JPH02283353A - Method for automatically starting record and apparatus for inspecting fetus - Google Patents

Abstract

PURPOSE:To enable a work of finding out a good position for picking up fetus' heartbeat signals to be carried out promptly without recording noises and wasting recording paper by detecting and evaluating a pickup condition of the fetus' heartbeat signals and starting up a recorder automatically when a good pickup condition is obtained. CONSTITUTION:Fetus' heartbeat signals picked up by a probe 1 are filtered and amplified by a main amplification circuit 2, put into an real time auto-correlation arithmetic circuit 3 to have an autocorrelation computed in real time and a correlation wave form is sent to an operation processing circuit 4. In the operation processing circuit, a pickup condition of fetus' heartbeat signals is evaluated based on the input correlation wave form, and the result of this evaluation and a specified evaluation value for starting an automatic recording are compared with each other. If the result of comparative discrimination satisfies the specified value, a record start signal and a fetus' heartbeat number, which is converted from an periodic information in the correlation wave form, are sent to an operation output circuit 5. The operation output circuit displays the evaluation result segmentally, displays the fetus' heartbeat number digitally and moreover records the wave form on a recorder 6. The segmental display of the evaluation result enables the pickup condition to be grasped precisely so that the probe can be set easily at a proper position.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to an automatic recording start method for a fetal monitoring device and a fetal monitoring device using the same.

(2) Prior Art In conventional fetal monitoring devices, when recording the fetal heart rate on a recorder, a location where fetal heartbeat signals can be obtained well is found, and then the recorder is turned on and recorded.

(3) Problems to be solved by the invention In this way, it is possible to find a site where the fetal heartbeat signal is well collected (
If the process is a two-step process, first activating the camera and then turning on the recorder, it will be necessary for the patient to find a site where the fetal heart rate signal is well captured and then turn on the recorder. , Since the mind moves to operate the switch of the recorder, it is predicted that the part that is in good sampling condition will move. This is due to the fact that the fetus often moves due to external factors, but it is also predicted that depending on the sensor receptacle of the probe etc., significant noise may be generated due to patient movement. Ru.

If the recorder is turned on from the beginning, the fetus will not move as a result of the switch operation, but it will cause problems such as meaningless noises being recorded, and the recording paper will also be wasted. ) There were some problems.

(4) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention detects the state of collection of fetal heartbeat signals and automatically operates the recorder when a good state of collection is achieved. The present invention provides a method for automatically starting recording, and a fetal monitoring device configured to implement this method.

More specifically, the present invention provides, as a first aspect, an automatic recording start method for evaluating the acquisition state of fetal heartbeat signals and automatically starting recording when an evaluation result of a predetermined value is obtained. It is clear that if an evaluation value when a good sampling condition is set as a predetermined value, recording will be automatically started, and the conventional problems will be solved. For evaluation of the collection state, for example, the method shown in "Method for evaluating the collection state of fetal heart rate signal, automatic selection method of correlation waveform for fetal heart rate counting, and fetal monitoring device (Patent Application No. 1982-3-288818)" can be used. Just use the method you have.

As a more specific method, a real-time autocorrelation calculation is performed on the fetal heartbeat signal, and a comparison calculation is performed on the obtained correlation waveform to evaluate the acquisition state of the fetal heartbeat signal, and an evaluation result of a predetermined value is obtained. A second invention provides an automatic recording start method for automatically starting recording when the recording occurs.

To give an example of a specific method, real-time autocorrelation calculation is performed on the fetal heartbeat signal collected from the mother's body to obtain a correlation waveform, and at least the origin correlation value, detection peak point correlation value, and correlation offset level of the correlation waveform are obtained. It is possible to perform a comparison operation using a plurality of values among the value, the minimum allowable origin value, and the maximum allowable origin value, and use the result as the evaluation result of the sampling state.

To explain in more detail, for example, the origin correlation value Imp(
If the correlation value at time difference 0) is less than the origin minimum allowable value CL (minimum value considered as a moderate input information amount) 4, it is evaluated that the amount of input information is insufficient, or the origin correlation value ImO is the origin maximum allowable value C
H (maximum value that is considered to be an appropriate amount of input information) or less] If it is 2, it is evaluated that the amount of input information is excessive due to noise contamination, or the origin correlation value I m O and the detection peak time correlation value ImP
(correlation value at the maximum point indicating the heartbeat cycle or correlation value at the maximum point determined to indicate true periodicity among multiple thick points) to each correlation offset l-1 noher value lm0FF (from the time difference O The minimum value of the correlation values up to the detection peak time, predetermined time difference, maximum time difference, etc., which is the value obtained by subtracting the level of the forgetting process from the past cycle information, the collected value of random noise levels other than the cycle information, etc. The total input value is calculated based on how much of the effective origin correlation value (origin correlation value - correlation offset level value) the effective detected peak point correlation value (detected peak point correlation value - correlation offset level value) accounts for. The acquisition status of fetal heartbeat signals can be evaluated by evaluating how much periodic information has been obtained from the amount of information. In this evaluation of the sampling state, in addition to the above-mentioned results, for example, information on abnormality in the attachment of the transducer can be included in the evaluation to obtain the evaluation result of the sampling state.

As a third invention, the acquisition state of the fetal heartbeat signal is evaluated by further performing an average calculation, etc. within a predetermined time on the results of comparison calculations, etc. for the correlation waveform obtained in the second invention, and a predetermined value is obtained. To provide an automatic recording start method for automatically starting recording when an evaluation result is obtained. According to this, more time elements are introduced, so that an evaluation result that incorporates more elements of the stability of the acquisition state of the fetal heartbeat signal can be obtained.

To be more specific, for example, using the evaluation of the collection state of the second invention mentioned above as the collection state information, average calculations are performed using the number of information, information value, information acquisition time, etc. within a predetermined time, and the result is calculated as the fetal heart rate. This is used as an evaluation result of the signal acquisition status. This evaluation result is obtained by averaging the collection status information in terms of time or amount of information, so it is possible to evaluate the collection status of the fetal heartbeat signal, which does not change instantaneously but gradually in terms of time or amount of information. can. Similarly to the second invention, in addition to the above-mentioned results, for example, information on abnormality in the attachment of the transducer can also be evaluated and used as the evaluation result of the sampling state.

The fourth invention is an apparatus for realizing the method of the above invention,
a correlation calculation means for performing real-time autocorrelation calculation on the fetal heartbeat signal and outputting a correlation waveform; an evaluation circuit for evaluating the acquisition state of the fetal heartbeat signal and outputting an evaluation result; and a predetermined circuit for automatically starting recording. A comparison circuit that compares the value and the evaluation result and outputs a recording start signal when the evaluation result is the predetermined value, and a counting circuit that calculates the fetal heart rate using the correlation waveform and outputs it. The present invention provides a fetal monitoring device equipped with an arithmetic processing means provided with each circuit, and a recorder that automatically starts recording in response to the recording start signal and records the fetal heart rate.

Further, a fifth invention is a device for stabilizing heart rate measurement using multiple input signals or for monitoring multiple intakes, etc. In the fourth invention, a plurality of correlation calculation means and calculation processing means are provided. This fetal monitoring device is equipped with a system and a recorder that automatically starts recording and records the fetal heart rate in response to the recording start signal that is first input.

The fourth and fifth inventions will be explained in detail by way of examples.

(5) Examples Examples will now be described in detail with reference to the drawings. 1st
The figure shows a block diagram of an embodiment of the fourth invention. In FIG. 1, 1 is a probe for collecting fetal heartbeat signals, 2 is a main amplifier circuit consisting of an analog amplifier and filter, etc., 3 is a real-time autocorrelation calculation circuit including an input time sharing circuit, 4 is CPU-ROM-
The arithmetic processing circuit is composed of RA and M/IO, 5 is an arithmetic output circuit, and 6 is a recorder. To explain these operations, the fetal heartbeat signal collected by the probe 1 is filtered and amplified by the main amplifier circuit 2, and the autocorrelation calculation circuit 3 performs autocorrelation in real time, and the correlation waveform is processed. Send to circuit 4. The arithmetic processing circuit 4 evaluates the acquisition state of the fetal heartbeat signal from the input correlation waveform, compares the evaluation result of the acquisition state, and the evaluation result with a predetermined evaluation value for automatically starting recording, and determines the result of the comparison. If is a predetermined value, period information obtained from the recording start signal and the correlation waveform is converted into a fetal heart rate and sent to the calculation output circuit 5. The calculation output circuit 5 displays the evaluation results in sections, displays the fetal heart rate numerically, and records the fetal heart rate as a waveform on the recorder 6. By displaying the evaluation results in sections, it is possible to grasp the sampling condition accurately and to easily position the probe at the appropriate location. It can be used more effectively.

FIG. 2 is a diagram showing the concept of correlation values used in calculations on correlation waveforms obtained by the real-time autocorrelation calculation circuit 3. In Fig. 2, ImO is the origin correlation value, which is the correlation value at time difference 0, and imP is the detection point correlation value, which indicates the heartbeat cycle and indicates the correlation value at the maximum maximum point or the true periodicity from among multiple maximum points. The correlation value at the determined maximum point, lm0FF, is the correlation offset level value, which is the minimum value of the correlation values from time difference 0 to the maximum time difference, and is the level of the forgetting process from past cycle information and the random noise level other than cycle information. It is a collection of values such as At this time, the S/N ratio is considered as an index for evaluating the sampling state, and is defined by the following equation.

ImP-1m0FF S/N ratio=ImO-ImOFF The amount of F is evaluated, and if it can be evaluated that this is appropriate, the S/N ratio is evaluated as the next step. The amount of input information is evaluated by focusing on the origin correlation value ImO and comparing it with the origin minimum allowable value CL and the origin maximum allowable value CH. If ImO < CL, the amount of input information is insufficient, and if ImO >= CH, human input due to noise etc. Evaluated as information overload. Table 1 shows an example of the sampling condition evaluation criteria and output display.

Figure 3 shows an evaluation circuit that performs real-time autocorrelation calculations on each of the two systems of fetal heartbeat signals collected from the mother's body, evaluates the collection state of each of the fetal heartbeat signals based on the correlation waveforms of the two systems, and outputs the evaluation results. and a counting circuit that automatically selects an appropriate correlation waveform to determine the fetal heart rate; and an output means that outputs the fetal heart rate obtained by the counting circuit and the plurality of evaluation results. This is a fetal monitoring device equipped with the present invention, and represents an embodiment of the fifth invention.

[Table 1] In Figure 3, 11 is a probe AφB512 for collecting two fetal heartbeat signals, two sets of main amplification circuits A-B consisting of analog amplifiers and filters, and 13 are human-powered time probes. Two sets of real-time autocorrelation calculation circuits A-B including a sharing circuit; 14 is a CPU including an automatic selection circuit;
-ROM-RAM.■ An arithmetic processing circuit consisting of 0, 15 an arithmetic output circuit, and 16 a recorder.

To explain these operations, two sets of fetal heartbeat signals collected by the probe 11 are filtered and amplified by the main amplification circuit 12, and then sent to the real-time autocorrelation calculation circuit 13.
is input. The real-time autocorrelation calculation circuit 13 calculates autocorrelation in real time and sends each correlation waveform to the calculation processing circuit 14.

The arithmetic processing circuit 14 evaluates the acquisition state of the fetal heartbeat signal from each input correlation waveform and outputs the evaluation result, and also compares the evaluation result with a predetermined value for automatically starting recording. When the value is a predetermined value, a recording start signal is output and sent to the calculation output circuit 15. Further, a correlation waveform determined to be appropriate is automatically selected from each evaluation result, and period information obtained from the selected correlation waveform is converted into fetal heart rate, which is also sent to the calculation output circuit 15. The calculation output circuit 15 displays each evaluation result in sections, and also displays the fetal heart rate numerically, and the recorder 16 records it as a fetal heart rate curve.

When adapting to feeding, the recorder 16 automatically starts recording when one of the recording start signals is output from the arithmetic processing circuit 14, and records each fetal heart rate as a fetal heart rate curve. In this case, since the other sampling state that does not output the recording start signal is defective, the configuration may be such that the baseline is recorded until the recording start signal is output.

(7) Effects of the Invention According to the present invention, since there is no need to move the fetus due to switch operation, the problem of meaningless noise being recorded and the problem of wasting recording paper can be solved. In addition, since the conventional process of turning on the recorder after finding a site with good conditions for collecting fetal heart rate signals is no longer required, the patient is freed from the troublesome operation of equipment, making it easier for the patient to simply find the appropriate site. monitoring can be started automatically. Furthermore, the present invention can be utilized more effectively by displaying the obtained evaluation results.

[Brief explanation of drawings]

1 and 3 are configuration diagrams of the main parts of embodiments of the fourth and fifth inventions of the present invention, respectively. It is also a configuration diagram of an embodiment. FIG. 2 is an example of a correlation waveform diagram for explaining the concept of correlation waveforms. 1... Probe, 11... Probe A-B, 2...
...Main amplifier circuit, 12...Main amplifier circuit'#1A-B,
3... Real-time autocorrelation calculation circuit, 13... Real-time autocorrelation calculation circuit A-B, 4, I4
...... Arithmetic processing circuit, 5.15...
Arithmetic output circuit, 6.16... Recorder] 5 ← Σ圀

Claims (1)

[Claims] 1) An automatic recording start method for automatically starting recording when a predetermined evaluation result is obtained by evaluating the acquisition state of fetal heartbeat signals. 2) The evaluation is performed by performing real-time autocorrelation calculation on the fetal heartbeat signal and performing a comparison calculation on the obtained correlation waveform, and the result is used as at least a part of the evaluation result. How to automatically start recording sections. 3) Perform real-time autocorrelation calculations on the fetal heartbeat signal, perform comparison calculations, etc. on the obtained correlation waveforms to obtain collection status information, and perform the above evaluation by performing average calculations, etc. within a predetermined time on the collection status information. 2. The automatic recording start method according to claim 1, wherein the evaluation result is used as at least a part of the evaluation result. 4) Correlation calculation means that performs real-time autocorrelation calculation on the fetal heartbeat signal and outputs a correlation waveform, an evaluation circuit that evaluates the acquisition state of the fetal heartbeat signal and outputs the evaluation result, and a predetermined circuit that automatically starts recording. a comparison circuit that compares the value with the evaluation result and outputs a recording start signal when the evaluation result is the predetermined value; and a counting circuit that calculates the fetal heart rate using the correlation waveform and outputs it. A fetal monitoring device comprising: arithmetic processing means equipped with a circuit; and a recorder that automatically starts recording in response to the recording start signal and records the fetal heart rate. 5) The apparatus includes a plurality of systems of the correlation calculation means, a plurality of systems of the calculation processing means, and a recorder that automatically starts recording in response to the first input recording start signal and records the fetal heart rate. A fetal monitoring device according to claim 4.