JP4283608B2 - Medical equipment - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to vascular access to a patient in a medical device such as a dialysis device, a heart-lung machine, or an infusion pump. Application of monitoring Relates to a medical device.
[0002]
[Prior art]
As medical devices that move or circulate liquids through a blood vessel access to a patient's blood vessels, dialysis devices, cardiopulmonary devices, infusion pumps, and the like are known. For example, taking a dialysis machine as an example, the liquid that is connected to the patient's blood vessel via vascular access and moves to the blood vessel is blood. It is a system that removes the waste products and returns the filtered blood to the body to circulate the blood. In the case of an infusion pump, the liquid that is connected to the patient's blood vessel via the vascular access and moves to the blood vessel corresponds to a liquid medicine or nutrient solution, and the medicine or nutrient solution is transferred via the vascular access. The system is injected into the patient's body.
[0003]
Here, the dialysis apparatus will be described in detail. First, a blood vessel cannula (needle) is inserted into a blood vessel to realize blood vessel access, and the liquid derived from the patient's body by driving a blood pump via the blood vessel access, that is, blood passes through the dialyzer, The waste and water in the blood are removed and purified by the osmotic pressure difference between the dialysate flowing outside the hollow fiber and the blood flowing inside the hollow fiber and ultrafiltration. The dialysis treatment is generally performed over a long period of 4 to 5 hours, and during this treatment period, the dialysis patient spends sleeping, watching TV, or reading.
[0004]
However, there is a risk that a serious accident such as dropping of a blood vessel cannula (needle) due to tumbling during sleep may occur. For example, if the needle on the venous side is removed, blood may continue to flow out. On the other hand, if the needle on the venous side is removed, there is a risk that air will flow into the blood vessel, which is a serious problem for patient safety. . For this reason, the arterial side detects air bubbles with a bubble detector, and measures are taken to detect the dropout of the arterial needle. In addition to detachment of the vascular cannula, problems such as poor circulation of blood to be dialyzed due to twisting of the vascular tube may occur.
[0005]
Thus, Patent Document 1 discloses a method for detecting needle dropout for dialysis. According to this method, the pressure wave generated by the heart is detected by the pressure sensor through the blood to be dialyzed, and if the pressure wave is not detected, the needle has fallen off. The problem with this method is that in the dialyzed blood Applied The pressure wave generated is not only the pressure wave caused by the heart, that is, the pulse, but also the pressure wave caused by the blood pump, etc., and how to select only the pressure wave caused by the pulse is an issue. ing. According to the method of Patent Document 1, since the frequency of the pressure wave generated by the heart and the pressure wave generated by the blood pump are different, a means of extracting only the pressure wave caused by the heart using a bandpass filter or the like is employed. ing.
[0006]
[Patent Document 1]
Japanese National Patent Publication No. 11-513270
[0007]
[Problems to be solved by the invention]
However, the frequency of the pressure wave in the patient's heart, that is, the pulse rate is not constant, and the pulse rate changes when the patient's condition deteriorates. Then, when the rotation frequency of the blood pump and the pulse rate are close to each other or overlap each other, not only the frequency due to the blood pump but also the frequency due to the pulse rate is removed together by the above-described filter. Thus, there is a problem that it becomes impossible to detect the drop of the needle for vascular access in dialysis.
[0008]
The present invention has been made for the above-mentioned circumstances, and the object of the present invention is that the patient's condition deteriorates and the pulse rate etc. changes greatly, and the frequency of the pressure wave resulting from the pulse and the medical device Reliable monitoring of vascular access in medical devices, even if the frequency of pressure waves caused by blood pumps overlap Medical devices that can It is to provide.
[0009]
[Means for Solving the Problems]
The present invention is coupled to a patient's blood vessel via vascular access to move fluid to said blood vessel. Medical device having a mechanical device for applying pressure The above object of the present invention is to A pressure fluctuation means for rotating the rotation frequency of a pump constituting the mechanical device so as to change by a fixed frequency width around a reference frequency; a pressure detection means for measuring the pressure of the liquid; and Frequency analysis means for detecting a spectrum by performing frequency analysis of data for a certain period of time, and comparing the intensity of the frequency component resulting from the pulse of the patient output by the frequency analysis means with a predetermined value to detect abnormalities in the vascular access A determination means for determining Achieved by:
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a moving liquid in a medical device. Applied In addition to the pressure wave caused by the pump for moving the liquid, etc., the pressure wave due to blood pressure synchronized with the patient's pulse is mixed, so only the pressure wave due to the pulse is specified There is a need. Next, if the intensity of the pressure wave due to the pulse is measured and the intensity is an abnormally small value, or if the pressure wave due to the pulse does not exist, vascular access to the patient Judge that there is an abnormality. In other words, the intensity of the pressure wave is proportional to the blood pressure value of the patient, So much When the intensity of the pressure wave is weak, it is thought that it is not caused by hypotension, but the cause is that the patient's vascular access needle falls off or the vascular tube is twisted and the liquid does not move. This is the basic idea of the present invention.
[0015]
The most important point of the present invention is that a weak pressure wave caused by a pulse of a liquid moving between a medical device and a patient is Fourier-transformed without using a band-pass filter or the like as in the prior art, particularly fast Fourier transform. Separation is performed using frequency analysis such as conversion (hereinafter referred to as FFT). When trying to separate the pressure wave due to the pulse using a conventional bandpass filter etc., the period of the pressure wave caused by the blood circulation pump and the pressure wave due to the pulse approaches, or when both pressure waves overlap, it becomes impossible to separate However, if this invention is used, the outstanding effect that the malfunction can be avoided can be expected. In addition, since FFT analysis responds to repetitive occurrences, FFT analysis does not respond to irregular movements such as patient movements, so it can also be expected to be more resistant to irregular movements than the bandpass filter method. .
[0016]
In the present invention, the liquid moving between the medical device and the patient Applied The spectrum composed of each frequency component is detected by frequency analysis of the pressure wave, and the frequency component due to the pulse and the frequency component due to the blood pump or the like are separated.
[0017]
First, the principle of the present invention when the present invention is applied to a dialysis apparatus, which is an example of a medical apparatus, will be described with reference to FIGS. 1, 2, 3, and 4. As described above, in the dialyzer, the moving liquid corresponds to the blood of the patient. FIG. 1 shows a configuration diagram of a dialysis machine, and FIG. 2 shows an arterial pressure waveform and a venous pressure waveform of blood circulating through the dialysis machine. FIGS. 3A and 3B show the respective spectra after FFT analysis of the arterial pressure waveform and the venous pressure waveform of blood circulating in the dialyzer. FIG. 4 is a diagram in which the spectrum on the artery side in a state where the vascular cannula is attached and the spectrum when the vascular cannula is dropped are superimposed and displayed.
[0018]
In FIG. 1, the liquid moving through the vascular access is blood before dialysis containing waste or blood after dialysis. In such a dialysis device, the blood of the patient to be dialyzed is sent to the dialyzer 6 via the blood tube 2 and the arterial drip chamber 4 from the arterial cannula 1 inserted into the artery side blood vessel of the patient. In the dialyzer 6, waste or the like contained in the patient's blood is filtered, and the patient's blood from which the waste has been removed is sent to the venous drip chamber 8, and further through the venous blood tube 2, via the venous cannula 10 To the patient's blood vessels. This blood circulation is forcibly performed by the blood pump 3. The waste of blood is transferred to the dialysate by the dialyzer 6, and the dialysate containing the waste is transported through the dialysate tube 13.
[0019]
Here, as the pressure applied to the blood circulating in the extracorporeal circulation blood circuit, the pressure by the blood pump 3 is the highest, and the pressure by the dialysate circulation pump (not shown) and the pressure by the pulse of the patient are superimposed. For blood circulating in the extracorporeal blood circuit Applied An arterial pressure sensor 5 and a venous pressure sensor 9 are installed as pressure detection means for measuring these pressures.
[0020]
The arterial pressure data of the circulating blood obtained by the arterial pressure sensor 5 is sent to the control circuit 11 of the artificial dialysis machine. The pump control circuit 12 operates the blood pump 3 based on the rotation frequency according to the instruction from the control circuit 11, detects the rotation frequency of the blood pump 3, and transmits the detected rotation frequency to the control circuit 11. Has the function of
[0021]
2 shows the pressure waveform data of the circulating blood observed by the arterial pressure sensor 5 and the venous pressure sensor 9, and the data output to the negative side in FIG. The data output to the positive side in FIG. 2 is the output data of the vein pressure sensor 9.
[0022]
FIG. 3 is a spectrum diagram obtained by performing FFT analysis on these pressure waveform data. 3A is a spectrum diagram after FFT analysis of pressure waveform data on the artery side, and FIG. 3B is a spectrum diagram after FFT analysis of pressure waveform data on the vein side. That is, the pressure waveform data in FIG. 2 includes spectrum data as shown in FIGS. 3A and 3B, and when the pressure waveform data is subjected to FFT analysis, the pressure waveform data in FIGS. This means that a spectrum diagram such as B) is obtained. This is the point of the present invention, and the frequency components as shown in FIG. 3 (A) and FIG. 3 (B) are obtained by performing FFT analysis on the frequency components caused by the pulse that cannot be seen from the pressure waveform data of FIG. It is possible to obtain a spectrum composed of
[0023]
FIG. 4 is a diagram in which the frequency spectrum on the artery side in a state where the vascular cannula is attached and the spectrum when the vascular cannula is dropped are superimposed and displayed. Here, it should be noted that when the blood vessel cannula is dropped, only the frequency component due to the pulse disappears. This feature can be used to detect vascular cannula dropout.
[0024]
However, the problem here is that it is possible to extract only the frequency component due to the pulse in a state where the frequency component due to the mechanical device of the pumps and the frequency component due to the pulse are mixed. Is a challenge.
[0025]
For example, in the vein-side spectrum of FIG. 3B, in addition to the frequency component of the frequency fm caused by the pulse, the frequency component of the frequency f0 caused by the blood pump 3 and the frequency f1 caused by the dialysate circulation pump. Frequency components are mixed. Furthermore, frequency components resulting from the pump such as frequencies 2f0, 3f0, and 2f1 that are integral multiples of the basic frequencies f0 and f1 of the pump are also mixed. Therefore, how to specify only the frequency component resulting from the pulse from the mixed frequency components is a problem.
[0026]
In the present invention, blood is mixed with frequency components mixed in the circulating blood. Applied There are several ways to identify the frequency components resulting from the pressure of a mechanical device such as a pump being used.
[0027]
First, if a mechanical device such as a blood pump 3 or a dialysate circulation pump is operated before attaching a vascular access such as the arterial cannula 1 and the venous cannula 10, the blood pump 3 or the dialysate circulation pump is used. Only the frequency component of the resulting pressure wave can be detected. Note that the spectrum data of the frequency component resulting from the mechanical device obtained at this time can be obtained by collecting the data once within a period in which the mechanical device of the dialysis machine is not changed or does not change over time. If the data is stored in the storage means, it is not necessary to newly collect the data every dialysis.
[0028]
As a second method, with the arterial cannula 1 and the venous cannula 10 attached and performing dialysis, the blood pump 3 and the dialysate circulation pump are burdened on the patient centering on a reference frequency suitable for the dialysis condition of the patient. The pump is rotated by changing the frequency within a certain range within a range where no pressure is applied. The FFT analysis uses a characteristic that frequency components that appear repeatedly at the same frequency are detected, and frequency components whose frequency changes constantly cannot be detected. Therefore, if the pump is operated with the frequency varied within a certain range, the frequency component of the pressure wave caused by the pump is not detected by the FFT analysis means 5, and the frequency component of the pressure wave caused by the patient's pulse is detected by the FFT. It will appear as the output of the analysis means 5. It should be noted that when the rotational frequency of the pump is varied within a certain range, the frequency component due to the pump is varied at a constant period, especially when it is varied in synchronization with the sampling period of the FFT, compared with the case where it is varied without being synchronized. Can be better removed.
[0029]
The third method is different in principle from the first method and the second method, and utilizes the fact that neither the frequency component caused by a mechanical device such as a blood pump nor the frequency component caused by a pulse changes rapidly in a short time. If there is a frequency component that changes rapidly in a short time, the change is considered to be caused by abnormal vascular access, that is, detachment of the vascular cannula. In other words, when the vascular cannula is dropped, the frequency component caused by the pulse is rapidly extinguished. Specifically, a spectrum composed of frequency components subjected to FFT analysis is recorded as a first spectrum at a certain time, and after a short time has elapsed, for example, after about one second, the spectrum subjected to FFT analysis is recorded as the first spectrum. Record as 2 spectra.
[0030]
Then, the first spectrum and the second spectrum are compared, and specifically, the difference between each frequency component constituting the first spectrum and each frequency component constituting the second spectrum is taken. If the vessel cannula is not dropped, there is almost no difference between the first spectrum and the second spectrum, and therefore all frequency components should not remain. However, if the vessel cannula is dropped, the frequency component due to the pulse is present in the first spectrum but not in the second spectrum. The frequency component that remains is left.
[0031]
Here, the level of the intensity of the frequency component is included in the judgment element because the first spectrum and the second spectrum cannot be completely the same because of noise and the performance of the medical device. This is to ensure that the judgment can be made without being lost. In other words, the difference in frequency components caused by noise is very small, but the change in the intensity of the frequency components caused by the pulse caused by the drop of the vascular cannula is large compared to them. Can be judged reliably.
[0032]
Based on the basic idea described above, the basic implementation procedure of the present invention will be described.
[0033]
As a first step, blood circulating in the extracorporeal circuit Applied The pressure wave to be analyzed is subjected to FFT analysis, and the spectrum of all frequency components in which pressure waves caused by the pulse or blood pump are mixed is measured.
[0034]
In the second step, the frequency component of the pressure wave caused by the mechanical device that affects the pressure of the circulating fluid such as a blood pump other than the pulse or the dialysate circulation pump is specified. There are several methods for specifying the frequency component of the pressure wave caused by the mechanical device.
[0035]
In the third step, if the spectrum of the frequency component caused by the mechanical device obtained in the second step is removed from the spectrum composed of the frequency components mixed in the first step, the remaining frequency component is It can be specified as a frequency component resulting from the patient's pulse.
[0036]
In the fourth step, paying attention to the intensity of the frequency component resulting from the pulse obtained in the third step, the intensity is compared with a reference value for determining abnormality of the vascular access, and if the reference value is smaller than the reference value, abnormal vascular access Is determined.
[0037]
The above is the basic implementation procedure of the present invention. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0038]
FIG. 5 is a diagram showing a configuration of a blood vessel access monitoring circuit according to an embodiment of the present invention. The vascular access monitoring circuit can be realized by hardware or software, but the control circuit 11 is often configured by a microcomputer, and the vascular access monitoring circuit can also be configured by using the microcomputer to cope with the software. Therefore, it is not necessary to add new hardware, and the present invention is economically effective.
[0039]
First, the frequency analysis means 30 is arranged so that the pressure waveform data of the circulating blood obtained by the arterial pressure sensor 5 as the pressure detection means is input. The frequency analysis means 30 can be realized by software such as a program using a microcomputer or the like, or can be realized by hardware such as a dedicated FFT analysis IC. Using an IC is disadvantageous in terms of apparatus cost, but has advantages such as high analysis speed and no burden on the CPU of the microcomputer. When the FFT analysis is processed by software, there are no hardware additional elements for implementing the present invention, and there are no disadvantageous elements in the apparatus cost and the outer shape of the apparatus.
[0040]
Since it is necessary to set a fixed time (time interval) for FFT analysis, the frequency analysis means 30 has a function that can set a fixed time for FFT analysis. For example, in FIG. 2, it is set that FFT is applied to a fixed time from 0 to 5 seconds. The longer the interval, the more pressure waves that undergo FFT analysis.
[0041]
A storage means 31 is connected to the output of the frequency analysis means 30. The storage means 31 is a blood pump 3 or dialysis obtained by FFT analysis by the frequency analysis means 30 from the pressure wave data detected by the arterial pressure sensor 5. liquid A spectrum in which a frequency component caused by a mechanical device such as a circulation pump and a frequency component caused by a pulse are mixed is stored. The contents of the storage means 31 are always replaced with the latest data during dialysis. Since the storage unit 31 temporarily stores the output data of the frequency analysis unit 30, the storage unit 31 may be provided in the frequency analysis unit 30.
[0042]
What is important here is that the frequency component attributed to the mechanical device and the frequency component attributed to the pulse are stored in the storage means 31 as a spectrum in which both frequency components are added. . Therefore, if the frequency component caused by the mechanical device can be removed from the added frequency component, only the frequency component caused by the remaining pulse can be extracted. When a plurality of frequency components overlap, it is impossible to extract only a specific frequency component with the conventional technique. An embodiment in which the frequency components overlap will be described in detail later with reference to FIG.
[0043]
On the other hand, the removing means includes a storage means 32 and a subtracting means 33. Before storing the arterial cannula 1 and the venous cannula 10 in the blood vessel, that is, before attaching the vascular access, the FFT analysis unit 30 performs FFT analysis on the pressure wave data detected by the arterial pressure sensor 5. Blood pump 3 and dialysis liquid Only the spectrum of frequency components originating only from mechanical devices such as a circulation pump is stored.
[0044]
Before attaching the arterial cannula 1 and the venous cannula 10 before the start of dialysis, the storage means 32 stores spectrum data of frequency components caused only by the mechanical device once measured. Use data. As described above, the spectrum data of the frequency component due to the mechanical device obtained once measured can be used once if the mechanical device of the dialysis device is replaced or within a period that does not change over time. If data is collected and stored in the storage means 32, it is not necessary to newly collect the data every dialysis.
[0045]
The subtraction means 33 is arranged with the storage means 31 and the storage means 32 as inputs, and the blood pump 3 and dialysis stored in the storage means 31. liquid From the latest spectrum in which a frequency component caused by a mechanical device such as a circulation pump and a frequency component caused by a pulse are mixed, the blood pump 3 and dialysis stored in the storage means 32 liquid A frequency component caused only by a mechanical device such as a circulation pump is removed, and only a frequency component caused by a pulse is specified.
[0046]
The determining means for determining an abnormality in the vascular access includes an abnormality determination setting means 35 and a level detecting means 34. The abnormality determination setting means 35 is installed at an abnormality determination setting value that is a low value as a value of the intensity of the frequency component caused by the pulse, that is, a normal low blood pressure value, for example, a value corresponding to 10 mmHg. Yes. Then, the intensity of the frequency component caused by the pulse output from the subtracting means 33 is compared with the abnormality judgment set value indicated by the abnormality judgment setting means 35 by the level detection means 34, and the intensity of the frequency component caused by the pulse is judged abnormal. If it is smaller than the set value, it is determined that there is a vascular access abnormality such as vascular cannula dropout. The above description is about the blood vessel access monitoring circuit. Further, the result is transmitted to the vascular access alarm circuit 36, and an alarm is issued to promptly contact a medical person or a central monitoring apparatus that centrally manages a plurality of artificial dialysis apparatuses.
[0047]
Next, this example was particularly excellent Effect An embodiment in the case where the pulse rate to be exerted and the rotation frequency of the blood pump 3 etc. are the same and both frequency components overlap will be described with reference to FIG. That is, unlike the prior art, this embodiment is a frequency component that is surely caused by the patient's pulse even when the patient's pulse rate is very close to or overlapping with the rotation frequency of the blood pump 3 or dialysate circulation pump. It will be described below that the blood vessel access abnormality can be determined based on the frequency component.
[0048]
FIG. 6 shows the operation status of each means of the vascular access monitoring circuit according to the embodiment of the present invention in the above case. This case is a case where the frequency of the frequency component due to the pulse rate of the patient is fm, while the second harmonic of the frequency component frequency f0 due to the rotation of the blood pump 3 overlaps.
[0049]
First, the storage means 32 is the same as in FIG. 5, and the pressure wave detected by the arterial pressure sensor 5 is not attached to the arterial cannula 1 or the venous cannula 10, that is, before attaching the vascular access. From the data to the blood such as blood pump 3 or dialysate circulation pump which has been subjected to FFT analysis by FFT analysis means 30 Applied Only the spectrum of frequency components due to only the mechanical device of the pressure being stored is stored.
[0050]
However, in the storage means 31, as shown in FIG. 6, the frequency component of the frequency fm caused by the pulse and the frequency component of 2f0 of the double wave caused by the rotation of the blood pump 3 overlap. In the conventional method, in such a case, the bandpass filter or the like removes the pressure wave having the frequency 2f0 caused by the blood pump 3 and the pressure wave having the frequency fm caused by the pulse together, resulting in the pulse. The pressure wave could not be identified.
[0051]
However, in this embodiment, since the frequency component due to the mechanical device such as a pump is removed from the spectrum of the storage means 31, even if the frequency component due to the pulse overlaps with the frequency component due to the mechanical device, the subtracting means 33 As shown in FIG. 6, only the frequency component resulting from the pulse can be specified in the output of. Thereafter, the abnormality of the vascular access can be determined by comparing the intensity of the frequency component caused by the pulse with the abnormality determination setting value of the abnormality determination setting means 35.
[0052]
In other words, in this embodiment, blood vessel access can be reliably monitored even if the frequency of the pressure wave caused by the pulse that cannot be solved by the conventional method and the frequency of the pressure wave caused by a mechanical device such as a blood pump overlap. There is an effect that can be done. In addition, it is possible to realize proper vascular access monitoring without being confused by temporary pressure wave fluctuations caused by irregular movements that occur when the patient rolls over.
[0053]
The above examples are based on blood pump 3 and dialysis liquid From the spectrum in which the frequency component due to the circulation pump and the frequency component due to the pulse are mixed, blood pump 3 and dialysis liquid As a method of removing only the frequency component caused by the circulatory pump and detecting only the frequency component caused by the pulse, before attaching the vascular access, blood pump 3 or dialysis liquid It is the Example implement | achieved by the method of measuring only the frequency component resulting from a circulation pump.
[0054]
As an example of the second removal method, the blood pump 3 or the pump control circuit 12 is controlled from the control circuit 11 to the pump control circuit 12 in FIG. There is a method of giving a control instruction to rotate the dialysate circulation pump by changing the frequency within a certain range within a range that does not place a burden on the patient around a reference frequency suitable for the dialysis condition of the patient. Since the FFT analysis outputs only the frequency spectrum that repeatedly appears at the same frequency, the frequency change uses characteristics that do not appear as the output of the FFT analysis. In this case, as shown in FIG. 7, since the pump control circuit 12 rotates the pumps by changing the rotation frequency as described above, only the frequency spectrum resulting from the pulse appears in the storage means 31, and the pulse Only the frequency spectrum caused by the can be specified. Therefore, the output of the storage means 31 may be directly input to the level detection means 34.
[0055]
When the blood pump 3 and the dialysate circulation pump are changed in frequency within a certain width, if the frequency components caused by the pumps are not synchronized if they are changed at a fixed period in synchronization with the FFT sampling. Compared with this, there is an effect that it can be removed better.
[0056]
An embodiment of the third method will be described with reference to FIG. The pressure of blood to be dialyzed is detected by the arterial pressure sensor 5 which is a pressure detection means, and the pressure data is transmitted to the frequency analysis means 30 for frequency analysis, in this embodiment FFT analysis. A spectrum composed of frequency components subjected to the FFT analysis is stored in the storage unit 102 which is a storage unit. The spectrum recorded by the storage unit 102 is further sent to the storage unit 101 which is a storage unit, where it is recorded and stored. Then, by the time control of the timer 103, the spectrum of one second before recorded in the storage means 101 is extracted and sent to the subtracting means 33 after a predetermined time, in this embodiment, one second later. Therefore, in the present embodiment, the first storage unit corresponds to the storage unit 101, and the second storage unit corresponds to the storage unit 102.
[0057]
The subtracting means 33 takes the difference between the latest spectrum stored in the storage means 102 and the spectrum one second before the storage means 101. If there is no abnormality such as dropout of the blood vessel cannula or twisting of the blood vessel tube, there is no difference between the frequency component of the latest spectrum recorded in the storage means 102 and the frequency component of the spectrum one second before recorded in the storage means 101. There is no frequency component as the remainder.
[0058]
However, if there is an abnormality such as a drop in the blood vessel cannula or a twist in the blood vessel tube, the frequency component due to the pulse does not exist in the latest spectrum recorded by the storage means 102, whereas the 1 second recorded by the storage means 101. Since it exists in the previous spectrum, the frequency component resulting from the pulse remains in the remainder of the subtracting means 33.
[0059]
However, as described above, the latest spectrum recorded in the storage means 102 and the spectrum one second before recorded in the storage means 101 are not completely the same even for one second, and each frequency is different due to noise or the like. There are very small frequency components. In order not to erroneously determine that the vascular cannula has fallen off due to such a minute frequency component remaining, the level detection means 34 compares the abnormal value indicated by the abnormal setting value 35 with the intensity of all the remaining frequency components. If any frequency component is larger than the abnormal value, it is determined that the blood vessel access is abnormal such as vascular cannula dropout.
[0060]
In the above description, the circulating blood to be measured is measured with the arterial pressure sensor 5 to detect an abnormality in the arterial vascular access. However, even when measured with the venous pressure sensor 9, FIG. ), The abnormalities in the vascular access on the venous side can be monitored in the same manner by using the embodiments shown in FIGS.
[0061]
That is, from the arterial pressure data obtained by the arterial pressure sensor, it is possible to detect an abnormal vascular access on the arterial side, that is, the omission of the arterial vascular cannula, and from the venous pressure data obtained by the venous side pressure sensor Side vascular access abnormalities, that is, venous side vascular cannula dropout can be detected. Therefore, the present invention is not a method in which abnormalities in blood vessel access cannot be detected unless both the arterial pressure data and the venous pressure data are provided. There is the advantage of being able to monitor vascular access in the presence of sensors. Depending on the medical device, there may be only one pressure sensor, and in such a case, this is the excellent effect of the present invention.
[0062]
In addition, although the embodiment using the pressure sensor attached to the drip chamber as the pressure detection means for circulating blood if it is a dialysis device has been described, if the pressure of the moving liquid can be measured, The method is not limited. For example, the present invention can be implemented wherever the pressure of circulating blood in the dialyzer is measured. For example, since blood moves through the blood tube, the blood tube expands and contracts due to the pressure of the moving blood. Therefore, measuring the expansion and contraction of the blood tube can perform the same function as measuring the pressure of the moving blood. A specific sensor for measuring the expansion and contraction of the blood tube 3 is shown in FIG. Reference numeral 205 denotes a tube deformation measuring sensor, which has a mechanism for transmitting deformation of the blood tube that expands and contracts due to a change in pressure of the moving blood to the variable rod 215 and detects the displacement by the displacement sensor 212. Details thereof are disclosed in JP-A Nos. 2002-186590 and 2002-186665.
[0063]
In addition, instead of directly measuring the pressure of the moving blood, the dialyzer transmits the pressure of the circulating blood to the dialysate via the dialyzer, so the dialysate pressure is measured and included in the pressure wave. It is also possible to monitor the vascular access by identifying the frequency component due to the pulse that is detected.
[0064]
The present invention can also be used to monitor abnormalities in vascular access during dialysis, but can also be used to confirm that the vascular cannula is securely attached before dialysis. The procedure was attributed to the pulse because the frequency component due to the pulse can be measured if the blood pressure is measured with the vascular cannula attached to the patient and the pump machinery stopped. If the frequency component exists, it can be determined that the vascular access is normal. There is also an effect that this judgment can be used for the safe operation of the dialyzer by using it as an interlock for the operation of the dialyzer.
[0065]
As described above, according to the present embodiment, in the dialysis apparatus, the state of vascular access of the patient during dialysis can be detected quickly, for example, a serious accident for the patient such as detachment of the vascular cannula. Measures to prevent this can be taken quickly. In addition to the detection of a serious accident such as a drop of a vascular cannula, there is an effect of detecting an accident that causes a decrease in dialysis function such as a twist of a vascular tube.
[0066]
In particular, this example is superior to the method of monitoring the vascular access by detecting the pressure wave caused by the same pulse in the conventional dialysis apparatus, the rotation frequency of the blood pump and the pulse rate overlap. Even in cases, blood vessel access can be reliably monitored. In addition, since the FFT analysis is used in this embodiment, it is possible to reliably monitor the blood vessel access of the patient by preventing the malfunction due to the pressure wave to the blood of the dialysis apparatus caused by irregular movement such as the patient turning over. Has an excellent effect.
[0067]
In the above description, the case where the FFT analysis is used as the frequency analysis means for separating the frequency component of the pressure wave caused by the pulse and the frequency component of the pressure wave caused by the mechanical device such as pumps has been described. Needless to say, frequency analysis means capable of distinguishing these pressure wave frequencies other than FFT analysis, for example, a normal Fourier transform, a MEM method (maximum entropy method), or the like can be used.
[0068]
The present invention can be applied not only to blood vessel access monitoring in a dialysis machine but also to medical devices in general such as an infusion pump device and a heart-lung machine.
[0069]
In the above description, FIG. 10 shows an embodiment when the present invention is applied to an infusion device. Unlike a dialysis machine or the like, an infusion device does not circulate blood and does not measure the pressure of circulating blood. In the case of an infusion infusion device, the infusion infused into the blood vessel corresponds to a liquid that moves into the blood vessel, and the pressure applied to the infusion is detected by the pressure detecting means 5, and is caused by the frequency component and pulse caused by the infusion pump 300. Since frequency components are mixed, it is possible to detect the dropout of the vascular cannula by extracting only the frequency components due to the pulse.
[0070]
Therefore, if this invention is used, it can apply also to medical devices, such as a dialysis device, a heart-lung machine, an infusion device, or a blood transfusion device, and the effect which can monitor the abnormality of vascular access can be expected.
[0071]
【The invention's effect】
As described above, according to the blood pressure access monitoring method and medical device of the medical device of the present invention, the intensity of the frequency spectrum of the pressure wave caused by the patient's pulse from the pressure applied to the liquid of the medical device. By monitoring the system, it is possible to monitor the vascular access status of the medical device correctly without imposing a burden on the patient or medical staff, adding a special device, and ensuring the patient's safety. it can.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an extracorporeal circulation circuit of a dialysis apparatus.
FIG. 2 is a diagram showing an arterial pressure waveform and a venous pressure waveform of circulating blood in a dialysis device.
FIG. 3 is a diagram showing a spectrum after FFT analysis of an arterial pressure waveform and a venous pressure waveform of circulating blood in a dialysis apparatus.
FIG. 4 is a diagram showing an artery side spectrum when a blood vessel cannula is dropped and when it is not dropped.
FIG. 5 is a configuration diagram of a blood pressure access monitoring circuit when applied to a dialysis apparatus according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating an operation of a blood pressure access monitoring circuit when a frequency component caused by a pulse and a frequency component caused by a pump overlap.
FIG. 7 is a configuration diagram of a blood pressure access monitoring circuit according to an embodiment that employs a method of changing the rotational frequency of pumps.
FIG. 8 is a configuration diagram of a blood pressure access monitoring circuit according to an embodiment that adopts a method of monitoring an abnormality in blood vessel access from a change in frequency spectrum distribution with a predetermined time in between.
FIG. 9 is a diagram showing a configuration of pressure detection means for detecting the pressure of a liquid from deformation of a tube used for moving the liquid.
FIG. 10 is a configuration diagram when the present invention is applied to an infusion device.
[Explanation of symbols]
1 Arterial cannula
2 Blood tube
3 Blood pump
4 Arterial drip chamber
5 Arterial pressure sensor
6 Dialyzer
7 Bubble sensor
8 Venous drip chamber
9 Venous pressure sensor
10 Venous cannula
11 Control circuit
12 Pump control circuit
13 Dialysate tube
30 Frequency analysis means
31 Memory means
32 storage means
33 Subtraction means
34 Level detection means
35 Abnormality judgment setting means
36 Blood vessel access alarm circuit
101 Storage means
102 memory means
110 timer
300 infusion pump

Claims (1)

In a medical device having a mechanical device that is coupled to a patient's blood vessel via a vascular access and applies pressure to move liquid to the blood vessel, the rotational frequency of the pump constituting the mechanical device is centered on a reference frequency A pressure fluctuation means for rotating to change by a constant frequency width; a pressure detection means for measuring the pressure of the liquid; and a frequency analysis means for detecting a spectrum by performing frequency analysis on data of the measured pressure for a certain period of time. A medical device comprising: a determination unit that compares the intensity of the frequency component caused by the pulse of the patient output by the frequency analysis unit with a predetermined value to determine abnormality in the vascular access.

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