JPH01190365A - Safety device for medical apparatus - Google Patents

Abstract

PURPOSE:To activate a safety device when an abnormal signal is generated but to neglect the abnormal signal and continue the processing when a patient is not connected to a blood passage, by sending an output from a blood abnormality sensor through two different routes: one with a microcomputer and the other without a microcomputer, and making both the routes generate an abnormal signal respectively. CONSTITUTION:A part A and a part B respectively generate an abnormal signal without and with a microcomputer based on an output from a bubble sensor 7. A part C generates an abnormal signal with a watch dog timer 14. A gate circuit 20 works with a negative logic; that is, when an abnormal signal is outputted, the gate circuit 20 controls a driving circuit 16 to make a blood passage switch mechanism 9 block a blood passage, and when an abnormal signal is not outputted, the gate circuit 20 controls the driving circuit 16 to make the mechanism 9 open the passage. Since the safety device thus constructed has an override mechanism, it neglects an abnormal signal and proceeds with a blood process routine when a patient is not connected to the blood passage.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a safety device for medical equipment that processes blood collected from a patient and then returns the processed blood to the patient.

<Prior Art> Conventionally, there is an apparatus that collects blood from a patient or the like who requires treatment, separates and removes components in the blood, and returns the treated blood.

FIG. 4 shows such a blood component removal device.

In the figure, 1 is a patient, 2 is a blood pump installed in a flow path 3 for introducing blood from the patient, and 4 is a tube-shaped membrane 4a, for example.
5 is a plasma pump, 6 is a selective remover that selectively removes specific components contained in plasma, and 7 is a return to patient 1; A bubble detector is provided in the blood flow path 8, 9 is a blood flow path opening/closing mechanism, and 10 is a control device.

With this configuration, blood collected from the patient 1 is sent to the plasma separator 4 and separated into blood cell components and plasma. Outer room 4
The plasma separated in step c is sent to a selective removal device 6, where specific components (for example, riboproteins, etc.) contained in the plasma are selectively removed. The plasma processed by the selective removal device 6 is mixed with blood cell components from the inner chamber 4b of the plasma separator 4, and is returned to the patient 1 via the bubble detector 7 and the blood flow path opening/closing mechanism 9.

In such devices, air bubbles may be mixed in during the blood processing process. If blood is returned to patient 1 with air bubbles mixed in, it will lead to a serious accident.

Therefore, when air bubbles are detected in the blood by the air bubble detector 7, a detection signal is sent to the control device 10.
The blood flow path opening/closing mechanism 9 is activated by a drive signal from the blood flow path opening/closing mechanism 9 to close the blood return flow path 8 to prevent air bubbles from entering the patient's body.

The safety device of a medical device constituted by the air bubble detector 7, the blood flow path opening/closing mechanism 9, and the control device 10 is required to operate reliably, and conventionally, the configuration shown in FIG. 5 has been used. It is taken.

In this figure, the same elements as those in FIG. 4 are given the same reference numerals. 11 is a comparator, 12 is a latch circuit that latches the output of the comparator 11 in synchronization with the emission of the ultrasonic waves, and 13 is a microcomputer that reads the signal latched by the latch circuit 12 at a constant cycle.

14 is a watch dog timer that monitors abnormalities in the operation of the microcomputer 13; for example, it monitors interrupt instructions that are added at regular intervals when executing routines within the microcomputer 13, and when the instructions are interrupted, it starts its own count. Compare with the value and issue an abnormal signal. 15
is an AND gate that operates with negative logic, and 16 is a drive circuit for driving the blood flow path opening/closing mechanism 9.

With such a configuration, the bubble detector 7 is, for example, an ultrasonic detector in which an ultrasonic transmitter and an ultrasonic receiver are arranged opposite to each other with the blood return flow path 8 interposed therebetween. Ultrasonic waves are emitted at regular intervals from an ultrasonic transmitter, and bubbles are detected based on the difference in the propagation efficiency of ultrasound between gas and liquid. When the blood flowing through the flow path 8 does not contain air bubbles, the ultrasonic output is detected, the output of the comparator 11 becomes H level, and this value is latched in the latch circuit 12. On the other hand, if the blood contains air bubbles, no ultrasonic output is detected and the output of the comparator 11 becomes level 14, and this value is latched in the latch circuit 12. The microcomputer 13 reads these values and determines whether or not to activate the safety device. If it is determined that the safety device needs to be activated, it provides an abnormal signal of level I to the OR gate 15. On the other hand, watch
Even when the dog timer 14 detects an abnormality in the microcomputer 13, an L level abnormality signal is given to the OR gate 15.

When any of these abnormal signals is given, the drive circuit 1
6 controls the blood flow path opening/closing mechanism 9 to close the flow path 8.

<Problems to be Solved by the Invention> However, in such a device, there are some abnormalities in the microcomputer 13 that cannot be detected by the watch dog timer 14, and in such an abnormal state, the microcomputer 13 If the detection output is misread, the blood flow path opening/closing mechanism 9 may not operate reliably.

Furthermore, in such medical equipment, there are cases where it is desired to proceed with the sequence in a state where the patient's chopsticks 1 are not connected to the blood flow path 8. In the conventional device, regardless of whether the patient 1 is connected to the blood flow path or not, when air bubbles are detected by the air bubble detector 7, the blood flow path opening/closing mechanism 9 is turned on and the flow path 8 is blocked, causing the sequence to be interrupted. I couldn't proceed.

The technical problem to be solved by the present invention is to realize a safety device that operates reliably when there are air bubbles in the blood, and allows the sequence to proceed when the patient is not connected to the blood flow path. There is a particular thing.

Means for Solving the Problems> The configuration of the present invention includes, in the medical device, one or more blood abnormality detectors that measure blood flowing through the blood flow path and detect abnormalities in the blood, and the blood abnormality detector. a microphone computer to which at least one detection output of the device is applied, and which generates an abnormal signal when a patient is connected to the blood flow path;
A watch that monitors the operation of this microcomputer.
a dog timer, a signal processing circuit that processes the detection output from the blood abnormality detection circuit, and an abnormal signal from this circuit, an abnormal signal from the microcomputer, and an abnormal signal from the watch dog timer. and an override signal applied to execute a blood processing routine when a patient is not connected to the blood flow path, and a logic circuit actuated by the output of the logic circuit to interrupt said blood flow path. and a blood flow path opening/closing mechanism, which operates the blood flow path opening/closing mechanism when one of the abnormal signals is given, and ignores the abnormal signal and opens/closes the blood flow path when the override signal is given. The problem lies in the structure being configured so that the mechanism does not operate.

Function> The above technical means works as follows. That is, the detection output of the blood abnormality detector is given to a route that goes through the microcomputer and a route that does not go through it, respectively, and generates abnormality signals, and there is a possibility that the detection output may be caused by a cause that cannot be detected by the watch dog timer. Even if the microcomputer becomes abnormal, an abnormality signal can be generated through another route, and the safety device can be operated reliably.

Furthermore, since it has an override function, when the patient is not connected to the blood flow path, the abnormal signal can be ignored and the blood processing routine can proceed.

<Example> The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are flow charts and timing charts for explaining the operation of the apparatus according to an embodiment of the present invention shown in FIG. In FIG. 1, the same elements as those in FIG. 5 are given the same reference numerals, and explanations thereof will be omitted. - The part A surrounded by the dotted chain line is a part that generates an abnormal signal without going through the microcomputer 13 based on the output of the bubble detector 7, - The part B surrounded by dots is a part that generates an abnormal signal based on the output of the bubble detector 7 A portion C that generates an abnormal signal via the watch dog timer 13, and a portion C surrounded by a dashed line is a portion that generates an abnormal signal through the watch dog timer 14.

17 is a comparator with the same configuration as comparator 11 to which the output of bubble detector 7 is given; 18 is a retriggerable one-shot multivibrator that is triggered by the output of comparator 17, and is longer than the measurement period of bubble detector 7. Generates a pulse with a time width. This output is connected to latch circuit 12 and OR gate 1
given to 9. 20 is the output from OR gate 19,
An OR gate that operates with negative logic to which the output from the microcomputer 13 and the output from the watch dog timer 14 are applied; 21 is a power supply for the drive circuit 16; 22 is a power switch; 23 is an OR gate 19; This is a power switch drive circuit that operates with the output of 24 is a switch that provides an override signal.

The operation of the apparatus configured in this way will be explained with reference to FIGS. 2 and 3. Figure 3(a).

(b) shows the output of the air bubble detector 7. The air bubble detector 7 emits ultrasonic waves every t = 10 msec to detect air bubbles. Figure (a) shows the detection output when there are no air bubbles in the blood. Figure (b) shows the detection output when there are bubbles. In the presence of air bubbles, the ultrasonic energy is significantly attenuated, resulting in a lower detection output level. Figure 3 (
C).

(d) represents the output of the comparator 11.17, Figure (c) represents the output when there are no bubbles, Figure (d) represents the output when there are bubbles, Figure 3 (e) .

(f) represents the output of the latch circuit 12, and latching is performed at the location indicated by the arrow. ), Figure (e) represents the output when there are no bubbles, and Figure (f) represents the output when there are bubbles. Fig. 3 (g> shows the output of the three-coupled one-shot multivibrator 18. If the bubble-free state is continuously measured, the output at H level will be maintained, but for example after P1, if there is a bubble, has an output waveform as shown by the dotted line.Figure 3 (h) and (i) are OR gate 1
Figure (i) represents the output when there is a bubble and there is no override signal.

The operations of parts A, B, and C will be explained according to the flowchart of FIG. In part A, in step (1) comparator 1
When the output at level 7 indicates that there are bubbles, the output at level I in FIG. 3(f) is applied to one input of the OR gate 19.

If there is no override signal in the OR gate 19 in step (2), an abnormality signal shown in FIG. 3(i) is output to the gate circuit 20 in step (3). At the same time, an output is sent to the power switch drive circuit 23, and the switch 22 is switched to the state shown in the figure, so that the safety device can be driven (step (4)
).

If the output of the comparator 17 is free of bubbles in step (1),
and if there is an override signal in step (2),
Proceeding to step (5), no abnormal signal is output to the AND gate 20 (the state shown in FIG. 3(h)), and the power switch drive circuit 23 is not driven (step (6)).

In part B, when the outputs of the comparator 11 and the retriggerable one-shot multivibrator 18 match in step (7), it is determined that air bubbles are present in step (8), and further, in step (9), the patient's blood flow is The state of the connection to the road is considered and it is determined whether it is necessary to bring it to a safe state.

If it is determined that it is necessary to lead to a safe state, an L level abnormal signal is output to the gate circuit 20 (step <1
0)). Even when the outputs do not match in step (7), an L level signal is applied to the gate circuit 20.

If it is determined in step (8) that there are no bubbles, and if it is determined in step (9) that there is no need to lead to a safe state, no abnormality signal is output to the gate circuit 20 (step (11)).

In part C, when the watch dog timer (W, D, T,) 14 is activated in step (12), an L level abnormality signal is given to the gate circuit 20. When the watch dog timer 14 does not operate, no abnormal signal is given to the gate circuit 20 (step (14))
.

The gate circuit 20 operates with negative logic, and controls the drive circuit 16 so that the blood flow path opening/closing mechanism 9 closes the blood flow path when the output is at the L level (step (15)).

If no abnormality signal is given to the gate circuit 20, the drive circuit 16 is controlled so that the blood flow path opening/closing mechanism 9 is opened (step (16)).

<Effects of the Invention> According to the present invention, the detection output of the blood abnormality detector is given to a route via the microcomputer and a route not via the microcomputer, respectively, to generate abnormality signals, and・Even if the microcomputer becomes abnormal due to a cause that cannot be detected by the dog timer, an abnormal signal can be generated through another route and the safety device can be reliably activated.

Furthermore, the retriggerable one-shot multivibrator monitors dynamic changes in the detection output of the blood abnormality detector, and there is little possibility of false detection.

Furthermore, since it has an override function, when the patient is not connected to the blood flow path, the abnormal signal can be ignored and the blood processing routine can proceed.

Although the above embodiment of the present invention uses a bubble detector to detect air bubbles in blood, it is also applicable to a blood leakage sensor that detects red blood cell components leaked into separated plasma or a dialysis machine. The present invention can also be implemented in air bubble detectors and blood leak sensors without any difficulty. Further, in the embodiment, there is only one bubble detector, but the present invention is not limited to this, and a plurality of detectors may be used, and a predetermined detection output from them may be used.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the apparatus according to the present invention, Fig. 2 and Fig. 3
The figures are a flowchart and a timing chart for explaining the operation of the device according to the embodiment of the present invention shown in FIG. 1, FIG. 4 is a configuration diagram showing a blood component removal device, and FIG. FIG. DESCRIPTION OF SYMBOLS 1... Patient, 4... Plasma separator, 6... Selective remover, 7... Air bubble detector, 8... Blood flow path for blood return,
9...Blood channel opening/closing mechanism, 11...Comparator, 12.
...Latch circuit, 13...Microcomputer, 1
4... Watch dog timer, 16... Drive circuit, 17... Comparator, 18... Retriggerable one-shot multivibrator, 19.20... Gate, 21... Power supply, 22・・・Power switch, 23・
...Drive circuit, 24...Switch that gives an override signal Fig. 3 (i)

LFigure 4Figure 5

Claims (1)

[Claims] A medical device that processes blood collected from a patient and returns the processed blood to the patient, including one or more blood abnormality detectors that measure blood flowing through a blood flow path and detect abnormalities in the blood, and the blood abnormality detector. a microcomputer that is provided with at least one detection output of the blood flow path and that generates an abnormal signal when a patient is connected to the blood flow path; a watch dog timer that monitors the operation of the microcomputer; a signal processing circuit that processes the detection output from the detection circuit; an abnormal signal from this circuit; an abnormal signal from the microcomputer;
An abnormal signal from the dog timer is given, and
a logic circuit that is provided with an override signal that is applied to execute a blood processing routine when a patient is not connected to the blood flow path; and a blood flow path that is actuated by the output of the logic circuit to interrupt said blood flow path. an opening/closing mechanism, which operates the blood flow path opening/closing mechanism when one of the abnormal signals is given, and operates the blood flow path opening/closing mechanism ignoring the abnormal signal when the override signal is given. A safety device for medical equipment, characterized in that it prevents