JPS63216538A - Apparatus for continuously measuring and recording heart rate output quantity - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a continuous measuring and recording device for cardiac output used when performing cardiac function tests.

[Prior Art] Conventionally, an indicator dilution method has been used to measure cardiac output by right heart catheterization for cardiac function testing. This indicator dilution method includes a thermodilution method that calculates cardiac output from heat diffusion, a dye dilution method that calculates cardiac output from changes in illuminance due to dye diffusion, and a method that calculates cardiac output from changes in resistance due to electrolyte diffusion. There are electrolyte dilution methods to determine the amount. This thermodilution method will be explained.

In right heart catheterization, as shown in Fig. 16, a catheter 4 is introduced from the jugular vein, femoral vein, contralateral vein, etc., passes through the superior vena cava or vena cava, the right atrium, and the right ventricle, and its tip reaches the pulmonary artery. It is placed so that it is located inside. The catheter 25 is arranged such that the discharge port 26 is located in the right atrium and the thermistor 1 is located in the pulmonary artery. When a liquid with a temperature higher or lower than the blood temperature is injected into the right atrium from the discharge port 26, the liquid is diffused and diluted in the right atrium and right ventricle. The temperature of this diluted liquid is determined by a thermistor 27 located in the pulmonary artery.
The Stewart
Cardiac output is calculated using the following equation (1) using the Hamilton method.

S, ・C1・ (Tb-T+)・■1 CO=□... (1) S, ・cb, lC: △Tbdt Here, CO: Cardiac output, Sl: Specific gravity of injected liquid CI: Injection Specific heat of liquid, ■1: Volume of injected liquid TI: Temperature of injected liquid, Tb: Temperature of blood Sb 2 Specific gravity of blood, C
b: Specific heat of blood f7ΔTb d t: Area of thermodilution curve.

[Problems to be solved by the invention ■; Now, in the thermodilution method described above, as can be seen from the formula for calculating cardiac output, the amount of injected liquid and its temperature greatly affect the accuracy of the calculated value. Affect. Incidentally, normally, the liquid temperature T is accurately measured with a thermistor, etc., and then the catheter 26 is brimmed to inject the indicator liquid into the blood vessel. This may result in cooling or heating, which may cause errors in measurement values. Therefore, in the past, the amount of liquid remaining inside the catheter was calculated based on the inner diameter of the catheter (French size).
Based on the amount of injected fluid, etc., a correction constant is determined based on Edwards' formula, and this correction constant is applied to the calculation of cardiac output.
The effect of the residual liquid mentioned above was reduced.

However, the correction constant obtained from Edwards' formula is just a list of numerical values and has no meaning to the measurer, so calculation errors may occur when determining the correction constant.
Furthermore, human error occurred when inputting the determined correction constant into the measuring device. This error is not limited to thermodilution methods, but is a problem that occurs in indicator dilution in general, since indicator dilution methods use catheters.

■: Now, as you can see from Figure 17, if the operation of injecting the indicator liquid and the start of the integral calculation are not performed at the specified timing, the integral calculation will be performed after the blood temperature has decreased, etc. This may cause calculation errors. However, in the past, the measurer relied on intuition to instruct the measuring device to start measurement, that is, to start integration, after injecting the liquid, so there was always the possibility of a measurement error occurring. This error factor is not limited to the thermodilution method, but is also a general problem of indicator dilution.

■: In measuring cardiac output based on the thermodilution method described above,
The temperature of the injected indicator liquid is measured, usually by immersing it in an ice or wetting solution that is maintained at a predetermined temperature.

Therefore, if an experienced measurer or absolutely accurate measurement of cardiac output is not required, the above solution temperature may be considered as the indicated liquid temperature TI.

d) On the other hand, in the method of measuring cardiac output using the thermodilution method or indicator dilution method described above, cardiac output is measured intermittently every time the indicator liquid is injected, so it is not possible to measure the cardiac output continuously. It cannot be used to measure cardiac output. Further, if measurements are to be made frequently, the total amount of liquid to be injected increases, which increases the burden on the subject, and at the same time increases the risk of infection due to the liquid injection operation, which is not preferable.

In order to eliminate the disadvantages associated with cardiac output measurement according to the conventional indicator dilution method, in particular the thermodilution method, which allows only one-shot measurement, the applicant of the present invention filed a patent application filed in Japanese Patent Application No. -24
In No. 4586 (Japanese Unexamined Patent Publication No. 125329/1983), we proposed a completely new cardiac output measurement device that enables continuous measurement of cardiac output. This continuously measurable cardiac output measuring device allows continuous recording.

■: Furthermore, the above-mentioned Japanese Patent Application No. 59-244586 discloses that from the measurement of cardiac output and blood flow velocity by a single thermodilution method,
The gist of this study is to find the relationship between cardiac output and blood flow velocity, and then calculate cardiac output from this relationship and blood flow velocity. That is,
There is a fixed relationship between cardiac output and blood flow velocity, so unless you are looking for an absolute cardiac output value, you can simply find the blood flow velocity value and calculate the relative change in cardiac output. It becomes possible to know.

Therefore, the object of the present invention is to
By further developing the principle of the device capable of continuously measuring cardiac output shown in No. We are proposing a continuous measuring and recording device for stroke volume.

[Means and effects for solving the problems] The structure of the present invention for achieving the above-mentioned problems is based on the idea that the cardiac output value is determined by measuring the cardiac output at least once based on the dilution method. A stroke volume measuring means, a blood flow velocity measuring means for measuring a blood flow velocity value, a cardiac output value based on the dilution method, and a blood flow velocity value corresponding to the measurement of the cardiac output value. a function value calculation means for calculating a function value representing the relationship between The present invention is characterized by comprising a cardiac output calculation means for continuously calculating the value of cardiac output, and a recording means for recording the cardiac output value at each of the above-mentioned times in chronological order.

[Margin below] [Examples] Examples according to the present invention will be described in detail below with reference to the accompanying drawings.

<External Appearance of Example Device> FIGS. 1A to 1C are plan views of a continuous measurement and recording device for cardiac output to which the present invention is applied.

A front view and a back view are shown. FIG. 2A shows the appearance of the catheter connected to this measuring device, FIG. 2B shows a cross-sectional view of the distal end of the catheter along the longitudinal direction, and FIG. 2C shows a cross-sectional view of the opening of the catheter. .

The principle of this measuring device is to measure the initial cardiac output co based on indicator dilution methods such as thermodilution method, electrolyte dilution method, 2-dye dilution method, etc., and the blood flow velocity V when this cardiac output is measured. Then, a parameter S that connects this blood flow velocity V to the cardiac output CO is determined. After determining this parameter, the cardiac output t COI at any time can be determined from this blood flow velocity vl and the parameter S by simply measuring the blood flow velocity Ml at any time.

The measuring method for determining the initial cardiac output Co may be any of the indicator dilution methods described above, but the embodiments shown in FIG. 1A and subsequent figures are particularly based on the thermodilution method.

The external appearance of the measuring device 100 shown in FIGS. 1A to 1C will be explained. FIG. 1A is a top view of apparatus 100. 50
is a well-known plotter. This plotter 50 outputs measurement results and the like. 52 and 53 are switches for specifying the output mode on the plotter 50 when measuring the initial cardiac output value CO by the thermodilution method. The switch 52 is
Specifies that co is to be output as a numerical value (Figure 5). The switch 53 specifies that changes in blood temperature Tb, etc. are output as a curve (FIG. 4). switch 57.5
8 is the paper feed speed of the plotter 50 (20 mm/hour and 10 m/hour)
m/min).

54 is a switch that instructs to output the 12 hours' worth of COI etc. on the plotter 50 (Fig. 8); 55 is a switch that outputs the data such as col stored in the memory for the past 30 minutes on the plotter 50 (Fig. 8); 6 and 7). 80 is a memo switch, and when this switch is pressed, the recording paper is fed 6 cm. 56 is a switch for instructing to output changes in (01, T I, V 1, etc.) on recording paper in real time (FIGS. 6 and 7).

Switches 59, 60 (Fig. 1A), at, 62 (first
Figure B) etc. are switches for manually setting desired data when inputting the data into the device 100, and the setting values are sequentially determined by the catheter diameter (unit:
French), injection volume of indicator liquid (unit: ml), body surface area (4111th position: m2), and initial CAL value (unit: L/min).

64 is a switch that sets the mode of the measuring device to continuous mode, and at the same time, when the mode is set to continuous mode, this switch/
Indicator 64 lights up.

Reference numeral 65 denotes a single (intermittent) mode switch/indicator, which is mainly used when returning from continuous mode to single mode when it is desired to set parameter S again. Lights up when in intermittent mode (SINGLE mode). Display 68 is a four-digit LED that digitally displays cardiac output. Switches 66 and 67 are 3-digit L
This is for specifying whether the temperature displayed on the ED display 69 is the blood temperature Tb or the indicator liquid temperature T1.

The ENTRY switch/indicator 70 indicates that the initial cardiac output value CO has been measured by the thermodilution method, and the CO
Displays that it is now possible to register (ENTRY) as data. This ENTRY indicator 7
When this switch 70 is pressed while 0 is lit, the CO is registered as data. This registration is performed using the initial cardiac output value C using the thermodilution method in order to obtain the parameter S.
This is because the measurer measures O several times and determines and registers the most reliable data among them, thereby making the average value of the registered data the CO.

The 5TART switch/indicator 72 indicates that the initial cardiac output value Co measurement by thermodilution is ready, and pressing this switch at that point starts the integration based on the Stuart-Hamilton equation.

The display 71 is a bar graph, and mainly displays the value of blood temperature Tb in real time.

73 and 74 are the connector 15 of the catheter 4 (FIG. 2A) which has a built-in blood temperature sensor, and the connector 16 of the temperature probe 12 (FIG. 2A) for measuring the temperature of the injected fluid, respectively.
It is a connector for connecting.

Switch 75 in FIG. 1C is a rotary switch that manually sets the temperature of the injectate. 76 is an R5232C interface connector for communicating with other external measuring devices, and 78 is a connector for communicating with other external measuring devices (or from the device) such as blood temperature Tb, blood flow velocity V1, cardiac output CO1, etc. A terminal 77- for outputting an analog signal is a connector for connecting a power cable.

Functions of the Measuring Device> The features of the embodiment device shown in Figures 1A to 1C and Figures 2A to 2C are as follows: ■: To correct the influence of the indicator liquid remaining in the catheter. Instead of having to calculate the correction constants based on the conventional Edwards formula, the measurer creates a table of correction constants in advance and uses the table as data to access when injecting the indicated liquid. This measuring device is provided with a switch 59 for setting and inputting the inner diameter size (unit: French) of the catheter used for the test, and a switch 60 for manually setting the amount of liquid to be injected (unit: ml).

■: After injecting the indicator liquid into the blood vessel, the change in blood temperature Tt is automatically recognized without the operator's intervention, and integration based on the above Stewart-Hamilton equation (1) is started. do.

■: Temperature probe 1 to measure the temperature of the indicator liquid.
2 is used, but when the connector 16 of this probe 12 is not connected to the measuring device 100, this disconnection is detected and the value set on the switch 75 (Fig. 1C) on the back of the device is used to indicate the liquid temperature. Manpower as TI.

■Second, measure Co by thermodilution method and parameter S
Then, from then on, COl + blood temperature" b
+Blood velocity V1, etc. are stored in memory and output on recording paper as necessary. The mode of output is (i): The measured < CO, etc. are output on the recording paper of the plotter 50 in substantially real time (FIGS. 6 and 7). This is done by pressing the "Continuous Record" switch 56.

(it): C for the past 30 minutes stored in memory
The data such as Ol etc. is reproduced and output (Fig. 6).

Figure 7). This is done by pressing switch 55.

(iii): The past 12 hours of data such as Co, etc. are compressed and reproduced and output on the plotter 50 (FIG. 8). this is,
This is convenient when measuring data on a patient who requires rest and noiselessness because the plotter does not make any print noise.

(2): The parameter S is manually set via the switch 62, and Coi can be continuously determined from this S and the blood flow velocity vI. This is useful when you want to know the relative changes in Coi.

(2): With the bar graph display 71, changes in blood temperature Tb can be visually confirmed when determining the initial cardiac output value CO using the thermodilution method. In particular, this bar graph can not only display the temperature change by changing it every moment, but also can display the blood temperature baseline (reference temperature value Tbo) and maximum temperature Tb, , □ fixed.

■: The wooden device has a built-in battery (148 in FIG. 9) to protect stored data from failures such as power outages. When the output voltage of this battery 148 decreases, the LED 78 is blinked to call attention to it. .

■: C01 to an external measuring device other than this measuring device 100.
Analog output circuits (142, 151) are provided for outputting the signals from the terminal 78 as analog signals.

@: R32 to an external measuring device other than this measuring device 100
It is equipped with a circuit (144) that outputs COI and the like as a digital signal through a V.32 interface.

<Structure of Catheter> FIG. 2A shows a catheter incorporating a thermistor for measuring blood temperature Tb for the thermodilution method, a thermistor for measuring blood flow velocity, etc. In the same figure,
Catheter 4 is configured to have 4 lumens.

This catheter 4 has a pressure detection port 18 provided at its tip.
A balloon 17 made of a flexible elastic body is attached a few mm back from the tip so as to cover the entire tip of the catheter tube, and a device for injecting or extracting air to expand and deflate the balloon 17. Balloon side hole 25 provided on the side of the balloon inner tube and 10 to 2 holes from the tip.
A thermistor 1 provided at a position of 0 mm, a thermistor 2 provided further 10 to 15 mm from there to the base side,
Furthermore, it has a discharge port 3 provided at a position spaced apart from the thermistor 1.2 in a range of 8.5 to 38 cm and spaced apart from the tip in a range of 12 to 40 cm. The thermistor 1 is used to measure the thermal equilibrium part for measuring the blood flow velocity V (vl). Thermistor 2 measures the diluted blood temperature T necessary to measure the initial cardiac output Co by the thermodilution method.

used to measure The discharge port 3 is for discharging an indicator liquid.

The catheter 4 shown in Fig. 2A is connected to a vein, femoral vein, or contravening vein, and is used in the pulmonary artery via the femoral vein or vena cava, the right atrium, and the right ventricle; therefore, the direction of blood flow is Considering that it is from the catheter proximal end side to the distal end side, the thermistor 2 is connected to the discharge port 3.
It is provided on the distal side (that is, on the downstream side of blood flow) when viewed from above. On the other hand, in the case of a catheter that is conduited from a peripheral artery and used in the aorta, the thermistor 2 is placed on the proximal end side of the catheter when viewed from the discharge port 3 because the blood flow direction is opposite. .

FIG. 2B shows a sectional view of the main part of the catheter 4.

In the same figure, the pressure detection port 18', the balloon side hole 25,
Thermistors 1, 2 and discharge port 3 communicate with the four lumens, respectively. These four lumens are a pulmonary artery pressure lumen 19 that transmits the pressure of the pulmonary artery, and a balloon lumen 20 that is an air passage that expands and deflates the balloon 17.
, a thermistor lumen 21 for housing the thermistor 1.degree. 2 and their lead wires, and an injection lumen 23 for passing an indicator liquid for dilution. Furthermore, these four lumens are independent, and a second lumen is provided at the rear end of the catheter.
As shown in Figure A, it is connected to a pulmonary artery pressure measuring tube 8, a balloon tube 6, a thermistor tube 12, and an indicator fluid injection tube 10. each tube 8,6
．． 10 is equipped with a connector 7.9.11 at its rear end. The thermistor tube 12 is connected to a connector 15, through which lead wires 22.24 are passed, each connected to the thermistor 1.2.

Furthermore, the catheter of the embodiment shown in FIGS. 2A to 2C will be described in detail. FIG. 2B is an enlarged cross-sectional view of the thermistor 1, thermistor 2, and the balloon 17, and FIG. 2C is an enlarged sectional view of the catheter tube 4 at III-H1.
FIG. As shown in Fig. 2c, the four-lumen structure of this catheter described above includes a balloon lumen 20, a pulmonary artery pressure lumen 19, and an injection lumen 23 (second c.
) and the thermistor lumen 21. The balloon lumen 20 has a balloon side hole 25 and communicates with the balloon tube 6. The pulmonary artery pressure lumen 19 has a pressure detection port 18 and communicates with the pulmonary artery pressure measurement tube 8 . The injection lumen 23 is located 12 to 4 mm from the tip of the catheter.
It has a discharge port 3 at a position of 0 cm and communicates with the indicator liquid injection tube 1o on the base side. Moreover, the thermistor lumen 21 is located at a position 1 to 2 cm 1 l from the tip, and further 1 to 1.5 cm 1 1 from there to the base side! Thermistor 1 and thermistor 2 are installed in side holes 26 and 27 at the lower positions, respectively, and the thermistor lead wires 22 and 24 from thermistor 1 and 2 are built in. In this case, it communicates with the thermistor tube 13.

In addition, if the thermistor 1 is a self-heating type thermistor,
It is more preferable to locate it on the downstream side of the thermistor 2 with respect to the blood flow direction. That is, when measuring cardiac output with the catheter 4, it is necessary to accurately measure the temperature of the blood flow diluted by the thermistor 2, and the thermistor 2 is made less susceptible to the influence of the thermistor 1, which is a self-heating type. It's for a reason.

The characteristics of the thermistor 1 used in the catheter of the example are B
25-45 = 3500, R(37) = 1000 Q
Thea'), Sonodai Kisaha, 1.18LX0゜4wX0.
15t (J11th position is mm). The characteristics of thermistor 2 are 82s-as = 3980 K, R(37)
=40KO1 Its size is 0.50'Xo.

16”xo, 15t. Thermistor 1 is 0°01~
It is preferable to generate a calorific value of 50 Joules, as higher calorific values may increase blood salt levels or even damage blood vessel walls if they come into contact, and lower calorific values reduce detection sensitivity. Both are unfavorable because they become smaller.

Operation procedure of the measuring device> In order to better understand this measuring device, please refer to Figures 3A and 3.
The operating procedure from the operator's perspective will be explained using Figure B.

First, in step S1, the injectate temperature probe 12 is connected to the measuring device main body 100. In step S2, the temperature probe 12 is placed in a water-cooled container (in this embodiment, the measurement device 100 is
Immerse in the injection instruction liquid (provided inside). This liquid may be physiological saline or the like. After brimming the catheter 4 in step S3, it is inserted up to the pulmonary artery in step S4. The catheter 4 is inserted from a vein in the upper or lower limb and placed in the pulmonary artery. Next, in step S5, the connectors of the catheter shown in FIG. 2A are connected to the main body of the apparatus. When these connectors are connected to the device, first, the catheter 4 is positioned in the blood vessel through the pressure detection port 18, the tube 8. This is confirmed based on the blood pressure value and pressure waveform detected from the arterial pressure that has passed through the connector 9. After the catheter is indwelled, the pulmonary artery pressure is measured, and the balloon 17 is inflated to occlude the pulmonary artery to determine the pulmonary artery wedge pressure. In this way, the catheter 4 is left in place.

Next, in step S6, predetermined values are set using the switches 59-61. The switch 62 is set when measuring the relative CO+ (described later), and is not necessary when measuring the initial cardiac output value co by the thermodilution method, which will be described now. do not have.

In step S7, the measuring device is powered on. Step S
While confirming that there is no abnormal display (indicating a device failure) in step S9, the 5INOLE indicator 65 is turned on in step S9.
Wait for the light to turn on. When indicator 65 lights up,
The BLOOD indicator 66 lights up, and the blood temperature T in the pulmonary artery is displayed on the display 69. If you want to know the temperature of the injectate at this point, press the INJECTATE switch 67 and the display 69 will display the injectate temperature T.
I will be displayed. Note that the TI display automatically returns to the BLOOD display after 30 seconds have elapsed, and the display 69 displays T again.

The reason why the display automatically returns to T is as follows.
This is because Tb is more meaningful as information to the operator. On the other hand, the bar graph display 71 at this point should be displaying the base line of the blood temperature Tb.

Furthermore, in step S10, the 5TART indicator 72
Wait until it lights up. When this indicator lights up, it means that preparations are ready to start measuring the initial cardiac output value CO using the thermodilution method.

In step Sit, the mode of information to be output to the plotter 50 is selected by the switch 52 or 53, if necessary. In step S12, the cock 11 is opened to inject the liquid into the blood vessel.

After liquid injection, the measuring device automatically reads the change in Tb and determines the optimal time to start integration. If the operator presses the 5TART switch 72 before detecting this optimum point, the integration of T starts from the point of press. If the switch 72 is not pressed, the Tb data from the time determined by the device itself is integrated. CO measurement calculation using this thermodilution method usually completes in a few seconds, but changes during that time are stored in a predetermined memory (RAM 132 in Fig. 9).
It is displayed on the display 69 and bar graph display 71. Further, if the switch 53 has been pressed, the change in blood temperature Tb as shown in FIG. 4 is output to the plotter 50. These displays allow the operator to confirm that the device is operating normally. In FIG. 4, the blood temperature T becomes negative upward. Note that the date, time, and other information are also output on this graph for the convenience of the measurer.

The output example shown in FIG. 4 has an output speed of 300 nm/min.

When the measurement of CO by thermodilution is completed, the value is displayed digitally on the display 68, and if the switch 52 is pressed, the measurement result is outputted by the plotter 50 as shown in FIG. . In this FIG. 5, in addition to the date and time, the heart rate ICO, the body surface area BSA manually input from the switch 61, the blood temperature BT (=Tb), the catheter inner diameter CAT (=Fr), and the indicated liquid injection 1IV (
= V+), cardiac index CI (=CO/BSA), infusate temperature IT (=T+), and ** indicating registered.
The display of ENTRY**, etc. are also recorded. C.O.
When the measurement is completed, the ENTRY indicator 70 lights up (
This can be confirmed by step 515).

If the measurer determines that the obtained data on Co, etc. is reliable, he or she may register the data using E.
NTRY switch 70 is pressed (step 517). After a while, the 5TART indicator 72 lights up again. This completes the measurement of the initial cardiac output CO using the thermodilution method.

If you want to obtain more accurate CO, repeat the operations from step Sll described above to obtain a plurality of measurement data. The ENTRY switch 70 is pressed and registered for each measurement, and the initial cardiac output value Co value is determined from the plurality of CO values entered. Note that the first 1.2 measurement data are unreliable, so it would be better not to register them.

Once sufficiently reliable CO data has been obtained in the manner described above, it is time to start continuous CoI measurements. This is done by simply pressing the C0NTINUoUS switch 64 at the end. When this switch 64 is pressed, C0N
T I NtJOUS indicator 64 lights up,
The entire measuring device is in continuous measurement mode. Furthermore, S I N
When the 0LE switch 65 is pressed, the measuring device goes into intermittent mode again.

When the device is in the continuous measurement mode and the continuous recording switch 56 is pressed, the blood temperature BT (=Tb), Co (
= COi).

The blood flow velocity v (vI) is output on the plotter 50.

Figure 6 shows paper feed speed of 10mm/min, Figure 7 shows paper feed speed of 20mm/min.
It is output at a paper feed speed of mm/hour.

Although not shown in FIGS. 6 and 7, it goes without saying that various data such as the date shown in FIG. 5 are output together with the graph. In addition, in the example shown in Figure 7, the thermodilution method is used to measure the initial cardiac output value and CO value again at around 4:30 pm, so changes in the graph appear around that time. .

<Configuration of Measuring Apparatus> The entire measuring apparatus 100 with the catheter 4 and the injectate temperature probe 12 connected is as shown in FIG. This measuring device consists of two electrically isolated measuring circuits 120 and 130. The circuit 120 mainly converts electrical signals (voltage) from the thermistors 1 and 2 in the catheter 4 and the thermistor 12a in the probe 12 into temperature data, and sends the data to the measurement recording circuit 130 via the optical communication circuit 108. send. The measurement recording circuit 130 determines the initial cardiac output value CO from the temperature data from the measurement circuit 120.
1 Blood flow velocity V, parameter S, continuous cardiac output Cot, etc. are calculated and displayed on the plotter 50 or on various displays. The local CPU 105 controls the measurement circuit 120, and the main CPU 133 controls the measurement recording circuit 130.

<Measurement circuit 120> Now, the catheter type sensor 150 shown in FIG. 9 uses the catheter 4 shown in FIG. Thermistor 2 detects the blood temperature inside
is built-in. This catheter-type sensor 150 is introduced to the pulmonary artery by right heart catheterization in a manner similar to that described above. Connector 15 of sensor 150
is coupled to the connector 73 of the main body 100. Thermistor 2
A constant voltage circuit 112 that drives the thermistor 2 and a blood temperature detection circuit 1 that measures the temperature of blood are connected via lead wires 24.
13.

The pulmonary artery blood temperature signal detected by the thermistor 2 is detected by the blood temperature detection circuit 113 as a voltage signal Eb. On the other hand, the thermistor 1 is connected to the thermistor temperature detection circuit 115 and the constant current circuit 11 via the lead wire 22.
Connected to 1. Then, a predetermined current IC is supplied to the thermistor 1 from the constant current circuit 111, and the thermistor 1 is heated.

Further, the temperature signal detected by the thermistor 1 is sent to the thermistor temperature detection circuit 115, and this detection circuit 11
5, it is detected as voltage Et.

The thermistor 12a in the injection liquid temperature probe 12 is driven by a constant voltage circuit 101, and the temperature change is detected by the circuit 102.
This current is detected as a current change, and this current is further detected as a voltage value E1. Thus, local CPU 1
05 is the output voltage E1.2 from the three thermistors 12a, 1.2. Et and Eb are the temperature TI of the injection liquid and the resistance Rt of the thermistor 1.

The temperature T of the thermistor 1 is converted into the blood temperature T.

This operation will be explained in more detail. Local CPU105
is an analog switch 10 with multiplexer function
EI by time division.

Et and E are manually input to the A/D converter 104, and the above voltage values are sequentially input into the RAM 107 as digital values. These voltage values are converted into temperature data from a voltage-to-temperature conversion table stored in the ROMj06. Further, the resistance value Rt of the thermistor I is calculated by Rt = Et/Ic. Here, IC is the current flowing through the thermistor. The local CPU 105 uses these T
Data such as I + Rt and T t + T b are sent to the measurement recording circuit 130 via an optical communication line. The local CPU 105 and the main CPU 133 perform the communication control (for example, the bowling/selecting method).

Measurement Recording Circuit 130> The measurement recording circuit 130 uses this simple communication control procedure to determine the temperature T1. Resistance Rt of thermistor 1,
Temperature Tt of thermistor 1, blood temperature T.

etc., and stores them in the RAM 132 in chronological order. C.P.
U133 is the initial cardiac output value C based on the above data.
O1 blood flow velocity v(v,) and continuous cardiac output Co are calculated.

The RTC (real-time clock circuit) 147 counts real time, and furthermore, for example, Tl-T of the LED display board 69.
It is used for time monitoring such as changes after 30 seconds of b.

Calculation of Initial Cardiac Output Value CO> FIG. 10A shows the structure of data stored in the RAM 132. The capacity of this RAM is an area (132
a) and an area where measured values such as continuous cardiac output Co at any time are stored for 30 minutes from these data (
132b) and a region (132C) in which 3-minute average values of data such as Cot etc. obtained by continuous calculation are stored for 12 hours.

FIG. 10B shows the correspondence between three address counters 160, 161, and 162 for storing data in the RAM 132 and the three areas (132a, 132b, 132c). A data storage address counter (SC pointer) 160 stores data from the measurement circuit 120 in the RAM 13.
Points to the address when storing in 2. The data read address counter (RC pointer) 161 is
RAM1 for calculating the initial cardiac output value CO.
32 and points to the address where the calculated value is to be stored. A data print address counter (PC pointer) 162 points to data to be accessed when outputting data on the plotter 50. The reason why three pointers are used in this way is that data storage, data reading, data output, etc. are performed independently and in parallel as subroutines.

In Figure 11, the main CPU 133 is the local CPU 10.
This routine receives measurement data from 5 and stores it in the RAM 132. As described above, the SC pointer 160 is used as a pointer at this time.

Figures 13A and B show the CP for measuring the initial cardiac output value Co value.
This is the control routine of U133.

First, in step S40, the READY state of the measuring device is confirmed. This state assumes that no hardware failure has occurred in at least the entire device, and that the blood temperature Tb
A stable state is defined as the detected state. Note that when this state is detected, the S I NGLE indicator 65 lights up as described above. In step S41, 5TAR
It is determined whether the T switch 72 has been pressed. If it has been pressed, the time t is set to the real-time clock R.
The RC pointer 161 is read from the TC 147 and set in step S51 based on the time t. Step S5
In step 2, the injection liquid temperature TI is known from the RAM 132. In step S53, according to the RC pointer 161, RAM1
One Tb is read from 32. In step S54, the time is determined from the previous data, and the base line temperature Tb0
Detect. In step S55, ΔTb (FIG. 17) is calculated. In step 356, ΣΔTb (integral) is calculated.

Step S57 and step 358 show control for dealing with the case where ΔTb is calculated due to noise in Tb. If it is noise, the ΔTb of this noise is the previous △
Although it increases compared to T, it will decrease someday, so the maximum value at the time of increase is detected, and if the maximum value is smaller than the threshold a, it is determined to be noise and the integral ΣΔTb is calculated in step S59. Clear. ΔT in step S57.

If it has further increased, it cannot be determined that it is noise, and the process advances to step S61. If it is determined to be noise,
At step 560, pointer RC is incremented by a predetermined value zb. This b is the approximate time width of the noise component, which is known from experience.

Step S61 determines whether the thermodilution curve has converged to Tbo. That is, the above steps are repeated and the integration continues until convergence.

Next, a case will be described in which the 5TART switch 72 is not pressed in step S41. This control starts integration when it is determined that the change in Tb is a predetermined change. Note that the 5TART switch 72 in step S41
Since the pressing of is detected by an interrupt, step 34
2 to step S47, if the upper distribution occurs,
Control is forced to proceed to step S50. Now, in step S42, Tb is stored in RAM1 according to the RC pointer 161.
Read from 32. In the loop of step S42 → step S43 → step S44 → step S42, since the change in Tb is captured from the moving average (16 samples) in this embodiment, the required number of samples is stored in the memory 13.
It is meant to be obtained from 2. The moving amount of the moving average is one sample data. Once the required number of samples is collected, the total number of samples for averaging will be collected every time one piece of sample data is read from the memory 132. In step S45, this moving average value Tb(n) is determined. In step S46, the previous moving average value Tb(n-1)
Find the difference between When this difference is greater than a predetermined threshold, it is determined that the change in blood temperature is due to the injection of the indicator fluid, and
In step s49, time t at the time of this change is calculated.

The subsequent control is the same as that using the 5TART switch 72 described above. If it is determined in step S47 that the change is less than the threshold value, the current average value Tb(n) is moved to the previous average value Tb(n-1) storage area in step 34B.

Returning to the explanation of step S63. Now, as mentioned above,
According to the Stewart-Hamilton equation, S, -C plate ・(Tb-T+) ・■
1CO=−−1−−−−−−5b−Cb・
SC: Δ”rbcit where, Co: cardiac output, SI: specific gravity of injected liquid C1: specific heat of injected liquid, vl: amount of injected liquid Tl: temperature of injected liquid, Tb: temperature of blood Sb: specific gravity of blood , Cb
: Specific heat of blood. The above formula becomes (7b-T+) CO=A □ △Tbdt. Here, S, -C, -V,.

A=□Sb'Cb. In this correction constant A, S ++S kl+c
b, c 1, etc. are fixed, but V is affected by the fact that even if the indicator liquid is injected, it remains in the catheter and does not flow out into the blood. That is, the above V1 is only a nominal value. Conventionally, as mentioned above,
A was obtained from Edwards' equation, but in this embodiment, with the aim of improving the reliability of operations by the operator, this correction constant A is made into a table (Fig. 12) and stored in the ROM 131.
It is stored inside. One correction constant A from this table
When pulling, as shown in FIG. 12, the inner diameter Fr of the catheter 4 and the nominal liquid injection amount m1 input from the switches 59 and 60 are used as address data. The correction constant data stored in the above table is obtained in advance from actual measurement results obtained when various amounts of injected liquid are changed for catheters of various sizes. If the catheter size and injection volume used in the actual measurement of CO by thermodilution method are
If it does not correspond to the above table, the corresponding correction constant A is determined by linear interpolation.

Return to the explanation of the flowchart. In step 361 and above,
When the calculation of the integral of ΣΔTb is completed, in step 363, as described above, the inner diameter Fr of the catheter is manually set using the switches 59 and 60.

Based on the indicator liquid ff1m1, etc., the correction constant A is read from the table (FIG. 12) stored in the ROM 131. In step S64, an initial cardiac output value CO is calculated based on the Stewart-Hamilton equation described above.

In step S65, these values are outputted onto the plotter 50 as shown in FIGS. 4 and 5, for example.

<Measurement of continuous COI> First, the principle by which CO can be calculated continuously will be explained. If the resistance value of the thermistor 1 is Rt, and the current value given to the thermistor 1 by the constant current circuit 111 is IC, then
The thermistor 1 is heated and the amount of heat generated per unit time is: IC2·Rt. If the heated thermistor 1 is placed in blood at a blood flow velocity V, the heated thermistor 1 will be cooled down depending on the blood flow velocity V. The amount of heat cooled by the blood flow is K-■·(Tt-Tb), where Tll is the blood temperature, Tt is the heated thermistor temperature, and K is the proportionality constant. Now, the temperature of the thermistor 1 is maintained at such a temperature that the amount of heat generated by heating and the amount of heat cooled are equal. This temperature is the thermal equilibrium temperature.

If the above is expressed in a formula, it becomes the following formula (2).

lc"-Rt=-V-("rt-Tb)...
-(2) From equation (2), equation (3) for determining blood flow velocity V is derived.

■ = (1/K) (Ic2・Rt)/ (”rt
-Tb) (3) That is, data Rt obtained from thermistor 1.

Tt, and blood temperature T obtained from thermistor 2,
From this, the blood flow velocity ■ can be determined. In addition, heating thermistor 1
Since is driven by the constant current circuit 111, instead of detecting the resistance value, the voltage difference t between both ends of the lead wire of the heating thermistor l is detected. may be detected. Details of this case are described in the above-mentioned Japanese Patent Laid-Open No. 125329/1983. Further, although the constant current value IC can be applied even if the current of the constant current circuit 111 is detected, it is also possible to provide it in the ROM 131 as a constant term in the same way as the proportional constant.

Now, if the blood vessel cross-sectional area of the pulmonary artery is S, then there is a relationship as shown by equation (4) between the initial cardiac output value CO and the initial blood flow velocity value ■.

C0=S-■ ...(4) Therefore, from the initial cardiac output value CO and the initial blood flow velocity value V,
The blood vessel cross-sectional area S is determined according to equation (4), and this value S is held in the measurement recording circuit 130 as a calibration value (parameter). In this way, once the parameter S is determined, the CPU 133 automatically calculates the continuously measured blood flow velocity Vl.
By multiplying by the parameter S, it becomes possible to obtain a continuous cardiac output value COI. That is, C
O, = S ・ ■Bird = (S/K) - (I C' - Rt) / (Tt - TI
, )...(5).

FIG. 14 shows the control procedure of the CPt 1133 which calculates this CO□ and stores it in the RAM 132. Before starting this control, the initial cardiac output CO has already been measured. Steps 381 to 385 are controls for determining the above-mentioned parameter S.

In step S80, it is determined whether the measuring device 100 is in continuous mode. This mode is entered by pressing the C0NT I NUOUS switch 64, which takes nine lines.

If it is continuous mode, in step S81, the local CP
Instruct U105 to heat the thermistor 1 via the optical communication path. In step S82, the thermistor 1 waits for the thermal equilibrium between heating and cooling to be reached. Eventually, Tt, Rt from the local CPU.

Tb, etc. are sent and stored in the RAM 132 in chronological order according to the flowchart of FIG. Therefore, data in the RAM 132 is accessed using the RC pointer 161 according to time t when a certain period of time has elapsed. In step 584, the initial blood flow velocity V is calculated based on equation (3),
In step 385, the parameter S is determined from the relationship between the initial cardiac output value Co and the blood flow velocity ■ according to equation (4). In this way, preparations for continuous CO measurement were completed. The following controls are the first CO and the CO at any time.

Since this is common in the calculations, the calculation control of C01 with respect to Vl at an arbitrary time will be explained.

In step S86, it is checked whether the continuous mode has been canceled. This is because the parameter S representing the blood vessel cross-sectional area usually changes over time. Therefore, -Cm tube cross-sectional area S
Even if S is held as a parameter, an accurate cardiac output may not be obtained due to a change in the blood vessel cross-sectional area S. Therefore, the initial cardiac output CO is appropriately measured by thermodilution method in preparation for the next continuous measurement of COl.

Unless the continuous mode is canceled, the process advances to step S87 and calculates co,=v,-5. In step 388, the average value of Vl and COI for 3 minutes is calculated in order to reproduce the lapse of 12 hours (FIG. 8). These values are stored in area 132c within RAM 132.

Then, in step S90, the RC pointer is incremented by 1 in order to calculate the next COI.

In this way, COI, etc. can be continuously calculated each time T t, Rt, T b, etc. are sent.

In this way, the cardiac output C01 could be measured by measuring only the blood flow velocity Ml.

<Data Recording> In addition to recording the thermodilution curves and thermodilution values shown in Figures 4 and 5, this measuring device also has a plotter for the Ike 1 value in parallel with the continuous measurement of CO. Continuous recording function to output to 50 (
(by switch 56), recording and reproducing function to output measured values for the past 30 minutes to plotter 50 (by switch 55)
There are output functions such as a progress chart output function (by switch 54) that outputs measured values for the past 12 hours (average values every 3 minutes) to plotter 50.

The output format by continuous recording and recording/reproduction is as shown in FIG. 6 (paper feeding speed 10 ms/min) and FIG. 7 (20 mS/hour).

Figure 8 shows the output format of the progress chart. In this progress chart, 3
co (=CO+) and blood temperature BT (=Tb) every hour
Record the value of along with the graph.

Now, this kind of recording is done in continuous mode (CONTINUOUS mode).
(when the OUS indicator 64 is lit), therefore, in parallel with the output to the plotter 50, it is necessary to take in data from the local CPU 105, calculate/store CO1, etc. For this control, access to the RAM 132 is performed using a PC pointer 162 for plotter output, an SC pointer 160 for data capture, and an RC pointer 160 for calculation/storage, as shown in FIG. 10B. ing.

<Substitute for injection liquid temperature> Since the indicator liquid to be injected is placed in a water-cooled container, it can be said that its temperature is almost determined by the water-cooling temperature. Therefore, when this ice-cooling temperature is known (for example, in degrees), it can be regarded as the indicated liquid temperature.

Therefore, in this measuring device, when the temperature probe 12 is not connected, it is detected and the temperature set by the switch 75 is regarded as the liquid temperature T1, and used for calculating the initial cardiac output co. .

Therefore, since the thermistor 12'a of the temperature probe 12 is connected to the constant voltage circuit 101, the injection liquid temperature detection circuit 102 detects the current flowing through the thermistor 12a. El corresponding to this zero current is set to the local CPL110.
5, this local CPU becomes the main CPU 13.
3, send a signal to that effect. Or CPU1
05 is E+f! corresponding to this zero current! : When converting to temperature TI, it is converted to an impossible value and the main CPU
133. With these, CPU133
can detect that the temperature probe 12 is disconnected.

FIG. 15 shows this control procedure. Main C in Figure 13
Instead of step S52 in which the PLJ 133 reads T1 from the RAM 132, step 5100 in FIG.
Then, it is determined whether the TI sent from the local CPU 105 is data indicating that the probe 12 is not connected. If the data indicates the connection status, step 51
01, Tl in this RAM 132 is used for measurement. If it is not connected, in step 5102, the data set in the switch 75 is taken in as T1.

<Measurement of relative change in cardiac output> The embodiment of the measuring device described above actually determines the initial cardiac output value CO by the thermodilution method, and calculates the value from the relationship between this CO and the initial blood flow velocity V. After determining the parameter S, the cardiac output Co can be continuously calculated by simply measuring the blood flow velocity v1 at any time.
The characteristic is that 1 is required. That is, C01ccvl, and changes in Vl reflect relative changes in Co.

Therefore, if you record the change in vl, you can directly record the change in CO.
This means that the relative change in l has been recorded. On the other hand, the approximate value of the parameter S is known if the subjects are the same and the measurer is aware of the parameter S during the measurement. Therefore, in the measuring device of this embodiment, this approximate parameter S
is input as the "initial CAL value" from the switch 62, thereby making it possible to omit measurement of the initial cardiac output value CO by thermodilution.

Application to other dilution methods> As is clear from the above explanation, the continuous cardiac output measurement of the above-mentioned embodiment is performed once the initial cardiac output co is measured by some method. If so, then the parameter S is measured and held, and thereafter the cardiac output ff1COI is continuously determined by only measuring the blood flow velocity 1. Therefore, in the present invention, the initial cardiac output CO is not limited to the method of obtaining the initial cardiac output CO by measurement using the thermodilution method as in the above embodiment, but the initial cardiac output CO can be obtained by, for example, the dye dilution method, the electrolyte dilution method, etc. It is also possible to obtain CO.

In this case, in the dye dilution method, the amount of pigment in the blood is measured by measuring changes in illuminance, such as at the earlobe, and in the electrolyte dilution method, changes in blood resistance are measured using two electrodes installed in a catheter. The cardiac output CO is obtained.

In other words, the amount of data (for example,
The manual function (Fr, ml) can also be applied to general indicator dilution methods using catheters. Further, the automatic measurement start function (2) is directly applied to detecting the points of change in the above-mentioned changes in illuminance and changes in resistance value. In addition, the continuous cardiac output measurement function (■) calculates the parameter S based on the initial cardiac output CO obtained by a general indicator dilution method, and then calculates the CoI from the blood flow velocity Vl at any time. It is also applicable to calculating .

Furthermore, as another modification and modification, we propose the following mechanism for detecting the connection of the temperature probe 12. That is, a biased protrusion is provided at a portion of the main body of the measuring device to which the connector 16 of the probe is connected. When the connector 16 is connected, this protrusion is pushed back. When the protrusion is pressed, the end of the protrusion is arranged to provide a ground signal to the measurement circuit 120, for example. The measurement circuit 120 can determine whether the probe 12 is connected or disconnected based on the presence or absence of this ground signal. In addition, the above protrusion is
It is electrically insulated from the circuit 120 except for its ends. This is to keep the entire circuit 120 electrically floating.

As another modification, blood flow rate measurement using thermistor 1 not only detects thermal equilibrium under constant current, that is, changes in thermistor resistance using voltage, etc., but also detects the temperature difference necessary to keep the temperature difference from blood temperature constant. A current may be applied and the current may be measured. In other words, there is a method of controlling the thermistor salt at an upper limit of 42° C., which does not affect living organisms, and measuring the current. Further, the blood flow rate sensor is not limited to a thermistor, and other means may be used.

[Effects of the Invention] As explained above, according to the device for continuously measuring and recording cardiac output of the present invention, it is possible to record continuous changes in cardiac output substantially in real time. Measurement and recording equipment can be provided.

[Brief explanation of the drawing]

1A, 1B, and 1C are a plan view, a front view, and a rear view of a measuring device according to an embodiment, and FIG. An overall perspective view, a cross-sectional view of the main parts, and a cross-sectional view of the opening of the catheter to be used. Figure 3 is a procedure diagram explaining the operating procedure of the measuring device of the example. Figures 4 and 5 show the thermodilution method using the device of the example. Figures 6 to 8 are diagrams showing examples of output results when cardiac output is measured based on the results of continuous measurement, and Figure 9 is a measurement The circuit diagrams of the main parts of the device, Figures 10A and 10B are diagrams explaining the RAM management within the measuring device, Figures 11, 13A, 13B, 14, and 15.
The figures are a flowchart showing the control procedure according to the embodiment, Figure 12 is a diagram showing a table storing the correction constant A, and Figures 16 and 17 are the principles of cardiac output measurement using the conventional thermodilution method. FIG. In the figure, 1.2, 12a... Thermistor, 4... Catheter, 8, 8, 10, 13. 14... Duplex, 7°9.
11, 15. 16... Connector, 12... Infusate temperature probe, 50... Plotter, 52, 53, 54.
55, 56, 57.58・φ・Switch, 59160.
61, 62.75...Setting manual switch, 64.65
, 66.67.70.72...Switch/indicator, 68...4-digit LED display, 69...3-digit L
ED display, 71...LED bar graph, 73...
Catheter connection connector, 74...Temperature probe connection connector, 100...Measuring device, 1o1°112...
- Constant voltage circuit, 111... Constant current circuit, 102...
Injection liquid temperature detection circuit, 103...analog switch,
104...A/D converter, 105,133...CP
U, 106,131・ROM, 107.132...R
It is AM. (Others - Namu・74.Kari 11th Ward 12th Figure 15th

Claims (2)

[Claims] (1) a cardiac output measuring means for determining a cardiac output value by measuring the cardiac output at least once based on a dilution method; a blood flow velocity measuring means for measuring a blood velocity value; function value calculation means for calculating a function value representing the relationship between a cardiac output value based on the dilution method and a blood flow velocity value corresponding to the measurement of the cardiac output value; and the blood flow velocity measuring means. cardiac output calculation means that continuously calculates a cardiac output value at each time based on the blood flow velocity value at each time measured by and the function value; and the cardiac output at each time. 1. A continuous measuring and recording device for cardiac output, comprising a recording means for recording values in time order. (2) The continuous measurement and recording device for cardiac output according to claim 1, wherein the dilution method is a thermodilution method, a dye dilution method, or a resistance value dilution method.