JPH0361448B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] There are two methods for measuring blood pressure, intracranial pressure, intrauterine pressure, etc., including directly inserting a small pressure transducer into the body, and measuring biological pressure using a catheter. There are two ways to measure the pressure using a pressure transducer outside the body. The present invention relates to improvements in pressure sensors in the former method.

[Prior art]

A pressure sensor with a built-in pressure transducer at the tip of the catheter has less disturbance in the pressure waveform due to catheter vibration, which is seen with external transducer types, and there is no delay or blunting of the waveform, making it possible to accurately measure in-vivo pressure. Particularly useful for measurements.

However, since the pressure-receiving surface is directly inserted into the body, the environment such as temperature, humidity, and osmotic pressure of this part changes significantly before and after insertion, and depending on the insertion location. On the other hand, the coating material that encloses the pressure transducer element is a plastic material such as synthetic rubber or urethane, and its water absorption properties have the disadvantage of causing drift in the baseline (pressure reference point) and changes in sensitivity.

[Purpose of the invention]

Therefore, the present inventors conducted various studies with the aim of improving the above-mentioned drawbacks and obtaining a sensor for measuring in-vivo pressure that has excellent stability during measurement and improved safety and antithrombotic properties. Summer.

[Structure of the invention]

As a result, a film made of metals such as gold, silver, nickel, platinum, palladium, titanium, or alloys is attached to the pressure receiving part of the pressure sensor or the entire catheter by electroplating, vacuum deposition, sputtering, etc. By letting
It has been discovered that a pressure sensor with low water absorption and high stability and antithrombotic properties can be obtained.

One embodiment of the present invention will be described in detail with reference to the drawings.

In Figure 1, a diaphragm 1, a piezo element 2,
3, 4, 5, a catheter-type pressure sensor consisting of a metal plate 6, a connecting rod 7, a housing 8, a plastic coat 9, a metal membrane 10, and a catheter body 11 is shown.

When pressure is transmitted to the diaphragm 1 through the metal membrane 10 and the plastic coat 9, the connecting rod 7 connected thereto pushes down the metal plate 6, causing distortion. Four piezo elements 2, 3, 4, and 5 are bonded to the top and bottom of the metal plate 6 as shown in FIG. 1, thereby forming a bridge circuit as shown in FIG. When pressure is applied, the piezo elements 2 and 3 on the metal plate 6 contract, and the piezo elements 4 and 5 on the opposite side expand, so the resistance value of each piezo element changes, and a voltage proportional to the resistance change is created within the bridge. Current flows. This output current is passed through the catheter to an amplifier system and the pressure is measured. The piezo element may be provided only on one side of the metal plate 6, and in this case, 2 and 3 in FIG. 2 are fixed resistors.

According to the present invention, the material of the surface metal film is gold,
Single metals such as silver, platinum, palladium, nickel, etc. or alloys are good, and the thickness is 0.005μm to 0.5μm.
However, for the purpose of preventing water permeability,
It is more desirable if the thickness is 0.03 μm or more. Further, from the standpoint of antithrombotic properties, a thickness of 0.05 μm or more is desirable. In terms of adhesion strength, it is best to keep it as low as possible; if the thickness is 0.5 μm or more, there is a risk of peeling off when the catheter is bent.

In the following, an example of measuring internal pressure in a living body according to the present invention will be described. Using an adult mongrel dog weighing 10 to 15 kg, the carotid pulse and jugular vein were ligated cranially, and a sensor with gold sputtered on the surface was inserted from the side toward the heart, with the pressure receiving part of the sensor located at the origin of each aorta. It was placed so that it was in the central and central veins. 1 day after detention
Arterial pressure waveforms and right atrial pressure waveforms were measured on the 3rd and 5th days, but there was no slowing of the waveforms, which was thought to be due to thrombus, and the blood pressures showed reasonable values. Also, detention 5
The autopsy findings on the same day showed a slight thrombus in the carotid arteries and veins where blood flow was blocked, but no thrombi were found in the pressure-sensitive areas, and good results were obtained regarding antithrombotic properties. The reliability of the measured values was also maintained.

〔Effect of the invention〕

As described above, the present invention has excellent stability, safety, and antithrombotic properties as a sensor for measuring various internal pressures in a living body, and is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a catheter-type pressure sensor showing one embodiment of the present invention, and FIG. 2 is a diagram of its bridge circuit. In the figure, 1 is a diaphragm, 2, 3, 4 and 5
is a piezo element, 6 is a metal plate, 7 is a connecting rod, 8 is a housing, 9 is a plastic coat, 10 is a metal film,
11 is a catheter body...

Claims (1)

[Claims] 1 It has a pressure-receiving surface on the tip or the side of the tip, and consists of a diaphragm on the pressure-receiving surface, a pressure transducer, a catheter, etc., and has a metal film made of gold, platinum, silver, nickel, etc. attached to the surface to improve stability and A sensor for measuring in-vivo pressure with improved antithrombotic properties.