JP6016145B2 - Concentration measuring device and method of operating the concentration measuring device - Google Patents

Description

  The present invention relates to a concentration measuring apparatus and a concentration measuring method.

As an apparatus for noninvasively measuring the concentration information of hemoglobin in a living body, for example, there is one described in Patent Document 1. In this apparatus, after light is incident on the living body, light scattered inside the living body is detected by each of the plurality of photodiodes. Based on the intensity of the detected light, the rate of change of the detected light quantity with respect to the distance direction from the light incident point is calculated. The hemoglobin oxygen saturation is calculated based on a predetermined relationship between the change rate of the detected light quantity and the light absorption coefficient. Further, based on a predetermined relationship between a change in the detected light amount with time and a change in the light absorption coefficient with time, each of oxygenated hemoglobin (O ₂ Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) A change in density is calculated.

JP 7-255709 A

Susumu Suzuki et al. “Tissue oxygenation monitor using NIR spatially resolved spectroscopy”, Proceedings of SPIE 3597, pp.582-592

  The main target patients in the field of emergency lifesaving in recent years are cardiopulmonary arrest outside the hospital. The number of cardiopulmonary arrest outside the hospital exceeds 100,000 per year, and the lifesaving of these patients is a great social demand. An essential procedure for out-of-hospital cardiopulmonary arrest is chest compressions combined with mechanical ventilation. Chest compression is an act of artificially pulsating a stopped heart by periodically compressing the lower half of the sternum with another person's hand. The main purpose of chest compression is to supply blood oxygen to the brain of cardiopulmonary arrest. Therefore, whether or not chest compression is properly performed greatly affects the life and death of a cardiopulmonary arrest person. Therefore, a useful method and apparatus for objectively determining whether or not chest compression is appropriately performed is desired.

  The present invention has been made in view of such circumstances, and preferably detects a change in concentration caused by chest compression in order to objectively determine whether chest compression is being performed appropriately. It is an object of the present invention to provide a concentration measuring apparatus and a concentration measuring method capable of performing the above.

In order to solve the above-described problem, the concentration measuring apparatus according to the present invention is at least one of the total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that varies due to repeated chest compressions. Is a concentration measuring device that measures the amount of relative change in time, and detects the light incident part that enters the measurement light into the head and the measurement light that propagates inside the head, and according to the intensity of the measurement light A light detection unit that generates a detection signal, and at least one of a total hemoglobin concentration, an oxygenated hemoglobin concentration, and a deoxygenated hemoglobin concentration that fluctuates due to repeated chest compressions based on the detection signal A calculation unit for obtaining a temporal relative change amount, and a calculation period of the relative change amount is 0.2 seconds or less, and warns a chest compression enforcer based on the relative change amount .

In addition, the concentration measurement method according to the present invention includes a temporal relative change amount of at least one of total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that varies due to repeated chest compressions. A light incident step for entering measurement light into the head, and light for detecting the measurement light propagating through the head and generating a detection signal corresponding to the intensity of the measurement light Based on the detection step and the detection signal, a temporal relative change amount of at least one of total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that fluctuates due to repeated chest compressions is calculated. determined, and an arithmetic step of warning to enforcement's chest compressions based on the relative change amount calculation period of the relative change amount is less than 0.2 seconds.

  The present inventor measured the relative change in the total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration of the head at a frequency sufficiently faster than the heartbeat frequency using a concentration measuring device using near infrared light. As a result, it was found that in the compression of the sternum, every time the sternum is periodically compressed, a constant change occurs in the total hemoglobin concentration or oxygenated hemoglobin concentration inside the head (that is, the brain). This phenomenon is considered to be caused by an increase in blood flow in the brain due to chest compression, and can be an objective material for determining whether chest compression is performed appropriately.

In general, it is said that a suitable period of chest compression is about 100 times per minute (that is, once every 0.6 seconds) or more. And if the calculation period of a relative change amount is 1/3 or less, the density | concentration change resulting from chest compression can be detected. That is, when the calculation period of the relative change amount is 0.2 seconds or less, it is possible to suitably detect a change in density caused by chest compression. Further, in the above-described concentration measuring apparatus and concentration measuring method, a warning is given to the person who performs chest compression based on the relative change amount . As a result, it is possible to more reliably notify the practitioner of chest compression that the ratio of oxygenated hemoglobin in the blood sent to the head is reduced. This warning can be performed by outputting a warning sound or displaying a warning.

  In addition, the amplitude of change in concentration due to chest compression (for example, about 1 μmol) is the amplitude of normal cycle of normal subjects or the change of longer cycle that occurs in various treatments for cardiopulmonary arrest (normally , A few μmol or more). Therefore, if a value corresponding to the total hemoglobin concentration or the oxygenated hemoglobin concentration is simply measured, it is extremely difficult to observe the fluctuation due to chest compression. Therefore, in the concentration measuring apparatus and the concentration measuring method described above, in the calculation unit or calculation step, at least one of the total hemoglobin concentration, the oxygenated hemoglobin concentration, and the deoxygenated hemoglobin concentration as a temporal relative change amount from a predetermined frequency. You may obtain | require the relative variation | change_quantity from which the small frequency component was removed. Usually, the cycle of concentration change caused by chest compression (that is, a preferable compression cycle at the time of chest compression) is shorter than the cycle of main concentration change in a state where various treatments are performed on a cardiopulmonary arrest person. Therefore, by obtaining a relative change amount from which a small frequency component (that is, a long period component) has been removed, it is possible to more appropriately extract information relating to the concentration change caused by chest compression. Then, based on this information, the enforcer can objectively determine whether or not chest compression is being performed appropriately. This enables the practitioner to perform or maintain more appropriate chest compressions. In the concentration measuring apparatus and concentration measuring method described above, “the frequency component smaller than the predetermined frequency has been removed” means that the frequency component due to chest compression is sufficiently distinguishable from the proportion of the frequency component smaller than the predetermined frequency. It is small until it appears to some extent, and is not limited to one in which frequency components smaller than a predetermined frequency are completely removed.

  The concentration measuring apparatus and the concentration measuring method may be characterized in that the predetermined frequency is 1.66 Hz or less. Thereby, the information regarding the density | concentration change resulting from chest compression can be extracted suitably.

  The concentration measuring apparatus further includes a display unit that displays a calculation result of the calculation unit, the calculation unit obtains the time change amplitude of the temporal relative change amount of the total hemoglobin concentration, and the display unit displays the amplitude value. May be displayed. Similarly, the concentration measuring method may be characterized in that, in the calculation step, the amplitude of the temporal change of the temporal relative change amount of the total hemoglobin concentration is obtained and the numerical value of the amplitude is displayed. By referring to the displayed numerical values, the practitioner can refer to the amount of blood sent into the brain, and it is possible to appropriately determine whether the compression strength of the sternum is sufficient.

  The concentration measuring apparatus further includes a display unit that displays a calculation result of the calculation unit, and the calculation unit displays a temporal relative change amount of the total hemoglobin concentration and a temporal relative change amount of the oxygenated hemoglobin concentration. In addition, the display unit may display a graph showing the temporal relative change in the oxygenated hemoglobin concentration and the temporal relative change in the deoxygenated hemoglobin concentration included in the total hemoglobin concentration in a color-coded manner. Good. Similarly, the concentration measuring method obtains a temporal relative change amount of the total hemoglobin concentration and a temporal relative change amount of the oxygenated hemoglobin concentration in the calculation step, and a temporal relative change amount of the oxygenated hemoglobin concentration. And a temporal relative change amount of the deoxygenated hemoglobin concentration included in the total hemoglobin concentration may be displayed in a graph with different colors. By referring to the displayed information, the operator can visually and intuitively recognize the ratio of oxygenated hemoglobin in the blood that is sent into the brain, and can quickly determine the necessity of artificial respiration. can do.

  The concentration measuring apparatus further includes a display unit that displays a calculation result of the calculation unit, wherein the calculation unit calculates information on the fluctuation frequency of the relative change amount, and the display unit displays the information. Also good. Similarly, the concentration measurement method may be characterized in that, in the calculation step, information on the fluctuation frequency of the relative change amount is calculated and the information is displayed. By these, it is possible to inform the practitioner of the current frequency (cycle) of chest compression and to urge the operator to approach the appropriate frequency (cycle).

  The concentration measuring apparatus may further include a display unit that displays a calculation result of the calculation unit, wherein the calculation unit calculates the hemoglobin oxygen saturation, and the display unit displays the hemoglobin oxygen saturation.

  According to the concentration measuring apparatus and the concentration measuring method of the present invention, it is possible to suitably detect a change in concentration caused by chest compression in order to objectively determine whether or not chest compression is appropriately performed.

It is a conceptual diagram of the density | concentration measuring apparatus which concerns on one Embodiment of this invention. (A) It is a top view which shows the structure of a probe. (B) It is a sectional side view along the II-II line of (a). It is a block diagram which shows the structural example of a density | concentration measuring apparatus. It is a flowchart which shows the density | concentration measuring method by one Embodiment. (A) is a diagram showing an incident timing of the laser beam having a wavelength lambda ₁ to [lambda] _3. (B) It is a figure which shows the output timing of the digital signal from an A / D conversion circuit. It is a graph which shows the filter characteristic of a digital filter. Using the digital filter having the characteristics shown in FIG. 6, frequency components smaller than a predetermined frequency are removed from frequency components included in the temporal relative change amount (ΔO ₂ Hb) of oxygenated hemoglobin, and repeated chest compressions It is a graph which shows the result of having extracted the time fluctuation part resulting from the spontaneous heartbeat imitating in (5). This is due to a spontaneous heartbeat that simulates repeated chest compressions by removing frequency components smaller than a predetermined frequency from frequency components included in the temporal relative change amount (ΔcHb) of total hemoglobin by using smoothing filtering. It is a graph which shows the result of having extracted the time fluctuation part. It is a figure for demonstrating the concept of the filter process which arranges the maximum part and minimum part of a fluctuation | variation uniformly. It is a figure which shows the example of the display screen in a display part.

  Hereinafter, embodiments of a concentration measuring apparatus and a concentration measuring method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a conceptual diagram of a concentration measuring apparatus 1 according to an embodiment of the present invention. This concentration measuring apparatus 1 is caused by repeated chest compressions in order to provide an objective judgment material as to whether or not chest compressions (arrow A in the figure) are properly performed on the cardiopulmonary arrest person 50. Variation of the total hemoglobin (cHb) concentration, oxygenated hemoglobin (O ₂ Hb) concentration, and deoxygenated hemoglobin (HHb) concentration of the head 51 from the initial amount (relative change amount) And the measurement result is displayed on the display unit 15 to notify the person who is performing chest compressions. The concentration measuring apparatus 1 makes light of a predetermined wavelength (λ ₁ , λ ₂ , λ ₃ ) incident on a predetermined light incident position from the probe 20 fixed to the head 51, and from the predetermined light detection position on the head 51. by detecting the intensity of the emitted light, examined by oxygenated hemoglobin (O 2 _Hb) and deoxygenated hemoglobin (HHb) the influence on the light, oxygenated hemoglobin (O 2 _Hb) and de based on this The temporal relative change amount of oxygenated hemoglobin (HHb) is repeatedly calculated. In addition, the time-series data that is the calculation result is filtered to remove low-frequency components, so that the short-term time fluctuations resulting from repeated chest compressions are extracted, and the time fluctuations are visible. Display. For example, near infrared light is used as the light having a predetermined wavelength.

  FIG. 2A is a plan view showing the configuration of the probe 20. Moreover, FIG.2 (b) is a sectional side view along the II-II line of Fig.2 (a). The probe 20 has a light incident part 21 and a light detection part 22. The light incident part 21 and the light detection part 22 are arranged with an interval of, for example, 5 cm, and are substantially integrated by a flexible black silicon rubber holder 23. In addition, this space | interval should just be about 3-4 cm or more.

  The light incident portion 21 includes an optical fiber 24 and a prism 25, and has a structure in which measurement light transmitted from the main body portion 10 of the concentration measuring apparatus 1 is incident substantially perpendicularly to the skin layer of the head. The measurement light is, for example, pulsed laser light and is sent from the main body 10.

  The light detection unit 22 detects the measurement light propagated inside the head, and generates a detection signal corresponding to the intensity of the measurement light. The photodetection unit 22 is, for example, a one-dimensional photosensor, and includes N array photodetection elements 26 arranged in the distance direction from the light incident unit 21. The light detection unit 22 further includes a preamplifier unit 27 that integrates and amplifies the photocurrent output from the light detection element 26. Thereby, a weak signal can be detected with high sensitivity to generate a detection signal, and this signal can be transmitted to the main body 10 via the cable 28. The light detection unit 22 may be a two-dimensional light sensor, or may be configured by a charge coupled device (CCD). The probe 20 is fixed to the forehead portion having no hair, for example, with an adhesive tape, a stretchable band, or the like.

  FIG. 3 is a block diagram illustrating a configuration example of the concentration measuring apparatus 1. The concentration measuring apparatus 1 shown in FIG. 3 includes a main body 10 in addition to the probe 20 described above. The main body unit 10 includes a light emitting unit 11, a sample hold circuit 12, an A / D conversion circuit 13, a CPU 14, a display unit 15, a ROM 16, a RAM 17, and a data bus 18.

The light emitting unit 11 includes a laser diode and a circuit that drives the laser diode. The light emitting unit 11 is electrically connected to the data bus 18 and receives an instruction signal for instructing driving of the laser diode from the CPU 14 also electrically connected to the data bus 18. The instruction signal includes information such as the light intensity and wavelength (for example, any one of the wavelengths λ ₁ , λ ₂ , and λ ₃ ) of the laser light output from the laser diode. The light emitting unit 11 drives the laser diode based on the instruction signal received from the CPU 14 and outputs laser light to the probe 20 via the optical fiber 24. The light emitting element of the light emitting unit 11 may not be a laser diode as long as it can sequentially output light of a plurality of wavelengths in the near infrared region. Further, as the light incident part 21, a light emitting diode such as an LED built in the probe 20 may be used.

  The sample hold circuit 12 and the A / D conversion circuit 13 receive the detection signal transmitted from the probe 20 via the cable 28, hold it, convert it into a digital signal, and output it to the CPU 14. The sample hold circuit 12 simultaneously holds (holds) the values of the N detection signals. The sample hold circuit 12 is electrically connected to the data bus 18, and receives a sample signal indicating the timing for holding the detection signal from the CPU 14 via the data bus 18. When receiving the sample signal, the sample hold circuit 12 simultaneously holds the N detection signals input from the probe 20. The sample hold circuit 12 is electrically connected to the A / D conversion circuit 13 and outputs each of the held N detection signals to the A / D conversion circuit 13.

  The A / D conversion circuit 13 is means for converting the detection signal from an analog signal to a digital signal. The A / D conversion circuit 13 sequentially converts the N detection signals received from the sample hold circuit 12 into digital signals. The A / D conversion circuit 13 is electrically connected to the data bus 18 and outputs the converted detection signal to the CPU 14 via the data bus 18.

The CPU 14 is a calculation unit in the present embodiment, and based on the detection signal received from the A / D conversion circuit 13, the temporal relative change amount (ΔO ₂ Hb) of the oxygenated hemoglobin concentration contained in the head is Necessary ones of the temporal relative change amount (ΔHHb) of the deoxygenated hemoglobin concentration and the temporal relative change amount (ΔcHb) of the total hemoglobin concentration, which is the sum of these, are calculated. Further, the CPU 14 performs a filtering process on these temporal relative change amounts (ΔO ₂ Hb, ΔHHb, ΔcHb), and removes frequency components smaller than a predetermined frequency from among the frequency components included therein, so that the sternum Extract time fluctuations due to repeated compression. After performing such processing, the CPU 14 sends the result to the display unit 15 via the data bus 18. Note that a method for calculating a temporal relative change amount (ΔO ₂ Hb, ΔHHb, ΔcHb) based on the detection signal and a filtering method will be described later. The display unit 15 is electrically connected to the data bus 18 and displays the result sent from the CPU 14 via the data bus 18.

  Next, the operation of the concentration measuring apparatus 1 will be described. In addition, the concentration measurement method according to the present embodiment will be described. FIG. 4 is a flowchart showing the concentration measurement method according to the present embodiment.

First, the light emitting unit 11 sequentially outputs laser beams with wavelengths λ _{1 to} λ ₃ based on an instruction signal from the CPU 14. These laser beams propagate through the optical fiber 24, reach the light incident position of the forehead, and enter the head from the light incident position (light incident step, S11). The laser light incident in the head is scattered in the head and propagated while being absorbed by the component to be measured, and a part of the light reaches the light detection position of the forehead. The laser light that has reached the light detection position is detected by the N light detection elements 26 (light detection step, S12). Each photodetecting element 26 generates a photocurrent according to the intensity of the detected laser beam. These photocurrents are converted into voltage signals (detection signals) by the preamplifier unit 27, and these voltage signals are sent to and held by the sample hold circuit 12 of the main body unit 10, and then digitalized by the A / D conversion circuit 13. Converted to a signal.

Here, FIG. 5A is a diagram illustrating the incident timing of the laser beams having wavelengths λ _{1 to} λ ₃ , and FIG. 5B is a diagram illustrating the output timing of the digital signal from the A / D conversion circuit 13. FIG. As shown in FIG. 5, when a laser beam having a wavelength λ ₁ is incident, N digital signals D ₁ (1) to D ₁ (N) corresponding to the N photodetectors 26 are sequentially obtained. Subsequently, when the laser beam having the wavelength λ ₂ is incident, N digital signals D ₂ (1) to D ₂ (N) corresponding to the N photodetecting elements 26 are sequentially obtained. In this manner, the A / D conversion circuit 13 outputs (5 × N) digital signals D ₁ (1) to D ₅ (N).

Subsequently, the calculation unit 14 calculates hemoglobin oxygen saturation (TOI) based on the digital signals D (1) to D (N). In addition, the calculation unit 14 uses at least one digital signal from among the digital signals D (1) to D (N) to change the oxygenated hemoglobin concentration with respect to time (ΔO ₂ Hb), deoxygenated hemoglobin. A temporal relative change amount (ΔHHb) of the concentration and a temporal relative change amount (ΔcHb) of the total hemoglobin concentration, which is the sum of these, are calculated (calculation step, step S13). Then, of the frequency components included in these relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb), frequency components smaller than the predetermined frequency are removed by filtering (calculation step, S14). These relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb) after the filter processing are displayed on the display unit 15 (step S15). In the concentration measuring apparatus 1 and the concentration measuring method in the present embodiment, steps S11 to S15 described above are repeated.

  Here, the said calculation by the calculating part 14 in calculation step S13 and S14 is demonstrated in detail.

In some light detection position, the value of the laser beam wavelength lambda ₁ to [lambda] ₃ detection signals corresponding to the respective at time _{T 0 D λ1 (T 0)} ~D λ3 (T 0), likewise the value at time _{T 1} D _{Assuming that λ1} (T ₁ ) to D _λ3 (T ₁ ), the amount of change in detected light intensity at times T _{0 to} T ₁ is expressed by the following equations (1) to (3).



However, in the equations (1) to (3), ΔOD ₁ (T ₁ ) is a temporal change amount of the detection light intensity at the wavelength λ ₁ , ΔOD ₂ (T ₁ ) is a change amount of the detection light intensity at the wavelength λ ₂ , ΔOD ₃ (T ₁ ) is a temporal change amount of the detected light intensity at the wavelength λ ₃ .

Also, if the temporal relative change amounts of the oxygenated hemoglobin and deoxygenated hemoglobin concentrations between time T ₀ and time T ₁ are ΔO ₂ Hb (T ₁ ) and ΔHHb (T ₁ ), respectively, (4).

However, in the formula (4), the coefficients a11 to a23 are constants obtained from the extinction coefficients of O ₂ Hb and HHb with respect to light of wavelengths λ ₁ , λ ₂ , and λ ₃ . Moreover, the temporal relative change amount ΔcHb (T ₁ ) of the total hemoglobin concentration in the head can be obtained by the following equation (5).

The CPU 14 performs the above calculation for one detection signal in the N light detection positions, and each temporal relative change amount (ΔO ₂ Hb,) of the oxygenated hemoglobin concentration, the deoxygenated hemoglobin concentration, and the total hemoglobin concentration. ΔHHb, ΔcHb) is calculated. Further, the CPU 14 performs, for example, any one of the following filter processes on the temporal relative change amounts (ΔO ₂ Hb, ΔHHb, ΔcHb) calculated in this way.

(1) Filter processing by digital filter Let X (n) be a data string related to temporal relative change amounts (ΔO ₂ Hb, ΔHHb, ΔcHb) obtained at a predetermined cycle. However, n is an integer. For this data string X (n), a non-cyclic linear phase digital filter is realized by multiplying each data by, for example, the following filter coefficient A (n) with n = 0 as the time center.
A (0) = 3/4
A (3) = A (−3) = − 1/6
A (6) = A (−6) = − 1/8
A (9) = A (-9) =-1/12

More specifically, the delay operator of the data string X (n) is expressed by the following equation (6). Note that f is a time frequency (unit: 1 / sec). Further, ω is an angular frequency, and ω = 2πf. T is a period in which the data string X (n) is obtained, and is set to a period of, for example, 1/20 second in order to measure a fluctuation waveform up to about 150 times per minute (2.5 Hz).

At this time, the digital filter characteristic when the above-described filter coefficient A (n) is used is described by the following equation (7).

As described above, the digital filter is represented by a product-sum operation between the data string X (n) and each corresponding coefficient. Then, when the time frequency f in the equation (7) is converted into a time frequency F (unit: 1 / min) in every minute, the following equation (8) is obtained.

FIG. 6 is a graphical representation of this R (F) and shows the filter characteristics of the digital filter. In FIG. 6, the horizontal axis represents the heart rate per minute, and the vertical axis represents the value of R (F). Further, FIG. 7 uses the digital filter shown in FIG. 6 to remove (reduce) frequency components smaller than a predetermined frequency among frequency components included in the temporal relative variation (ΔO ₂ Hb) of oxygenated hemoglobin. It is a graph showing the result of extracting the time variation due to the spontaneous heartbeat that simulates repeated chest compressions. In FIG. 7, a graph G31 shows a relative change amount (ΔO ₂ Hb) before the filter process, and a graph G32 shows a long-period component (predetermined frequency) included in the relative change amount (ΔO ₂ Hb) before the filter process. The graph G33 shows the relative change amount (ΔO ₂ Hb) after the filtering process. As shown in FIG. 7, the above-described digital filter can suitably extract a time variation due to repetition of spontaneous heartbeat or chest compression.

(2) Filter processing by smoothing calculation (least square error curve fitting) In the above-described data string X (n), n = 0 is set as the time center, and during a predetermined time before and after that (for example, 3 seconds, 5 beats) Least square error curve fitting using a high-order function (for example, a quartic function) is performed on the obtained data string X (n). Then, the constant term of the obtained higher-order function is regarded as a smooth component (frequency component smaller than a predetermined frequency) at n = 0. That is, by subtracting the smoothed frequency component from the original data X (0), the frequency component smaller than the predetermined frequency is removed from the frequency components included in the relative change amount, and the time resulting from repeated chest compressions Fluctuations can be separated and extracted.

  FIG. 8 shows that the frequency component smaller than the predetermined frequency is removed (reduced) from the frequency components included in the temporal relative change amount (ΔcHb) of the total hemoglobin by using such a filtering process, and the compression of the chest compression is repeated. It is a graph which shows the result of having extracted the time fluctuation part resulting from the spontaneous heartbeat imitating in (5). In FIG. 8, a graph G41 shows a relative change amount (ΔcHb) before the filter process, and a graph G42 shows a long-period component (a frequency component smaller than a predetermined frequency) included in the relative change amount (ΔcHb) before the filter process. The graph G43 shows the relative change amount (ΔcHb) after the filter processing, and the graph G44 shows the average amplitude for 5 seconds in the relative change amount (ΔcHb) after the filter processing. As shown in FIG. 8, it is possible to suitably extract the time variation due to the repetition of the spontaneous heartbeat and the chest compression by the above-described filtering process by the smoothing calculation.

(3) Filter processing for uniform variation maximum and minimum portions FIG. 9A and FIG. 9B are diagrams for explaining the concept of this filter processing. In this filter processing, for example, a local maximum value in the time change of the relative change amount (ΔO ₂ Hb, ΔHHb, or ΔcHb) is obtained, and the local maximum value P1 of the time change graph G51 is constant as shown in FIG. By considering it as a value, a frequency component smaller than a predetermined frequency included in the relative change amount (ΔO ₂ Hb, ΔHHb, or ΔcHb) is removed. Alternatively, for example, a minimum value in the time change of the relative change amount (ΔO ₂ Hb, ΔHHb, or ΔcHb) is obtained, and the minimum value P2 of the time change graph G51 is regarded as a constant value as shown in FIG. 9B. As a result, frequency components smaller than the predetermined frequency included in the relative change amount (ΔO ₂ Hb, ΔHHb, or ΔcHb) are removed. As described above, by bringing the maximum value P1 and / or the minimum value P2 close to a constant value, it is possible to suitably extract the time fluctuation due to repeated chest compressions.

The effects of the concentration measuring apparatus 1 and the concentration measuring method according to the present embodiment having the above configuration will be described below. In view of the above-described solution, the present inventor uses a concentration measurement device using near infrared light to calculate a relative change amount (ΔcHb, ΔO ₂ Hb) of the total hemoglobin concentration and oxygenated hemoglobin concentration of the head. Measurements were made at a much faster frequency. As a result, it was found that in the compression of the sternum, every time the sternum is periodically compressed, a constant change occurs in the total hemoglobin concentration or oxygenated hemoglobin concentration inside the head (that is, the brain). This phenomenon is considered to be caused by an increase in blood flow in the brain due to chest compression, and can be an objective material for determining whether chest compression is performed appropriately. However, the amplitude (for example, about 1 μmol) of the concentration change resulting from the compression of the chest is a long-term change that occurs in a normal activity state of a healthy person or various treatments performed on a cardiopulmonary arrest person. Compared to the amplitude (usually several μmol or more). Therefore, if a value corresponding to the total hemoglobin concentration or the oxygenated hemoglobin concentration is simply measured, it is extremely difficult to observe the fluctuation due to chest compression.

Therefore, in the concentration measurement apparatus 1 and the concentration measurement method according to the present embodiment, the temporal relative change amounts (ΔcHb, ΔO ₂ Hb, and the total hemoglobin concentration, the oxygenated hemoglobin concentration, and the deoxygenated hemoglobin concentration in the calculation step S13. The CPU 14 obtains ΔHHb) and removes frequency components smaller than a predetermined frequency from frequency components included in the relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb). Usually, the cycle of concentration change caused by chest compression (that is, a preferable compression cycle at the time of chest compression) is shorter than the cycle of main concentration change in a state where various treatments are performed on a cardiopulmonary arrest person. Therefore, by removing small frequency components (that is, long-period components) from the measured relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb) as in the concentration measuring apparatus 1 and the concentration measuring method according to the present embodiment, the sternum is removed. It is possible to suitably extract information related to density changes caused by compression. Then, based on this information, the enforcer can objectively determine whether or not chest compression is being performed appropriately. This enables the practitioner to perform or maintain more appropriate chest compressions.

  In the present embodiment, “filter processing for removing frequency components smaller than a predetermined frequency” means that the ratio of frequency components smaller than a predetermined frequency is such that the frequency components resulting from chest compressions can be sufficiently identified. This is a process for reducing the frequency, and is not limited to a process for completely removing a frequency component smaller than a predetermined frequency.

The relative variation (when the calculated frequency, 5 Hz or _{more) (ΔcHb, ΔO 2 Hb,} ΔHHb) calculating the period of 0.2 seconds or less is preferably. In general, it is said that a suitable period of chest compression is about 100 times per minute (that is, once every 0.6 seconds) or more. And if the calculation period of a relative change amount is 1/3 or less, the density | concentration change resulting from chest compression can be detected suitably.

Further, in the above-described filtering process, by removing the frequency components smaller than the predetermined frequency from the frequency components included in the relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb), the time variation due to repeated chest compressions is removed. Extract. This predetermined frequency is preferably 1.66 Hz or less. Thereby, the information regarding the density | concentration change resulting from the chest compression about 100 times or more per minute can be extracted suitably.

Here, the screen display in the display unit 15 will be described. FIG. 10A and FIG. 10B are examples of display screens in the display unit 15. In the display screen shown in FIG. 10 (a), the temporal relative change amount (ΔO ₂ Hb) of the oxygenated hemoglobin concentration after filtering and the temporal relative change amount (ΔHHb) of the deoxygenated hemoglobin concentration after filtering. ) Are displayed as individual graphs G11 and G12, respectively. In one embodiment, the horizontal axis of the graphs G11 and G12 indicates time, and the vertical axis indicates the amount of change.

In addition, the display screen shown in FIG. 10B shows a graph G21 representing the temporal relative change amount (ΔcHb) of the total hemoglobin concentration after the filter processing, and further, among the amplitudes of the graph G21, A region B22 occupied by the temporal relative change amount (ΔO ₂ Hb) of the oxygenated hemoglobin concentration and a region B23 occupied by the temporal relative change amount (ΔHHb) of the deoxygenated hemoglobin concentration are displayed in different colors. In one embodiment, the horizontal axis of the graph G21 indicates time, and the vertical axis indicates the amount of change. Thus, the area B22 and the area B23 are displayed in different colors, so that the displayed information is referred to by the chest compression practitioner, and the ratio of oxygenated hemoglobin in the blood sent to the head is visualized. Can be recognized intuitively and intuitively, and the necessity of artificial respiration can be quickly determined.

In addition, the display unit 15 displays the time variation amplitude of the total hemoglobin concentration (ΔcHb) (amplitude A1 shown in FIG. 10 (b)) and the time relative variation amount (ΔO) of the oxygenated hemoglobin concentration. time variation of the amplitude of the ₂ Hb) may display the information of the numerical values relating to the ratio (A2 / A1) and A2) as shown in (FIG. 10 (b) (first information). Alternatively, the display unit 15 displays the integrated value I1 (the sum of the areas of the regions B22 and B23 shown in FIG. 10B) of the temporal change in the total hemoglobin concentration (ΔcHb) and the oxygenated hemoglobin. Information such as a numerical value regarding the ratio (I2 / I1) to the integrated value I2 (area of the region B22 shown in FIG. 10 (b)) of the temporal change in concentration (ΔO ₂ Hb) over time Information) may be displayed. By displaying either or both of these, the person performing chest compressions can refer to the displayed information to know the ratio of oxygenated hemoglobin in the blood sent to the head. It becomes possible to judge the necessity of this. These pieces of information are calculated by the CPU 14 and sent to the display unit 15. These pieces of information may be average values for a predetermined time (for example, 5 seconds).

  Further, when the calculated ratio (A2 / A1) or ratio (I2 / I1) is smaller than a predetermined threshold value (for example, 90%), the CPU 14 gives a warning to the chest compression enforcer. Also good. As a result, it is possible to more reliably notify the practitioner of chest compression that the ratio of oxygenated hemoglobin in the blood sent to the head is reduced. As such a warning method, for example, an output of a warning sound or a warning display instruction to the display unit 15 is preferable.

In addition, the display unit 15 displays information (third information) regarding the fluctuation frequency of the temporal relative change amount (ΔcHb, ΔO ₂ Hb) of the total hemoglobin concentration and / or the oxygenated hemoglobin concentration after the filtering process is performed. May be. By this, the practitioner can be informed of the current frequency (cycle) of chest compression, and can be prompted to approach an appropriate frequency (cycle), for example, 100 times per minute. This information is calculated by the CPU 14 and sent to the display unit 15. This information may be an average value for a predetermined time (for example, 5 seconds).

  Further, the display unit 15 may display the numerical value of the amplitude (A1 shown in FIG. 10B) of the temporal change of the temporal relative change amount of the total hemoglobin concentration. Thus, the chest compression operator can refer to the displayed numerical value to know the amount of blood sent into the brain, and can suitably determine whether or not the compression strength of the sternum is sufficient. The numerical value may be an average value for a predetermined time (for example, 5 seconds). In addition, the main body 10 may output a sound (for example, a pseudo-pulse sound such as a beep) every time the numerical value of the amplitude exceeds a predetermined value. As a result, it is possible to more reliably notify the practitioner whether or not an appropriate blood volume has been sent into the brain.

The concentration measuring apparatus and the concentration measuring method according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, in the concentration measuring apparatus 1 and the concentration measuring method according to the above-described embodiment, the relative change amounts (ΔcHb, ΔO ₂ Hb, ΔHHb) of the total hemoglobin concentration, the oxygenated hemoglobin concentration, and the deoxygenated hemoglobin concentration are obtained. However, in the concentration measuring apparatus and the concentration measuring method according to the present invention, the chest compression is appropriately performed by obtaining at least one of the relative change amounts (ΔcHb, ΔO ₂ Hb) of the total hemoglobin concentration and the oxygenated hemoglobin concentration. Objective judgment material regarding whether or not it is being performed can be presented.

Further, the filtering process in the concentration measuring apparatus and the concentration measuring method according to the present invention is not limited to the one exemplified in the above embodiment, and a frequency component smaller than a predetermined frequency is removed from the relative change amount (ΔcHb, ΔO ₂ Hb). If it is a filter process which can do, it is used suitably in this invention.

Further, in the present invention, the degree of hemoglobin oxygen saturation obtained by near-infrared spectroscopy as well as the relative changes (ΔcHb, ΔO ₂ Hb, ΔHHb) of the total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration (TOI) may also be displayed on the display unit together with these as a graph or a numerical value. Thereby, the improvement of the cerebral oxygen state by chest compression can be confirmed, and a practitioner's motivation can be maintained. The TOI may be an average value for a predetermined time (for example, 5 seconds).

<Appendix>
An object of the present invention may be to provide a concentration measuring apparatus and a concentration measuring method capable of objectively determining whether or not chest compression is appropriately performed. In order to solve this problem, the concentration measuring device is a concentration that measures a temporal relative change amount of at least one of the total hemoglobin concentration and oxygenated hemoglobin concentration of the head, which fluctuates due to repeated chest compressions. A measurement apparatus, a light incident unit that makes measurement light incident on the head, a light detection unit that detects measurement light propagated inside the head and generates a detection signal according to the intensity of the measurement light; Filter processing for obtaining a temporal relative change amount of at least one of the total hemoglobin concentration and the oxygenated hemoglobin concentration based on the detection signal, and removing a frequency component smaller than a predetermined frequency from the frequency components included in the relative change amount It is good also as providing the calculating part which performs.

  The concentration measurement method is a concentration measurement method for measuring a temporal relative change amount of at least one of the total hemoglobin concentration and the oxygenated hemoglobin concentration of the head, which varies due to repeated chest compressions, Based on the light incident step of entering the measurement light into the head, the light detection step of detecting the measurement light propagated inside the head and generating a detection signal according to the intensity of the measurement light, and the detection signal, A calculation step of performing a filter process for obtaining a temporal relative change amount of at least one of the total hemoglobin concentration and the oxygenated hemoglobin concentration, and removing a frequency component smaller than a predetermined frequency among frequency components included in the relative change amount; It is good also as providing.

  The present inventor measured the relative change in the total hemoglobin concentration and oxygenated hemoglobin concentration in the head using a concentration measuring device using near infrared light at a frequency sufficiently faster than the heartbeat frequency. As a result, it was found that in the compression of the sternum, every time the sternum is periodically compressed, a constant change occurs in the total hemoglobin concentration or oxygenated hemoglobin concentration inside the head (that is, the brain). This phenomenon is considered to be caused by an increase in blood flow in the brain due to chest compression, and can be an objective material for determining whether chest compression is performed appropriately. However, the amplitude of the concentration change (for example, about 1 μmol) caused by such compression of the chest is a long-term change that occurs in a normal activity state of a healthy person or various treatments performed on a cardiopulmonary arrest person. It is negligible compared with the amplitude (usually several μmol or more). Therefore, if a value corresponding to the total hemoglobin concentration or the oxygenated hemoglobin concentration is simply measured, it is extremely difficult to observe the fluctuation due to chest compression.

  Therefore, in the concentration measuring apparatus and the concentration measuring method described above, the calculation unit or the calculation step obtains the temporal relative change amount of the total hemoglobin concentration and / or the oxygenated hemoglobin concentration, and the frequency component included in the relative change amount. Of these, frequency components smaller than a predetermined frequency are removed. Usually, the cycle of concentration change caused by chest compression (that is, a preferable compression cycle at the time of chest compression) is shorter than the cycle of main concentration change in a state where various treatments are performed on a cardiopulmonary arrest person. Therefore, as in the above-described concentration measuring apparatus and concentration measuring method, information on the concentration change caused by chest compression is preferably extracted by removing a small frequency component (that is, a long period component) from the measured relative change amount. can do. Then, based on this information, the enforcer can objectively determine whether or not chest compression is being performed appropriately. This enables the practitioner to perform or maintain more appropriate chest compressions. In the concentration measuring apparatus and the concentration measuring method described above, “filter processing for removing frequency components smaller than a predetermined frequency” means that the frequency component due to chest compression is sufficiently identified as the ratio of frequency components smaller than the predetermined frequency. This is a process of reducing the frequency until it appears as much as possible, and is not limited to a process that completely removes a frequency component smaller than a predetermined frequency.

  Further, the concentration measuring apparatus and the concentration measuring method may be characterized in that a calculation period of the relative change amount is 0.2 seconds or less. In general, it is said that a suitable period of chest compression is about 100 times per minute (that is, once every 0.6 seconds) or more. And if the calculation period of a relative change amount is 1/3 or less, the density | concentration change resulting from chest compression can be detected. That is, when the calculation period of the relative change amount is 0.2 seconds or less, it is possible to suitably detect a change in density caused by chest compression.

  The concentration measuring apparatus and the concentration measuring method may be characterized in that the predetermined frequency is 1.66 Hz or less. Thereby, the information regarding the density | concentration change resulting from chest compression can be extracted suitably.

  The concentration measuring apparatus further includes a display unit that displays a calculation result of the calculation unit, and the calculation unit displays a temporal relative change amount of the total hemoglobin concentration and a temporal relative change amount of the oxygenated hemoglobin concentration. The ratio (A1) of the temporal change of the temporal relative change amount of the total hemoglobin concentration and the amplitude (A2) of the temporal change of the temporal relative change amount of the oxygenated hemoglobin concentration (A2) The first information regarding A2 / A1) may be obtained, and the display unit may display the first information. Similarly, the concentration measurement method obtains a temporal relative change in total hemoglobin concentration and a temporal relative change in oxygenated hemoglobin concentration in a calculation step, and calculates the temporal change in total hemoglobin concentration after filtering. First information relating to a ratio (A2 / A1) of the amplitude (A1) of the temporal change of the relative change amount and the amplitude (A2) of the temporal change of the oxygenated hemoglobin concentration is obtained, One information may be displayed. By referring to the displayed first information, the practitioner can refer to the ratio of oxygenated hemoglobin in the blood sent into the brain, and can appropriately determine the necessity of artificial respiration. It becomes.

  Further, the concentration measuring apparatus may be characterized in that, when the ratio (A2 / A1) is smaller than a predetermined threshold, the calculation unit performs at least one of an output of a warning sound and a warning display instruction to the display unit. . Similarly, the concentration measurement method may be characterized in that, in the calculation step, when the ratio (A2 / A1) is smaller than a predetermined threshold value, at least one of warning sound output and warning display is performed. By these, the practitioner can be more surely notified that the ratio of oxygenated hemoglobin in the blood sent into the brain is reduced.

  The concentration measuring device further includes a display unit that displays a calculation result of the calculation unit, and the calculation unit displays a temporal relative change amount of the total hemoglobin concentration and a temporal relative change amount of the oxygenated hemoglobin concentration. The obtained integrated value (I1) of the temporal change in the relative change in the total hemoglobin concentration and the integrated change in the temporal change in the temporal change in the oxygenated hemoglobin concentration (I2). At least one may be obtained, and the display unit may display at least one of the integral value (I1) and the integral value (I2). Similarly, the concentration measurement method obtains a temporal relative change in total hemoglobin concentration and a temporal relative change in oxygenated hemoglobin concentration in a calculation step, and calculates the temporal change in total hemoglobin concentration after filtering. At least one of the integral value (I1) of the relative change in time and the integral value (I2) in the temporal change of the oxygenated hemoglobin concentration is obtained, and the integral value (I1) and the integral value are obtained. At least one of (I2) may be displayed. By these, the enforcer can refer to the displayed value to determine whether or not the compression strength of the sternum is appropriate.

  Further, in the concentration measuring apparatus, after the calculation unit obtains both the integral value (I1) and the integral value (I2), the concentration measurement apparatus is configured to obtain a second value regarding the ratio (I2 / I1) between the integral value (I1) and the integral value (I2). The second information may be further obtained, and the display unit may further display the second information. Similarly, the concentration measurement method relates to the ratio (I2 / I1) between the integral value (I1) and the integral value (I2) after obtaining both the integral value (I1) and the integral value (I2) in the calculation step. The second information may be further obtained, and the second information may be further displayed. By referring to the displayed second information, the practitioner can refer to the ratio of oxygenated hemoglobin in the blood sent into the brain, and can appropriately determine the necessity of artificial respiration. It becomes.

  The concentration measuring apparatus may be characterized in that, when the ratio (I2 / I1) is smaller than a predetermined threshold, the calculation unit performs at least one of outputting a warning sound and a warning display instruction to the display unit. . Similarly, the concentration measurement method may be characterized in that, in the calculation step, when the ratio (I2 / I1) is smaller than a predetermined threshold value, at least one of warning sound output and warning display is performed. By these, the practitioner can be more surely notified that the ratio of oxygenated hemoglobin in the blood sent into the brain is reduced.

  The concentration measuring apparatus further includes a display unit that displays a calculation result by the calculation unit, and the calculation unit obtains the amplitude (A1) of the temporal change in the temporal relative change amount of the total hemoglobin concentration after the filter processing, The display unit may display a numerical value of the amplitude (A1). Similarly, the concentration measurement method is characterized in that, in the calculation step, the amplitude (A1) of the temporal change of the temporal relative change amount of the total hemoglobin concentration after the filter processing is obtained and the numerical value of the amplitude (A1) is displayed. Also good. By referring to the displayed numerical values, the practitioner can refer to the amount of blood sent into the brain, and it is possible to appropriately determine whether the compression strength of the sternum is sufficient.

  Further, the concentration measuring device may be characterized in that the calculation unit outputs a sound each time the numerical value of the amplitude (A1) becomes a predetermined value or more. Similarly, the concentration measuring method may be characterized in that in the calculation step, a sound is output every time the value of the amplitude (A1) becomes a predetermined value or more. By these, the practitioner can be more surely notified that the amount of blood sent into the brain is insufficient.

  The concentration measuring apparatus further includes a display unit that displays a calculation result of the calculation unit, and the calculation unit displays a temporal relative change amount of the total hemoglobin concentration and a temporal relative change amount of the oxygenated hemoglobin concentration. The display unit obtains a graph showing the temporal relative change in the oxygenated hemoglobin concentration after filtering and the temporal relative change in the deoxygenated hemoglobin concentration included in the total hemoglobin concentration. This may be a feature. Similarly, the concentration measurement method obtains the temporal relative change in total hemoglobin concentration and the temporal relative change in oxygenated hemoglobin concentration in the calculation step, and the time of oxygenated hemoglobin concentration after filtering. The relative relative change amount and the temporal relative change amount of the deoxygenated hemoglobin concentration included in the total hemoglobin concentration may be color-coded and displayed in a graph. By referring to the displayed information, the operator can visually and intuitively recognize the ratio of oxygenated hemoglobin in the blood that is sent into the brain, and can quickly determine the necessity of artificial respiration. can do.

  In addition, the concentration measuring apparatus further includes a display unit that displays a calculation result by the calculation unit, the calculation unit calculates third information related to a fluctuation frequency of the relative change amount after the filter processing, and the display unit includes a third unit. This information may be displayed. Similarly, the concentration measurement method may be characterized in that, in the calculation step, the third information related to the fluctuation frequency of the relative change amount after the filter processing is calculated and the third information is displayed. By these, it is possible to inform the practitioner of the current frequency (cycle) of chest compression and to urge the operator to approach the appropriate frequency (cycle).

  Further, the concentration measuring apparatus may be characterized in that the calculation unit removes a frequency component smaller than a predetermined frequency among the frequency components included in the relative change amount by a digital filter. Similarly, the concentration measuring method may be characterized in that, in the calculation step, frequency components smaller than a predetermined frequency among frequency components included in the temporal relative change amount are removed by a digital filter. As a result, it is possible to suitably remove long-period components from the measured relative change amount, and to accurately extract information related to the concentration change caused by chest compression.

  Further, in the concentration measuring apparatus, the calculation unit calculates data obtained by smoothing the temporal change of the relative change amount, and subtracts the data from the relative change amount, thereby obtaining a predetermined frequency from the frequency components included in the relative change amount. A small frequency component may be removed. Similarly, the concentration measurement method calculates the data obtained by smoothing the temporal change of the temporal relative change amount in the calculation step, and subtracts the data from the temporal relative change amount to obtain the temporal relative change amount. It is good also as removing the frequency component smaller than a predetermined frequency among the frequency components contained in. As a result, it is possible to suitably remove long-period components from the measured relative change amount, and to accurately extract information related to the concentration change caused by chest compression.

  Further, in the concentration measuring apparatus, the calculation unit obtains at least one of a maximum value and a minimum value in the time change of the relative change amount, and the frequency included in the relative change amount based on at least one of the maximum value and the minimum value. A frequency component smaller than a predetermined frequency may be removed from the components. Similarly, the concentration measurement method obtains at least one of a local maximum value and a local minimum value in the temporal change in the temporal relative change amount in the calculation step, and based on at least one of the local maximum value and the local minimum value, A frequency component smaller than a predetermined frequency may be removed from frequency components included in the relative change amount. As a result, it is possible to suitably remove long-period components from the measured relative change amount, and to accurately extract information related to the concentration change caused by chest compression.

  DESCRIPTION OF SYMBOLS 1 ... Concentration measuring device, 10 ... Main-body part, 11 ... Light emission part, 12 ... Sample hold circuit, 13 ... Conversion circuit, 14 ... Operation part, 15 ... Display part, 16 ... ROM, 17 ... RAM, 18 ... Data bus, DESCRIPTION OF SYMBOLS 20 ... Probe, 21 ... Light incident part, 22 ... Light detection part, 23 ... Holder, 24 ... Optical fiber, 25 ... Prism, 26 ... Photodetection element, 27 ... Preamplifier part, 28 ... Cable, 50 ... Cardiopulmonary arrest person, 51: Head, P1: Maximum value, P2: Minimum value.

Claims (4)

A concentration measuring device that measures a temporal relative change amount of at least one of total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that fluctuates due to repeated chest compressions,
A light incident part for injecting measurement light into the head;
A light detection unit that detects the measurement light propagated inside the head and generates a detection signal corresponding to the intensity of the measurement light;
An arithmetic unit that obtains at least one temporal relative change amount of the total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that fluctuates due to repeated chest compressions based on the detection signal And
The calculation period of the relative change amount is 0.2 seconds or less,
A concentration measuring device that warns a person performing chest compressions based on the relative change amount .   The concentration measurement apparatus according to claim 1, wherein the warning is performed by outputting a warning sound or displaying a warning. A method of operating a concentration measuring apparatus that measures a temporal relative change amount of at least one of total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration, which fluctuates due to repeated chest compressions. There,
A light incident step for injecting measurement light into the head;
A light detection step of detecting the measurement light propagated inside the head and generating a detection signal according to the intensity of the measurement light;
Based on the detection signal, a temporal relative change amount of at least one of total hemoglobin concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration that fluctuates due to repeated chest compressions, A calculation step that warns a person performing chest compressions based on the relative change amount,
The operation method of the concentration measuring apparatus, wherein the calculation period of the relative change amount is 0.2 seconds or less. The operation method of the concentration measuring apparatus according to claim 3, wherein the warning is performed by outputting a warning sound or displaying a warning.