JPH0243362Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a catheter used for invasive blood pressure measurement that directly measures blood pressure changes in blood vessels.

In invasive blood pressure measurement, a catheter is placed in the blood vessel of the living body, and the blood pressure changes are transmitted to the pressure transducer at the rear using the fluid filled in the catheter, which converts the blood pressure changes into electrical signals and generates waveforms. Or the display area is recorded as a numerical value.

However, the tip of a conventional catheter used for such invasive blood pressure measurement has a simple tube-shaped opening, and the fluid inside the catheter, such as physiological saline and blood, does not flow through the tip opening. are in contact with each other.
Therefore, the turbulent flow of blood in the catheter tip region during or after catheter insertion and the diffusion of the fluid within the catheter into the blood over time result in blood entering the catheter. Condensation occurs on the inner wall of the catheter, and the constriction of the catheter caused by this condensation causes a large error in blood pressure measurement. Furthermore, if fluid leaks in the catheter system, blood will immediately flow backwards, making it very easy for blood to clot. Therefore, in order to prevent this blood clot, in conventional invasive blood pressure measurement, a solution prepared by diluting heparin in physiological saline to 1 to 10 units/ml is injected into the catheter every 15 to 60 minutes. This required extremely troublesome operations.

In view of this point, it is an object of the present invention to provide an invasive blood pressure measurement catheter that does not cause blood clots on its inner wall. And to achieve this purpose,
This invention focuses on the existence of so-called magnetic fluid, which is made by colloidally dispersing ultrafine ferromagnetic particles in a base liquid, and creates a magnetic field at the open tip of the catheter, and injects the magnetic fluid into this magnetic field. By holding it, a liquid diaphragm can be formed.

Next, the present invention will be explained based on the illustrated embodiments.

10 is a catheter composed of a flexible tube 1 and an injection needle 2 connected thereto. According to the present invention, a recess is formed in the distal end of the catheter, that is, the distal end of the tube 1 having an outer diameter of, for example, 0.4 mm. A permanent magnet 3 is fixed. This permanent magnet has magnetic poles facing each other on the inner surface of the tube 1, so that the vicinity of the opening 4 of the tube 1 has a magnetic flux density sufficient to attract the magnetic fluid 18.
For example, magnetic fields of several hundred Gauss are being created. The structure after the catheter 10 is the same as that of the conventional one. That is, 12 is a syringe for injecting physiological saline into the catheter 10, 13 is a pressure transducer that detects the blood pressure applied to the tip of the catheter 10 into which physiological saline has been injected, and 14 is a syringe that connects to the injection needle 2 by rotating operation. A three-way socket 15 selectively communicates between the syringe 12, between the syringe 12 and the pressure transducer 13, and between the injection needle 2 and the pressure transducer 13; This is the main body of the measuring device that amplifies the blood pressure signal and displays or records it as a blood pressure signal.

On the other hand, the magnetic fluid 18 held by the magnet 3 should naturally be non-toxic and should be sterilized beforehand. In order to suppress diffusion into the blood, the base liquid is preferably made into an insolubilized magnetic fluid, such as oil used for infusion into people with low fat, and preferably has low viscosity from the viewpoint of frequency characteristics.

Hereinafter, an invasive blood pressure measurement method using the catheter 10 according to the present invention will be described.

First, the tube 1 is communicated with the syringe 12 through the injection needle 2 by operating the three-way pot 14, and physiological saline 19 is injected to fill the tip. Then, as shown in FIG. 2, the tube 1 is inserted into the magnetic fluid 18 housed in the container 20, and the magnetic fluid 18 is attracted and held by the permanent magnet 3 and taken out. As a result, a diaphragm 21 made of the magnetic fluid 18 is formed at the tip of the tube. Subsequently, the tube 1 is inserted into an indwelling needle (not shown) located in the blood vessel to be measured, so as to be ready for measurement. Then, by operating the three-way knob 14, the input tube of the transducer 13 is communicated with the syringe 12, and the syringe 12 is removed to perform zero balance adjustment in the measuring device main body 15. And Mikata Kotuku 14
The pressure transducer 13 is brought into communication with the injection needle 2, and blood pressure measurement is started. During the measurement, the physiological saline 19 is separated from the blood by the diaphragm 21, and no outflow into the living body occurs.

FIG. 3 shows a disposable catheter according to another embodiment of the present invention. That is, this catheter is composed of a tube 31 without an injection needle, and a bag 30.
It is sterilized and packed. A diaphragm 3 made of magnetic fluid is attached to the tip of the tube 31 by a magnet 32 in advance.
3 is formed, the inside of which is filled with a harmless catheter fluid 34, and sealed with a membrane 35 at the rear end. For measurement, the bag 30 is torn and the tube 31 is taken out. Then, the input tube 42 of the pressure transducer 41 housed in a ring-shaped container 40 having a corresponding shape is pushed into the membrane 35 and connected by locking pieces 46 and 47 formed on the tube 31 and the container 40, respectively. let Such a catheter eliminates the need for a three-way socket, and also eliminates the possibility of extruding the fluid inside the catheter or the diaphragm due to an erroneous operation.

In addition, as a method of forming the magnetic pole, a magnetization process or embedding in a tube may be considered. In addition, the inner diameter of the catheter tip, the arrangement of magnetic poles, its formation method, strength, and shape, the viscosity of the base liquid of the magnetic fluid, the water rupture properties, etc., are determined by the desired strength, frequency characteristics, or anticoagulability of the diaphragm. Various shapes can be considered from the viewpoint of cost and the like.

As described above, according to the present invention, a diaphragm can be formed between the catheter internal fluid and blood and its position can be fixed by a simple method of simply forming a magnetic pole for attracting magnetic fluid at the tip of the catheter. Therefore, since blood clots do not occur inside the catheter, measurement accuracy is improved, and instruments and operations for preventing blood clots are not required.

[Brief explanation of the drawing]

Fig. 1 is a measurement device using the catheter of the present invention (the main part is a cross-sectional view), Fig. 2 is an explanatory diagram of forming a diaphragm at the tip of the catheter of the present invention, and Fig. 3
The figure shows a variant of the catheter according to the invention. DESCRIPTION OF SYMBOLS 1...Tube, 2...Syringe needle, 3, 32...Permanent magnet, 4...Catheter opening, 18...Magnetic fluid, 2
1,31...diaphragm.

Claims (1)

[Scope of utility model registration request] A catheter for invasive blood pressure measurement, characterized in that a magnetic pole is formed at the distal end portion, and a magnetic fluid that forms a liquid diaphragm is held in the magnetic pole.