JPH0442009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an indwelling blood pressure monitor that can accurately detect blood pressure in arteries and veins in the body.

Currently, measuring blood pressure of patients in operating rooms, ICUs (intensive care units), and CCUs (cardiac care units) is extremely important in understanding the patient's progress after surgery.

In recent years, with the development of compact pressure sensors along with the development of IC technology, external blood pressure monitors used to measure a patient's blood pressure have become compact and can be easily attached to the patient's wrist, upper arm, etc. using adhesive tape. It became a convenient thing.

However, in actual measurements, as shown in Figure 1, a blood pressure monitor that measures blood pressure outside the body consists of a puncture part A that punctures into the patient's body D, and a small pressure sensor B.
In this embodiment, the two are connected by a tube C at a certain distance. Therefore, it is inconvenient to remove air bubbles from the tube beforehand during measurement, or to remove the blood pressure monitor during blood coagulation or measurement. Furthermore, conventional external blood pressure monitors have had various difficult problems in that they are affected by the compliance of the puncture needle, tube, and blood pressure monitor itself, making it impossible to record electrical waveforms that correspond to accurate blood pressure.

The present invention has been developed in view of the above-mentioned conventional problems, and its purpose is to easily puncture a patient's artery or vein at a desired position, and to maintain the needle continuously for a long time while indwelling in the blood vessel. An object of the present invention is to provide a device that can measure blood pressure in a stable state.

That is, the indwelling blood pressure type of the present invention consists of a blood pressure sensor and a guide tube for inserting and holding the blood pressure sensor. A flexible tube provided with a pressure receiving hole, a base having a through hole through which atmospheric air can be introduced into the tube at a position facing the pressure receiving hole, and a pressure receiving diaphragm provided between the through hole and the pressure receiving hole. A strain gauge for detecting pressure is arranged on the pressure receiving diaphragm,
A strain gauge for detecting bending is arranged on the outer peripheral surface of the pressure receiving diaphragm, and a pressure element placed on the base, and an electrically insulating material provided between the pressure receiving hole and the pressure element. The guide tube has a thin tip and is flexible, and the inner cavity wall has a concave groove and can maintain airtightness when the blood pressure sensor is inserted. It is characterized by this.

According to the present invention, the puncture into the patient's internal blood vessel is performed through the guide tube.
The blood vessel can be easily punctured at the desired location. Moreover, since the blood pressure sensor inside the body is maintained in a protected state by the guide tube, blood pressure can be measured in a stable state even during long-term measurements.

Further, in the blood pressure sensor of the present invention, the distal end portion of the pressure receiving diaphragm can directly contact the blood of the object to be measured, so that the pressure of the blood can be detected with high accuracy. Moreover, the resulting electrical pressure waveform is accurate and free of distortion, since it is not affected by the traditional drawbacks of bubble removal and compliance due to long tubes. Therefore,
Very useful information can be obtained for analyzing blood pressure in blood vessels.

Further, both the guide tube and the flexible tube used in the blood pressure sensor of the present invention are made of flexible materials. Moreover, the distal end is made as thin and flexible as possible so that it can adapt to the patient's movements even after being inserted into the blood vessel that is the subject to be measured.

However, too extreme patient movement,
In other words, when bending occurs in the guide tube and flexible tube, the pressure element is deformed because the plate thickness of the pressure element is very thin, and an output is generated due to the bending.Whether the output is due to actual blood pressure or the output due to the bending. become indistinguishable. According to the present invention, if a malfunction occurs, it can be recognized immediately, and blood pressure can be measured with higher accuracy.

Embodiments of the present invention will be described below with reference to the drawings.

The in-body sphygmomanometer which is an embodiment of the present invention is the second embodiment of the present invention.
As shown in the figure, it consists of a flexible guide tube 1 and a blood pressure sensor 2 inserted into the guide tube 1. Further, in the figure, 3 is a dedicated monitor device that displays measured values.

The guide tube 1 is made of a material such as polyethylene or Teflon, and has an excellent surface smoothness.
It has a tapered shape 11 that gradually becomes larger in diameter from the tip to the base, and a collar 12 made of polyethylene is integrally formed at the base. Further, the inside of the guide tube 1 is smooth and has vertical grooves in its length direction to prevent blood from coming into close contact with the guide tube during long-term measurements.

The blood pressure detection portion disposed at the tip of the blood pressure sensor 2 includes a hollow flexible tube 21 as shown in FIG.
sealed by. A pressure receiving hole 23 is provided on the side surface at a predetermined distance from the tip. An insulating base 22b on which a pressure element 24 is installed is provided at a position facing the pressure receiving hole 23.

As shown in FIG. 4, the pressure element 24 has a pressure receiving diaphragm 25 etched into a rectangular shape by chemical etching. The pressure element 24 has a length of 1.5 mm, a width of 0.5 mm, and a thickness of 0.15 mm, and the sensitive diaphragm 25 has a length of 0.4 mm, a width of 0.2 mm, and a thickness of 0.15 mm.
It is about 8 μm. Four strain gauges 25a, 2 are mounted on the pressure receiving diaphragm 25 by a diffusion method.
5b, 25c, and 25d are formed, of which two strain gauges 25a and 25b are installed in the peripheral portion. The strain gauges 25a, 25b, 25c, 25d
Both ends of the gauge are connected by low-resistance lead portions 26 using a diffusion method, and these lead portions and the gauge are integrally formed at the same time during the diffusion process. This lead portion 26 is called a diffusion lead,
An aluminum electrode 27 is provided at the end of the diffusion lead by vapor deposition.

A SiO ₂ film is formed on the entire upper surface of the pressure element 24 except for the aluminum electrode 27, and the strain gauges 25a, 2
5b, 25c, 25d and the diffusion lead 26 are electrically insulated.

Gold wires 28 each having a diameter of about 50 μm are connected to the aluminum electrodes 27 by ultrasonic bonding, so that electrical signals can be extracted to the outside. In order to extract the electric signal, a full bridge circuit 25e is constructed with four gauges 25a, 25b, 25c, and 25d as shown in FIG.

The input voltage of the full bridge circuit 25e is applied to the aluminum electrodes 27f and 27g, and the output voltage is taken out from the aluminum electrodes 27h and 27i. When pressure is applied to the pressure receiving diaphragm 25, the gauge 25 in the center part
The resistance values of the gauges 25c and 25d at the periphery decrease while the resistance values of the gauges 25c and 25d at the periphery increase. Since the amount of change is proportional to the pressure, the full bridge circuit 25
From e, it is possible to detect an electrical signal that is effectively proportional to the pressure.

In addition, two pairs of bending stress detection strain gauges 214a, 214b, 214c,
214d is formed by thermal diffusion or ion implantation of impurity boron. and the strain gauge 214a,
214b, 214c, and 214d are wired to an electrode 216 using aluminum vapor-deposited wires 215, and integrally constitute a bridge circuit 214e. An electrical signal proportional to the bending stress can be effectively detected from the bridge circuit 214e.

The base 22 is made of stainless steel, and its overall shape has a diameter of 1.15 mm to match the inner diameter of the flexible tube 21 of 1.17 mm.
It has a cylindrical shape with a length of 6.2 mm and a flat element installation part on which the insulating base 22 is placed. An introduction hole 22c with a diameter of 0.5 mm is provided for introducing the. Further, an introduction groove 22d for introducing a reference pressure is provided connected to the introduction hole 22c, and the introduction groove 22d is connected to the flexible tube 2 in order to keep the zero point of the pressure element 24 stable.
It is connected to the atmosphere through the inside of the pressure receiving diaphragm 25, so that atmospheric pressure can be introduced to the lower surface of the pressure receiving diaphragm 25. Therefore, pressure measurements are performed using atmospheric pressure as a reference.

Further, a lead hole 22e having a diameter of 0.5 mm is passed through the other end of the base 22 toward the element installation portion, and a lead wire 29 is passed through the lead hole 22e and fixed with an epoxy adhesive.

The pressure element 24 placed on the element installation part is not firmly fixed to the insulating substrate 22b with an adhesive or the like as in the past, but is simply installed, and the pressure element 24 is not firmly fixed to the insulating substrate 22b using an adhesive or the like as in the past. I'm trying to eliminate the influence from the table.

After installing the pressure element 24, the flexible tube 2
The upper surface and periphery of the pressure element 24 installed on the side surface of the pressure element 24 inside the pressure receiving hole 23 is filled with a protective film 211 made of silicone rubber to perform pressure sealing. The protective film 211 is used not only for pressure sealing but also for improving electrical insulation and mechanical safety.

Furthermore, the pressure receiving hole 23 at the tip of the blood pressure sensor 2
protrudes from the tip of the guide tube 1 and is slightly long so that it can be immersed directly into the blood within the blood vessel of the subject to be measured and blood pressure can be measured. In addition, a pressure element 24 built into the base of the sensor 2
An electrical connector 212 is disposed to relay the lead wire 29 drawn out from the guide tube 1, and the guide tube 1 is sealed to prevent body fluids such as blood from leaking outside through the guide tube 1 during measurement. Further, a stopper portion 213 is arranged so that the guide tube 1 and the sensor 2 can be easily fitted and removed, so that the two can be fixed.

The output of the electrical connector 212 is input to the dedicated monitor device 3. The dedicated monitor device 3 is shown in FIG. The dedicated monitor device 3 supplies stable power to the sensor 2 and displays the output obtained from the sensor 2.

That is, the bridge circuit 25e that detects the blood pressure of the sensor 2 includes a differential amplifier 31 that amplifies its output to a predetermined signal magnitude, and the operational amplifier 31.
An isolation amplifier 32 is connected to safely amplify the output of the isolation amplifier 32, and a signal processing circuit 33 is provided to process the output of the isolation amplifier 32, and the output of the signal processing circuit 33 is connected to a display meter 34. do. The display meter 34 is engraved so that the pressure applied to the sensor 2 can be directly displayed.

Furthermore, the bridge circuit 214e that detects the bending stress of the sensor 2 has an operating range set for the outputs of the differential amplifier 38 and the error dynamic amplifier 38 that amplify the output to a predetermined signal magnitude. A level setting device 39 is provided, and the output of the level setting device 39 is connected to an alarm device 40a and an alarm lamp 40b, respectively.

On the other hand, a stabilized power supply circuit 36 is connected to the 100V commercial power supply via an isolation transformer 35 to improve safety, and a current limiting circuit 37 is further connected to prevent large current from flowing to the sensor 2. and is connected to the sensor 2.

In addition, for convenience in use, when inserting the guide tube 1, the inner diameter of the guide tube 1 should be smaller than the inner diameter of the guide tube 1.
A removable metal needle 4, which is slightly longer than the guide tube 1 and has a sharp tip, is used. It is used when inserted into a blood vessel that is a subject to be measured.

Due to the above configuration, this embodiment has the following effects. That is, when measuring using this indwelling blood pressure monitor, please follow the steps 6-a to 6-
As shown in Fig. c, when puncturing the blood vessel wall of an artery or vein through the patient's skin and subcutaneous tissue with an indwelling blood pressure monitor, a solid metal needle 4 is first inserted into the guide tube 1 as a preparatory step. Puncture into the blood vessel from an oblique direction while keeping it fixed (Figure 6-a).
In this case, since the tip 4a of the metal needle 4 is sharp and the tip of the guide tube 1 is also tapered 11, it is possible to puncture the target puncture site of the subject extremely easily. . Next, blood vessel D
When the tip of the guide tube 1 is inserted therein, the metal needle 4 is removed (Fig. 6-b), and the blood pressure sensor 2 is inserted into the guide tube 1 instead and fixed (Fig. 6-c). .

Since the guide tube 1 and the blood pressure sensor 2 are both made of flexible materials, they can be positioned along the blood vessel wall without applying undue stress to the subcutaneous tissue or the blood vessel wall after insertion. can. If the guide tube 1 is fixed with surgical tape in this state, the sensor 2 can be left in the patient's body without placing a large burden on the patient.

A pressure receiving hole 23 is provided in the side wall of the distal end of the sensor 2 placed in the blood vessel, and a pressure element 24 is located on the lower surface of the pressure receiving hole 23 via a protective film 211 made of adhesive silicone rubber. There is.

Therefore, when the blood pressure in the blood vessel is applied as hydrostatic pressure to the pressure element 24, the diaphragm of the pressure element 24 is deformed. This deformation is caused by pressure element 2.
Gauge 25 of pressure receiving diaphragm 25 formed above
The resistance values of a, 25b, 25c, and 25d change, resulting in a resistance change proportional to the pressure.

And the gauges 25a, 25b, 25c, 2
The resistance change of 5d is recorded as an electric signal on a dedicated monitor 3.
Output to.

The signal input to the dedicated monitor device 3 is input to a differential amplifier 31 and amplified to a constant magnitude,
The signal is input to the isolation amplifier 32. The signal input to the isolation amplifier 32 is input to the signal processing circuit 33 as a voltage signal.
The signal processing circuit 33 averages the input signal, processes it into maximum value, minimum value, waveform, etc., and outputs it to the display meter 34.

Furthermore, when the extracorporeal indwelling blood pressure sensor 2 is inserted into the blood vessel of the subject, if it receives a bending stress greater than that of the patient, the resistance values of the bending stress detection strain gauges 214a, 214b, 214c, and 214d arranged on the pressure element will change. At the same time, the output signal is output to the dedicated monitor 3, and since the dedicated monitor is equipped with an alarm, it is possible to know any deficiencies in the measurement status by the differential of the alarm, and the operating range of the alarm can be determined in advance. By setting this, if a problem occurs during measurement, it can be recognized immediately and blood pressure can be measured more accurately.

[Brief explanation of the drawing]

FIG. 1 is a state diagram showing the installation state of a conventional external blood pressure monitor, FIGS. 2 to 6-c show Embodiment 1 of the present invention, and FIG. 2 is a configuration diagram of an indwelling blood pressure monitor.
Fig. 3 is a sectional view of the blood pressure sensor, Fig. 4 is a schematic diagram showing the pressure element of the blood pressure sensor, Fig. 5 is a circuit diagram of the dedicated monitor device, Fig. 6-a, 6-b, 6
Figure -c is a diagram showing the mounting state of the blood pressure sensor. 1...Guide tube, 2...Blood pressure sensor,
3... Dedicated monitor device, 4... Metal needle, 21...
... Flexible tube, 22 ... Base, 23 ... Pressure receiving hole, 24 ... Pressure element, 25 ... Pressure receiving diaphragm, 25a, 25b, 25c, 25d ... Strain gauge, 214a, 214b, 214c, 214d ...
...Strain gauge for bending stress detection.

Claims (1)

[Claims] 1. Consisting of a blood pressure sensor and a guide tube for inserting and holding the blood pressure sensor, the blood pressure sensor has a sealed tip and a pressure receiving hole provided in the side surface near the tip. a flexible tube; a base having a through hole through which atmospheric air can be introduced into a position facing the pressure receiving hole within the tube; and a pressure receiving diaphragm provided between the through hole and the pressure receiving hole, the pressure receiving diaphragm a pressure element having a strain gauge for detecting pressure disposed on the top thereof, a strain gauge for detecting bending disposed on the outer peripheral surface outside the pressure receiving diaphragm and placed on the base; and the pressure receiving hole; The guide tube includes an electrically insulating and elastic protective film provided between the pressure element, the guide tube has a thin tip and is flexible, and the inner cavity wall has a groove and the blood pressure sensor is An indwelling blood pressure monitor characterized by having a hollow wall that maintains airtightness when inserted.