JPH0417836A - Natural heart synchronizer and medical pump driver using the same - Google Patents

Abstract

PURPOSE:To maintain synchronization with a natural human heart even when a blood pressure wave is disturbed by a trigger pulse as generated when a level of a cardiac sound exceeds a specified value by inputting a cardiac sound waveform extracted into a signal generation means to be compared with the specified value. CONSTITUTION:A high pass filter 332 lets a frequency component of 50Hz or more contained in a arterial pressure signal pass and an internal cardiac sound is extracted from the arterial pressure sound. The internal cardiac sound extracted from the high pass filter 332 is inputted into a comparator circuit 334 after the removal and amplification of humming noises with a signal amplification/humming removal circuit 333. The comparator circuit 334 is equipped with a comparator 334a and a variable resistor 334b for setting a reference level. The comparator 334a outputs a trigger pulse to an electronic controller 32 when a level of the internal cardiac sound signal exceeds a reference level. A driver is combined based on the trigger pulse detected with a blood pressure wave form synchronizing circuit 33 even when a blood pressure waveform is disturbed by body motion, breathing or the like of a patient thereby enabling synchronization with a natural human heart accurately.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a device that generates an electrical signal synchronized with the natural heartbeat, such as an artificial heart, etc. Used in medical equipment that operates as

(Prior Art) In order to treat a patient using a medical pump, the medical pump must be driven in synchronization with the natural heartbeat. In order to drive medical pumps in synchronization with the natural heartbeat, the use of electrocardiograms and blood pressure signals has been considered.

In order to obtain a blood pressure signal, a device has conventionally been used that generates a trigger pulse at an inflection point of a blood pressure waveform detected by a blood pressure sensor.

(Problems to be Solved by the Invention) However, the blood pressure waveform detected by the blood pressure sensor is disturbed by the patient's body movements, breathing, and the like. When a disturbance in the blood pressure waveform occurs, conventional synchronizers have a problem in that a trigger pulse unrelated to the natural heartbeat is generated during treatment, resulting in inaccurate synchronization.

The present invention has been made to solve these problems with conventional devices, and its technical problem is to accurately maintain synchronization with the natural heart even if the blood pressure waveform is disturbed.

[Structure of the invention]

(Means for solving the problem) The technical means taken to achieve the above-mentioned technical problem are a blood pressure sensor that measures blood pressure and a method of extracting high frequency components from the signal output by the blood pressure sensor. The present invention includes an extracting means and a signal generating means for generating a trigger pulse when the level of the signal extracted by the extracting means exceeds a predetermined value.

(Operation) According to the above-mentioned technical means, the heart waveform included in the blood pressure waveform is extracted by the extraction means.

The extracted heart waveform is input to the signal generating means and compared with a predetermined value. When the level of the heart waveform exceeds a predetermined value, the signal generating means generates a trigger pulse.

Even if there are disturbances in the blood pressure waveform due to the patient's body movements or breathing,
There is almost no effect on the heart sound waveform. Therefore, if a trigger pulse is generated when the level of the heart waveform exceeds a predetermined value, synchronization with the natural heart can be accurately maintained even if the blood pressure waveform is disturbed.

(Example) Hereinafter, a preferred example apparatus to which the present invention is applied will be described with reference to the accompanying drawings.

FIG. 6 is a perspective view depicting a hospital bed 2 of a patient 1 undergoing treatment using an intra-aortic balloon pump (hereinafter simply referred to as a balloon pump). A balloon pump drive device 3 (hereinafter referred to as a drive device) is installed near the hospital bed 2. A hull pump 4 is connected to the drive device 3.

The balloon pump 4 is inserted into the body of the patient 1 (into the descending aorta) from the base of the patient's 1 foot 1a. The method of inserting the balloon pump 4 into the body of the patient 1 has already been introduced in many documents and is well known, so a detailed explanation will be omitted. The balloon pump 4 can be inserted into the body of the patient 1 using, for example, the Seldinger method.

Hereinafter, with reference to FIG. 1, a driving device 3 to which the present invention is applied will be described. FIG. 1 is a block diagram depicting the configuration of the drive device 3. As shown in FIG.

The balloon pump 4 has a tube section 4 connected to the drive device 3.
a, a balloon portion 4b that inflates and deflates within the aorta, and an arterial pressure sensor 4c fixed to the tip of the balloon portion 4b.
Equipped with The drive device 3 also includes a positive and negative pressure generator 31 that alternately supplies positive pressure and positive pressure to the balloon pump 4, an electronic control device 32, and a blood pressure waveform synchronization circuit 33.

In the device of this embodiment, the arterial pressure sensor 4c is a small pressure sensor the size of a grain of rice, and generates an electrical signal at a level proportional to the magnitude of the arterial pressure within the aorta.

The positive and negative pressure generator 31 includes a positive pressure source 311, a positive pressure source 312,
It includes a positive pressure on/off valve 313, a depressurization on/off valve 314, and an isolator 315. The isolator 315 is
-Next chamber 315a and secondary chamber 3150
, and a movable membrane 315b separating the secondary chamber 315a and the secondary chamber 3150. - The next chamber 315a is filled with the atmosphere, and the second chamber 315c is filled with shuttle gas.

In this embodiment, helium gas is used as the shuttle gas.

The primary side changer 315a has a positive pressure on/off valve 313,
A pressure relief opening/closing valve 314 is connected.

When the positive pressure on/off valve 313 is opened and the depressurization on/off valve 314 is closed, the positive pressure source 311 is connected to the next chamber 315a.
Positive pressure from the At this time, the movable membrane 315b is displaced toward the secondary chamber 315c. At this time, the balloon portion 4b of the balloon pump 4 is inflated. On the contrary, the depressurization on/off valve 314 opens and the positive pressure on/off valve 313 opens.
When closed, the positive pressure source 31 is connected to the negative side chamber 315a.
Depressurization from 2 is led. At this time, the movable membrane 315b is displaced toward the primary chamber 315a, and the balloon pump 4
deflate the balloon portion 4b.

The blood pressure waveform synchronization circuit 33 determines the natural heart beat from the arterial pressure signal output by the arterial pressure sensor 4C, and outputs a trigger pulse synchronized with the natural heart beat to the electronic control device 32. The blood pressure waveform synchronization circuit 33 also includes an arterial pressure sensor 4C.
The output signal is amplified and an arterial pressure signal indicating the blood pressure in the aorta is output to the electronic control unit 32. Positive pressure opening/closing valve 313
The pressure relief opening/closing valve 314 is connected to the blood pressure waveform synchronization circuit 33.
The electronic control unit 32 operates based on the output signal of the switch.

This will be explained below with reference to FIG. FIG. 2 is a block diagram depicting details of the blood pressure waveform synchronization circuit 33. The blood pressure waveform synchronization circuit 33 includes a signal amplification and hum removal circuit 331,
Bypass filter 332, signal amplification and hum removal circuit 333, comparison circuit 334, and common phase removal circuit 33
5.

The arterial pressure sensor 4C includes a bridge circuit and outputs a potential difference proportional to the arterial pressure from two output terminals. The potential difference output by the arterial pressure sensor 4c is transferred to the in-phase phase removal circuit 33.
5 is input. The common phase removal circuit 335 removes the same 7F phase signal included in the two input signals,
Reduce noise.

The signal amplification and hum removal circuit 331 removes hum noise and noise from the arterial pressure signal output from the in-phase phase removal circuit 335, amplifies the signal, and outputs the signal to the electronic control unit 32.

Bypass filter 332 has 5 0 included in the arterial pressure signal.
Passes frequency components of 14z and above. Bypass filter 332 extracts the intracardiac heart sound signal from the arterial pressure signal. The extracted intracardiac heart sound signals include the first sound that occurs when blood is pumped into the aorta (when the atrioventricular valves of the native heart close) and the first sound that occurs when blood is pumped into the native heart (when the atrioventricular valves of the native heart close).
This includes the second sound that occurs (when the semilunar valve closes).

The intracardiac heart sound signal extracted by the bypass filter 332 undergoes hum noise removal and amplification by a signal amplification and hum removal circuit 333, and is then input to a comparison circuit 334.

The comparison circuit 334 includes a comparator 334a and a reference level setting variable resistor 334b. Comparator 334a outputs a trigger pulse to electronic control unit 32 when the level of the intracardiac heart sound signal exceeds a reference level.

Hereinafter, with reference to FIG. 3, a schematic operation of the electronic control device 32 will be described.

FIG. 3 is a diagram depicting the relationship between the waveforms of the electrocardiogram, arterial pressure, and cardiac sound, and the expansion and contraction of the balloon pump 4.

The balloon pump 4 is deflated shortly before the first sound occurs, ie at the beginning of systole. Due to the contraction of the balloon pump 4, the arterial pressure in the aortic root 42 decreases, causing the ventricle 4 to decrease.
Since blood can be easily pumped out from the patient 3, the blood flow increases, which is helpful for the recovery of the patient 1. Further, the balloon pump 4 is inflated shortly after the second sound is generated, that is, at the beginning of diastole. Due to the expansion of the balloon pump 4,
The arterial pressure in the aortic root 42 increases and the amount of blood flowing into the coronary artery 44 increases, which promotes the supply of oxygen and nutrients to the heart, helping to recover the weakened heart. , Figures 4a and 4
FIG. b is a flowchart depicting a program executed by the electronic control unit 32. This will be explained with reference to FIGS. 4 and 3. When the electronic control device 32 is powered on, the electronic control device 32 executes the flow from step SO onwards.

Electronic side? The I[+ device 32 first initializes various flags and human output ports necessary for subsequent processing (step St).

Second, the electronic control unit 32 refers to the arterial pressure signal and trigger pulse input from the blood pressure waveform synchronization circuit 33.

(Step S2).

The electronic control device 32 determines whether the second sound is detected (step S3). When the second sound is detected, blood extraction from the natural heart ends, so the electronic control unit 32 opens the positive pressure opening/closing valve 313 to apply positive pressure to the balloon pump 4 and inflate the balloon pump 4 (step 34
).

When the balloon pump 4 is inflated, the electronic control device 32 starts a timer (step S5). After the second sound is detected, when the set time tl has elapsed (step S6
), blood is extracted from the natural heart into the aorta, so the electronic control unit 32 opens the depressurization on/off valve 314 to apply depressurization to the balloon pump 4, thereby deflating the balloon pump 4 (step S7).

After the balloon pump 4 is deflated, the process returns to step S2 and is repeated.

As described above, in steps S2 to S7, the trigger pulse (second sound) input from the blood pressure waveform synchronization circuit 33
Positive pressure on/off valve 313 and depressurization on/off valve 314 depending on
A process of inflating and deflating the balloon pump 4 by alternately opening and closing the balloon pump 4 is executed.

Hereinafter, the heart sound detection process will be explained with reference to FIG. 4b.

The electronic control unit 32 operates until a trigger pulse is input.
The systolic blood pressure and the diastolic blood pressure of the patient 1 are measured, and the intermediate value M between the systolic blood pressure and the diastolic blood pressure is calculated (steps S21 to S23). When a trigger pulse is input to the electronic control device 32 (step 523), the electronic control device 32 compares the arterial pressure at the time the trigger pulse is detected with the intermediate value M (step 52
4). As schematically illustrated in FIG. 5, if the trigger pulse corresponds to the second sound, the arterial pressure will be higher than the intermediate value M. Conversely, if the trigger pulse corresponds to the first sound, the arterial pressure will be lower than the intermediate value M.

Therefore, if the arterial pressure is higher than the intermediate value M (Yes), the electronic control unit 32 stores the determination result that it is the second sound in the register R (step 525). Furthermore, when the arterial pressure is lower than the intermediate value M (N
O) stores the determination result that it is the first note in register R (step 526).

Thereafter, the electronic control unit 32 performs processing to return to the main routine (step 527).

Through the processing described above, when the blood pressure waveform synchronization circuit 33 generates a trigger pulse, it is determined whether the trigger pulse corresponds to the first sound or the second sound.

As described above, in the device of this embodiment, the intra-aortic balloon pump 4 is driven based on the trigger pulse detected by the blood pressure waveform synchronization circuit 33.

Further, an arterial pressure sensor 4C is integrated into the balloon pump 4. Therefore, treatment of the patient 1 can be started by simply inserting the balloon pump 4 into the patient 1 and connecting the tube section 4a and the arterial pressure sensor 4C to the drive device 3. Therefore, it is possible to treat patient l earlier than with conventional devices.

Further, since no special sensor is required other than the arterial pressure sensor 4C, it can be combined with a drive device using an electrocardiogram, for example. In this case, the device of this embodiment can be used as a backup device for a drive device that uses an electrocardiogram, or the drive device that uses an electrocardiogram can be used as a backup device for the device of this embodiment.

In the present embodiment, only an example is shown in which the intra-aortic balloon pump 4 is driven in synchronization with the second sound, but it goes without saying that it is possible to drive the intra-aortic balloon pump 4 in synchronization with the first sound. Further, the drive device 3 to which the present invention is applied can drive not only the intra-aortic balloon pump 4 but also a medical pump such as an artificial heart.

〔Effect of the invention〕

According to the present invention, a trigger pulse is generated based on a heart waveform included in a blood pressure waveform. Therefore, even if the blood pressure waveform is disturbed due to the patient's body movements or breathing, the same period as the natural heart is maintained accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram depicting the configuration of the drive device. FIG. 2 is a bronc diagram depicting details of the blood pressure waveform synchronization circuit. FIG. 3 is a diagram depicting the relationship between electrocardiogram waveforms, arterial pressure waveforms, centripetal waveforms, and inflation/deflation of the balloon pump. Figures 4a and 4b are flowcharts depicting programs executed by the electronic control unit. FIG. 5 is a waveform diagram depicting the relationship between the arterial pressure waveform and the trigger pulse. FIG. 6 is a perspective view depicting a hospital bed of a patient being treated using an intra-aortic balloon pump. 1... Patient, 2... Hospital bed, 3... Drive device, 4...
...Aortic balloon pump, 4C...Arterial pressure sensor (blood pressure sensor), 3I...Positive pressure generator, 311...Positive pressure source, 312...Removal source, 313...
・Positive pressure on/off valve (switching valve), 314... Depressurization on/off valve (switching valve), 32... Electronic control device, 33... Blood pressure waveform synchronization circuit, 331.333... Signal amplifier, 332 ... Bypass filter (extraction means), 334.
... Comparison circuit (signal generation means).

Claims (2)

[Claims] (1) a blood pressure sensor that measures blood pressure; an extraction means that extracts high frequency components from a signal output by the blood pressure sensor; and when the level of the signal extracted by the extraction means exceeds a predetermined value; A natural heart synchronization device comprising: signal generating means for generating a trigger pulse; (2) A positive pressure source that generates a predetermined positive pressure, a negative pressure source that generates a predetermined negative pressure, a switching valve that alternately outputs the positive pressure and the negative pressure to a medical pump, and the switching valve. In a medical pump drive device that includes an electronic control device that switches in synchronization with the natural heart, the electronic control device further includes a blood pressure sensor that measures blood pressure, and an extraction device that extracts high frequency components from the signal output by the blood pressure sensor. A medical pump driving device comprising: means for generating a trigger pulse when the level of the signal extracted by the extracting means exceeds a predetermined value.