JPS5931330B2 - Gas measurement catheter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catheter that collects one or more gases present in the blood or tissues of a living body and is used in conjunction with an analysis device such as a mass spectrometer.

Various catheters of this type have been developed in the past, the representative ones being U.S. Pat. No. 3,658,053 (Japanese Patent Publication No. 55-4421), U.S. Pat.
No. 448, JP-A-50-80187, etc. are known.

Although each of these conventional devices has structural differences, they utilize a silicone or Teflon membrane as the gas permeable material.

This method of collecting analysis gas using a silicone or Teflon membrane relies on gas diffusion in the silicone or Teflon medium, as will be detailed later.
The drawback was that the response time was very long.

For example, the 90% response time for oxygen gas and carbon dioxide gas of a silicone membrane with a wall thickness of 0.26 Fa is 50 seconds and 60 seconds, respectively, and the response time of oxygen gas and carbon dioxide gas of a Teflon membrane with a wall thickness of 0.05 m is 50 seconds and 60 seconds, respectively. The gas 90% response times were 80 seconds and 130 seconds, respectively.

Such a long response time to gas detection not only delays the response to changes in gas pressure within the body, but also makes it difficult to confirm minute changes.

Furthermore, although the gas permeability of silicone membranes is superior to that of Teflon membranes, they are weak in strength, and if the thickness is made thinner, there is a risk of rupture, making it dangerous to reduce the outer diameter of the catheter.

Furthermore, when gas is collected through a silicone or Teflon membrane, the gas uptake is affected by the gas partial pressure in the blood or tissue and by blood temperature changes; Another drawback was that corrections had to be made each time there was a change.

Therefore, the object of the present invention is to significantly shorten the response time when collecting gas in blood or tissue compared to conventional methods, to avoid adverse effects on living organisms, etc. when collecting gas, and to avoid the problem of temperature changes unlike conventional methods. The object of the present invention is to provide a gas measuring catheter that does not require correction, has high mechanical strength, and is safe.

The present invention provides a catheter for use with an analysis device for collecting one or more gases present in the blood or tissues of a living body, the catheter having an opening in the distal end portion made of a material that does not permeate the gas. A gas measuring catheter is provided, which includes a thin tube having a gas permeable polypropylene hollow fiber porous membrane coated on the outer circumferential surface and one end surface of the thin tube.

Further, the present invention provides a gas measuring catheter in which the gas-impermeable thin tube is made of a metal tube, and gas introduction holes of the required size and number are formed on the side surface of the distal end thereof.

The present invention further provides that the gas-impermeable thin tube is constituted by a metal tube, a porous body or an elastic body is attached to the thin tube so as to protrude from the tube end portion, and a hollow fiber-like porous membrane made of polypropylene is covered thereon. The present invention provides a gas measurement catheter that uses the following methods.

The present invention also provides a gas measuring catheter in which the gas-impermeable thin tube is made of vinylidene chloride or a compound of vinylidene chloride and other plastics, and gas introduction holes of the required size and number are formed on the side surface of the distal end of the tube. Provided.

Furthermore, the present invention provides a gas-impermeable capillary tube comprising a suitable plastic tube coated with vinylidene chloride on the inside and/or outside, and a porous body or an elastic body protruding from the end portion of the tube. The present invention provides a gas measuring catheter in which a hollow fiber porous membrane made of polypropylene is adhered thereon.

Next, the catheter for measuring blood or tissue gas in a living body according to the present invention will be described in detail with reference to the embodiments shown in the drawings.

As shown in FIG. 1, this type of catheter 1 is used by being connected to an analysis device 4 such as a mass spectrometer via a connector 2 with a filter and a connecting tube 3, and being inserted into a blood vessel 5. .

At this time, in the case of conventional catheters, the gas that diffuses through the silicone membrane or Teflon membrane is detected, and in the case of the catheter according to the present invention, which will be described later, the gas that flows in through the polypropylene hollow fiber porous membrane is detected. do.

In either method, to explain the example of blood, the gas sampled through the membrane has a degree of vacuum of about 10-1) on the analyzer side and arterial blood (usually 0.2 partial pressure 100 mHg).
.

Due to the pressure gradient between the CO2 partial pressure (401 mHg), the pressure shifts from the blood side to the catheter side, and equilibrium is eventually reached.

The time it takes to reach equilibrium is the response time, and since it takes time for the pressure (concentration) gradient to become small for equilibrium above 90%, the 90% response time is generally measured.

As mentioned above, it is better for this response time to be as short as possible, but it is influenced by the gas permeability coefficient of the material constituting the membrane.

Table 1 shows a comparison of the properties of the polypropylene hollow fiber porous membrane used in the catheter of the present invention and conventional silicone and Teflon membranes.

As is clear from Table 1 above, when a silicone membrane with a wall thickness of 0.26M is used as in the conventional catheter, the 90 response times for 02 gas and CO2 gas are 50 seconds and 60 seconds, respectively.
When using a Teflon film with an inner thickness of 0.0571 gN, the response times of 90 seconds for 02 gas and CO2 gas are 80 seconds and 130 seconds, respectively. 9 in the case of a hollow fiber porous membrane manufactured by
The 0% response time is only a few seconds, which is very fast and allows various treatments to be performed effectively.

The reason why the polypropylene hollow fiber porous membrane used in the present invention has a significantly shorter response time than the silicone or Teflon membranes used in conventional catheters is thought to be as follows.

The gas permeability coefficient of gas permeable membranes used in catheters is determined by the diffusion coefficient and solubility.
on), and is the amount of light per unit time when a gaseous body is dissolved into a membrane medium from a living body, etc., and the dissolved gas diffuses within the membrane medium and exits.

Silicone and Teflon membranes take advantage of the properties of blood or tissue gases that dissolve and diffuse through these materials, resulting in slower diffusion rates and therefore longer response times. ing.

On the other hand, in the polypropylene porous membrane used in the present invention, after being dissolved in this material, it flows (volume flow) through the countless pores in the material, so the flow is significantly faster than diffusion. Become.

Therefore, their response times vary significantly as shown in the table above.

As described above, the catheter number of the present invention and the membrane material used utilize the so-called diffusion phenomenon as in conventional membrane materials, and the present invention is novel based on a technical idea different from conventional membrane materials. This can be understood from this explanation.

As described above, the amount of gas permeation through the polypropylene hollow fiber porous membrane used in the catheter of the present invention is large.

In reality, if too much is ingested from one blood or tissue, the gas concentration in the ingested area decreases and exceeds the amount of gas diffusing into this area from other areas, causing the measured value to be lower than the actual value. The measurement may become meaningless.

The polypropylene porous membrane used in the present invention has a gas permeability coefficient of the order of 10□4, and it was confirmed that such a situation does not occur.

In addition, when this type of measurement is carried out continuously for a long period of time, if the amount of gas ingested is too large, it will affect the living body, but this problem is not affected by the catheter of the present invention, as will be described later in the examples. It was confirmed that there was no such thing.

Further, the polypropylene hollow fiber porous membrane used in the catheter of the present invention has the following characteristics.

The porosity can be changed over a range of 10 to 60 inches,
The response time can be adjusted depending on the shape of the catheter, and
Gas intake can be optimized.

Furthermore, since it is hydrophobic, there is little decrease in gas permeation efficiency due to wetting.

Furthermore, it has excellent mechanical strength, is flexible and does not break due to bending, and has high tensile strength.

The bursting strength is 5Kp/7 or more, and the permeability pressure is 1
Since it is 0 Kp/d or more, water does not permeate until the bursting pressure is reached.

It also has properties that make it difficult to cause blood coagulation.

Next, various structural examples of the catheter of the present invention and examples in which the same are used for blood gas measurement will be described.

Example I As shown in FIG.
In the configuration example, a side hole 8 is formed at the tip of a gas-impermeable metal tube 7, and a hollow fiber porous membrane 9 made of polypropylene (hereinafter referred to as PP) is coated on the metal tube 7. There is.

This PP hollow fiber porous membrane 9 is hermetically sealed at the distal end 10 by thermal melting, and the metallic tube 7 and the catheter base 11 are entirely brought into close contact by heating and tensioning.

Inside the catheter 6, the mass spectrometer 4 measures 10
Since the vacuum is approximately 1.5 mm, the gas in the blood passes through the PP hollow fiber porous membrane 9 covering the side hole 8, passes through the catheter 6, and reaches the mass spectrometer 4, where it is analyzed. be done.

In this configuration example, the metal tube 7 has an outer diameter of 0.2M.
If eight side holes 8 are opened, the gas permeation area will be 0.25-.

With a porosity of 25% and an air permeation rate of 0.52
History C・d・儂Hg% When using a PP hollow fiber porous membrane 9 with a wall thickness of 0.05 mm, the gas intake per second is 0.
．． 99 x 10" CC/sec.

In this case, the 90-degree response time is very fast, only a few seconds, as shown in Table I, and with this level of gas intake, even if the measurement is continued for a long time, it will not affect the living body.

Embodiment ■ As shown in FIG.
In the configuration example, a gas-permeable porous body 12 such as a sintered body is connected to the tip of a gas-permeable metal tube 7 with an outer diameter that is the same as the outer diameter of the metal tube 7. A hollow fiber porous membrane 9 made of PP is coated on top.

The PP hollow fiber porous membrane 9 is hermetically sealed at the distal end 10 by thermal melting, and is closely attached to the metal tube 7 at the catheter base 11 by heating and tensioning.

The gas in the blood is removed from the tip 10 of the hollow fiber porous membrane 9 made of PP.
and is guided into the catheter 6 via the porous body 12.

The outer diameter of the catheter 6 is 0.571 m, and the gas permeable tip 1
The length of 0 is 4wl11 The porosity of porous body 12 is 30 factor, porosity is 25%, air permeation amount is 0.52X10'c
ccm, /sec -crlt -crn PP of Hg
When using hollow fiber porous membrane 9 (thickness 0.05 m),
The gas intake amount per second is 7.44xlO"cC7historyC.

In this case, the 90% response time is very fast, only a few seconds, as shown in Table I, and this level of gas intake has no effect on living organisms.

Since the porous body 12 is provided, the step of forming side holes in the metal tube 7 is omitted, making manufacturing easier, and gas can be taken in from a wide range.

Example ■ As shown in FIG. 4, the third embodiment of the catheter 6 according to the present invention
In the configuration example, an elastic body 13 such as a spring net having the same outer diameter as the metal tube 7 is supported at the tip of the gas-impermeable metal tube 7 by a relay pipe 14, and a PP hollow fiber-like porous body is placed on top of the elastic body 13. A membrane 9 is coated thereon.

This porous membrane 9 is hermetically sealed at the distal end 10 by thermal melting, and is closely attached to the metallic tube 7 at the catheter base 11 by heating and tensioning.

Gas in the blood passes through the PP hollow fiber porous membrane 9 covering the elastic body 13 and is introduced into the catheter 6 through gaps between the elastic body 13 such as a spring.

In such a configuration, the outer diameter of the catheter is 0.5 mm, the spring length is 4 wl1, the porosity is 15%, the air permeation rate is 0.31 x 10-4, and the Hg PP hollow tube has an air permeation rate of 0.31 x 10-4. When the porous membrane 9 (thickness: 0.0571 gIl) is used, the gas intake amount per second is 7.4xlO'cc/SeC.

In this example, the 90% response time is very fast, a few seconds, as shown in Table I, and this level of intake does not affect the living body.

Furthermore, since the tip is supported by an elastic body, it is flexible and does not put a burden on the blood vessel even when inserted into the blood vessel, which is preferable.

Embodiment ■ As shown in FIG.
In the configuration example, a thick PP tube 15 is coated with vinylidene chloride to a thickness of 10μ on the inner and/or outer surface.
A small diameter part 16 is formed at the tip of the membrane, a side hole 8 is provided in this small diameter part 16, a PP hollow fiber porous membrane 9 is placed over this small diameter part, and the base 17 is fused to the PP tube 15. , the tip portion 10 is hermetically sealed by thermal melting.

The gas in the blood passes through the PP hollow fiber porous membrane 9 covering the side hole 8 and is introduced into the catheter 6.

In such a configuration, if eight side holes 8 each having an outer diameter of 0.2 mm are formed, the gas permeation area will be 25 m1.

Porosity: 25, air permeation: 0.52X 10'CC
P which is C77L/sec -crd -crn Hg
When the P hollow fiber porous membrane 9 (thickness: 0.05 m) is cut into a square, the gas intake per second is 0.99 x 10-5 cc,
&c.

90 response time is only a few seconds as shown in Table I.

Assuming that the total length of the catheter 6 is 300+J, the outer diameter is o, s m, and the wall thickness is 0.3 m, 02. The total gas intake of CO2 and N2 is 4 per second.
．． 93 x 10' CC/sec.

This amount is the PP hollow fiber porous membrane 9 covering the side hole 8.
It accounts for 0.5% of the amount of gas extracted from the gas and has almost no effect on measurements.

Furthermore, since the catheter 6 is flexible, it does not place any burden on the blood vessels.

Embodiment ■ As shown in FIG.
In the configuration example, the tip of the (1) PP tube 15 has a wall thickness coated with vinylidene chloride to a thickness of 10μ on the inner and/or outer surface, and the tip is tapered to have a small inner diameter, and the tip is attached to the porous body 12. 10 is covered with a PP hollow fiber porous membrane 9 sealed by heat melting, and this is inserted into the small diameter tip 18 of the tube 15 and fused.

The gas in the blood is removed from the tip 10 of the hollow fiber porous membrane 9 made of PP.
and is introduced into the catheter 6 via the porous body 12.

In this configuration, the outer diameter is 0.2m and the wall thickness is 0.05M.
, the length of the tip part 10 is 4 mm, the porosity is 25 mm, and the air permeation amount is 0.52 x 10 - 1.
rLHg PP hollow fiber porous membrane 9, empty bone-JL
When using the porous body 12 with a porous body 12 having a porous material ratio of 30%, the gas intake amount per second is 2.98 x 10-5 CC/sec.

The outer diameter of the catheter 6 is set to 0.8w1. , the wall thickness is 0.371
1! If the total length of I11 is 30ON, the total gas intake from sources other than the porous membrane 9 is 4.93 x 10”cc/
sec.

(The amount of m(7) corresponds to 0.17% of the amount of gas collected from the PP hollow fiber porous membrane 9 covering the porous body 12,
It has almost no effect on measurements.

Additionally, the 90-degree response time of this catheter is only a few seconds, as shown in Table I.

Furthermore, gas can be taken in from a wide range, and it can be made thinner than the catheter body, making it easier to insert into blood vessels and the like.

In addition, since the catheter is flexible, it does not place a burden on blood vessels.

For ease of understanding, the data regarding the above embodiments are briefly shown in the following table (2).

As is clear from the above embodiments and the description of the technical concept, the gas measuring catheter of the present invention has many effects as compared to similar conventional catheters, as described below.

(1) The response time to changes in gas partial pressure is short.

(2) Errors do not occur in measured values due to temperature changes in the medium to be measured.

(3) Since the gas intake amount is on the order of 10"Cf,/sec, it is not affected by the speed of blood and does not affect the living body even in long-term measurements.

(4) By using a hollow fiber porous membrane made of PP, the outer diameter of the catheter can be made smaller, the diameter of the side holes can be made smaller, and the number of side holes can be reduced, thereby reducing the risk of membrane tearing and simplifying the catheter production process. Ru.

(5) Blood coagulation is less likely to occur in the PP hollow fiber porous membrane.

The gas measuring catheter of the present invention can be used not only for measuring gases in the blood and tissues of a living body, but also for tissues other than a living body, an artificial heart-lung machine, and the like.

Further, the above-mentioned portions are merely examples of the present invention, and various changes can be made within the scope of the present invention.

For example, the gas-permeable thin tube may be made of metal tubes such as stainless steel mentioned in the examples, plastics treated with gas-impermeable treatment, or other materials that have gas-impermeable properties and have a certain degree of strength. Anything is fine.

Similarly, the constituent materials, shapes, etc. of the porous body 12 and the elastic body 13 are not limited to the above examples.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing how the catheter is used, and FIGS. 2 to 6 are longitudinal sectional views of various embodiments of the gas measuring catheter according to the present invention. 1...catheter, 2...connector with filter, 3...connecting tube, 4...
・Mass spectrometer 1.5... Blood vessels, 6.
... Catheter of the present invention, 7 ... Metal tube, 8 ... Side hole, 9 ... PP hollow fiber porous membrane, 10 ... ...Tip, 11...
... Base, 12 ... Porous body, 13 ...
...Spring, 14...Relay tube, 15...
...PP tube, 16...Small diameter part, 1
7...Welded part, 1B...Tapered tip part.

Claims (1)

[Scope of Claims] 1. A catheter used with an analysis device for collecting one or more gases present in the blood or tissues of a living body, etc., wherein the catheter has a distal end portion made of a material that does not permeate the gas. 1. A gas measuring catheter comprising: a thin tube having an opening; and the gas-permeable polypropylene hollow fiber porous membrane coated on the outer peripheral surface and one end surface of the thin tube. 2. The gas-impermeable thin tube is made of a metal tube,
2. The gas measurement catheter according to claim 1, wherein the gas introduction holes of a required size and number are formed on the side surface of the distal end. 3. The gas-impermeable thin tube is made of a metal tube,
A porous body or an elastic body is attached to the thin tube so as to protrude from the tube end portion, and the hollow fiber-like porous membrane made of polypropylene is applied thereon to impart flexibility and/or supporting force. The gas measuring catheter according to claim 1, characterized in that: 4. The gas-impermeable thin tube is made of vinylidene chloride or a compound (composition) of vinylidene chloride and other plastic, and gas introduction holes of the required size and number are formed on the side surface of the tip of the tube. A gas measuring catheter according to claim 1. 5. The gas-impermeable capillary is made of a suitable plastic tube coated with vinylidene chloride on the inside and/or outside, and a porous body or an elastic body is attached to the capillary tube so as to protrude from the tube end. 2. The gas measuring catheter according to claim 1, wherein said hollow fiber porous membrane made of polypropylene is applied thereon to provide flexibility and/or supporting force.