Wearable device for determining fetal physiological condition

Abstract

In an embodiment of the present disclosure, a device and method for determining a fetal heart rate and heart rate variability of a pregnant woman and a fetus are contemplated. The method includes generating a spectral transform from a waveform representing a hemodynamic parameter specific to an individual, determining a candidate residual signal contained within an area independent of an excluded area of ​​the spectral transform, identifying a candidate residual signal from the candidate residual signals, comparing the candidate residual signal with a target signal representing an oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter, and determining that the candidate residual signal is associated with the heart rate of a fetus located within the individual in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 424,290, filed November 10, 2022, entitled "Wearable Devices for Fetus Physiological Condition Determination," which is incorporated herein by reference in its entirety.

[0002] (Technical field) Embodiments of the present invention relate to devices that may be worn on an individual's wrist or placed on the chest area, as well as various methods and uses associated therewith. [Background technology]

[0003] (background) This section is intended to introduce various aspects that may be related to embodiments of the present invention, as described and / or claimed below. This discussion is believed to be helpful in providing background information to facilitate a better understanding of various aspects of embodiments of the present invention. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0004] A wide variety of devices have been developed to monitor the physiological characteristics of patients. Such devices provide patients, doctors, and other healthcare professionals with the information they need to ensure the best possible medical care for their patients. As a result, such monitoring devices are becoming an integral part of modern medicine.

[0005] One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and devices built on pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry can be used to measure various blood characteristics, such as the arterial blood oxygen saturation of hemoglobin (SPO2) and the blood pulsation rate corresponding to each of a patient's heartbeats. Indeed, the "pulse" in pulse oximetry refers to the time-varying volume of arterial blood at the measurement site during each cardiac cycle. Those skilled in the art will appreciate that pulse oximetry techniques, which may be referred to as photoplethysmography, or briefly PPG, are used to obtain the above physiological parameters.

[0006] In the field of medicine, it is also desirable to regularly monitor the health of pregnant women and the fetus they are carrying. In particular, monitoring the woman's physiological parameters and determining and / or deriving one or more physiological characteristics of the fetus based on these parameters, i.e., hemodynamic parameters, may enable the determination of any sudden changes in the woman's health and / or the fetus's condition. Several such devices are currently available, but are based on Doppler and cardiotocography ("CTG") technology. Therefore, these devices are required to be placed directly on the mother's abdomen to detect the fetal heart rate. Therefore, these devices do not allow for real-time monitoring of the mother's health and that of the fetus over an extended period of time.

[0007] The following commonly-owned patent disclosures are hereby incorporated by reference in their entireties: U.S. Pat. No. 9,314,197, entitled "Wearable pulse oximetry device," U.S. Pat. Nos. 8,868,149 and 9,149,216, each entitled "Photoplethysmography device and method," PCT Application No. PCT / IB2017 / 058022, entitled "Wrist-Sensor Pulse Oximetry Device and Method," and U.S. Patent Application Publication No. 2020 / 0015,723, entitled "Wrist-Sensor Pulse Oximetry Device And Method." [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 9,314,197 [Patent Document 2] U.S. Patent No. 8,868,149 [Patent Document 3] U.S. Patent No. 9,149,216 Summary of the Invention [Means for solving the problem]

[0009] (summary) Embodiments of the present disclosure contemplate devices and methods that address and overcome various deficiencies. In particular, devices and methods for determining the fetal heart rate and heart rate variability of a pregnant woman and that of the fetus are contemplated. The systems may include a device that utilizes photoplethysmography ("PPG") optical technology (e.g., a PPG sensor) to determine various physiological parameters of the pregnant woman and utilizes at least one of these parameters to determine physiological parameters of a fetus carried by the woman. Such a device may be positioned on the pregnant woman's wrist, although any location on the body from which a pulse can be determined is also contemplated. In embodiments, a device in the form of a chest patch may be placed on the pregnant woman's chest area and utilized to obtain one or more hemodynamic parameters specific to the woman, which in turn may be utilized to determine, for example, the heart rate of a fetus carried by the pregnant woman.

[0010] In one embodiment, a method for determining at least physiological parameters characteristic of a fetus located within an individual includes generating a spectral transform from a waveform representing a hemodynamic parameter characteristic of the individual, the spectral transform including a plurality of harmonics within a sampling period, the plurality of harmonics representing the hemodynamic parameter; determining a plurality of candidate residual signals contained within an area independent of an excluded area of ​​the spectral transform; identifying a candidate residual signal from the plurality of candidate residual signals; comparing the candidate residual signal with a target signal representative of an oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter; and determining, in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual, that the candidate residual signal is associated with a heart rate of the fetus located within the individual.

[0011] In another embodiment, a device includes a sensor, at least one light source, a processor, a network communications interface, and a memory. The processor is configured to: generate a spectral transform from a waveform representative of a hemodynamic parameter specific to the individual, the spectral transform including multiple harmonics within a sampling period, the multiple harmonics representing the hemodynamic parameter; determine a plurality of candidate residual signals contained within an area independent of an exclusion area of ​​the spectral transform; identify a candidate residual signal from the plurality of candidate residual signals; compare the candidate residual signal with a target signal representative of an oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter; and determine, in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual, that the candidate residual signal is associated with a heart rate of a fetus located within the individual. [Brief explanation of the drawings]

[0012] For a better understanding of several embodiments of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.

[0013] [Figure 1] FIG. 1 is a diagram of a pulse oximeter.

[0014] [Figure 2] FIG. 2 is a perspective view of a wrist-wearable device according to an exemplary embodiment of the present invention.

[0015] [Figure 3] FIG. 3 depicts another embodiment and perspective view of an exemplary device that may be placed on the chest of a pregnant woman.

[0016] [Figure 4] 4A and 4B depict an example implementation of an application of an example device of the present disclosure, according to one or more embodiments described and illustrated herein.

[0017] [Figure 5] FIG. 5 depicts two distinct example graphical representations containing individual-specific physiological data.

[0018] [Figure 6] FIG. 6 depicts three distinct graphical representations that are the result of one or more processing operations performed on a sampled hemodynamic waveform associated with a PPG signal, according to one or more embodiments described and illustrated herein.

[0019] [Figure 7] FIG. 7 depicts two distinct graphical representations associated with the heart rate variability of a woman (e.g., a pregnant woman) generated as a result of one or more processing operations performed on a sampled hemodynamic waveform associated with a PPG signal, according to one or more embodiments described and illustrated herein.

[0020] [Figure 8] FIG. 8 depicts a workflow illustrating an example implementation of the methods and devices of the present disclosure, according to one or more embodiments described and illustrated herein.

[0021] [Figure 9] FIG. 9 depicts a graphical representation of various harmonic components of a filtered and detrended hemodynamic signal according to one or more embodiments described and illustrated herein.

[0022] [Figure 10] FIG. 10 depicts a graphical representation of residual signal area from one or more candidate signals that may be utilized to potentially determine fetal heart rate, according to one or more embodiments described and illustrated herein.

[0023] [Figure 11]FIG. 11 depicts the presence of a residual signal that can be further analyzed to determine the fetal heart rate, according to one or more embodiments described and illustrated herein. DETAILED DESCRIPTION OF THE INVENTION

[0024] (Detailed explanation) Referring now specifically to the drawings in detail, it should be understood that the details shown are by way of example and for purposes of illustrative discussion of preferred embodiments of the invention only. The description considered in conjunction with the drawings will make apparent to those skilled in the art how several forms and embodiments of the invention may be embodied in practice.

[0025] It is also to be understood that embodiments of the invention are not limited in their application to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. Embodiments of the invention may be practiced or carried out in a variety of other ways. In addition, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0026] FIG. 1 illustrates a pulse oximeter. In particular, FIG. 1 illustrates a sensor 10 adapted to be placed on a finger 12 of a user, such as a patient. Sensor 10 includes a clip formed of two clip portions 14 and 16 adapted to clip and restrain sensor 10 to finger 12 while pulse oxygen measurements are taken. Sensors of a type similar to sensor 10 are typically coupled to a cable 18 that couples sensor 10 to a monitoring system adapted to receive and process signals from sensor 10. Thus, when used in a continuous monitoring mode, such sensors typically require the patient (or user) to be confined to an area in the immediate vicinity of the monitoring system, thereby limiting patient mobility. Additionally, the pinching pressure applied by clip portions 14 and 16 on the patient's finger 12 may, over time, cause the patient to perceive discomfort, thereby requiring the patient to remove sensor 10. As a result, such sensors are not suitable for long-term, continuous pulse oximetry.

[0027] The device illustrated in Figures 2 and 3 addresses and overcomes various deficiencies.

[0028] Turning now to the figures, FIG. 2 is a perspective view of device 200 (e.g., a wrist-wearable device) in accordance with an exemplary embodiment of the present invention. Device 200 may be a wrist-type oximeter device adapted to be worn on a user's wrist, as further shown in FIG. 2. In some embodiments, device 200 is adapted to acquire data, including, for example, pulse data, oxygen saturation (SPO2) data, and / or other data, from a user while the user wears device 200 on their wrist. Thus, a user can wear device 200 in a manner similar to that of wearing a watch, a wristband, or any clothing, jewelry, or apparel adapted to be worn on the user's wrist. In this manner, a user can wear device 200 while performing any daily and ordinary activity that the user would otherwise perform in their daily life, such as walking, running, cycling, etc. According to embodiments of the present disclosure, device 200 can be conveniently worn at any time or location by those users required or desiring to obtain pulse oximetry and pulse rate data, for example, without being attached to a sophisticated monitoring device or confined to a particular monitoring area. Thus, device 200 is a standalone, self-powered device adapted to, for example, acquire, analyze, and process various optical-electromagnetic signals from which pulse oximetry data is ultimately obtained. Device 200 may further include a wired or wireless interface, thereby enabling device 200 to communicate and / or relay data signals to external and / or remote devices. Thus, in some embodiments, device 200 can collect oximetry data and provide it to any remote user, facility such as a hospital or clinic, or anyone requesting or interested in such pulse oximetry data of the user.

[0029] 2, device 200 may include a display 202 that displays, for example, data measured by device 200. Such data may include pulse rate data (e.g., "PULSE 76") and data regarding the wearer's blood oxygen saturation of hemoglobin (e.g., "SPO 2 97%"). In some embodiments, display 202 may be, for example, an LED display, such as an organic light-emitting diode ("OLED") display, a liquid crystal display ("LCD"), or any other suitable display. In some embodiments, device 200 may include one or more physical buttons or user input interfaces (e.g., alphanumeric buttons or a user interface into which a user may type any combination of numbers and / or letters as desired or required while the device is in use). Alternatively, or in addition, in some embodiments, one or more buttons or user interface inputs may be located on any side or sides of device 200, or any other area of ​​device 200 that is accessible to a user. In some embodiments, device 200 may alternatively or additionally measure and / or display other data, including, for example, data regarding one or more vital signs, data regarding one or more blood analytes, blood pressure data (e.g., "BP 117 / 76"), and / or stroke volume (e.g., "SV 73").

[0030] FIG. 3 depicts another embodiment and perspective view of exemplary device 300 that may be placed on the chest of an individual, e.g., a pregnant woman. In an embodiment, exemplary device 300 may be a patch worn on the woman's chest area that serves to monitor various physiological parameters specific to the woman, e.g., data related to hemodynamic parameters such as heart rate, pulse rate, etc., and blood pressure may be acquired in real time. Additionally, in an embodiment, various positions of the pregnant woman during pregnancy may be monitored and determined in real time. For example, device 302 and / or device 200 may be utilized to determine posture, e.g., sitting, standing, lying down, etc. The precise position in which the woman may lie may also be determined. Data specific to these physical postures or orientations may be correlated with various hemodynamic parameters, e.g., heart rate, pulse rate, blood pressure, etc. The correlation may be utilized to generate recommendations for specific positions that are suitable for the expectant mother. In an embodiment, these recommendations may be displayed on the display of device 200. In some embodiments, these recommendations may be transmitted wirelessly by exemplary device 300 to, for example, the pregnant woman's smartphone and output on the smartphone's display. Other such examples are also contemplated. In embodiments, data specific to blood pressure, heart rate, pulse rate, etc. may also be transmitted by exemplary device 300 to the pregnant woman's smartphone. The transmitted hemodynamic data may be output on the pregnant woman's smartphone.

[0031] FIG. 4A depicts an example implementation of an application of the exemplary device 300 of the present disclosure, according to one or more embodiments described and illustrated herein. FIG. 4A illustrates a pregnant woman lying in a first position 402, which is an unfavorable position. In particular, the first position 402 is such that the pregnant woman presses her abdomen against the surface of the mattress, thereby potentially squeezing the fetus and harming its health. Accordingly, the device 200 or the exemplary device 300 may determine the orientation of the pregnant woman in real time and generate an audio and / or audio-visual alarm. In an embodiment, the audio alarm may be a beep notifying the pregnant woman that she is positioned in an unfavorable physical orientation. In an embodiment, the audio-visual alarm may be transmitted to the pregnant woman's smartphone and output on the smartphone screen. For example, the audio-visual alarm may be output by the pregnant woman's smartphone as a result of transmission from the exemplary device 300. In an embodiment, the audiovisual alarm may be, for example, a text message such as "ADJUST POSITION" combined with a beep output by the exemplary device 300. In an embodiment, the smartphone may also vibrate.

[0032] FIG. 4B depicts an example implementation of an application of the exemplary device 300 of the present disclosure, according to one or more embodiments described and illustrated herein. FIG. 4B depicts a second posture 404 or orientation that may be detected by the device 200 or the exemplary device 300. The second posture 404, as shown, may be determined to be a preferred position because the pregnant woman is likely to have a pillow between her legs and is reclining on her right side, as if the side of her stomach were placed on a mattress. Such a position would not place any pressure on the fetus. The exemplary device 300 may generate an audio alarm in the form of a sound different from the sounds described above, indicating that the pregnant woman's current orientation is safe and preferred and should therefore be maintained. Similarly, the exemplary device 300 may transmit an audiovisual recommendation, which may be output, for example, on the pregnant woman's smartphone. In an embodiment, the audio-visual recommendation may be a text message such as "MAINTAIN POSITION" or "MAINTAIN CURRENT POSITION" combined with an audio output such as a beep with a pattern or frequency that varies from the beep described above with respect to FIG. 4A.

[0033] In an embodiment, device 200 may be a wrist-wearable device, and exemplary device 300 may be a patch wearable on an individual's chest; however, other designs, shapes, dimensions, and configurations of these devices are also contemplated. Furthermore, device 200 and device 300 may each include at least one light source, at least one sensor, a processor, memory, a communications interface, and a battery. Furthermore, each device is communicatively coupled to one or more external devices, such as a server, smartphone, laptop, etc., and the processor is operable to execute software applications that enable the determination of various physiological and hemodynamic parameters utilized to determine various physiological conditions of the pregnant woman, as well as at least the fetal heart rate. In an embodiment, these devices may also each include an accelerometer, which serves to enable the determination of the individual's position, movement, or orientation.

[0034] FIG. 5 depicts two distinct example graphical representations including physiological data specific to an individual. The data may be collected using a PPG sensor-based device, e.g., device 200 and / or example device 300. In particular, the first example graphical representation 500 depicts time values ​​on an example X-axis 502 and blood pressure values ​​on an example Y-axis 504. In particular, the first example graphical representation 500 depicts a systolic blood pressure curve 506 (shown in purple) and a diastolic blood pressure curve 508 (shown in blue) over a particular time frame, e.g., a time frame ranging from 0 to 1,800 seconds. The second example graphical representation depicts time values ​​on an example X-axis 512 and a respiration rate on an example Y-axis 514. In particular, the variation in respiration rate of, for example, a pregnant woman is illustrated using a respiration curve 516 (shown in green).

[0035] 6 depicts three distinct graphical representations that are the result of one or more processing operations performed on sampled hemodynamic waveforms associated with PPG signals, according to one or more embodiments described and illustrated herein. In particular, the third exemplary graphical representation 600 depicts a heart rate curve 602 (shown in blue), an oxygen level curve 606 (shown in red), and a fetal heart rate curve 610 (shown in blue).

[0036] 7 depicts two distinct graphical representations associated with the heart rate variability of a woman (e.g., a pregnant woman) generated as a result of one or more processing operations performed on a sampled hemodynamic waveform associated with a PPG signal, according to one or more embodiments described and illustrated herein. As shown, the exemplary heart rate variability curve 712 spans the range of 200 seconds to 1,800 seconds, with a minimum value occurring at the 1,000 second time point and a maximum value occurring at the 1,800 second time point. Additionally, as shown, the general activity curve 706 spans the range of 0 seconds to 1,800 seconds and exhibits a sudden spike in activity at approximately the 700 second mark.

[0037] 8 depicts a workflow 800 illustrating an example implementation of the methods and devices of the present disclosure, according to one or more embodiments described and illustrated herein. Prior to detailing the steps included as part of workflow 800, an overview of the method steps for determining fetal physiological parameters may be beneficial.

[0038] The step of determining fetal physiological parameters may be based on processing of measured hemodynamic signals. In particular, devices 200 and 300 measure hemodynamic signals in the form of pulse waveforms, which are processed to determine blood pressure data, respiratory rate data, heart rate data, cardiac variability data, etc. These signals may be photoplethysmographic (PPG signal-based) or based on ultrasound or bioimpedance readings. As illustrated in FIGS. 6 and 7 , various physiological parameters may then be calculated from the extracted signals as part of one or more processing operations. Such physiological parameters may be calculated in the time dimension or the frequency dimension. In an embodiment, the calculation of physiological parameters from signals extracted from a pregnant woman is part of determining one or more signals representative of the fetal heart rate. It should be noted that the calculation of physiological parameters is associated with directly sampled hemodynamic waveform signals of PPG nature. The signals may also be ultrasound or electrical in nature. Furthermore, it should be noted that the signals graphically represented in FIGS. 6 and 7 are the result of processing operations performed on the sampled hemodynamic waveforms of the PPG.

[0039] During operation and implementation, signal components corresponding to the first, second, and third harmonics may be associated with physiological parameters specific to pregnant women, such as hemodynamic parameters such as heart rate and blood pressure. Additionally, specific exclusion spectral areas or forbidden zones (illustrated in FIGS. 9-11 and described in more detail below) may be identified and designated. These forbidden zones are found within the spectral areas where the signal frequency is below 1.7 Hz and above 4 Hz. Additionally, each of the first, second, and third harmonics, as well as the individual thickness ranges for each of these harmonics, are also included within the forbidden zones. In short, the forbidden zones do not correspond to or include signals (e.g., residual signals, as described below) that may be utilized to determine the precise final fetal heart rate.

[0040] In operation and during implementation, specific spectral components of a signal (e.g., a residual signal) may be identified and / or selected to determine the fetal heart rate, for example, by assessing whether the signal spectral components conform to or satisfy a particular set of numerical properties, i.e., properties associated with general physiological parameters of the fetus. Note that the signal is extracted or identified from a spectral area that is independent of the excluded area. For example, average fetal heart rate variability level, average margin of fetal heart rate amplitude change, etc. may be utilized as the numerical properties that must be satisfied to associate the signal components with the fetal physiological parameters. Note that the comparison process will be described in further detail below.

[0041] Finally, the extracted or determined signal may be validated using at least one of the physiological parameters calculated from the signal characteristic of the pregnant woman, and the validation method may involve correlating the dynamics of the fetal parameter with at least one physiological parameter of the mother.

[0042] Returning to the workflow 800 illustrated in FIG. 8 , note that a hemodynamic signal, such as a pulse waveform, may be acquired using device 200 worn on the pregnant woman's wrist or exemplary device 300 placed on the woman's chest, as illustrated in FIG. 3 . In embodiments, the acquired physiological data may be stored in the memory of device 200 and / or device 300. In embodiments, the collected data may be transmitted to one or more devices external to device 200, 300 (e.g., one or more servers). In embodiments, the hemodynamic signal acquired by device 200 or device 300 may take the form of a blood pressure wave, which is distinctive in that it is a pulsatile signal associated with one or more arteries of the heart. In embodiments, this pulsatile signal may be captured over various time periods or sampling windows, e.g., a 30-second sampling window, a 60-second sampling window, etc. (block 802).

[0043] In embodiments, following capturing hemodynamic data (e.g., represented by blood pressure waves), one or more signal processing operations may be performed on the captured hemodynamic data. In embodiments, these signal processing operations may be performed manually or automatically without user intervention. In particular, a low-pass filter may be applied to the acquired hemodynamic data represented by blood pressure waves purified from high-frequency noise (block 804). As a result, data associated with frequencies above a certain threshold are filtered out from the blood pressure waves, and only those frequencies at or below the threshold are retained. In this manner, application of the low-pass filter removes frequency values ​​corresponding to noise or interference.

[0044] In an embodiment, an additional signal processing operation, i.e., a detrending operation, may be performed on the signal (block 806). In an embodiment, the detrending operation corresponds to the application of a function that removes the "best-fit line" from the data set, in this case the detrended blood pressure waveform data represented by the aligned blood pressure waveform. In an embodiment, the use of a detrending operation or function allows for the identification of periodic patterns or other equivalent patterns within the waveform. The detrending operation also allows for the identification of sudden increases, decreases, or equivalent fluctuations present within the data set, waveform, etc.

[0045] In an embodiment, following performance of the detrending operation, a spectral transform may be generated (block 812), either manually or automatically, without user intervention. The generation of the spectral transform allows for a graphical representation of the individual harmonic components of the detrended signal. Note that graphical representations of the harmonic components of the detrended signal are illustrated in FIGS. 9-11 and described in more detail below. Additionally, note that another output from the detrending operation may be a calculation of the oxygen level present in, for example, the pregnant woman's bloodstream (block 808). Note that the oxygen level calculation may be collected (block 810) and potentially stored, for example, in memory of device 200 and / or exemplary device 300.

[0046] Following the performance of the spectral transformation, a buffering operation associated with the remaining spectrum may be performed (block 816), and the remaining spectrum may be compared to a list of criteria. As described above, the remaining spectrum may be compared to a list of criteria (e.g., average fetal heart rate variability, average margin of fetal heart rate amplitude change, etc.) (block 818). A buffer may then be constructed for the particular spectral candidate (block 820), and a weighted fetal heart rate value may be determined (block 822). Finally, a fetal-specific heart rate curve may be generated (block 824), and a correlation may be performed between the collection of oxygen level calculations associated with the pregnant woman as determined in block 810 and the heart rate curve generated in step 824. In an embodiment, if there is no anti-correlation, i.e., an inverse correlation, between the oxygen level calculations and the fetal HR curve, process flow proceeds to block 802. However, if an anti-correlation (i.e., an inverse correlation) is determined to exist such that the inverse correlation meets or exceeds a particular threshold, the heart rate curve determined in block 824 may be classified as the accurate final heart rate curve of the fetus. While the above is a summary of workflow 800, a more detailed description of at least a subset of steps 812-824 is provided below.

[0047] 9 depicts a graphical representation of various harmonic components of a filtered and detrended hemodynamic signal according to one or more embodiments described and illustrated herein. In FIG. 9, the first harmonic 902, second harmonic 904, and third harmonic 906 (above 4 Hz) of a pregnant woman's heart rate are shown. The first, second, and third harmonics 902, 904, and 906, as well as frequencies above 4 Hz and frequencies below 1.7 Hz, are identified for purposes of exclusion, which in turn allows for the identification of one or more additional candidate signals corresponding to the fetal heart rate.

[0048] 8 , frequencies corresponding to the first harmonic 902, the second harmonic 904, the third harmonic 906, and frequencies above 4 Hz are identified as an exclusion area or “forbidden zone” either manually or automatically without user intervention. In other words, the first, second, and third harmonics 902, 904, 906, and frequencies above 4 Hz, as well as frequencies below 1.7 Hz, may not be included or classified as candidate signals for fetal heart rate. Note that the size of the forbidden zone incorporates the width of each of the harmonics and is therefore slightly larger than the frequencies corresponding to the first, second, and third harmonics 902, 904, and 906.

[0049] Further, in embodiments, the prohibited zones include frequency ranges above and below a particular threshold frequency. For example, as illustrated in FIG. 10 , all frequencies below a frequency corresponding to, for example, less than 1.7 Hz and all frequencies above a frequency corresponding to, for example, 4 Hz are included as part of the prohibited zone or zones. In other words, signals within these zones may not correspond to or may not be utilized to determine the fetal heart rate. All frequencies below the first harmonic 902 are indicated using a brown rectangle (representing frequency range 908), and all frequencies above 4 Hz are indicated using a blue rectangle (representing frequency range 910). In short, the prohibited zones include the frequency range below the first harmonic 902, the frequency range above 4 Hz, the frequency range below 1.7 Hz, and frequency values ​​corresponding to the first harmonic 902, the second harmonic 904, and the third harmonic 906. Thus, any frequency that falls outside the identified prohibited zone may be classified as a candidate signal (e.g., a residual signal) that may be utilized to determine the fetal heart rate. Note that the identification of the prohibited zone as described above and illustrated in FIG. 9 corresponds to block 814 described above.

[0050] 10 depicts a graphical representation of residual signal areas 1000 and 1002 from one or more candidate signals that may be utilized to potentially determine a fetal heart rate, according to one or more embodiments described and illustrated herein. As shown, residual signal areas 1000 and 1002 are identified between the first and second harmonics 902 and 904, and between the second and third harmonics 904 and 906 (below 4 Hz).

[0051] 11 depicts the presence of residual signals that may be further analyzed to determine the fetal heart rate, according to one or more embodiments described and illustrated herein. In particular, as illustrated in FIG. 11, residual signals 1102, 1104 are illustrated as existing between the first harmonic 902 and the second harmonic 904, and residual signals 1108, 1110 are additional residual signals illustrated as existing between the second harmonic 904 and the third harmonic 906 (when their values ​​are above 1.7 Hz and below 4 Hz).

[0052] As part of identifying residual signals 1102, 1104, 1108, and 1110 that are deemed suitable residual signals, i.e., residual signals that can be utilized to determine fetal heart rate, they may be observed within a 20-second window. Such an observation process is a step of buffering the residual spectrum (block 816). At the end of the steps performed in block 816, a particular set of residual signals within the 20-second window have been identified as potentially suitable residuals for determining fetal heart rate. The steps for identifying suitable residual signals are described below.

[0053] In an embodiment, after a set of candidate residual signals within the 20-second window is identified, these candidate residual signals are correlated or tested against a list of criteria, i.e., one or more numerical properties that characterize normal or typical physiological behavior of the fetus (block 818). In an embodiment, the numerical criteria may correspond to specific numerical values ​​representing the average variability of heart rate, the average variability of heart rate amplitude, the average change in heart rate, etc. If a candidate residual signal fails to satisfy one or more of the list of numerical criteria, the candidate residual signal is filtered out. In other words, these signals are determined to be unsuitable signals from which the fetal heart rate may be determined. Conversely, one or more residual signals that satisfy the numerical criteria (e.g., associated with the average variability of heart rate, the average variability of heart rate amplitude, and the average change in heart rate) are identified as suitable residual signals from which the fetal heart rate may be determined (block 820). After determining suitable residual signals, weighting coefficients may be determined for the residual signals.

[0054] In particular, in an embodiment, weighting factors may be determined for residual signals 1102, 1104, 1106, and 1108 (block 822) such that these sets of signals may be fused to determine a single residual signal. For example, in an embodiment, weighting factors may correspond to a weighted average of residual signals 1102, 1104, 1106, and 1108, which is then applied to these signals to fuse them to generate a single signal. For example, residual signals 1102 and 1104 may be fused to generate a single signal, and residual signals 1106 and 1108 may be fused to generate another single signal.

[0055] After calculation of the weighting coefficients, the residual signal to which the weighting coefficients are applied may be determined to be the fetal heart rate curve, which may need to be verified (block 824). The results of the verification step allow for the identification of a final, or reliable, accurate, fetal heart rate curve (block 828). In an embodiment, as illustrated in FIG. 9, it may be determined automatically, without user intervention, or manually whether the SPO2 level (e.g., the oxygen level present in the pregnant woman's blood cells) as determined in block 810 is inversely correlated with the residual signal to the fetal heart rate curve, as determined in block 824. If an inverse correlation exists, it may be determined that the fetal heart rate curve determined in block 824 is the potentially final, accurate heart rate of the fetus. In an embodiment, if an inverse correlation exists, additional physiological data, i.e., hemodynamic data, may be collected, and the steps described above and illustrated in FIGS. 8-11, i.e., steps 802-824, may be repeated to identify the fetal heart rate.

[0056] Supplementary Note 1: A method for determining at least physiological parameters characteristic of a fetus located within an individual, the method comprising: generating a spectral transform from a waveform representing a hemodynamic parameter characteristic of the individual, the spectral transform including a plurality of harmonics within a sampling period, the plurality of harmonics representing the hemodynamic parameter; determining a plurality of candidate residual signals contained within an area independent of an exclusion area of ​​the spectral transform; identifying the candidate residual signals from the plurality of candidate residual signals; comparing the candidate residual signals with a target signal representative of an oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter; and determining that the candidate residual signals are associated with a heart rate of the fetus located within the individual in response to identifying an inverse correlation between the candidate residual signals and the target signal of the individual.

[0057] Appendix 2: The method of Appendix 1, further comprising obtaining hemodynamic parameters specific to the individual in which the fetus is located using sensors of a device placed on the individual.

[0058] Appendix 3: The method of Appendix 1, wherein the individual-specific hemodynamic parameter is the individual's heart rate.

[0059] Appendix 4: The method of Appendix 2, wherein the device is worn on the individual's wrist.

[0060] Appendix 5: The method of Appendix 2, wherein the device is placed on the individual's chest.

[0061] Appendix 6: The method of any of Appendixes 1-5, further comprising performing one or more signal processing operations on a waveform representing the hemodynamic parameter.

[0062] Appendix 7: The method of Appendix 6, wherein performing one or more signal processing operations includes applying a low-pass filter to a waveform representing the hemodynamic parameter and performing a detrending operation on the waveform representing the hemodynamic parameter.

[0063] Appendix 8: The method of any of Appendixes 1-7, wherein identifying a candidate remaining signal from the plurality of candidate remaining signals includes fusing, within an additional sampling period, at least two distinct candidate target remaining signals from the plurality of candidate remaining signals.

[0064] Appendix 9: The method of Appendix 8, wherein fusing at least two distinct candidate target remaining signals includes determining one or more weighting factors specific to the at least two distinct candidate target remaining signals, and applying the one or more weighting factors to the at least two distinct candidate target remaining signals to identify the candidate remaining signals.

[0065] Appendix 10: The method of Appendix 9, wherein one or more weighting factors is a weighted average.

[0066] Appendix 11: The method of any of Appendixes 1-10, further comprising determining that the candidate residual signal is independent of the fetal heart rate in response to identifying a correlation between the candidate residual signal and the target signal of the individual.

[0067] Appendix 12: The method of any of Appendixes 1-11, wherein the excluded area includes multiple harmonics that represent hemodynamic parameters of the individual.

[0068] Addendum 13: The method of any of Addendums 1-12, wherein the exclusion area includes a first set of frequencies below a threshold frequency value and a second set of frequencies above an additional threshold frequency value.

[0069] and determining, in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual, that the candidate residual signal is associated with a heart rate of a fetus located within the individual.

[0070] Appendix 15: The device of Appendix 14, wherein the processor is further configured to use the sensor to acquire hemodynamic parameters specific to the individual in which the fetus is located.

[0071] Appendix 16: The device of any of Appendixes 14 or 15, wherein the hemodynamic parameter specific to the individual is the individual's heart rate.

[0072] Appendix 17: The device of any of Appendixes 14-16, wherein the device is worn on the wrist of an individual.

[0073] Appendix 18: The device of any of Appendixes 14-17, wherein the device is placed on the chest of the individual.

[0074] Addendum 19: A device described in any of Addendums 14-18, wherein the processor is further configured to perform one or more signal processing operations on a waveform representing the hemodynamic parameter.

[0075] Addendum 20: A device described in any of Addendums 14-19, wherein the processor is configured to perform one or more signal processing operations by applying a low-pass filter to a waveform representing the hemodynamic parameter and performing a detrending operation on the waveform representing the hemodynamic parameter.

[0076] Addendum 21: The device of any of Addendums 14-20, wherein the processor is configured to identify a candidate remaining signal from a plurality of candidate remaining signals by fusing, within an additional sampling period, at least two distinct candidate target remaining signals from the plurality of candidate remaining signals.

[0077] 22. The device of claim 21, wherein the processor is configured to fuse the at least two distinct candidate target remaining signals by determining one or more weighting coefficients specific to the at least two distinct candidate target remaining signals and applying the one or more weighting coefficients to the at least two distinct candidate target remaining signals to identify the candidate remaining signals.

[0078] Addendum 23: A device described in any of Addendums 14-22, wherein one or more weighting coefficients is a weighted average.

[0079] Addendum 24: The device of any of Addendums 14-23, wherein the processor is further configured to determine that the candidate remaining signal is independent of the fetal heart rate in response to identifying a correlation between the candidate remaining signal and the target signal of the individual.

[0080] Appendix 25: A device described in any of Appendixes 14-24, wherein the exclusion area includes multiple harmonics representative of hemodynamic parameters of the individual.

[0081] Addendum 26: The device of any of Addendums 14-25, wherein the exclusion area includes a first set of frequencies below a threshold frequency value and a second set of frequencies above an additional threshold frequency value.

[0082] Addendum 27: The device of any of Addendums 14-26, wherein the hemodynamic parameter is at least one of the individual's heart rate, the individual's pulse rate, or the individual's blood pressure.

[0083] In the above description, an embodiment is an example or implementation of the present invention. Various appearances of "one embodiment," "an embodiment," or "some embodiments" do not necessarily all refer to the same embodiment.

[0084] While various features of embodiments of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although embodiments of the invention may be described herein for clarity in the context of separate embodiments, the invention may also be implemented in a single embodiment.

[0085] Embodiments of the invention may include features from different embodiments disclosed above, and embodiments may incorporate elements from other embodiments disclosed above. The disclosure of elements of some embodiments of the invention in the context of a specific embodiment should not be taken as limiting their use to only the specific embodiment.

[0086] Furthermore, it is to be understood that embodiments of the invention may be made or practiced in a variety of ways and that embodiments of the invention may be implemented in ways other than those outlined within the above description.

[0087] The present invention is not limited to the figures or corresponding descriptions contained herein. For example, in methods according to some embodiments of the present invention, flow need not move through each illustrated step or state or in the exact same order as described.

[0088] Unless otherwise defined, the meanings of technical and scientific terms used herein are those commonly understood by one of ordinary skill in the art to which this invention belongs.

[0089] While this specification refers to a limited number of embodiments, these should be construed as exemplification of some of the preferred embodiments, rather than as limitations on the scope of the invention. Other possible variations, modifications, and applications are also within the scope of the embodiments of the invention.

Claims

1. 1. A method for determining at least physiological parameters characteristic of a fetus located within an individual, comprising: generating a spectral transform from a waveform representative of the individual-specific hemodynamic parameter, the spectral transform including multiple harmonics within a sampling period; determining a plurality of candidate residual signals that fall within an area independent of the exclusion area of ​​the spectral transform; identifying a candidate residual signal from the plurality of candidate residual signals; comparing the candidate residual signal with a target signal representative of the oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter; determining, in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual, that the candidate residual signal is associated with a heart rate of the fetus located within the individual; A method comprising:

2. 10. The method of claim 1, further comprising obtaining the hemodynamic parameters specific to the individual in which the fetus is located using a sensor of a device placed on the individual.

3. The method of claim 1 or claim 2, wherein the hemodynamic parameter specific to the individual is the heart rate of the individual.

4. The method of claim 2 or claim 3, wherein the device is worn on the individual's wrist.

5. The method of claim 2 or claim 3, wherein the device is placed on the individual's chest.

6. The method of any of claims 1-5, further comprising performing one or more signal processing operations on said waveform representing said hemodynamic parameter.

7. said performing said one or more signal processing operations applying a low pass filter to the waveform representing the hemodynamic parameter; performing a detrending operation on the waveform representing the hemodynamic parameter; The method of claim 6, comprising:

8. The method of any one of claims 1 to 7, wherein the identifying the candidate remaining signal from the plurality of candidate remaining signals comprises fusing, within an additional sampling period, at least two distinct candidate target remaining signals from the plurality of candidate remaining signals.

9. The fusion of the at least two distinct candidate target residual signals comprises: determining one or more weighting factors specific to the at least two distinct candidate target residual signals; applying the one or more weighting factors to the at least two distinct candidate target residual signals to identify the candidate residual signals; and The method of claim 8, comprising:

10. The method of claim 9 , wherein the one or more weighting factors is a weighted average.

11. The method of any of claims 1-10, further comprising determining that the candidate residual signal is independent of the heart rate of the fetus in response to identifying a correlation between the candidate residual signal and the target signal of the individual.

12. The method of any of claims 1-11, wherein the exclusion area includes the plurality of harmonics representative of the hemodynamic parameter of the individual.

13. A method according to any preceding claim, wherein the exclusion area comprises a first set of frequencies below a threshold frequency value and a second set of frequencies above an additional threshold frequency value.

14. A device, A sensor, at least one light source; a processor; a network communication interface; Memory and Equipped with The processor: generating a spectral transform from a waveform representative of a hemodynamic parameter specific to the individual, the spectral transform including a plurality of harmonics within a sampling period, the plurality of harmonics representing the hemodynamic parameter; determining a plurality of candidate residual signals that fall within an area independent of the exclusion area of ​​the spectral transform; identifying a candidate residual signal from the plurality of candidate residual signals; comparing the candidate residual signal with a target signal representative of the oxygen level present in the individual's bloodstream, the target signal being derived from the hemodynamic parameter; determining, in response to identifying an inverse correlation between the candidate residual signal and the target signal of the individual, that the candidate residual signal is associated with a heart rate of a fetus located within the individual; A device configured to:

15. 15. The device of claim 14, wherein the processor is further configured to use the sensor to obtain the hemodynamic parameters specific to the individual in whom the fetus is located.

16. 16. The device of claim 14 or claim 15, wherein the hemodynamic parameter specific to the individual is the heart rate of the individual.

17. A device according to any one of claims 14 to 16, wherein the device is worn on the wrist of the individual.

18. The device of any of claims 14-17, wherein the device is placed on the chest of the individual.

19. The device of any of claims 14-18, wherein the processor is further configured to perform one or more signal processing operations on the waveform representing the hemodynamic parameter.

20. The processor: applying a low pass filter to the waveform representing the hemodynamic parameter; performing a detrending operation on the waveform representing the hemodynamic parameter; 20. The device of claim 19, configured to perform the one or more signal processing operations by:

21. The device of any of claims 14-20, wherein the processor is configured to identify the candidate remaining signal from the plurality of candidate remaining signals by fusing, within an additional sampling period, at least two distinct candidate target remaining signals from the plurality of candidate remaining signals.

22. The processor: determining one or more weighting factors specific to the at least two distinct candidate target residual signals; applying the one or more weighting factors to the at least two distinct candidate target residual signals to identify the candidate residual signals; and 22. The device of claim 21, configured to fuse the at least two distinct candidate target residual signals by:

23. A device according to any one of claims 14 to 22, wherein the one or more weighting factors are a weighted average.

24. The device of any of claims 14-23, wherein the processor is further configured to determine that the candidate remaining signal is independent of the heart rate of the fetus in response to identifying a correlation between the candidate remaining signal and the target signal of the individual.

25. A device according to any one of claims 14-24, wherein the exclusion area includes the plurality of harmonics representative of the hemodynamic parameters of the individual.

26. A device according to any one of claims 14 to 25, wherein the exclusion area comprises a first set of frequencies below a threshold frequency value and a second set of frequencies above an additional threshold frequency value.

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