JP2971182B2 - Blood leak detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a blood leak in an artificial dialysis machine without causing an erroneous detection due to air bubbles, dirt, or offset voltage of an electric circuit, and performs a start-up inspection of the artificial dialysis machine. The present invention relates to a blood leak detector that can be automatically implemented.

[0002]

2. Description of the Related Art In general, an artificial dialysis apparatus draws blood from the vein side of a human body, introduces the blood into a dialyzer using a semi-permeable membrane, and contacts the dialysate through the semi-permeable membrane in the dialyzer. It is known as a dialysis treatment device configured to remove waste products from blood and then return it to the human body again.

However, when extracorporeal circulation of blood is performed using this type of artificial dialysis apparatus, for example, if a semi-permeable membrane has a pinhole or the like, blood leakage occurs on the dialysate side, which causes dialysis treatment for a long time. In this case, a considerable amount of blood is lost, which is extremely dangerous for the human body.

[0004] From such a viewpoint, conventionally, in this type of artificial dialysis apparatus, various blood leak detection apparatuses which detect the incorporation of blood into the dialysate and generate an alarm or the like have been proposed. Therefore, as a conventional blood leakage detection device, a method of detecting the mixed state of blood dispersed in the dialysate using photoelectric photometry is preferable. The following two types are known. Have been.

That is, in the first method, a light-emitting element having one peak wavelength range is provided on the light-emitting side, and a decrease in the amount of transmitted light in a subject (dialysis fluid) is detected by the light-receiving element on the light-receiving side. This is a method of detecting blood leakage. However, in the first method, the amount of transmitted light decreases not only when blood is mixed into the dialysate but also when air bubbles are mixed in or the protein or the like causes contamination. There is a high possibility that erroneous detection is performed, and there is a disadvantage that reliability is lacking.

On the other hand, in the second method, a light emitting element having two peak wavelengths having different absorption rates for blood is provided on the light emitting side, and the light is transmitted through the subject (dialysis fluid) and reaches the light receiving element on the light receiving side. The decrease in the amount of transmission of the two wavelengths of light is the same when both are caused by air bubbles and dirt as described above, and in the case of blood leakage, the wavelength susceptible to blood is significantly reduced. This is a method that can reliably detect blood leakage.

[0007]

However, according to the above-described second method, blood leakage is detected based on the difference between the amounts of transmitted light of two wavelengths. It is necessary to adjust the operation circuits on the light emitting side and the light receiving side so that the differential output of the voltage level obtained by converting the amount of transmitted light without blood leakage, bubbles and dirt becomes zero. For this reason, there is a difficulty in designing and manufacturing a circuit for performing photoelectric photometry.

The first and second systems in the conventional blood leakage detecting device have a disadvantage that both are affected by an offset voltage of an electric circuit which fluctuates depending on a temperature, thereby causing erroneous detection or malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to prevent the occurrence of bubbles and dirt in a dialysate, to prevent erroneous detection due to the offset voltage of an electric circuit, and to simply and adjust a circuit for performing photoelectric photometry. With an unnecessary configuration, it is possible to always achieve high sensitivity and appropriate detection of blood leakage with high sensitivity, and it is also possible to safely and automatically carry out a start-up inspection before starting dialysis treatment with an artificial dialysis machine, and to manufacture at lower cost It is an object of the present invention to provide a blood leak detector that can perform the blood leak detection.

[0010]

According to the blood leak detector of the present invention, a light-emitting element is separately illuminated by light having two peak wavelengths having different absorption rates for blood, and a dialysate is transmitted to the blood-leakage detector. In the blood leak detector for detecting the blood leak state in the dialysate by receiving and comparing the voltage levels obtained by converting the transmission amounts of the two wavelengths of light to the dialysate, the light emitting element is connected to the light emitting element via a resistor. A light-emitting side circuit configured to directly connect a drive circuit and drive the drive circuit with an oscillation circuit that outputs two predetermined light-emission pulse voltage signals, and an output of the light-receiving element are synchronized directly via a current-voltage conversion circuit. Through the circuit, in synchronization with the two light emission pulse voltage signals, the transmission amounts of the light of the two wavelengths are obtained as converted DC voltages, respectively, and these DC voltage levels are A / D
A light receiving side circuit configured to perform detection of the blood state leakage by comparing calculated the magnitude through a converter and a microcomputer, characterized in that the provided.

In the blood leakage detector, an AND circuit is provided in a light emitting side circuit between a driving circuit for emitting light having two wavelengths in a light emitting element and an oscillation circuit for outputting a predetermined pulse voltage signal. It can be configured such that emission of light having two wavelengths can be stopped simultaneously. In this case, the emission of light having two wavelengths is simultaneously stopped in a state where there is no blood leak, air bubbles and dirt in the dialysate, the offset voltage of the light receiving side circuit at this time is calculated, and then the light having two wavelengths is calculated. Light is emitted separately, the output voltage of the light receiving side circuit at this time is calculated, a correction value is calculated from the offset voltage and the output voltage, and then the emission of light having two wavelengths is periodically stopped simultaneously. It is preferable that the microcomputer be configured to calculate a corrected output voltage value that is not affected by the offset voltage based on the offset voltage at that time and the correction value. Further, in a light emitting side circuit in which a drive circuit is directly connected to a light emitting element via a resistor, an auxiliary resistor is further connected and disposed between a connection point between the resistor and the drive circuit, and the auxiliary resistor and The contacts of the automatic switch were connected in parallel, and the resistance value of the auxiliary resistor was adjusted so that the ratio of the voltage levels on the light receiving side of the two wavelengths of light when the contacts of the automatic switch were open had a predetermined blood leak. It is also possible to adopt a configuration in which the ratio is set to a value equivalent to that at the time.

[0012]

According to the blood leak detector of the present invention, the light emitting side circuit is connected to the drive circuit directly to the light emitting element via the resistor, and the drive circuit outputs the predetermined pulse voltage signal to the oscillation circuit. The light-receiving-side circuit directly connects the output of the light-receiving element via a current-to-voltage conversion circuit to a synchronous circuit.
In synchronization with the two emission pulse voltage signals.
The amount of transmitted light of two wavelengths is obtained as a converted DC voltage, and the DC voltage level is calculated and compared via an A / D converter and a microcomputer to detect a blood leakage state. With this configuration, it is not necessary to correct the light emission intensity of the light emitting element or to adjust the amplification factor of the light receiving signal of the light receiving element. Therefore, the use of these adjustment electric parts is omitted, and the configuration is simple and the sensitivity is high. Can obtain a stable DC voltage with good reliability
Blood leak detector that can perform high detection .

In particular, according to the blood leak detector of the present invention, the correction of the difference between the voltage levels obtained by converting the transmission amounts of the light of the two wavelengths on the light receiving side into zero in the absence of blood leak, air bubbles and dirt. The calculation can be performed, and erroneous detection due to air bubbles and dirt other than blood leakage can be reliably prevented, and appropriate monitoring of blood leakage can be achieved.

In the blood leak detector according to the present invention, the light emitting side circuit is configured so that light having two wavelengths can be stopped simultaneously in the light emitting element, so that the light is corrected without being affected by the offset voltage. The detected voltage value is obtained, thereby preventing an erroneous detection operation affected by an offset voltage of an electric circuit which fluctuates with temperature, and constantly monitoring blood leakage accurately.

Further, in the blood leak detector of the present invention, an auxiliary resistor connected in parallel with the contact of the automatic switch is connected to the light emitting side circuit, and the resistance value of the auxiliary resistor is set to the contact of the automatic switch. Before the start of dialysis treatment of the artificial dialysis device by setting the ratio of the voltage level on the light receiving side of the two wavelengths of light when the valve is open to the same ratio as when there is a predetermined blood leak. It is possible to automatically carry out a start-up inspection of the work.

[0016]

Next, an embodiment of a blood leak detector according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block circuit diagram showing an embodiment of a blood leak detector according to the present invention, and FIG. 2 is a waveform diagram showing an operation state of the block circuit of FIG. 1 and 2, reference numeral 10 denotes a light emitting element, 12 denotes an oscillating circuit for generating a constant pulse voltage V1, 14 denotes an inverting circuit for generating an inverted output pulse voltage V2 of the output pulse voltage V1 of the oscillating circuit, 16 , 18 denote driving circuits for outputting light having two peak wavelengths having different absorption rates for blood to the light emitting element 10, respectively. However, on the light emitting side, the pulse voltage V1 of the oscillation circuit 12 is on the one hand driven by the drive circuit 18 and the resistor R via the inverting circuit 14.
The circuit is configured to supply the light to the light emitting element 10 via 1 and to supply the light to the light emitting element 10 via the driving circuit 16 and the resistor R2.

Reference numeral 20 denotes a light-receiving element, 22 denotes a current-voltage conversion circuit, 24 and 26 denote amplification circuits, and 28 and 30 drive the light-emitting element 10 based on pulse voltages V1 and V2 for driving the light-emitting element 10. A synchronization circuit for synchronizing the pulse with the output pulse of the light receiving element 20 (see V4 and V5);
Reference numeral 34 denotes a rectifier circuit, 36 denotes an A / D conversion circuit, and 38 denotes a microcomputer. However, on the light receiving side, after directly converting the output of the light receiving element 20 to the voltage V3 by the current / voltage conversion circuit 22 without amplifying the output,
In order to compare the voltage levels obtained by converting the transmission amounts of the two wavelengths, the amplification circuit 24, the synchronization circuit 28,
The signal is transferred to the A / D conversion circuit 36 via the rectification circuit 32, and is transferred to the A / D conversion circuit 36 via the amplification circuit 26, the synchronization circuit 30, and the rectification circuit 34. Microcomputer 3 converts the D-converted signal
The circuit is configured to monitor the blood leakage by inputting it to 8 and calculating the voltages of the two wavelengths and comparing them.

The blood leak detector of the present embodiment thus configured has two peak wavelengths having different absorptivity to blood, for example, 550 nm and 650 n on the light emission side.
A light emitting device 10 having a peak wavelength of m is used. Therefore, the light-receiving element 20 on the light-receiving side that has passed through the subject (dialysis fluid)
The reduction rate of the amount of transmission of the two wavelengths of light that has reached the above is the same when both are caused by bubbles or dirt, and in the case of blood leakage, the wavelength (550 nm) that is easily affected by blood is significantly reduced. . The voltage level converted from the amount of transmitted light is
Since the side circuit is synchronized with the light emitting side circuit,
As a result, a stable DC voltage can be obtained
Can be accurately detected. Therefore, in this case, it is necessary to reduce the difference between the voltage levels obtained by converting the transmission amounts of the two wavelengths of light on the light receiving side to zero in a state where there is no blood leakage, bubbles, or contamination. Therefore, in this embodiment, the light emitting element 1
The DC output V6, V7 on the light receiving side in a state where there is no blood leakage, bubbles or dirt is adjusted without adjusting the light emission intensity of 0 or the amplification factor of the light receiving element 20.
6 and input to the microcomputer 38 to calculate and compare the voltages of the two wavelengths, thereby making the difference 0.
Is obtained by the following equation (1). V6−aV7 = 0 (1) Then, by appropriately correcting the voltage of the one wavelength with the correction value a and comparing this with the voltage of the other wavelength, it is possible to achieve appropriate monitoring of blood leakage. .

FIG. 3 is a block circuit diagram showing another embodiment of the blood leak detector according to the present invention, and FIG. 4 is a waveform diagram showing an operation state of the block circuit of FIG. In the circuit of this embodiment, the same components as those of the circuit shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, in the embodiment circuit shown in FIG. 1, AND circuits 40 and 42 are provided between the light emitting side oscillation circuit 12 and the drive circuit 16 and between the inversion circuit 14 and the drive circuit 16, respectively. And place these AND
The oscillation circuit 12 is connected to one input terminal of each of the circuits 40 and 42.
The circuit configuration is such that the microcomputer 38 supplies a signal V8 for stopping the light emission of the light emitting element 10 irrespective of the oscillating operation of. The other circuit configuration is the same as that of the embodiment shown in FIG.

In the blood leakage detector of this embodiment having the above-described structure, the emission stop signal V8 simultaneously stops emission of two wavelengths on the light emission side, thereby reducing the offset voltage generated in the circuit on the light reception side. Can be determined automatically. That is, in this case, the microcomputer 38 calculates the offset voltage as follows.

First, light emission of two wavelengths in the light emitting element 10 is simultaneously stopped in a state where there is no blood leakage, air bubbles or dirt in the subject (dialysis fluid), and the offset voltages V6 'and V7' at this time are reduced. It is determined by the following equations (2) and (3). V6 '= V6 (2) V7' = V7 (3) Next, the light emitting element 10 is caused to emit light at two wavelengths separately in the same state as above, and the output voltages V6 and V7 at this time and the offset voltage V6 ', From V7 ', a correction value a' is obtained by the following equation (4). V6−V6 ′ = a ′ (V7−V7 ′) (4) Thereafter, light emission of the two wavelengths in the light emitting element 10 is periodically stopped at the same time, and the offset voltages V6 ″, V
7 "is obtained by the following formulas (5) and (6) in the same manner as described above, and is substituted into the following formulas (7) and (8) together with the correction value a ', whereby the correction not affected by the offset voltage is performed. V6 ″ = V6 (5) V7 ″ = V7 (6) Vx = V6−V6 ″ (7) Vy = a ′ (V7−V7 ″) (8) By comparing the corrected voltage values Vx and Vy, it is possible to prevent an erroneous detection operation that is affected by an offset voltage of an electric circuit that fluctuates with temperature, and to always accurately monitor blood leakage. Therefore, according to the electric circuit of the present embodiment, there is no need to provide a thermistor or the like for temperature correction.

FIG. 5 is a block circuit diagram showing still another embodiment of the blood leak detector according to the present invention. In the circuit of this embodiment, the same components as those of the circuit shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, a resistor R3 is further connected between the connection point of the driving circuit 18 on the light emitting side and the resistor R1 in the circuit shown in FIGS. Automatic switch 50 such as a relay in parallel with
Are connected. In this case, the resistance value of the resistor R3 is such that when the contact 52 of the automatic switch 50 is open, the ratio of the voltage level on the light receiving side of the light of the two wavelengths is equal to that when a predetermined blood leak occurs. Set to a value that will result in a difference. The automatic switch 50 is configured to open and close by a signal from the microcomputer 38.

In the blood leakage detector of this embodiment having the above-mentioned structure, the contact 52 of the automatic switch 50 is closed when the light receiving side is in the blood leakage monitoring state, and when the sensitivity of the detector is checked. By setting the microcomputer 38 in advance so as to give a command to open, the start-up inspection before starting the dialysis treatment of the artificial dialysis machine or the operation check of the blood leakage detector during the dialysis is automatically performed. be able to.

FIG. 6 is a block circuit diagram showing still another embodiment of the blood leak detector according to the present invention. The circuit of this embodiment is different from the circuits shown in FIGS. 5 and 3 in that a decimal Johnson counter 60 is provided instead of the inverting circuit 14, and the output signal of the decimal Johnson counter 60 is sent to the synchronization circuits 28 and 30, respectively. Inverting circuits 70 and 72 are connected and arranged on a signal line to be supplied.
Amplifying circuits 80 and 82 are connected and arranged on the output side of the circuit 34, respectively. Other configurations are described in FIGS.
Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

According to the blood leak detector of the present embodiment configured as described above, as is apparent from FIG. 7, both peaks are emitted between the emission of one peak wavelength and the emission of another peak wavelength. Since the emission of the light having the wavelength is stopped, mutual interference that occurs when a light-emitting element and a light-receiving element with low response speed are used can be prevented. Therefore, FIG. 5 and FIG.
The blood leak detection operation by the embodiment circuit shown in FIG. 1 can be made more accurate and highly reliable. In the circuit of this embodiment, if the outputs of the rectifier circuits 32 and 34 are sufficiently obtained, the amplifier circuits 80 and 82 can be omitted.

Although the preferred embodiment of the detector of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the spirit of the present invention. Of course.

[0030]

As is apparent from the above-described embodiment, according to the present invention, the light emitting side circuit connects the drive circuit directly to the light emitting element via the resistor and connects the drive circuit to the predetermined pulse voltage. It is configured to be driven by an oscillation circuit that outputs a signal, and the light receiving side circuit directly outputs the output of the light receiving element to the light emitting pulse voltage signal and the synchronous circuit via a current / voltage conversion circuit.
The more synchronized transmission amounts of the two wavelengths of light are respectively obtained as converted DC voltages, and these DC voltage levels are represented by A
By detecting and detecting the blood leakage state by calculating and comparing the magnitude through the / D converter and the microcomputer, the light emitting intensity of the light emitting element is corrected, and the light receiving signal of the light receiving element is amplified. There is no need to adjust the rate, etc., and therefore, the use of these adjusting electric parts is omitted, and a DC voltage with a simple configuration and high sensitivity and stability can be obtained.
And a blood leakage detector capable of performing highly reliable detection can be obtained.

In particular, according to the blood leak detector of the present invention, the voltage level of the voltage converted from the transmission amount of the light of the two wavelengths on the light receiving side in a state where there is no blood leak, bubbles, or dirt using a microcomputer. By performing the correction operation to make the difference 0, it is possible to reliably prevent erroneous detection due to bubbles and dirt other than blood leakage, and to achieve appropriate monitoring of blood leakage.

In the blood leak detector according to the present invention, the light emission side circuit is configured so that light having two wavelengths can be stopped simultaneously in the light emitting element, so that the light is corrected without being affected by the offset voltage. The detected voltage value is obtained, thereby preventing an erroneous detection operation affected by an offset voltage of an electric circuit which fluctuates with temperature, and constantly monitoring blood leakage accurately. Therefore, in this case, there is no need to provide a thermistor or the like for temperature correction in the electric circuit.

Further, in the blood leakage detector of the present invention, an auxiliary resistor connected in parallel with the contact of the automatic switch is connected and arranged in the light emitting side circuit, and the resistance value of the auxiliary resistor is set to the contact of the automatic switch. Before the start of dialysis treatment of the artificial dialysis device by setting the ratio of the voltage level on the light receiving side of the two wavelengths of light when the valve is open to the same ratio as when there is a predetermined blood leak. Start-up inspection can be performed automatically.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing one embodiment of a blood leak detector according to the present invention.

FIG. 2 is a waveform diagram showing an operation state of the blood leak detector shown in FIG.

FIG. 3 is a block circuit diagram showing another embodiment of the blood leak detector according to the present invention.

FIG. 4 is a waveform diagram showing an operation state of the blood leak detector shown in FIG.

FIG. 5 is a main part circuit diagram showing still another embodiment of the blood leak detector according to the present invention.

FIG. 6 is a block circuit diagram showing still another embodiment of the blood leak detector according to the present invention.

FIG. 7 is a waveform diagram showing an operation state of the blood leak detector shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Light emitting element 12 Oscillation circuit 14 Inversion circuit 16, 18 Drive circuit 20 Light receiving circuit 22 Current-voltage conversion circuit 24, 26 Amplification circuit 28, 30 Synchronization circuit 32, 34 Rectification circuit 36 A / D conversion circuit 38 Microcomputer 40, 42 AN
D circuit 50 Automatic switch 52 Contact point 60 Decimal Johnson counter 70,72 Inverting circuit 80,82 Amplifying circuit

Claims (4)

(57) [Claims] 1. A light-emitting element which emits light separately with light having two peak wavelengths having different absorptivity to blood, transmits a dialysate, receives light by a light-receiving element, and transmits light of two wavelengths to the dialysate. In the blood leak detector that detects a blood leak state in the dialysate by comparing the voltage level obtained by converting the amount, a drive circuit is directly connected to the light emitting element via a resistor, and the drive circuit is connected to a predetermined circuit. a light emitting side circuit configured to drive the oscillation circuit for outputting two light emission pulse voltage signal, via a direct current voltage conversion circuit to output of the light receiving element, the synchronization times
Through the path and in synchronization with the two light-emission pulse voltage signals, to obtain the converted DC voltages of the transmission amounts of the light of the two wavelengths, respectively, and these DC voltage levels are used for the A / D converter and the microcomputer. blood leakage detector to the light-receiving side circuit configured to perform detection of the leakage blood state by calculating the magnitude comparator, characterized in that the provided through. 2. The light emitting side circuit, wherein an AND circuit is provided between a driving circuit that emits light having two wavelengths in the light emitting element and an oscillation circuit that outputs a predetermined pulse voltage signal, and has two wavelengths. 2. The blood leakage detector according to claim 1, wherein the blood leakage detector is configured to stop light emission at the same time. 3. A method for simultaneously stopping emission of light having two wavelengths in a state in which there is no blood leakage, bubbles, or contamination in the dialysate,
The offset voltage of the light receiving side circuit at this time is calculated, and then the light having two wavelengths is separately emitted, and the output voltage of the light receiving side circuit at this time is calculated, and the correction value is calculated from the offset voltage and the output voltage. , The emission of light having two wavelengths is periodically stopped at the same time, and based on the offset voltage at that time and the correction value, a corrected output voltage value that is not affected by the offset voltage is calculated. 3. The blood leak detector according to claim 2, which comprises a computer. 4. A light emitting side circuit in which a drive circuit is directly connected to a light emitting element via a resistor, an auxiliary resistor is further connected between a connection point between the resistor and the drive circuit, and the auxiliary resistor is connected to the light emitting element. A contact of an automatic switch is connected in parallel with the resistor, and the resistance value of the auxiliary resistor is set to a predetermined value for the ratio of the voltage level on the light receiving side of the two wavelengths of light when the contact of the automatic switch is opened. 3. The blood leak detector according to claim 1, wherein the blood leak detector is set to a value that is equivalent to a ratio when there is an error.