JPH0431695B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention connects the rear end of a catheter inserted into a blood vessel to a pressure measurement transducer, and measures the blood pressure value from the piezoelectric conversion signal. This invention relates to an invasive blood pressure measuring device.

(Prior art) In this type of blood pressure measurement device, the position of the pressure measurement transducer is adjusted so that the open point to the atmosphere is at the pressure reference point of the subject, that is, the height of the heart (tricuspid valve). In this state, the pressure receiving surface of the transducer is opened to the atmosphere, zero adjustment is performed, and then blood pressure is measured.

(Problem to be Solved by the Invention) However, when the patient's basic condition changes, the head of blood in the catheter relative to the transducer changes, and therefore blood pressure changes, such as central venous pressure, usually by several mmHg. On the other hand, there is a problem that changes in body position, which are approximately 0.73 mmHg/cm, affect the measured values to a non-negligible extent. For this reason, especially when measuring over a long period of time, it has been difficult to perform stable monitoring without readjusting the atmospheric release point of the transducer to the height of the pressure reference point.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an invasive blood pressure measuring device of the type mentioned at the beginning that is not affected by changes in the subject's body position.

(Means for Solving the Problems) In order to achieve this object, the present invention provides a blood pressure measuring catheter 10 with a blood pressure measuring tube 11; 41 having an open tip and a blood pressure measuring tube 11; Liquid filling tube for height correction 12; 4
2 and a diaphragm 14; 44 impermeable to liquids and permeable to air on the surface adjacent to the distal end portion of the tube, and the distal end thereof is closed;
It is composed of three tubes integrated with a height correction atmosphere open tube 13; 43 whose rear end is open to the atmosphere during measurement. A base 17; 39 is placed at the rear end of the blood pressure measurement tube 11; 41.
Pressure measurement transducer 1 installed on
8; Blood pressure measurement circuit section 21, 24, 25, which connects 30 and detects and displays or records a blood pressure value from the output signal of this transducer.
26; 40 further follows, and furthermore, at the rear end of the liquid filling tube 12; 42, a pressure measurement transducer is installed to set a head value corresponding to the height position of the diaphragm 14; 44 with respect to the pressure measurement transducer 18; 30. A height correction means for detecting the blood pressure value and correcting the blood pressure value was followed.

This correction means includes a correction liquid filling tube 1
2; Composed of a pressure measurement transducer 19 connected to the rear end of 42 and attached to the base 17, and blood pressure correction circuits 22 and 23 that correct the blood pressure value from the output signal of this transducer. Or,
Alternatively, the rear end of the liquid filling tube 12; 42 is connected to the other inlet 30b of the differential pressure transducer 30, whose one inlet 30a is connected to the rear end of the blood pressure measurement tube 11; 41 as a pressure measurement transducer. Possible ways to do this are to

(Operation) During measurement, the tip of the liquid-filled tube 12; 42 of the blood pressure measurement catheter 10 is positioned at the height of the pressure reference point. As a result, the liquid filling tube 12; 42 has a diaphragm 14;
4, it generates a pressure corresponding to the head for the pressure measuring transducer 18; 30, and therefore the head value also varies in accordance with the amount of height variation of the pressure reference point. Thereby, the height correction means corrects the blood pressure value corresponding to the head exhibited by the liquid filling tube 12; 42. In other words, when the dedicated pressure measurement transducer 19 is connected to the rear end of the liquid filling tube 12; 42, the circuit is Then, correction is made in response to the height deviation of the opening at the tip of the blood pressure measurement tube 11; 41 with respect to the pressure reference point at the start of measurement and subsequent changes in standard.

(Embodiment of the Invention) FIG. 1 shows an invasive blood pressure measuring device according to an embodiment of the present invention.

In the figure, reference numeral 10 denotes a blood pressure measuring catheter that is flexible, straight, and has a normal diameter. This catheter 10 has a blood pressure measurement tube 11 with an open tip, and the tip position is aligned with this tube.
and a liquid-filled tube 12 whose tip is closed and filled with, for example, saline, and an adjacent surface at the tip of this tube that is impermeable to saline and permeable to air, for example, Gore-Tex. It is equipped with a water-repellent diaphragm 14 such as a membrane filter, and similarly has closed tips that are substantially aligned in position,
In addition, an atmosphere-opening tube 13 whose rear end is bent laterally from the catheter 10 and is open to the atmosphere is formed.

The rear end of the blood pressure measurement tube 11 is connected to the pressure transducer 1 through one inlet 15a of the three-way valve 15.
8 and the liquid filling tube 12 is connected to the three-way valve 16
is connected to a pressure transducer 19 for height correction through one inlet 16a. These transducers 18, 19 are mounted on a common base 17 whose position is adjustable or fixed in the vertical direction.

The transducers 18 and 19 include a three-way valve 1.
By manually operating the levers 15c and 16c of 5 and 16, the pressure receiving surface is opened to the atmosphere through the other inlet 15b and 16b, and when the auto zero switch is operated, an automatic balancing operation is automatically performed based on the piezoelectric conversion value at that time. Auto-zero circuits 21 and 22, a correction circuit 23 that subtracts the output signal of the auto-zero circuit 22 whose polarity is ± from the output signal of the auto-zero circuit 21 during measurement, and a correction circuit 23 that processes the height-corrected blood pressure signal and displays it on the cathode ray tube 25. and recorder 26
A blood pressure measurement circuit 20 with a height correction circuit and a signal processing/output circuit 24 for recording the blood pressure follows.

The operation of the invasive blood pressure measuring device configured as described above is as follows.

The blood pressure measurement catheter 10 is inserted in a conventional manner into a blood vessel 2 as close as possible to a pressure reference point (tricuspid valve) in the chest 1 . Atmospheric open tube 13
The rear end is led out from the chest 1 and is open to the atmosphere. The inlets 15b and 16b are aligned at the same height on the base 17, and the transducer 1 is inserted through the inlets 15b and 16b using levers 15c and 16c.
8 and 19 are opened to the atmosphere, and the auto zero circuits 21 and 2 are activated by operating a switch.
2 to perform automatic balancing operation.

Blood pressure measurement is then started by returning the levers 15c and 16c to their original positions. In this state, when the base 17 is positioned below the chest 1, the transducer 19 is positioned at the tip of the blood pressure measurement catheter 10 and the inlet 1 of the transducer 18.
5b, the auto-zero circuit 22 outputs a correction signal with a + sign at a corresponding level. On the other hand, the transducer 18 detects and performs piezoelectric conversion, and the auto zero circuit 21
The blood pressure signal generated is subtracted in the correction circuit 23, and the actual blood pressure signal whose level has been reduced is taken into the signal processing/output circuit 24, and the blood pressure data is displayed on the cathode ray tube 25 and recorded on the recorder 26. Ru.

During this time, if the head of the catheter 10 changes from its initial position due to a change in body position, the transducer 19 receives and corrects the pressure change corresponding to this head change by interlocking the liquid filling tube 12. . This allows highly accurate blood pressure data to be monitored that is not affected by changes in body position.

When the base 17 is adjusted to the pressure reference point of the chest 1, the inlet 15b,
16b is located above the pressure reference point, the auto zero circuit 22 outputs a sign of - at the corresponding level.
A correction signal is output and subtracted from the actual blood pressure signal in the correction circuit 23 to increase its level.

FIG. 2 shows another embodiment in which the height correction means does not include any circuitry.

In this case, blood pressure measurement tube 1 in FIG.
1 and the liquid-filled tube 12 are provided with a differential pressure transducer 30 at the rear end instead of a dedicated transducer. That is, this differential pressure transducer is attached to a base 39 and includes a pressure receiving chamber 34 and a liquid filling tube 12 that communicate with the blood pressure measurement tube 11 through the three-way valve 31 and the inlet 30a.
Pressure receiving chambers 35 communicating through a three-way valve 32 and an inlet 30b are arranged side by side and separated by a downwardly extending magnetic diaphragm 33, and a bridge circuit is configured with a coil 36 and a coil 37 so as to detect the displacement of this diaphragm. are doing. The blood pressure measurement circuit section 40 is composed of an excitation/receiving circuit 41 that performs bridge zero adjustment and temperature compensation, and a signal processing/output circuit 42 that detects a blood pressure value from its output signal and displays or records it. ing.

During measurement, the pressure receiving chambers 34, 3 are supplied through the inlets 31a, 32a by operating the levers of the three-way valves 31, 32.
The excitation/receiving circuit 4 is opened to the atmosphere.
The blood pressure value signal outputted by No. 1 is set to zero. Next, return the lever to its original position and start measurement. The pressure receiving chamber 34 receives the pressure corresponding to the blood pressure and the head, while the pressure receiving chamber 35 receives the pressure corresponding to the same head of the liquid filling tube 12, and subtracts that amount from the pressure receiving value of the pressure receiving chamber 34. When the body position changes upward, the pressure received by the pressure chamber 34 changes from the blood pressure received by the pressure chamber 3.
When the diaphragm 33 is displaced so as to subtract the pressure deviation received in the pressure chamber 5 and moves downward, the pressure receiving chamber 3
Add the received pressure value of 5. As a result, the excitation/reception circuit 41 outputs a height-corrected blood pressure signal, and the signal processing/output circuit 42 outputs a signal for monitoring.

FIG. 3 shows another embodiment of the Swan-Ganz catheter in which the blood pressure measurement tube 41 is located a distance corresponding to the central venous pressure measurement position behind the pressure reference point position, and a liquid-filled tube 42 with a diaphragm 44. is formed at a position where it is placed at the pressure reference point together with the atmosphere open tube 43.
The rear ends of these tubes 41 and 42 are connected to the first
Connect the pressure transducers shown in Figures 1 and 2. In this case as well, if the tip of the liquid-filled tube 42 is positioned at the reference height, that is, near the tricuspid valve, the blood pressure measurement tube 41 can be measured regardless of body position changes even if the blood pressure measurement tube 41 deviates from the reference height from the relationship shown below and in Figure 3. becomes possible.

That is, P is the absolute pressure of the pump system when it is at the reference height, P _H is the pressure due to the reference height H, P _h is the hydrostatic pressure corresponding to the displacement height h, the pressure P _{A at} the measurement point A of the blood pressure measurement tube 41, Measurement point B of liquid filling tube 42
If the pressure P _B is , then P _A measures the pump system pressure higher than the actual one by P _h , and the actual head should be lower than P _H by P _h , so P _A = (P + P _h ) +(P _H −P _h )=P+P _H. In other words, this relationship holds even if the magnitude or polarity of P _h changes due to changes in body position (even if measurement point A shifts upward in the figure). On the other hand, pressure P _B at measurement point B =
P _H and therefore according to the invention P _A −P _B =P
Based on, the pump system pressure P is measured not only P _H but also independently of P _h .

(Effects of the Invention) As described above, according to the present invention, by positioning at least the tip of the liquid-filled tube at the pressure reference point, it is not necessary to adjust the height of the pressure transducer at the start of measurement, and the subsequent height Since fluctuations are also compensated for, highly accurate blood pressure data can be obtained even when blood pressure is monitored over a long period of time. In particular, the accuracy of trend data for pressures with low absolute values, such as central venous pressure, is greatly improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a catheter portion of an invasive blood pressure measuring device according to one embodiment of the present invention and a diagram showing an attached circuit, and FIG. 2 is a diagram showing a catheter of an invasive blood pressure measuring device according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a main part of a catheter portion of an invasive blood pressure measuring device according to still another embodiment of the present invention. 10... Catheter, 11, 41... Blood pressure measurement tube, 12, 42... Liquid filling tube, 1
3,43... Atmosphere open tube, 14,44...
Diaphragm, 17, 39... Base, 18, 19... Pressure transducer, 30... Differential pressure transducer.

Claims (1)

[Scope of Claims] 1. A blood pressure measurement catheter includes a blood pressure measurement tube with an open tip, a liquid filling tube for height correction with a closed tip and filled with liquid, and the distal end portion of the liquid filling tube. A height correction atmosphere having a diaphragm impermeable to the liquid and permeable to the air on the adjacent surface thereof, the tip of which is closed, and the rear end of which is open to the atmosphere during measurement. Consisting of at least three tubes integrated with an open tube, a pressure measurement transducer attached to a base is connected to the rear end of the blood pressure measurement tube, and the output signal of this transducer is connected to the rear end of the blood pressure measurement tube. A blood pressure measuring circuit section for detecting and displaying or recording a blood pressure value is further followed, and a head value corresponding to the height position of the diaphragm with respect to the pressure measuring transducer is provided at the rear end of the liquid filling tube. An invasive blood pressure measuring device, characterized in that it is followed by a height correcting means for correcting the blood pressure value detected by a pressure measuring transducer. 2. The height correction means includes a pressure measurement transducer connected to the rear end of the liquid filling tube and attached to the base, and a blood pressure correction circuit that corrects the blood pressure value from the output signal of this transducer. The invasive blood pressure measuring device according to claim 1, characterized in that it is comprised of: 3. The height correction means is connected to the other inlet of the differential pressure transducer, one inlet of which is connected to the rear end of the blood pressure measurement tube as a pressure measurement transducer;
2. The invasive blood pressure measuring device according to claim 1, wherein said invasive blood pressure measuring device is constructed by connecting a rear end of a liquid-filled tube.