JP2017200554A - Fetus heart beat-labor pain composite transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid labor and time by integrating two sensors of Doppler and labor pain mounted on an abdominal wall of a pregnant woman to also collect a Doppler signal at a mounting position of a labor pain meter, in fetus monitoring.SOLUTION: There is provided a configuration for obtaining a Doppler signal of a fetus heart using incidence at an oblique angle from part directly under the pit of the stomach, the part being an optimum position for a labor pain meter. For the purpose, a variable angle probe (Fig.1) of a semi-sphere liquid chamber dome type is used. Being magnetically attracted by a magnet piece (4) with a knob (3) from the outside, a transceiver assembly (2) freely moves along a ceiling on the inner side of a semi-sphere part of a dome-like liquid chamber (1) while changing the transceiver assembly's direction to set an azimuth angle of an ultrasonic beam (13) transmitted/received via a contact surface (5) in an arbitrary manner. A pressure sensor (10) is also provided inside the liquid chamber; static pressure received by the contact surface (5) is detected according to Pascal's principle by the pressure sensor to obtain an externally measured labor pain signal.SELECTED DRAWING: Figure 1

Description

Summary:
In fetal monitoring practiced clinically, two transducers, Doppler and labor, are separately mounted on the abdominal wall of the maternity at the optimal positions. In the research on which the present invention is based, in order to avoid this complexity, an attempt was made to collect both signals from one place on the abdominal wall by integrating them, and since a favorable result was obtained, it is reported and a patent application is filed. The manual preset steerable high oblique incidence Doppler probe of the liquid chamber structure that forms the basis of the present invention differs from some non-steerable integrated designs in the past in the optimal location of the tonometer. A Doppler signal of the fetal heart near the pelvic cavity is collected at a high angle oblique incidence from a certain groove.

Background and outline of research:
In fetal monitoring practiced clinically, for the past nearly 40 years, two transducers, Doppler and labor, have been installed on the abdominal wall of a maternal woman separately at their optimal positions. It is thought that such a method method has been understood as “that kind of thing” without raising the opinion of being complicated or troublesome. That is, as summarized in the literature (1), the external measurement painmeter is directly below the groovy part or just above the umbilical cavity where the base of the uterus can be touched, and the Doppler probe is below the normal surface of the body surface. It is installed on either the left or right side of the lower abdomen. In this research, in order to avoid the complication of placing these two sensors separately, we tried to integrate them and collect both signals from one place on the abdominal wall. We report good results. The manual preset steerable high oblique incidence Doppler probe of the liquid chamber structure in this study is different from some non-steerable integrated designs in the past. The Doppler signal of the fetal heart near the pelvic cavity is collected at an oblique incidence. The prototype operates stably continuously for a long time, and obtains a fetal heart rate chart of diagnostic quality.

A precedent by the same or similar thoughts:
As an example of a combined heartbeat and labor pain transducer, an example of adopting a fetal heart sound instead of Doppler as a fetal signal is adopted in the oldest fetal monitoring device of hp as seen in the literature (2). This is the external stress signal that is received by the pressure-sensitive terminal pressed against the abdominal wall, and the fetal heart sound is extracted from the vibration component. Since fetal heart sounds are received in a very wide angle range when viewed from the source, in other words, the radiation directivity is so wide that it can be detected along with labor signals at the lower groove or upper umbilical cavity. However, the fetal heart sound system has been replaced by Doppler, which has almost no restrictions when fetal monitoring is in widespread use in clinical practice, due to various other restrictions such as the high chance of noise contamination.
As an attempt to put into practical use a heartbeat / labor pain combined transducer in which the heartbeat side is Doppler, D.C. L. There are Thomas (3) (4), Kazuo Maeda (5), and the like. Thomas et al. Adopt a configuration in which the pressure-sensitive sensor part of the external measuring pain meter is made of a thick sound-transmitting object, a Doppler probe is placed on it, and the Doppler transmit / receive beam is set from the upper side to the lower contact surface. did. On the other hand, Maeda et al., Conversely, made a hole in the excess space in the center of the multi-element Doppler probe, and extended the pressure-sensing terminal of the externally mounted pain meter on the abdominal wall via the hole. Touched. Both of these cases were reported to have worked well at the academic presentation stage, but the Doppler beam was fixed, so their combined transducers also sensed external labor pains at the optimal position for Doppler, i. In other words, the labor force signal waveform obtained is not the optimal one, and at least the common sense has a problem that the signal is different from the labor signal waveform collected at the bottom of the groove. . For these reasons, and the profound and large size of the resulting composite transducer, their proposals and prototype trials have not been adopted for clinical use.

Methodology for problem setting and problem solving:
As explained below, in this study, in contrast to Maeda and Thomas et al., The fetal heart that is at or near the optimal position for labor measurement, and that is obliquely distant from that position is measured with a high oblique incidence Doppler probe. It aims to capture and capture two signals simultaneously in parallel while sharing the contact surface with the external survey painmeter. In this study, we first tried to practically capture the fetal heart coming obliquely far from the lower part of the groove with a high oblique incidence Doppler probe. In addition, a feasibility study model has been developed and used as a prototype for a structure in which the direction of the high oblique incidence Doppler beam can be manually set or reset during operation over a wide range.

Summary of trial production as a preferred embodiment:
As shown in the sketch of the cross-sectional view of FIG. 1, a probe having a structure in which the transmitter / receiver assembly (2) is attached to the ceiling of the liquid chamber (1) forming a flat-bottomed hemispherical dome is used. Since the transducer can be slidably moved from the outside of the liquid chamber dome (1) with the magnet attached to the knob (3), the direction of transmitting and receiving the ultrasonic wave (13) can be adjusted with this knob (3). Can be set arbitrarily. This tangential magnetic attractive sliding mechanism is not a rotating or laterally moving sliding mechanism set to penetrate the wall of the liquid chamber, so it does not interfere with the sealing structure, and the liquid in the sliding part There is a feature that a packing or the like for sealing is not required.
The liquid (12) excellent in sound transmission to be put into the liquid chamber is sufficient for the time being, but the sound transmission liquid (12) in the liquid chamber will be further described later.
When the drawing knob (3) shown in the drawing is held, the transducer assembly (2) in the inside follows the inner surface of the dome (1) while changing the angle. The dome is 60 mm in diameter and 1 mm thick acrylic, the contact surface is a 0.25 mm thick polycarbonate thin plate, and the lump adhesion to these underframes (6) is fast-curing epoxy. The pedestal with the magnet attached to the back that forms the identity of the vibrator assembly (2) is a cork.
On the other hand, the stress applied to the contact surface (5) can be sensed in the same manner anywhere in the liquid chamber as the internal pressure of the sound-transmitting liquid in the liquid chamber based on the minute displacement and / or Pascal's principle. If a pressure sensor (10) is arranged somewhere, an external measurement pain signal can be obtained by this pressure sensor (10). The location is preferably a location where the ultrasonic beam is not obstructed no matter what angle the ultrasonic beam is set, so that the side wall end is preferred as shown.
Also, if this contact surface (5) is configured as a slightly convex surface rather than a flat surface (in the sense that it is made of a flat plate) and the corrugation (9) is applied to the edge portion, this hydraulic transmission type Although it is preferable because the linearity and dynamic range of the measurement pain measurement system can be improved as compared with the case of using only a flat plate, it is a range of practical freedom and is not an essential part of the present invention.
The lead wire (8) coming out from the transducer assembly (2) was appropriately water-tightly drawn out of the dome at a suitable location after migrating through the long liquid chamber, and collected together with the lead wire of the pressure gauge (10). It becomes the cable (11) and faces the fetal monitoring device main frame that cannot be seen in the figure.
On the other hand, there are belt holes at both ends of the underframe (6), and a mounting belt (7) that wraps around the pregnant woman's body is hung. It is attached with pulling force. This place is the same as a normal external survey painmeter.
That is, from the above, this product is composed of a sound-transmitting thin plate with the contact surface (5), which essentially forms one surface, as an acoustic opening and a pressure receiving surface, and is transparent behind the acoustic opening made of the thin plate. A liquid chamber filled with acoustic liquid (12) is provided, and an ultrasonic observation system is configured by oblique incidence with an angle with respect to the normal from the liquid chamber through the acoustic aperture, and the thin plate As a pressure receiving surface, a system for observing the stress from the outside that is in contact is constructed, and fetal heartbeat monitoring by ultrasonic Doppler method and labor monitoring by external measurement method are simultaneously performed in parallel on the contact surface. It was explained that it was a combined fetal heartbeat and labor pain transducer characterized by being constructed.
In addition, the system for observing the stress from the outside that is in contact with the thin plate forming the acoustic aperture as the pressure receiving surface is installed in a remote place that does not interfere with the ultrasonic system inside the sealed liquid chamber. It was explained that the fetal heartbeat / labor pain combined transducer is characterized in that it is configured to observe the pressure received by the opening surface, that is, the pressure receiving surface based on Pascal's principle.
Note that the main frame of the fetal monitoring device used for the evaluation of the prototype is hp8041A, the Doppler system is a long pulse / pulse Doppler, and the observation ultrasonic frequency is 1 MHz.
The trial run of the prototype was set and tried as shown in Fig. 2 on the stomach of a 41 week pregnant woman. Although the first trial is only Doppler observation, this position is usually the position where a tonometer is installed. When an ultrasonic beam is set in the direction shown in the figure, a fetal heart signal can be received. At this time, the direction of the beam was about 60 degrees when tilted slightly from the normal to the lower left, and was set as expected.
The resulting fetal heart rate diagram is shown in FIG. It is understood to have diagnostic quality.
The outline of the geometry during observation in the test run will be described with reference to FIG. That is, when the distance and direction from the probe TD1 to the fetal heart FH to be observed are visually observed, the total distance of the line of sight LS1 is about 20 to 25 cm, and the inclination θ of the sound ray is about 60 °. On the other hand, in a normal case, the line-of-sight distance LS2 with respect to the probe TD2 that is considered to be mounted at the position of the normal line N2 is estimated to be about 5 to 7 cm. The difference in the round-trip attenuation amount of the ultrasonic wave on the propagation path due to the difference (difference) in the distance is that the observed ultrasonic frequency is as low as 1 MHz. However, this is well within the dynamic range that can still be handled by the fetal monitoring device used. This also matches the approximate amplitude of the recorded signal. However, the line-of-sight distance of 25 cm to the target is almost the limit distance in the design of the long pulse / pulse Doppler system of this device, and further design measures are necessary when such oblique incidence long-range line-of-sight length is used regularly. There is a possibility.
On the other hand, as the sound-transmitting liquid in the liquid chamber, a liquid chamber-type ultrasonic system such as glycerine hydrate, mineral oil, castor oil, or silicone oil can be used as well as water, as well as previous examples. Here, if a sound-transmitting liquid that is significantly slower than the sound velocity of the living body's soft tissue that is in contact with the contact surface (essentially equivalent to water) is used as the sound velocity of the liquid in the liquid chamber, it is derived from this difference in sound velocity. Since refraction occurs, an exit angle that is significantly larger than the incident angle on the inner contact surface outside the contact surface, in other words, an incident angle on the target soft tissue of the living body is realized. In other words, this allows a wider range of incident angles on the soft tissue of the living body with a narrower range of movement of the sliding knob and the transducer assembly. A typical example of such a liquid whose sound speed is slower than that of water (approximately 1.5 km / s slightly) is silicone oil (approximately 1 Km / s slightly less).

Results and discussion:
From the trial trial experience described above, it is believed that fetal Doppler observation can be performed from the optimum position for the tocodynamometer. As a result, it is more practical and preferable than the collective barracks design of Thomas (3) (4) and Maeda (5), which are precedents of research and development with similar or the same purpose consciousness, especially if the Doppler beam is a manual preset. The heartbeat / labor pain combined transducer with the great feature of being steerable is realized, and it has a great advantage in the medical field. Further, unlike the Thomas and Maeda, the heartbeat / labor pain combined transducer of the present invention is not the case where the labor meter piggybacks on the Doppler probe and moves to the left or right side of the lower abdomen, which is the optimal position. This has another beneficial effect as the probe moves over the lower abdomen and moves to the location of the tocometer, just below the groove. That is, there are various interventions in the lower abdomen of the maternity during parturition, and it may get in the way if a Doppler probe is set there, but if the combined heartbeat and labor pain transducer of the present invention is used, That doesn't happen. In any case, the fact that two sensors become one is very beneficial to the medical field.

Summary of inventions as a result of research:
The invention as a result of this research consists of a sound-transmitting thin plate with the contact surface that essentially forms one surface as an acoustic opening and pressure-receiving surface, and the sound-transmitting property behind the acoustic opening made of the thin plate. A liquid chamber filled with a liquid is provided, and an ultrasonic observation system is constructed from the liquid chamber through the acoustic aperture at an oblique incidence angled with the normal line, and the thin plate is used as a pressure receiving surface. The system for observing the stress from the outside world is constructed, and these are configured so that fetal heartbeat monitoring by ultrasonic Doppler method and labor pain monitoring by external measurement method are simultaneously performed in parallel on the contact surface. It can be a fetal heartbeat / complexity transducer.
The invention as a result of this research further comprises a mechanism for changing the incident angle of the oblique incidence ultrasonic observation system at any time during operation in the fetal heartbeat / labor pain combined transducer, It can be a heart rate labor pain transducer.
The invention as a result of this research further has a mechanism in which the liquid chamber has a sealed structure, and the incident angle of the oblique incidence ultrasonic observation system can be changed at any time during operation from the outside of the liquid chamber. The fetal heartbeat / labor pain combined transducer is characterized in that it is configured to operate without using a sliding mechanism with a wall.
The invention as a result of this research further includes a mechanism for changing the incident angle of the oblique incidence ultrasonic observation system at any time during operation by a force transmission mechanism by magnetostatic magnetic attraction through the wall of the liquid chamber. The fetal heartbeat and labor pain transducer can be characterized by being constructed.
The invention as a result of this research is further designed so that the sound speed of the sound-transmitting liquid filling the liquid chamber is significantly slower than the sound speed of the biological soft tissue of the partner in contact with the contact surface. The fetal heartbeat / labor pain combined transducer can be configured such that an exit angle significantly larger than an incident angle on the inside is realized outside the contact surface.
The invention as a result of this research further provides a system for observing stress from the outside that is in contact with the thin plate forming the acoustic aperture as a pressure receiving surface, and does not interfere with the ultrasonic system inside the sealed liquid chamber. The fetal heartbeat / labor pain combined transducer can be installed at a remote location and configured to observe the pressure received by the opening surface, that is, the pressure receiving surface based on Pascal's principle at that location. .

References:
(1) Takeuchi, “Principles of Monitoring” Special Feature / CTG Textbook 2012-Japan Maternal Medicine Society Joint Project, Perinatal Medicine vol. 42 no. 4 pp415-423 20122.4
(2) "Cardiocography; Measurement Techniques and Interpretation of Fetal Heart Frequency Patterns" hp AN700 (Hewlett-Packard Co., Application Note 700)
(3) D.E. L Thomas et. al. , “A complete system for monitoring the fetal heart rate and uterine contractions” Med. Biol. Engineering. Nov. 1973 pp703-709
(4) The author (inventor), British Patent No. 1348154, filled 31 Aug. 1971, granted 13 March 1974
(5) Maeda, Nagata, “Delivery monitoring device with integrated heart rate and labor pains”, Journal of Japan Academy of Obstetrics and Gynecology vol. 41 no. 1 pp91-92, 194.1.

It is sectional drawing which shows the outline | summary of the fetal heartbeat labor pain combined transducer which becomes this research, ie, this invention. In this, (1) liquid chamber (2) transducer assembly (3) routing knob (4) magnet piece (5) contact surface (6) base frame (7) mounting belt (8) lead wire (9) corrugation (10) Pressure sensor (11) Cable (12) Sound-transmitting liquid (13) Ultrasonic wave (ultrasonic beam) transmitted and received It is a thing which shows the positional relationship (geometry) of the installation condition which becomes this research, ie, the fetal heartbeat labor pain combined transducer of this invention during the test run. In this, the transducer TD2 installed for commissioning TD1 Transducer that would normally be installed N1 Body surface normal at the position of TD1 Body surface normal at the position of N2 TD2 Fetal heart FH for LS1 TD1 Line of sight and line-of-sight distance to LS2 TD2 Line of sight and line-of-sight distance to fetal heart FH FH Fetal heart Instruction for associating the positional relationship between the AA ′ top view and the oblique section Fig. 3 shows a fetal heart rate diagram obtained by trial operation of the combined fetal heartbeat and labor pain transducer of the present invention, i.e. the present invention.

Claims (6)

A contact surface that essentially forms one surface is composed of a sound-transmitting thin plate as an acoustic opening and a pressure-receiving surface, and a liquid chamber filled with a sound-transmitting liquid is provided behind the sound opening made of the thin plate. An ultrasonic observation system is constructed from the liquid chamber through the acoustic aperture and at an oblique angle with respect to the normal, and stress from the outside that is in contact with the thin plate as a pressure-receiving surface is observed. And a fetal heartbeat / labor pain combined transformer characterized in that the fetal heartbeat monitoring by ultrasonic Doppler method and the labor pain monitoring by external measurement method are simultaneously performed in parallel on the contact surface. Deucer. 2. The fetal heartbeat / labor pain combined transducer according to claim 1, further comprising a mechanism for changing the incident angle of the oblique incidence ultrasonic observation system as needed during operation. 3. The fetal heartbeat / labor pain combined transducer according to claim 1 or 2, wherein the liquid chamber has a sealed structure, and a mechanism for changing the incident angle of the oblique incidence ultrasonic observation system at any time during operation is provided outside the liquid chamber. The fetal heartbeat / labor pain combined transducer, which is configured to operate without using a sliding mechanism penetrating through the wall of the fluid chamber. 5. The fetal heartbeat / labor pain combined transducer according to claim 1, 2 and 3, wherein the mechanism for changing the incident angle of the oblique incidence ultrasonic observation system as needed during operation is a magnetostatic magnetism through the wall of the liquid chamber. The fetal heartbeat / labor pain combined transducer, characterized by comprising a force transmission mechanism by suction. In the fetal heartbeat / labor pain combined transducer according to claim 1, the sound velocity of the sound-transmitting liquid filling the fluid chamber is designed to be significantly slower than the sound velocity of the soft tissue of the other body in contact with the contact surface, and the sound velocity difference The fetal heartbeat / labor pain combined transducer is configured such that an exit angle significantly larger than an incident angle on the inside is realized outside the contact surface. 2. The fetal heartbeat / labor pain combined transducer according to claim 1, wherein a system for observing stress from the outside that is in contact with a thin plate forming the acoustic aperture as a pressure receiving surface is disposed inside the sealed liquid chamber. The fetal heartbeat / labor pain combined transducer, characterized in that it is installed at a remote location that does not interfere with the sensor, and is configured to observe the pressure received by the aperture surface, ie, the pressure receiving surface, based on Pascal's principle at that location.

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