JPH0532098Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surgical device that ejects pressurized liquid and uses the ejected energy to resect living tissue, and relates to an improvement of its pressure detection device.

[Background Art] In recent years, liquid injection surgical devices have been used which perform surgery by ejecting pressurized liquid to a specific body part. Liquid injection surgery allows selective removal and release of soft areas and relatively hard areas such as muscles and blood vessels, which has the effect of suppressing bleeding during surgery and can be used in conjunction with other surgical devices. , or used effectively alone.

Regarding devices, various improvements have been made, such as a handpiece that incorporates a means for sucking and discharging the injected liquid into the nozzle, and a pressurizing means that takes sterilization into consideration.

[Problems to be solved by the invention] It goes without saying that in such a surgical device, due to the special nature of medical care, it is necessary to eliminate the negative effects on the living body due to misuse, including human error. In particular, in the liquid injection surgical method that is the subject of this application, since the injection pressure of the liquid has a significant effect on living organisms, it is an important technical point to accurately detect and control the pressure. be.

However, in conventional devices, mechanical pressure detection and control means and electrical pressure detection means were used, but there was no mechanism to determine whether pressure was being detected normally, and pressure problems caused by problems in the detection means were not available. There were cases in which it was not possible to quickly and accurately identify a detection error.

For example, with this device, it is necessary to sterilize the liquid-contact parts after the surgery is completed. For this reason, especially in the case of devices that detect pressure electrically, the pressure detection means is temporarily separated from the amplification means for sterilization, and then reassembled after the sterilization process is completed, but connection mistakes at this time often cause problems. There was a problem.

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following configuration. That is, in a liquid injection surgical device comprising a pressurizing means, a nozzle means for ejecting liquid, a piping means for connecting the pressurizing means and the nozzle means, and a valve means for restricting the ejection of liquid from the nozzle means, an electrical pressure detection means disposed in a conduit between the pressure detection means and the nozzle means; an amplification means for amplifying the electrical signal of the pressure detection means; and an amplification means for converting the amplified analog signal outputted from the amplification means into a digital signal. It is composed of a converting means for converting the signal, and a display means for displaying the signal output from the converting means, and a voltage is applied between the pressure detecting means and the amplifying means via a resistor, and the applied voltage is transferred to a capacitor. It is grounded through.

[Operation] Hereinafter, the operation of the present invention will be explained in detail based on the illustrated embodiment.

FIG. 1 shows an embodiment of the apparatus according to the present invention, in which numeral 1 denotes a pump as pressurizing means. 2
is a nozzle (nozzle means), which is integrated with a valve 3 (valve means) to form a so-called hand piece 4. 5 is a hose (piping means) that connects the pump 1 and the hand piece 4. 6 is pump 1
This sensor is a pressure detection means disposed at an appropriate position on the hose 5 from the pump 1 to the hand piece 4, between the pump 1 and the hose 5, or at an appropriate position on the discharge side of the pump 1. 7 is an amplifier (amplification means);
8 is an A/D converter (A/D conversion means), and 9 is a display (display means). Effectively, arithmetic means 10 are arranged between amplifier 7 and A/D converter 8.
11 is a power supply circuit connected to the circuit connecting the sensor 6 and the amplifier 7, with a resistor 12 interposed therebetween; 13 is a grounding circuit arranged in parallel with the power supply circuit 11, with a capacitor 14 interposed therebetween; Become. For the voltage V _D applied to the power supply circuit 11 , a voltage value is selected that is higher than the rated output voltage V _nax of the sensor 6 in the normal usage state and does not have an adverse effect on the sensor 6 .

Under normal usage conditions, pump 1 to nozzle 2
When pressure is generated in the pressurizing circuit, the sensor 6 placed at an appropriate position in the pressurizing circuit generates a voltage corresponding to the pressure, which is amplified by the amplifier 7 and A/D converter 8 The signal is converted into D and displayed digitally on the display 9. However, if the power transmission cable of sensor 6 is not connected properly due to a confirmation error during device assembly, the power supply circuit 11 and sensor 6
The circuit between the two is cut off. Therefore, since the display 9 displays a value unrelated to the actual pressure value, there is a risk of unexpected liquid ejection from the nozzle 2, and it takes time to investigate the cause of the pressure increase failure. .

According to the present invention, in the case of the connection error,
The signal circuit from sensor 6 is cut off, and power supply circuit 1
1 comes into play. In other words, the voltage is gradually increased while the power is supplied through the resistor 12 and charged to the capacitor 14, and after the capacitor 14 is charged, the supplied voltage passes through the amplifier 7 and the A/D converter 8, and then increases depending on the supplied voltage. It is displayed on the display 9 as a value. However, the power supply voltage V _D is the rated output voltage V _nax of the sensor 6
Since it is larger than , it can be determined by the calculation means 10, and control may be performed to display an abnormal message when the input voltage to the amplifier 7>V _nax .

Here, a more detailed electrical explanation will be given. In normal usage conditions, that is, in a state where the sensor 6 is normally connected, the voltage applied to the power supply circuit 11 acts on the sensor 6 side, but the resistance value of the resistor 12 arranged in the power supply circuit 11 is the resistance value of the sensor 6. Most of the applied voltage is reduced by the resistor 12, and the voltage applied to the sensor 6 becomes an extremely small value. Specifically, to explain based on the equivalent circuit of the sensor 6 shown in FIG. 2, the influence ΔV _S on the output voltage of the sensor 6 due to the internal impedance R _S of the sensor 6 is ΔV _S =V _O −V _O ′ = R _S (V _D −V _O ′) / (R _S + R _L ) = R _S・V _D / (R _S + R _L ) − R・V _O ′ / (R _S +
R _L ). In the device devised in this application, the pressure is 1Kgf/cm ²
It is necessary to recognize the pressure in the width of 0.1 Kgf/cm ^{2 or less, and it can be said that it is sufficient in terms of pressure detection accuracy if the influence on the output of the sensor 6 is suppressed to 0.1 Kgf/cm 2} or less. Output voltage of sensor 6
V _O ' is 0 for changes in detection pressure from 0 to 50 Kgf/cm ²
Assuming a change of ~5V, to suppress the influence of impedance R _S on the output voltage to within 0.01Kgf/cm ² , that is, to suppress the voltage change within 0.01V, from equation (1), ΔV _S =V _O −V _O ′=R _S・V _D / (R _S + R _L ) −R・V _O ′/(R _S +R _L ) = R _S・V _D / (R _S +R _L ) −RV _O ′ (R _S +R _L )＜0.01 All you have to do is satisfy the relationship.

Here, for a change in V _O ' of 0 to 5 V, the voltage change is maximum when V _O ' = 0 V according to the above formula, so if we calculate with V _O ' = 0 V, ΔV _S = R _S · V _D / (R _S + R _L ) < 0.01 (100V _D -1) R _S < R _L. Here, if V _D = 15V, the resistance of R _L is
It is sufficient to set it to a value larger than 1499 times R _S.

With R _L set by the above calculation, the pressure detected by the sensor 6 is outputted from the sensor 6 as a voltage based on the above formula, but as mentioned above, among the voltages applied from the power supply circuit 11, Since the amount acting on the sensor 6 is minute, the effect on the voltage output from the sensor 6 can be ignored. Therefore, the output voltage from the sensor 6 is
The pressure is detected effectively.

On the other hand, if the sensor 6 is not installed properly, or if a disconnection, poor contact, or other failure occurs inside the sensor 6, the circuit between the power supply circuit 11 and the sensor 6 will be cut off. Become. In such a case, a circuit is formed on the amplifier 7 side by blocking the voltage applied to the power supply circuit 11 on the sensor 6 side. However, since the impedance of the amplifier 7 is high, the charge applied to the power supply circuit 11 does not flow all at once to the amplifier 7, and a portion of the charge is transferred to the capacitor 14.
and the rest flows to the amplifier 7. In this way, the voltage sent to the amplifier 7 gradually increases due to the charge stored in the capacitor 14, and finally reaches the voltage supplied to the power supply circuit 11. That is,
A voltage V _D higher than the output voltage V _nax of the sensor 6 is input to the amplifier 7 .

[Example] Specifically, it is possible to implement as follows. First, if the supply voltage V _D to the power supply circuit 11 is set higher than the rated output voltage V _nax of the sensor 6 as described above, a voltage signal higher than V _nax will be detected as shown in Fig. 3. Sometimes it can be judged as abnormal. According to another method, the voltage
Calculate the rate of increase in V _O = ΔV _O /ΔT. sensor 6
The rate of increase A ₁ = determined by the time constant of the resistor 12 and capacitor 14 when the is not properly arranged.
The time constant is determined so that ΔV ₁ /ΔT ₁ is greater than the maximum sensor output voltage increase rate A ₂ = ΔV ₂ /ΔT ₂ due to pump 1 drive, and an abnormality is determined when the increase rate A exceeds A ₁ The decision is made by determining whether the pressure rise is due to the drive of the pump 1 or due to an abnormality.

An example of actual voltage, resistance, and capacitor capacity for performing such processing is as follows.

V _D = +15V, V _nax = +6V, value of resistor 12 = 2MΩ, capacitance of capacitor 14 = 1μF.

[Effects of the invention] As described above, according to the invention, it is possible to accurately detect poor connections, disconnections, and sensor failures caused by unconnected signal cables caused by human error or faulty equipment. This allows for quick recovery from unexpected equipment troubles.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the invention, Fig. 2 is a diagram showing an embodiment of the invention including an equivalent circuit of a sensor, Fig. 3 is a diagram showing voltage changes according to the invention, and Fig. 4. is a diagram similarly showing the rate of change in voltage. 1...Pump, 2...Nozzle, 3...Valve,
4...Handpiece, 5...Hose, 6...Sensor, 7...Amplifier, 8...A/D converter, 9...
Display device, 10... calculation means, 11... power supply circuit,
12...Resistor, 13...Grounding circuit, 14...Capacitor.

Claims (1)

[Scope of utility model registration request] A liquid injection surgical device comprising a pressurizing means, a liquid ejecting nozzle means, a piping means for connecting the pressurizing means and the nozzle means, and a valve means for restricting the ejection of liquid from the nozzle means. an electrical pressure detection means disposed in a conduit between the nozzle means; an amplification means for amplifying the electrical signal of the pressure detection means; and an amplification means for converting the amplified analog signal output from the amplification means into a digital signal. It is composed of a converting means and a display means for displaying a signal output from the converting means, and applies a voltage between the pressure detecting means and the amplifying means via a resistor, and also applies the applied voltage via a capacitor. A pressure detection device characterized by being grounded.