small hole when the tubular electrode is not heated. The tubular electrode according to claim 1, wherein the physiological saline solution in the internal space of the tubular electrode discharges the physiological saline solution through the small pores due to evaporation in addition to the expansion and an increase in the pressure. Cooling structure. The cooling structure according to claim 1 or 2 , wherein the inside of the tubular electrode is replenished with physiological saline via a check valve.

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