JP4169460B2 - Implantable electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a body-implanted electrode, and is particularly suitably used as a thoracoscopic implantable diaphragm pacing electrode by electrical stimulation.
[0002]
[Prior art]
Diaphragm pacing, which provides functional electrical stimulation of the phrenic nerve, is primarily a central alveolar hypoventilation syndrome (a syndrome that presents hypercapnia despite normal lung function; hypoventilation when sleeping) For patients who get worse, that is, they can't take in oxygen and get carbon dioxide) and high cervical cord injury (C6; {sixth from the top of the cervical cord} or more spinal cord damaged by accident or tumor) Has been done.
[0003]
Both of these procedures are intended to ventilate patients who need ventilator assistance to stimulate the phrenic nerve or the diaphragm to artificially breathe, thereby leaving the ventilator . This is because the ventilator interferes with mouth functions such as vocalization and meals and is not portable and has a limited range of action.
Conventionally, the diaphragm pacing electrode is sewn to the phrenic nerve (SURGICAL CLINICS OF NORTH AMERICA, VOL.60, NO.5, OCTOBER 1980, P1055) and directly sewn into the diaphragm (IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL.44) , NO.10, OCTOBER 1997, P921).
[0004]
[Problems to be solved by the invention]
However, it has not become as widespread as cardiac pacemakers. One of the reasons may be that the electrode implantation process is invasive (stress on the human body) because it involves an open thoracotomy.
Therefore, one object of the present invention is to solve this problem and provide an electrode that can be implanted in the body with minimal invasiveness. In particular, it is an object of the present invention to provide a diaphragm pacing electrode that can be implanted with minimal invasiveness under a thoracoscope.
[0005]
[Means for Solving the Problems]
In order to solve the problem, the implantable electrode of the present invention is
In an electrode including a conductor and a rubber insulator covering the conductor, the insulator is
A grasping portion having a through-hole capable of grasping a nerve and having an opening formed on one side of a radial cross section of the through-hole;
An extension extending elongated from the other side of the gripping part;
An upper beak that extends forward from the upper edge of the opening, has a thick tip, and has a small hole at the tip,
With a lower beak extending forward from the lower edge of the opening,
The conductor passes through the extension, and the lower end is exposed to the outside from the end of the extension and the upper end is exposed in the through hole.
[0006]
When using this body-embedded electrode, a thin wire such as a thread is passed through a small hole, and the upper and lower beaks are opened by pulling the thread in the body. Next, move the opening of the gripping part to the nerve using the beak as a guide, fit the nerve into the through hole from the opening, and then hold the nerve by fixing the upper and lower beaks together with fixing means such as a clip Can do. Since the insulator is made of rubber, opening and closing of the upper and lower beaks and enlargement / reduction of the opening are performed by elastic deformation of the insulator. And since the upper end of a conductor is exposed inside a through-hole, a nerve can be stimulated by supplying with electricity to the lower end of the conductor which has come out outside from the end of an extension part.
[0007]
At present, thoracoscopic surgery is widely used as a surgical procedure for various chest diseases. According to the electrode of the present invention, the nerve can be grasped only by fixing the upper and lower beaks to each other by a fixing means such as a clip, so that neither a sewing operation nor a hand touching the electrode is required. Therefore, it is minimally invasive. Since it is easy for a thoracic surgeon who is proficient in thoracoscopic surgery to perform electrode implantation, it is suitable for various treatments such as diaphragm pacing if clinical application is possible.
[0008]
When a sheet having a large number of irregularities in the surface direction is affixed to one or both of the upper and lower beak surfaces, the sheet becomes a non-slip against the fixing means such as the clip, and the fixing means It is preferable because it is difficult to come off from its beak.
In addition, if a reinforcing material is attached to one or both of the lower surface of the upper beak and the upper surface of the lower beak, the beak maintains a predetermined shape during the operation of fitting the nerve, so that the nerve is fitted into the through hole. It is preferable because the operation is easy when the upper and lower beaks are fixed to each other by the fixing means.
Further, as the shape of the conductor, the conductor is exposed in the through hole from the base of the upper beak through the thick part of the gripping part from the extension part, is folded and extends to the base of the lower beak along the wall surface of the through hole. It is preferable. This is because any position on the wall surface of the through hole can be brought into contact with the nerve, and electrical connection is ensured.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. 1 is a perspective view showing an embodiment of an in-vivo electrode, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a rear view, and FIG. 4 is a front view.
The electrode 1 is composed of two conductors 2 and 2 and an insulator 3 made of silicon rubber covering the conductors 2 and 2. The conducting wire 2 is obtained by soldering a combination of three platinum wires having a diameter of 0.03 mm and a stainless steel wire.
[0010]
The insulator 3 includes a grip portion 4, an extension portion 5, an upper beak 6, and a lower beak 7. The grasping portion 4 has a through hole 41 having a wall thickness of 2 mm, a width of 7 mm, and an outer diameter similar to that of a nerve such as the phrenic nerve, for example, a diameter of about 3 mm. An opening 42 is formed on the side. The extension portion 5 has an outer diameter of 2 mm and extends to a length of 300 mm from a position different from the opening 42 of the grip portion 4. The upper beak 6 has a thickness of 1 mm from the upper edge of the opening 42 and extends 5 mm forward, the tip is thickened to about 2 mm, and a small hole 61 having a diameter of 0.5 mm is formed at the tip. A sheet 62 made of net-like silicon is embedded in the lower surface of the upper beak 6. The lower beak 7 extends forward from the lower edge of the opening 42 with a substantially uniform thickness of 0.5 mm, and a sheet 71 of the same quality as the sheet 62 is embedded in the lower surface thereof.
[0011]
The conducting wire 2 passes through the extension portion 5 in the length direction, and the lower end thereof is exposed to the outside from the end of the extension portion 5 and is connected to the connector 8. On the other hand, the upper end of the conducting wire 2 passes through the thick part of the gripping part 4 so as to bypass the through hole 41, reaches the vicinity of the base of the upper beak 6, and then exits into the through hole 41 and turns back. It reaches the base of the lower beak 7 along the inner circumference. Of the conducting wire 2, the platinum wire portion is located on the upper side and the stainless steel wire portion is located on the lower side, and both are joined in the vicinity of the boundary between the grip portion 4 and the extension portion 5. Note that the stainless steel wire portion is processed into a strand shape and coated with Teflon to have a diameter of 0.25 mm. The conducting wires 2 and 2 are separated from each other so as not to short-circuit each other, and the interval between the platinum wire portions exposed in the through holes 41 is set to 3 mm.
[0012]
The insulator 3 may be formed by integrally forming the grip portion 4, the extension portion 5, and the upper and lower beaks 6 and 7 by a normal rubber molding technique, or may be fused after each element is separately molded. In the case of integral molding, the conductive wires 2 and 2 are fixed in a mold and the rubber is poured. In the case of separate molding, the gripping portion 4 is processed into a circular cross section with a silicon rubber sheet and a small hole for passing the conductor 2 is formed. Then, the conducting wire 2 is passed through a silicon tube, the tube is heat-softened to form an extension portion 5, and heat-sealed to the grip portion 4.
[0013]
When the body-embedded electrode 1 is used, the upper and lower beaks 6 and 7 are opened by passing the thread through the small hole 61 and pulling the thread in the body. Next, using the beaks 6 and 7 as a guide, the opening 42 of the gripping portion is moved to the nerve not shown, and after the nerve is fitted into the through hole 41 from the opening 42, the upper and lower beaks 6 and 7 are fixed to each other with clips. Thus, the nerve can be grasped. All these operations are performed under a thoracoscope. The grasped nerve contacts the platinum wire portion of the conducting wire 2 in the through hole 41.
[0014]
Since the insulator 3 is made of silicon rubber, the upper and lower beaks 6 and 7 are opened and closed and the opening 42 is enlarged and reduced by elastic deformation of the insulator 3. However, since the sheet 61 is provided on the lower surface of the upper beak 6, it does not deform excessively. And since the upper end of the conducting wire 2 exposed inside the through-hole is in contact with the nerve, the nerve can be stimulated by connecting the connector to a nerve stimulating device outside the body.
[0015]
Examples of the clip include Riga clip ERCA released by Johnson & Johnson Co., Ltd. Since the tip of the upper beak 6 is formed thick, and the sheet 71 is provided on the lower surface of the lower beak 7, the thick part and the sheet 71 serve as a slip stopper for the clip. Therefore, there is no worry of the clip coming off during nerve stimulation. The connector 8 is exemplified by a micro connector A-2P (manufactured by Unique Medical Co., Ltd.).
The shape of the conductor is not limited to the conductive wire 2 described above, and the upper end of the conductive wire 2 may protrude directly from the extension portion 5 into the through hole 41 as shown in the cross-sectional view of FIG. This may be backed by the wall surface of the through hole 41.
[0016]
【Example】
In order to confirm the effect of the present invention, a living body experiment was conducted using 5 adult adult dogs (15-25 kg). Thoracoscopic surgery: Olympus video monitor, Olympus video thoracoscope (a metal tube with a diameter of about 5 mm and a length of about 30 cm, with a CCD camera and light source at the tip), 5 mm port, 7 mm port Thoracoscopic forceps were used. The procedure is as follows.
[Experimental procedure]
[0017]
1. As a premedication, general anesthetic ketamine hydrochloride intramuscular injection (brand name ketalal intramuscular injection, Sankyo Co., Ltd.) 10 mg / kg is injected intramuscularly, transferred to the operating table, blood is collected from the right femoral artery, and spontaneous breathing. Measure blood gas partial pressure in room air. Shaving the forelimbs (front legs), securing a venous line (start of infusion), intravenous injection of pentobarbital salt (trade name Nembutal, manufactured by Dainippon Pharmaceutical Co., Ltd.) 10 mg / kg Introduction. Anesthesia was maintained by inhalation of the inhalation anesthetic halothane (trade name Frocene, manufactured by Takeda Pharmaceutical).
[0018]
2. Oral intubation of endotracheal tube and artificial respiration started. In the supine position (upward), the groin is shaved to expose the right femoral artery, the arterial line is inserted, and blood pressure, heart rate, and blood gas are monitored. Measured by collecting blood gas from the arterial line with artificial ventilation of both lungs. 3. Shaving the neck (neck), exposing the cervical trachea, and tracheotomy. Remove the endotracheal tube that has been orally intubated, re-intubate through the tracheostomy, and observe the tube with the left main bronchus (to the left of the trachea branching left and right) while observing with a bronchoscope. To do. This will ventilate only the left lung.
[0019]
4. Set to the left lateral position (position to sleep with the left side down), shave the right chest, open a wound of about 2cm in the right chest, and insert 5mm and 7mm ports between the right heel in two locations respectively. (4 places in total) Observe the inside of the thoracic cavity with a video thoracoscope, expel (displace) the right lung to the caudal (lower) side, check the superior vena cava, and run just above the superior vena cava (directly above) Check the right phrenic nerve.
[0020]
5. Remove the right phrenic nerve from the superior vena cava using thoracoscopic release forceps, taking care not to damage the nerve. A 4-0 nylon thread is passed through the small hole 61 of the electrode 1 of the above embodiment.
6. When sufficiently peeled, the electrode 1 is inserted into the thoracic cavity, the thread passed through the small hole 61 is pulled, the upper and lower beaks 6 and 7 are opened, and the phrenic nerve is grasped. When gripped, the beaks 6 and 7 are fixed using the rig clip ER220. Confirm the fixation and remove the nylon thread.
[0021]
7. Lead the connector 8 of the electrode 1 out of the body through a subcutaneous tunnel (tunnel made under the skin), connect one of the conductors 2 to the ground, and connect the other one to the Nihon Kohden Electric Stimulator SEN-3301 Connected to the cathode of the patient, send electrical stimulation, and confirm thoracoscopic contraction of the phrenic nerve. That is, confirm that the muscle (diaphragm) moves on the video monitor. The anode of the stimulator is connected to the skin as an indifferent electrode.
[0022]
8. Pull out the intubation tube a few centimeters, return the tip of the tube to the trachea, stop ventilation of the left lung only, remove the 5mm and 7mm ports as both lung ventilation, insert a 20fr trocar from one port insertion section, and Heimlich Connected to the valve (by letting the air that has entered the thoracic cavity escape outside the body, the right deflated right lung is inflated again). The remaining port insertion part was closed with sutures, and blood gas was measured with both lungs. Remove the ventilator and pace the phrenic nerve while monitoring room airflow, ie ventilation flow rate and volume without the addition of oxygen. The pacing conditions were [main interval: 3 sec (RR20 / min), interval: 20 msec, duration (stimulation time): 150 μsec, train (continuous): 65 times, and stimulation was twice the threshold (about 1-2 V)]. During this time, anesthesia of the experimental dog was maintained by intravenous injection of Nembutal (Pentobarbital, Dainippon Pharmaceutical Co., Ltd.), and spontaneous breathing was completely eliminated.
9. Measure the carbon dioxide partial pressure (paCO ₂ ) of the blood gas at 5, 15, 30, 45, 60 min (min) after the start of pacing. The measurement results are shown in FIG.
[0023]
[Evaluation]
In blood gas data, there is a gradual increase in pCO ₂ (increase in carbon dioxide in the blood) after 60-minute pacing (see Fig. 6), which is neuromuscular fatigue (the phrenic nerve and the diaphragm are fatigued by electrode stimulation). However, bilateral pacing should be considered. In the literature, in adult clinical cases, pacing was started 12-14 days after electrode implantation in the bilateral phrenic nerve, and pacing time was monitored from 2-3 minutes per hour to several days a day while monitoring neuromuscular fatigue. It is said that it will be carried out according to a strict schedule that takes at least 6 weeks. During this schedule, the muscle fibers of the diaphragm are replaced with non-fatigueing fibers, fatigue-registant fibers. I think that an increase in pCO ₂ is inevitable as one side of pacing in this experiment. However, if evaluation is performed based on a strict schedule such as that currently performed in clinical cases so as to prevent neuromuscular fatigue, the possibility of clinical application can be expected.
[0024]
【The invention's effect】
According to the present invention, an electrode can be implanted under a thoracoscope. Therefore, as an expected effect, the adaptation of diaphragm pacing has spread to cases that cannot withstand general surgical invasion, and for many patients with ventilatory insufficiency who have been confined to the ventilator and have been bedridden until now, ventilators Withdrawal, closure of the tracheostomy, and opening up a path to return to social activities. Electrode stimulation can be expected not only for the phrenic nerve but also for multiple organs in the future.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an implantable electrode according to an embodiment.
FIG. 2 is a longitudinal sectional view of the electrode.
FIG. 3 is a rear view of the same.
FIG. 4 is a front view of the same.
FIG. 5 is a longitudinal sectional view showing an implantable electrode according to another embodiment.
FIG. 6 is a graph showing the time course of carbon dioxide partial pressure (paCO ₂ ) before and after diaphragm pacing using the electrode of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Implantable electrode 2 Conductor 3 Insulator 4 Gripping part 5 Extension part 6 Upper beak 7 Lower beak 8 Connector

Claims (4)

In an electrode including a conductor and a rubber insulator covering the conductor, the insulator is
A grasping portion having a through-hole capable of grasping a nerve and having an opening formed on one side of a radial cross section of the through-hole;
An extension extending elongated from the other side of the gripping part;
An upper beak that extends forward from the upper edge of the opening, has a thick tip, and has a small hole at the tip,
With a lower beak extending forward from the lower edge of the opening,
The body-embedded electrode, wherein the conductor passes through an extension portion, the lower end thereof is exposed to the outside from the end of the extension portion, and the upper end is exposed in the through hole. The electrode according to claim 1, wherein a sheet having a large number of irregularities in the surface direction is attached to one or both of the upper surface of the upper beak and the lower surface of the lower beak. The electrode according to claim 1, wherein a reinforcing material is attached to one or both of the lower surface of the upper beak and the upper surface of the lower beak. The said conductor is exposed in a through-hole from the base of an upper beak through the thick part of a holding part from an extension part, and it is turned up and extends to the base of a lower beak along the wall surface of a through-hole. Electrodes.

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