Systems and methods for performing transabdominal fetal oximetry or pulse oximetry

Abstract

Systems, devices, and methods for performing transabdominal fetal oximetry and / or transabdominal fetal pulse oximetry using physiological characteristics and / or calibration factors can receive a physiological characteristic of a pregnant mammal and determine one or more potential effects of the physiological characteristic on the behavior of a light signal projected into the abdomen of the pregnant mammal. Then, in response to the effects, a calibration factor for the light signal can be determined. Then, the calibration factor can be used to calibrate fetal detection electronic signals so that levels of fetal hemoglobin oxygen saturation can be determined.

Description

[0001] Related applications

[0002] This application is incorporated herein by reference to U.S. Provisional Patent Application No. 62 / 878,243, filed July 24, 2019, entitled “SYSTEMS, DEVICES, AND METHODS FOR PERFORMING TRANS-ABDOMINAL FETAL OXIMETRY AND / OR TRANS-ABDOMINAL FETAL PULSE OXIMETRY USING PHYSIOLOGICAL CHARACTERISITICS AND / OR A CALIBRATION FACTOR”, and U.S. Provisional Patent Application No. 62 / 971,152, filed February 6, 2020, entitled “SYSTEMS, DEVICES, AND METHODS FOR PERFORMING FETAL OXIMETRY AND / OR FETAL PULSE OXIMETRY USING FETALDEPTH AND / OR A MATERNAL HEMOGLOBIN OXYGEN SATURATION LEVEL”. Technical Field

[0003] This invention relates to the field of medical devices, and more particularly to the field of transabdominal fetal blood oxygenation measurement and transabdominal fetal pulse blood oxygenation measurement. Background Technology

[0004] Oximetry is a method used to measure the oxygen saturation of hemoglobin in the blood of mammals. Typically, 90% (or higher) of adult hemoglobin is oxygen-saturated (i.e., bound to oxygen), while only 30-60% of fetal blood is oxygen-saturated. Pulse oximetry is a method that uses changes in blood volume during the heartbeat cycle to internally calibrate measurements of hemoglobin oxygen saturation in arterial blood.

[0005] Current methods for monitoring fetal health (such as monitoring fetal heart rate) are inefficient in determining the degree of fetal distress and sometimes provide false positive results that indicate fetal distress, which may lead to unnecessary cesarean sections. Summary of the Invention

[0006] This document discloses systems, apparatus, and methods for performing transabdominal fetal oxygenation and / or transabdominal fetal pulse oximetry using physiological characteristics and / or calibration factors. In some embodiments, physiological characteristics of a pregnant mammal can be received, for example, by a computer or processor. The effect of these physiological characteristics on the behavior of a light signal projected onto the abdomen of the pregnant mammal can then be measured. Example effects include absorption and scattering of the light signal. Next, in response to the measured effect of the physiological characteristics, a calibration factor for the light signal can be determined. In some embodiments, determining the calibration factor may include querying a database using the physiological characteristics to obtain a corresponding calibration factor. The measured calibration factor can then be stored in the database.

[0007] In some cases, the processor may also receive a composite detection electronic signal from a detector communicatively coupled to the processor. This composite electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein, which is detected by the detector and converted into the composite detection electronic signal. The emitted light signal may be a portion of the light projected onto the abdomen of the pregnant mammal and the fetus contained therein. A fetal signal can then be generated by separating the portion of the composite detection electronic signal corresponding to the light incident on the fetus. The separation of the fetal signal from the composite signal (maternal and fetal signals) can be achieved in various ways, including but not limited to: filtering, amplification, and / or processing using one or more input signals such as fetal heart rate, maternal heart rate, maternal pulse oxygenation, and / or maternal respiration rate to remove the portion of the composite signal contributed by the pregnant mammal and / or amplify the portion of the composite signal contributed by the fetus. Some of these techniques can also be used to remove noise (e.g., ambient light, harmonics, etc.) from the composite and / or fetal signals. Next, the calibration factor can be applied to the fetal signal to generate a calibrated fetal signal, which can then be processed to determine the fetal hemoglobin oxygen saturation level. This fetal hemoglobin oxygen saturation level can then be communicated to users, such as doctors, midwives, or nurses.

[0008] In some embodiments, the processor may receive a label indicating whether the fetal signal corresponds to pre- or post-ductal blood. Typically, this label is input by a clinician based on the location of the detector detecting the composite signal on the abdomen of the pregnant mammal, corresponding to the location on the fetus from which the composite signal was generated (e.g., head, chest, or limbs). This label, along with the fetal hemoglobin oxygen saturation level, can then be provided or displayed to a user, allowing the user to determine whether the fetal hemoglobin oxygen saturation level is dangerously low for the fetus.

[0009] In some embodiments, a maternal detection electronic signal may be received from a detector communicatively coupled to the processor. This maternal detection electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal (the light signal is not deep enough to reach the fetus), which is detected by the detector and converted into the maternal detection electronic signal. In some embodiments, the maternal detection electronic signal may be a short-interval signal passing only through maternal tissue. The emitted light signal may be a portion of the light projected by a light source onto the abdomen of the pregnant mammal. The maternal detection electronic signal can then be analyzed to determine the physiological characteristic of the pregnant mammal. The determined physiological characteristic and / or calibration factor of the pregnant mammal may be stored in a database.

[0010] The received physiological characteristics can be intrinsic or extrinsic, and can include, for example, the age of the pregnant mammal, the weight of the pregnant mammal, and the body mass index of the pregnant mammal. Sometimes, these physiological characteristics are received based on the clinician's observations, ultrasound equipment, Doppler equipment, abdominal images of the pregnant mammal, Fresnel scale readings, manual calipers, blood measuring devices, pulse oximeters, and / or scales.

[0011] In one embodiment, the received physiological characteristic is the skin color or melanin concentration of the pregnant mammal, and the determination of the effect of the physiological characteristic on the behavior of the light signal may include determining how much of the light signal is absorbed by the melanin / skin color of the pregnant mammal.

[0012] As an additional or alternative measure, the physiological characteristic of the reception may be the thickness of the muscle layer in the abdomen of the pregnant mammal. In this case, the effect of measuring this physiological characteristic on the behavior of the light signal may include measuring how much of the light signal is absorbed by the muscle layer in the abdomen of the pregnant mammal.

[0013] As an addition or alternative, the physiological characteristic of the reception is the thickness of the fat layer in the abdomen of the pregnant mammal, and wherein the effect of determining the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is scattered by the fat layer in the abdomen of the pregnant mammal.

[0014] As an addition or alternative, the physiological characteristic received may be the body mass index of the pregnant mammal, and wherein the determination of the effect of the physiological characteristic on the behavior of the light signal may include determining how much of the light signal is scattered or absorbed by the abdomen of the pregnant mammal due to the body mass index of the pregnant mammal.

[0015] As an additional or alternative, the physiological characteristic of the received signal may be the thickness of the abdomen of the pregnant mammal (also referred to herein as fetal depth). In this case, the effect of measuring this physiological characteristic on the behavior of the light signal may include measuring how much of the light signal is absorbed by the abdomen / abdominal tissue of the pregnant mammal.

[0016] As an additional or alternative, the physiological characteristic received may be the thickness of the abdomen of the pregnant mammal, and the effect of measuring the physiological characteristic on the behavior of the light signal may include measuring how much of the light signal is scattered by the abdomen of the pregnant mammal.

[0017] As an additional or alternative measure, the physiological characteristic received may include the hemoglobin concentration in the blood of the pregnant mammal. In these cases, the effect of measuring the physiological characteristic on the behavior of the light signal may include measuring how much of the light signal is absorbed by the hemoglobin of the pregnant mammal.

[0018] As an additional or alternative, the physiological characteristic received may be the hemoglobin oxygen saturation of the blood of the pregnant mammal, and the effect of measuring the physiological characteristic on the behavior of the light signal may include measuring how much of the light signal is absorbed by the oxygenated and / or deoxygenated hemoglobin of the pregnant mammal.

[0019] In another embodiment, a maternal detection electronic signal may be received from a detector communicatively coupled to a processor. This maternal detection electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal, which is detected by the detector and converted into the maternal detection electronic signal. The emitted light signal may be a portion of light projected (by a light source) onto the abdomen of the pregnant mammal. The maternal detection electronic signal can then be analyzed to determine the physiological characteristics of the pregnant mammal. Subsequently, in response to the analysis, a calibration factor for the light signal emitted from the pregnant mammal can be determined. In some embodiments, the physiological characteristics of the pregnant mammal may be associated with the calibration factor, and this association may be stored in a database.

[0020] In some cases, a composite detection electronic signal can be received from a detector communicatively coupled to the processor. This composite detection electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein, which is detected by the detector and converted into the composite detection electronic signal. The emitted light signal may be a portion of the light projected by a light source onto the abdomen of the pregnant mammal and the fetus contained therein. A fetal signal can then be generated by separating the portion of the composite detection electronic signal corresponding to the light incident on the fetus. A calibrated fetal signal can be generated by applying a calibration factor to the fetal signal. The fetal hemoglobin oxygen saturation level can then be determined using the calibrated fetal signal, and the fetal hemoglobin oxygen saturation level can be communicated to the user, for example, by displaying the fetal hemoglobin oxygen saturation on a display device.

[0021] In some embodiments, the calibration factor for measuring the optical signal in response to the influence includes querying a database to obtain a calibration factor corresponding to the physiological characteristic and receiving the queried calibration factor from the database.

[0022] In some cases, information about whether the fetal signal corresponds to pre- or post-ductal blood can be obtained from, for example, a clinician or physician, and this information can be provided to the user along with the fetal hemoglobin oxygen saturation level.

[0023] In some cases, maternal detection electronic signals can be received from a detector communicatively coupled to the processor. These maternal detection electronic signals may correspond to light signals emitted from the abdomen of the pregnant mammal, which are detected and converted into maternal detection electronic signals by the detector, without passing through or reaching the fetus. Therefore, it is a light signal that only passes through the maternal abdomen and does not penetrate sufficiently to reach the fetus. The maternal detection electronic signals can then be analyzed and / or processed, and the physiological characteristics of the pregnant mammal can be determined in response to the analysis.

[0024] In some cases, the physiological characteristic being measured is the skin color of the pregnant mammal, and the calibration factor can be correlated with how much light signal is absorbed by the skin color of the pregnant mammal. Alternatively, the physiological characteristic being measured can be the thickness of the muscle layer in the abdomen of the pregnant mammal, and the calibration factor can be correlated with how much light signal is absorbed by the muscle layer in the abdomen of the pregnant mammal.

[0025] As an alternative or supplementary measure, the physiological characteristic to be measured may be the thickness of the adipose tissue in the abdomen of the pregnant mammal, and the calibration factor may be correlated with how much of the light signal can be scattered by the adipose tissue in the abdomen of the pregnant mammal. Alternatively, the physiological characteristic to be measured may be the thickness of the abdomen of the pregnant mammal, and the calibration factor may be correlated with how much of the light signal can be absorbed by the abdomen of the pregnant mammal. Alternatively, the physiological characteristic to be measured may be the thickness of the abdomen of the pregnant mammal, and the calibration factor may be correlated with how much of the light signal can be scattered by the abdomen of the pregnant mammal. Alternatively, the physiological characteristic to be measured may be the hemoglobin concentration in the blood of the pregnant mammal, and the calibration factor may be correlated with how much of the light signal can be absorbed by the hemoglobin in the blood of the pregnant mammal. Alternatively, the physiological characteristic to be measured may be the hemoglobin oxygen saturation in the blood of the pregnant mammal, and the calibration factor may be correlated with how much of the light signal can be absorbed by the oxygenated and deoxygenated hemoglobin in the pregnant mammal. Attached Figure Description

[0026] Figure 1A This is a block diagram showing an example system consistent with some embodiments of the present invention for determining the oxygen saturation level of fetal hemoglobin and / or the presence of meconium in the amniotic fluid of pregnant mammals;

[0027] Figure 1B This is a block diagram of a processor-based example system that is consistent with some embodiments of the present invention and can store data and / or execute instructions for the process disclosed herein;

[0028] Figure 2A This is a block diagram showing an example fetal probe consistent with some embodiments of the present invention;

[0029] Figure 2B This is a block diagram showing another example of a fetal probe consistent with some embodiments of the present invention;

[0030] Figure 3A This shows example dimensions of tissue layers within the abdomens of two different mothers, each with a fetus, consistent with some embodiments of the present invention;

[0031] Figure 3B This shows example dimensions of tissue layers within the abdomens of two different mothers, each with a fetus, consistent with some embodiments of the present invention;

[0032] Figure 3C Provides a midsagittal plan view of the abdomen of a pregnant mammal (on which the fetal hemoglobin probe is located), consistent with some embodiments of the present invention;

[0033] Figure 4AAn example fetal hemoglobin probe, consistent with some embodiments of the present invention, is in contact with the abdomen of a pregnant mammal (showing different layers of maternal abdominal tissue);

[0034] Figure 4B Another example of a fetal hemoglobin probe in contact with the abdomen of a pregnant mammal, consistent with some embodiments of the present invention;

[0035] Figure 4C An example fetal probe, configured to detect two short-interval signals and one long-interval signal in contact with the abdomen of a pregnant mammal (wherein the layers of the maternal abdomen are shown as a single layer), consistent with some embodiments of the present invention, is shown.

[0036] Figure 4D An example fetal probe, configured to detect two short-interval signals and one long-interval signal in contact with the abdomen of a pregnant mammal (where some layers of the maternal abdomen are shown), is shown, consistent with some embodiments of the present invention.

[0037] Figure 5 A flowchart is provided showing a process for determining fetal hemoglobin oxygen saturation levels consistent with some embodiments of the present invention;

[0038] Figure 6 A flowchart is provided showing a process consistent with some embodiments of the present invention for determining the physiological characteristics of a pregnant mammal using received optical signals;

[0039] Figure 7A This is a flowchart illustrating an example process for determining fetal depth and / or fetal hemoglobin oxygen saturation levels according to some embodiments of the present invention;

[0040] Figure 7B Flowcharts are provided to illustrate example procedures for determining fetal depth according to some embodiments of the present invention;

[0041] Figure 7C A scatter plot is provided showing the percentage change in light transmission of the first to N fetal signals as a function of the distance between the light source and the detector, according to some embodiments of the present invention;

[0042] Figure 7D A scatter plot is provided showing the percentage change of light transmission of the first to N parent signals as a function of the distance between the light source and the detector, according to some embodiments of the present invention;

[0043] Figure 8 This is a flowchart illustrating an example process for determining fetal depth and / or fetal hemoglobin oxygen saturation levels according to some embodiments of the present invention;

[0044] Figure 9This is a flowchart illustrating an example process for determining fetal depth and / or fetal hemoglobin oxygen saturation levels according to some embodiments of the present invention;

[0045] Figure 10 A flowchart is provided showing a process according to some embodiments of the present invention for determining the level of fetal hemoglobin oxygen saturation by utilizing the physiological characteristics of a pregnant mammal determined by one or more maternal detection electronic signals.

[0046] Figure 11 A flowchart is provided showing a process 1100 for measuring the effect of physiological characteristics on the behavior of light passing through the abdomen and / or fetus of a pregnant mammal according to some embodiments of the present invention;

[0047] Figure 12 This is a flowchart illustrating an example process for determining fetal hemoglobin oxygen saturation levels using maternal hemoglobin oxygen saturation levels and / or fetal depth, according to some embodiments of the present invention.

[0048] Figure 13 A flowchart is provided showing a process consistent with some embodiments of the present invention for determining fetal hemoglobin oxygen saturation levels using calibration factors and / or physiological characteristics of pregnant mammals and / or fetuses;

[0049] Figure 14 A flowchart is provided showing a process for determining fetal hemoglobin oxygen saturation levels consistent with some embodiments of the present invention;

[0050] Figure 15A Provided is a flowchart showing a first portion of a process for determining composite fetal hemoglobin oxygen saturation levels consistent with some embodiments of the present invention; and

[0051] Figure 15B A flowchart is provided showing a second part of a process for determining the level of compound fetal hemoglobin oxygen saturation, consistent with some embodiments of the present invention. Detailed Implementation

[0052] The behavior of light incident on the abdomen of a pregnant mammal may be influenced by the abdominal tissues of that mammal (e.g., absorption and / or scattering). This can affect how much of the light incident on the maternal abdomen is incident on the fetus inside the pregnant mammal, and / or the clarity of the signal received from the maternal abdomen and / or the signal incident on the fetus. Knowing how much light incident on the fetus may be important for various reasons. For example, using oximetry calculatinos and / or the Beer-Lambert Law, the intensity of light incident on the fetus and / or the percentage of light transmitted through the abdomen of the pregnant mammal can be used to calculate fetal hemoglobin oxygen saturation. Furthermore, understanding the behavior of light incident on the abdomen of a pregnant mammal (absorption and / or scattering of light at different wavelengths, also referred to herein as the absorption coefficient or (μ)) is also important. a (λ)) and / or scattering coefficient (μ) s (λ) can be used to determine, for example, the effect of the interaction between the abdominal tissue of the pregnant mammal and light passing through its abdomen, which can lead to greater accuracy in calculating fetal hemoglobin oxygen saturation.

[0053] The amount of light reaching the fetus is often not linearly related to the amount of light projected onto the abdomen of the pregnant mammal. The geometry and / or intrinsic characteristics of each pregnant mammal / fetal combination within its respective tissue layers differ, such as hemoglobin oxygen saturation and / or blood flow through the tissues. This makes approximations of how much light reaches the fetus, or other one-size-fits-all calculations or corrections for fetal hemoglobin oxygen saturation, frequently inaccurate. Therefore, calibrating calculations using the physiological characteristics of pregnant mammals and / or pregnant mammal / fetal combinations may help to calculate fetal hemoglobin oxygen saturation more accurately.

[0054] Near-infrared (NIR) light is frequently used for transabdominal fetal oxygenation and / or fetal pulse oximetry. Near-infrared light projected onto the abdomen of a pregnant mammal can be absorbed by, for example, melanin in the mammal's skin, myoglobin (muscle) tissue, and hemoglobin in the mammal's blood; deoxygenated hemoglobin absorbs more light than oxygenated hemoglobin. Therefore, knowing the amount of melanin in the pregnant mammal's skin, the concentration of its myoglobin layer, and / or its hemoglobin oxygen saturation can help predict how much light or photons its hemoglobin may absorb. This absorption characteristic (which can be expressed mathematically as the absorption coefficient (μ)) is known. a (λ)—examples of which are provided in this paper) can make the calculation of fetal hemoglobin oxygen saturation more accurate by, for example, one or more methods disclosed in this paper.

[0055] Furthermore, the intensity of light incident on the abdomen of a pregnant mammal often decreases exponentially with distance (in this case, the distance between the mother's skin and the fetus's skin, or the depth of the fetus), according to, for example, the inverse square law, where the intensity of light incident on the fetus is proportional to the depth of the fetus.

[0056] Near-infrared light projected onto the abdomen of a pregnant mammal can be scattered by, for example, adipose tissue present in the mother's abdomen and located between the fetal hemoglobin oxygen saturation probe and the fetus.

[0057] Therefore, factors such as melanin content, hemoglobin oxygen saturation, myoglobin concentration, and / or adipose tissue thickness in pregnant mammals can affect how much light reaches the fetus. It is important to understand one or more of these physiological characteristics in pregnant mammals to determine how much light reaches the fetus, so as to ensure accurate analysis of light reflected from the fetus and subsequent calculations of fetal hemoglobin oxygen saturation.

[0058] In some cases, hemoglobin oxygen saturation calculations are performed using specific assumptions, including but not limited to: that the path lengths of light of different wavelengths passing through tissue are the same (or so close that their effect is negligible) and / or that the importance of light scattering behavior as it passes through tissue is negligible. While these assumptions may be suitable for simplified applications (e.g., measuring a user's hemoglobin oxygenation by projecting light through a finger or earlobe), they may not always apply (i.e., produce accurate results) when light is projected deep into tissue, as is the case when projecting light into the maternal abdomen to measure the hemoglobin oxygen saturation level of a fetus in a pregnant mammal, because, for example, deeper probe geometry when probing the maternal abdomen may exaggerate inconsistent wavelength path length differences. Because these assumptions may not always apply in this context, measurements or other calibration factors that take into account how layers of maternal tissue might affect the behavior of light as it passes through that tissue may improve the accuracy of measuring fetal hemoglobin oxygen saturation levels. Examples of such measurements and / or calibration factors will be discussed below.

[0059] Figure 1 provides an example system 100 for detecting and / or determining fetal hemoglobin oxygen saturation levels. Components of system 100 can be coupled together via wired and / or wireless communication links. In some cases, wireless communication between one or more components of system 100 can be achieved using a short-range wireless communication protocol designed to communicate over short distances with, for example, a computer or personal electronic device (e.g., a tablet or smartphone). Near field communication (NFC), radio frequency identification (RFID), and Wi-Fi.

[0060] System 100 includes a light source 105 and a detector 160, which may sometimes be housed in a single housing, which may be referred to as a fetal hemoglobin probe 115. The light source 105 may include one or more light sources, and the detector 160 may include one or more detectors.

[0061] Light source 105 can transmit light of one or more wavelengths (including NIR) into the abdomen of a pregnant mammal. Light source 105 can be, for example, an LED and / or a laser, an adjustable bulb and / or an adjustable LED that can be coupled to an optical fiber cable. In some cases, the light source can be one or more optical fiber cables optically coupled to a laser and arranged in an array. In some cases, light source 105 can be adjustable or user-configurable, while in others, one or more of the light sources can be configured to emit light within a predefined wavelength range. Alternatively or additionally, one or more filters (not shown) may be included. These filters / polarizers can also be adjustable or user-configurable.

[0062] Example light source 105 may have a small form factor and be highly efficient to operate, thereby saving space and / or limiting the heat emitted by light source 105, for example. In one embodiment, light source 105 is configured to emit light in the range of 770-850 nanometers. In some examples, light source 105 may be configured not to emit light that could, for example, irritate or burn the skin of a patient and / or harm the fetus. This can be achieved, for example, by configuring and / or instructing light source 105 to emit high-intensity / high-power light pulses for short periods of time. This high-intensity / high-power light pulse can be used, for example, to increase the likelihood that a detector such as detector 160, positioned far from the light source after the light is transmitted to and emitted from the abdomen of the pregnant mammal, will receive sufficient light for detection, in a manner that does not harm the pregnant mammal or its fetus. As an additional or alternative, one or more light sources 105 may be configured to emit light in a time-division multiplexed manner, so that signals received from, for example, each of a plurality of detectors (such as detector 160) can be distinguished from each other. Light emitted in a time-division multiplexed manner can be used by detectors closer to light source 105.

[0063] Detector 160 can be configured to detect light signals emitted by pregnant mammals and / or fetuses through, for example, transmission and / or backscattering. Detector 160 can convert this light signal into an electronic signal, which can be transmitted to a computer or processor and / or an on-board transceiver capable of transmitting the signal to the computer / processor. The emitted light can then be processed to determine how much light of different wavelengths passes through the fetus and / or is reflected and / or absorbed by fetal oxyhemoglobin and / or deoxyhemoglobin, thereby determining the fetal hemoglobin oxygen saturation level. This processing will be discussed in more detail below.

[0064] Example detectors include, but are not limited to, cameras, conventional photomultiplier tubes (PMTs), silicon PMTs, avalanche photodiodes, and silicon photodiodes. In some embodiments, the detector will have a low cost (e.g., $50 or less), low voltage requirements (e.g., less than 100 volts), and a non-glass (e.g., plastic) form factor. In other embodiments (e.g., non-contact pulse oximetry), a sensitive camera can be configured to receive light emitted from the abdomen of a pregnant mammal. For example, detector 160 may be a sensitive camera adapted to capture minute changes in fetal skin color caused by changes in cardiovascular pressure associated with fetal myocardial contraction. In these embodiments, detector 160 and / or fetal hemoglobin probe 115 may be in contact with or not in contact with the abdomen of the pregnant mammal, as this embodiment can be used to perform so-called non-contact pulse oximetry. In these embodiments, light source 105 can be used to provide light (e.g., in the visible spectrum, near-infrared, etc.) directed at the abdomen of the pregnant mammal, so that detector 160 can receive / detect light emitted from the abdomen of the pregnant mammal and the fetus. The emitted light captured by detector 160 can be transmitted to computer 150 for processing, thereby converting the image into a measurement of fetal hemoglobin oxygen saturation according to one or more processes described herein.

[0065] The fetal hemoglobin probe 115, light source 105, and / or detector 160 may have any suitable size, and in some cases, can be sized to fit the size of a pregnant mammal using any suitable sizing system (e.g., waist size and / or small, medium, large, etc.). Example lengths of the fetal hemoglobin probe 115 include lengths of 4 cm to 40 cm and widths of 2 cm to 10 cm. In some cases, the size and / or configuration of the fetal hemoglobin probe 115 or its components may be responsive to skin pigmentation in pregnant mammals and / or fetuses. In some cases, the fetal hemoglobin probe 115 may be applied to the skin of a pregnant mammal using tape or bands that engage with components (e.g., buckles, rings, etc.) (not shown). In some embodiments, the fetal hemoglobin probe 115 may be configured as a multi-parameter unit that can be configured to communicate bidirectionally, for example, with a computer 150 and / or processor, to integrate, share, and / or store data, for example, in different components of system 100.

[0066] System 100 includes several optional independent sensors / probes designed to monitor various aspects of maternal and / or fetal health and to be in contact with the pregnant mammal. These probes / sensors are an NIRS adult hemoglobin probe 125, an oximetry probe 130, a Doppler and / or ultrasound probe 135, and a uterine contraction measurement device 140. Not all embodiments of System 100 will include all of these components. In some embodiments, System 100 may also include an electrocardiogram (ECG) machine (not shown) for measuring the heart rate of the pregnant mammal and / or fetus, and / or an intrauterine oximetry probe (not shown) for measuring the fetal heart rate. The Doppler and / or ultrasound probe 135 may be configured to be placed on the abdomen of the pregnant mammal and may have a size and shape similar to a silver dollar coin, providing information about fetal position, orientation, and / or heart rate. The pulse oximetry probe 130 can be a conventional pulse oximetry probe, placed on the hand and / or fingers of a pregnant mammal to measure the hemoglobin oxygen saturation of the pregnant mammal. The NIRS adult hemoglobin probe 125 can be placed, for example, on the second finger of a pregnant mammal and can be configured to, for example, use near-infrared spectroscopy to calculate the ratio of oxyhemoglobin to deoxyhemoglobin in adults. The NIRS adult hemoglobin probe 125 can also be used to measure the heart rate of pregnant mammals.

[0067] Optionally, system 100 may include a uterine contraction measuring device 140 configured to measure the intensity and / or duration of uterine contractions in pregnant mammals. In some embodiments, uterine contractions are measured by the uterine contraction measuring device 140 as a function of pressure changing over time (e.g., in mmHg). In some cases, the uterine contraction measuring device 140 is and / or includes a tocotransducer, which is an instrument including a pressure-sensing area that detects changes in abdominal contour to measure uterine activity and thereby monitors the frequency and duration of contractions.

[0068] In another embodiment, the uterine contraction measuring device 140 may be configured to pass an electric current through a pregnant mammal and measure changes in electrical impedance during uterine contractions. Alternatively or additionally, uterine contractions may also be measured by near-infrared spectroscopy, for example, using light received / detected by detector 160, since uterine contractions (which are muscular contractions) are oscillations of the uterine muscles between a contracted and relaxed state. Oxygen consumption of the uterine muscles differs in these two phases, and these differences can be detected using NIRS.

[0069] Measurements and / or signals from the NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, and / or uterine contraction measurement device 140 can be transmitted to receiver 145 for transmission to computer 150 and display on display device 155, and in some cases can be considered as secondary signals. As described below, measurements provided by the NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, and uterine contraction measurement device 140 can be used in conjunction with fetal hemoglobin probe 115 to separate fetal pulse signals and / or fetal heart rates from maternal pulse signals and / or maternal heart rates. Receiver 145 can be configured to receive signals and / or data from one or more components of system 100 (including, but not limited to, fetal hemoglobin probe 115, NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, and / or uterine contraction measurement device 140). Communication between receiver 145 and other system components can be achieved using wired or wireless communication.

[0070] In some cases, one or more of the NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, and uterine contraction measurement device 140 may include a dedicated display to provide measurement results to, for example, a user or healthcare provider. It is important to note that not all of these probes are usable in every situation. For example, when a pregnant mammal uses the fetal hemoglobin probe 115 in a setting outside of a hospital or treatment facility (e.g., at home or workplace), some probes of system 100 (e.g., NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, and uterine contraction measurement device 140) may not be usable.

[0071] In some cases, receiver 145 may be configured to process or preprocess the received signal, thereby, for example, making the signal compatible with computer 150 (e.g., converting an optical signal to an electrical signal), amplifying the received signal, and / or improving the signal-to-noise ratio (SNR) by, for example, performing a Fast Fourier Transform (FFT), bandwidth narrowing, and / or phase-correlated filtering. In some cases, receiver 145 may reside within computer 150 and / or its components. In some embodiments, computer 150 may amplify or otherwise modulate the received detection signal to, for example, improve the SNR.

[0072] Receiver 145 may transmit received, preprocessed, and / or processed signals to computer 150. As described in more detail below, computer 150 may function to process the received signals and facilitate providing the results to display device 155. Example computers 150 include desktop and laptop computers, servers, tablet computers, personal electronic devices, mobile devices (e.g., smartphones), Internet of Things (IoT) devices enabling remote patient / pregnant mammal monitoring, etc. Example display devices 155 are computer monitors, tablet computers, and displays provided by one or more components of system 100. In some cases, display device 155 may reside in receiver 145 and / or computer 150. Computer 150 may be communicatively coupled to database 170, which may be configured to store information about physiological characteristics and / or combinations of physiological characteristics of pregnant mammals and / or their fetuses, the effects of physiological characteristics on photobehavior, information about calculations of hemoglobin oxygen saturation levels, calibration factors, etc. In some embodiments, database 170 may be local (e.g., coupled to computer 150) and / or remote (e.g., cloud computing database).

[0073] In some embodiments, a pregnant mammal may be electrically insulated from one or more components of system 100 by, for example, an electrical insulator 120. Example electrical insulator 120 includes a circuit breaker, a ground fault switch, and a fuse.

[0074] System 100 may also include an electrocardiogram (ECG) machine 175 and / or a ventilation / respiration signal source 180. The ECG 175 may be used to measure the heart rate of pregnant mammals and / or fetuses. In some embodiments, the ECG 175 may be a fetal ECG, which is used internally, for example, by placement in the birth canal, to measure the fetal heart rate.

[0075] In some embodiments, system 100 may include a ventilatory / respiratory signal source 180 configured to monitor the respiratory rate of a pregnant mammal and provide a respiratory signal indicating the respiratory rate of the pregnant mammal to, for example, a computer 150. Alternatively or additionally, the ventilatory / respiratory signal source 180 may be a ventilatory signal source obtained, for example, in conjunction with a ventilator. Examples of ventilatory / respiratory signal sources 180 include, but are not limited to, carbon dioxide measuring devices, stethoscopes and / or electroacoustic stethoscopes, devices for measuring chest cavity movement in pregnant mammals, and pulse oximeters. Signals from the pulse oximeter can be analyzed to determine changes in the PPG signal that may correspond to the respiration of the pregnant mammal. Alternatively or additionally, the ventilatory / respiratory signal source 180 may provide a respiratory signal corresponding to the frequency at which gases (e.g., air, anesthetics, etc.) are supplied to the pregnant mammal, for example, during surgical procedures. This respiratory signal can be used, for example, to determine the respiratory rate of the pregnant mammal.

[0076] In some embodiments, measurements provided by the NIRS adult hemoglobin probe 125, pulse oximetry probe 130, Doppler and / or ultrasound probe 135, uterine contraction measurement device 140, ECG 175, and / or ventilation / respiratory signal source 180 can be used in conjunction with the fetal probe 115 to separate the fetal pulse signal and / or fetal heart rate from the maternal pulse signal and / or maternal heart rate.

[0077] Figure 1B Embodiments of a processor-based system 151 for storing and / or executing instructions for the processes described herein are provided. The processor-based system 151 may represent, for example, a computing device 150. Note that not all of the various processor-based systems that can be used according to embodiments of the invention have all the features of system 151. For example, a particular processor-based system may not include a display, because display functionality may be provided by a client computer communicatively coupled to the processor-based system, or display functionality may be unnecessary. Such details are not important to the present invention.

[0078] System 151 includes a bus 12 or other communication mechanism for transmitting information, and a processor 14 coupled to the bus 12 to process information. System 151 also includes a main memory 16, such as random-access memory (RAM) or other dynamic storage device, coupled to the bus 12 to store information and instructions to be executed by the processor 14. The main memory 16 can also be used to store temporary variables or other intermediate information during the execution of instructions to be executed by the processor 14. System 151 also includes a read-only memory (ROM) 18 or other static storage device coupled to the bus 12 to store static information and instructions of the processor 14. A storage device 10 (which may be one or more of a hard disk, flash-based storage media, magnetic storage media, optical storage media (e.g., Blu-ray disc, digital versatile optical disc (DVD)-ROM), or any other storage media readable by the processor 14) is provided and coupled to the bus 12 to store information and instructions (e.g., operating system, application programs, etc.).

[0079] System 151 can be coupled to display 22 (e.g., a flat panel display) via bus 12 to display information to the user. Input device 24 (e.g., a keyboard including alphanumeric and other keys) can be coupled to bus 12 to transmit information and command selections to processor 14. Another user input device is cursor control device 26, such as a mouse, trackball, or arrow keys, used to transmit directional information and command selections to processor 14 and control cursor movement on display 22. Other user interface devices (e.g., microphone, speaker, etc.) are not shown in detail but may participate in the reception of user input and / or the presentation of output.

[0080] The processes described herein can be implemented by processor 14, which executes a suitable sequence of processor-readable instructions stored in main memory 16. Such instructions can be read into main memory 16 from another processor-readable medium (e.g., storage device 10), and execution of the instruction sequence contained in main memory 16 causes processor 14 to perform the relevant actions. In alternative embodiments, hardwired circuitry or firmware-controlled processing units (e.g., field-programmable gate arrays) can be used to replace or combine processor 14 and its associated computer software instructions to implement the invention. These processor-readable instructions can be expressed in any computer language.

[0081] System 151 may also include a communication interface 28 coupled to bus 12. Communication interface 28 provides a bidirectional data communication channel to a computer network, providing connectivity to the aforementioned plasma processing system. For example, communication interface 28 may be a local area network (LAN) card to provide data communication connectivity to a compatible LAN that is itself coupled to its computer system for communication. Precise details regarding such communication paths are not important to this invention. What is important is that system 151 can send and receive messages and data through communication interface 28, and in this way communicate with other controllers, etc.

[0082] Figure 2A This is a block diagram showing an example fetal probe 115A, which has a housing 111A that houses a light source 105 and a plurality of detectors 160A-160D arranged in an example array. The housing 111A can be any housing configured to house the components of the fetal probe 115A, including the light source 105, the plurality of detectors 160A-160D, an optional power supply 121 (e.g., a battery), a fetal depth probe 138, a maternal probe 133, a communication device (e.g., an antenna or transceiver) 142, a processor 151, a power port 141, and / or a communication port 131. The example fetal probe 115A includes a light source 105 substantially aligned along the Y-axis with the four detectors 160A-160D. In some embodiments, the gain or sensitivity of detectors 160A-160D may vary with their position relative to the light source 105, such that detectors positioned further away from the light source 105 (e.g., detectors 160A and 160B) have greater gain / sensitivity compared to detectors positioned closer to the light source 105 (e.g., detectors 160C and 160D).

[0083] In one example, the fetal probe 115A may include a light source 105 configured to emit light of multiple wavelengths (e.g., 735 nm, 760 nm, 810 nm, 808 nm, and / or 850 nm), and detectors 160A-160D may be configured to detect light / photons of each wavelength. An example distance between the light source 105 and detector 160A is 3 cm, between the light source 105 and detector 160B is 5 cm, between the light source 105 and detector 160C is 7 cm, and between the light source 105 and detector 160D is 10 cm.

[0084] Figure 2BThis is a block diagram showing an example fetal probe 115B, which has multiple light sources 105 and detectors 160A-160R arranged in an example array within a housing 111B. The housing 111B can be any housing configured to house the components of the fetal probe 115B, including multiple light sources 105, multiple detectors 160A-160R, an optional power supply 121 (e.g., a battery), a fetal depth probe 138, a maternal pulse oximetry probe 133, a communication device (e.g., an antenna or transceiver) 142, a processor 151, a power port 141, and / or a communication port 131.

[0085] Example fetal probe 115B includes a row of three light sources 105 generally centered along the Y-axis of housing 111B. The multiple light sources 105 may be substantially aligned with each other along the X-axis. The housing may also include nine detectors 160A-160I arranged in three rows and three columns above the light sources 105 and nine detectors 160J-160R arranged in three rows and three columns below the light sources 105. In some embodiments, the gain or sensitivity of detectors 160E-160R may vary with their position relative to the light sources 105, such that detectors positioned farther from the light sources 105 have greater gain / sensitivity, as described above with respect to fetal probe 115A.

[0086] Figure 2A and 2B The arrangement of the light sources and detectors described herein is provided as an example only and is not intended to limit the arrangement and / or number of light sources 105 and / or detectors 160 that can be used. Any arrangement thereof can be used to detect optical signals and convert them into the detection electronic signals described herein.

[0087] Figure 3A and 3B Illustrations 301 and 302 respectively provide some tissue layers present in the abdomens of two different mothers, including their respective fetuses. Information used to generate illustrations 301 and 302 can be received from, for example, ultrasound imaging devices (e.g., Doppler / ultrasound probe 135) and / or MRI images.

[0088] Figures 301 and 302 provide example dimensions of some maternal tissue layers and the fetus adjacent to the arrangement of the fetal hemoglobin probe 115, including the depth of the fetus within the abdomen of the corresponding pregnant mammal. Fetal depth can be understood as, for example, the distance between the epidermis of the pregnant mammal and the epidermis of the fetus, and / or the total width of the maternal tissue and amniotic fluid layers. Figure 301 shows the maternal abdominal tissue of a fetus at 29 weeks of gestation. The tissue layers shown in Figure 301 include the subcutaneous fat layer 305A, the abdominal muscle (skeletal muscle) layer 310A, the intraperitoneal fat layer 315A, the uterine wall (smooth muscle) layer 320A, the amniotic fluid layer 325A, and the fetus 330A. The width of each of these layers is measured at a location adjacent to (e.g., below) the fetal hemoglobin probe 115. The approximate location for the width measurement is indicated by a line connecting the top and bottom of the layer of interest. For example, in Figure 3A In the diagram, the width of the subcutaneous fat layer 305A is represented by line 1, the width of the abdominal muscle layer 310 by line 2, the width of the intra-abdominal fat layer 315A by line 3, the width of the uterine wall layer 320A by line 4, and the width of the amniotic fluid layer 325A by line 5. The approximate dimensions of these maternal tissue layers adjacent to (e.g., below) the fetal hemoglobin probe 115 are as follows:

[0089] Subcutaneous fat layer 305A: 10.2 mm (represented by line 1);

[0090] Abdominal muscle layer 310A: 7.1 mm (represented by line 2);

[0091] Intra-abdominal fat layer 315A: 2.0 mm (represented by line 3);

[0092] Uterine parietal layer 320A: 3.1 mm (represented by line 4);

[0093] Amniotic fluid layer 325A: 3.6 mm (represented by line 5); and

[0094] Fetal 330A.

[0095] In this example, the total distance from the maternal skin to the fetal skin at 330A (that is, the fetal depth) is 28 mm.

[0096] exist Figure 3B The fetus shown in Figure 302 is 35 weeks gestation. The tissue layers shown in Figure 302 include the subcutaneous fat layer 305B, the abdominal muscle (skeletal muscle) layer 310B, the intraperitoneal fat layer 315B, the uterine wall (smooth muscle) layer 320B, and the fetus 330B. The width of each of these layers is measured adjacent to (e.g., below) the fetal hemoglobin probe 115. The approximate location for the width measurement is indicated by a line connecting the top and bottom of the layer of interest. For example, in… Figure 3BIn the diagram, the width of the subcutaneous fat layer 305B is represented by line 1, the width of the abdominal muscle layer 310 by line 2, the width of the intra-abdominal fat layer 315B by line 3, and the width of the uterine wall layer 320B by line 4. The approximate dimensions of these maternal tissue layers adjacent to (e.g., below) the fetal hemoglobin probe 115 are as follows:

[0097] Subcutaneous fat layer 305B: 11.3 mm (represented by line 1);

[0098] Abdominal muscle layer 310B: 3.1 mm (represented by line 2);

[0099] Intra-abdominal fat layer 315B: 3.1 mm (represented by line 3);

[0100] Uterine parietal layer 320B: 2.3 mm (indicated by line 4); and

[0101] Fetal 330B.

[0102] In this example, the total distance from the mother's skin to the fetus (i.e., the fetal depth) is 19.8 mm. Since the fetus develops further and becomes larger at 35 weeks of gestation, the width of the amniotic fluid is negligible and not included in this example. Furthermore, for Figures 301 and 302, the width of the skin of pregnant mammals is approximately 1-1.5 mm and can also be ignored.

[0103] In some embodiments, fetus 330A and / or fetal layer 330B may be divided into one or more additional layers (not shown). These layers may be associated with one or more of, for example, fetal sebum, hair, skin, bones, etc. In some embodiments, information about one or more of these layers (e.g., the melanin content of fetal skin and / or hair color) may be inferred from, for example, the fetus's birth, fetal genetic testing, and / or direct observation of the fetus by, for example, optical microscopy and / or transvaginal examination.

[0104] Figure 3C A midsagittal plan view of the abdomen 305 of a pregnant mammal (on which the fetal hemoglobin probe 115 is disposed) is provided. As shown in Figure 3, the abdomen 305 of the pregnant mammal includes the fetus 310, the uterus 340, and approximate maternal tissues (e.g., skin, muscles, etc.) 330. The fetal hemoglobin probe 115 can be disposed at any location on the abdomen of the pregnant mammal, and in some cases, more than one fetal hemoglobin probe 115 may be disposed on the abdomen of the pregnant mammal. Figure 3C It also shows a first light signal 420A projected into the abdomen of a pregnant mammal, wherein the first light signal 420A penetrates only to the edge of the uterine wall 340, and is then backscattered or transmitted to the detector such as detector 160 of the fetal hemoglobin probe 115. Figure 3C The image also displays a second light signal 420B projected onto the abdomen of a pregnant mammal and passing through the fetus 310 before being detected by detector 160. The first light signal 420A may include light having a single wavelength or multiple wavelengths, which may be, for example, red or NIR. In some embodiments, the first light signal 420A may include light having two different wavelengths or wavelength ranges, one red and one NIR. The second light signal 420B may include light having a single wavelength or multiple wavelengths, which may be, for example, red or NIR. The wavelength of the second light signal 420B may be different from the wavelength of the first light signal 420A and / or projected onto the abdomen of the pregnant mammal at different times, so that the second light signal 420B can be distinguished from the first light signal 420A during the detection portions of the first and second light signals 420A and 420B, respectively. In some embodiments, the first and second light signals 420A and 420B may include light having two different wavelengths or wavelength ranges, one red and one NIR, which are slightly different from each other. For example, the first optical signal 420A can be red and the second optical signal 420B can be NIR; both the first and second optical signals 420A and 420B can be red or NIR. In these examples, the wavelengths of the first and second optical signals 420A and 420B can be selected such that any difference in their respective path lengths is negligible. These two wavelengths can be calculated using, for example, the Lambert-Beer or modified Lambert-Beer method described herein, utilizing, for example, the absorption of the optical signal or (μ) a (λ)) and / or scattering (μ) s The difference in (λ) is used to calculate pulse oximetry.

[0105] Figure 4A An example fetal hemoglobin probe 115C is shown in contact with the abdomen of a pregnant mammal in a manner similar to that shown in Figure 3. Figure 4A It also displays multiple organizational layers. More specifically, Figure 4A The diagram shows the first layer representing the maternal skin layer 415, the second layer representing the maternal subcutaneous fat layer 421, the third layer representing the maternal abdominal muscle (skeletal muscle) layer 425, the fourth layer representing the maternal intra-abdominal fat layer 430, the fifth layer representing the uterine wall (smooth muscle) layer 435, the sixth layer representing the amniotic fluid layer 440, and the seventh layer representing the fetus 310.

[0106] The fetal hemoglobin probe 115C includes a first light source 105A emitting a first beam 420A1, a second light source 105B emitting a second beam 420B1, and a detector 160. The first and / or second beams 420A1 and / or 420B1 may comprise light having one or more wavelengths and may be within, for example, the red, NIR, or infrared spectrum. In some cases, the characteristics of beam 420A1 may differ from the wavelength of beam 420B1 and / or may be projected onto the abdomen of a pregnant mammal at different times to distinguish the light projected from the two light sources when received by detector 160 and processed according to one or more processes described herein. In some embodiments, the fetal hemoglobin probe 115C may include a filter (not shown) for detector 160, which may be attenuated to allow detector 160 to detect equal amounts of light from the first and second light sources 105A and 105B.

[0107] In many cases, the depth of light propagation through the abdomen of a pregnant mammal depends on the distance between the light source and the detector. In some embodiments, the position of the first light source 105A and / or the second light source 105B (e.g., closer to or further away from the detector 160) can be adjusted to, for example, adjust the penetration depth of the light emitted therefrom. This adjustment can be facilitated by, for example, a track or other positioning device included in the fetal hemoglobin probe 115C (not shown). In some cases, the positioning of the first light source 105A and / or the second light source 105B can be adjusted in response to the depth of the fetus 310 within the abdomen of the pregnant mammal (i.e., a measurement of the width of the maternal tissue 405 located between the fetal hemoglobin probe 115C and the fetus 310). Measurements of the depth of the fetus 310 within the abdomen of the pregnant mammal can be provided by, for example, ultrasound or Doppler probes such as Doppler / ultrasound probe 135 and / or MRI images, some examples of which are shown in Figures 301 and 302.

[0108] In some embodiments, the first light source 105A may be positioned relative to the detector 160 such that light emitted from the first light source (i.e., beam 420A1) propagates only through the maternal tissue 405 and does not reach the fetus 310. The second light source 105B may be positioned away from the detector 160 (relative to the first light source 105A) such that light projected by the second light source 105B (i.e., beam 420B1) penetrates deeper into the abdomen of the pregnant mammal than beam 420A1, and is detected by the detector 160 for backscattering from the abdomen and / or transmission through the abdomen. In other words, light source 105A can be configured such that beam 420A1 is projected only into maternal tissue 405, so that portion of beam 420A1 detected by detector 160 can be backscattered and / or transmitted through maternal tissue 405, but not through fetus 310. Light source 105B can be configured such that beam 420B1 is projected into both maternal tissue 405 and fetus 310, so that portion of beam 420B1 detected by detector 160 can be backscattered and / or transmitted through both maternal tissue 405 and fetus 310. This positioning of the first light source 105A facilitates short separation (SS) measurements, and the path of the first beam 420A1 and / or the amount of the first beam 420A1 detected by detector 160 may be referred to herein as the SS channel. This positioning of the second light source 105B facilitates long separation (LS) measurements, and the path of the second beam 420B1 and / or the amount of the second beam 420B1 detected by the detector 160 may be referred to herein as the LS channel.

[0109] Figure 4B An example fetal probe 115D is shown, positioned on the abdomen of a pregnant mammal. Maternal tissue in the abdomen of the pregnant mammal is designated as maternal tissue 450, and the fetus within the abdomen of the pregnant mammal is designated as fetus 310.

[0110] The fetal probe 115D has a light source 105 and six detectors 160A, 160B, 160C, 160D, 160E, and 160F. Each detector has a different position relative to the light source 105, with the first detector 160A being closest to the light source 105 and the sixth detector 160F being furthest from the light source 105. The positions of detectors 160A-160F relative to the light source 105 are referred to herein as the light source / detector distance. In some examples, detectors 160A-160F can be arranged linearly and spaced 1 cm apart from each other, such that the first detector 160A is 1 cm away from the light source 105, the second detector 160B is 1 cm away from the first detector 160A, the third detector 160C is 1 cm away from the second detector 160B, the fourth detector 160D is 1 cm away from the third detector 160C, the fifth detector 160E is 1 cm away from the fourth detector 160D, and the sixth detector 160F is 1 cm away from the fifth detector 160E.

[0111] Light source 105 can project light signal 420 onto the abdomen 405 of a pregnant mammal, and the resulting light signal can be detected by one or more detectors 160A-160F. It is anticipated that the detector closer to light source 105 will detect a portion of the light signal that has been incident on the abdomen 405 of the pregnant mammal but not on the fetus 310. In some embodiments, the first detector 160A and / or the second detector 160B can be positioned, for example, by setting a light source / detector distance, so that most (if not all) of the light signals 420A2 and 420B2 detected by the first and second detectors 160A and 160B, respectively, is incident only on the abdomen 405 of the pregnant mammal (i.e., not on the fetus). As shown in FIG4, the third to sixth detectors 160C-160F can detect portions of the light signals 420C, 420D, 420E, and 420F incident on the pregnant mammal 405 and the fetus 310. In some cases, the third detector 160C can be positioned 3-5 cm away from the light source, and the sixth detector 160F can be positioned 6-10 cm away from the light source. As an additional or alternative measure, the third to sixth detectors 160C-160F can be positioned within 4-10 cm of the light source.

[0112] As the distance to the light source / detector increases, the proportion of the light signal corresponding to the light incident on the fetus 310 increases. Therefore, light signal 420F may include a higher proportion of light incident on the fetus compared to, for example, light signal 420E or 420D.

[0113] Figure 4C and 4D Show with Figure 4A and 4BThe example fetal probe 115E, shown in a manner similar to that of a pregnant mammal's abdomen, contacts the maternal tissue layer. Figure 4A The parent tissue layer shown. Figure 4C The illustrated embodiment uses a simplified maternal tissue layer 450, and Figure 4D The embodiments shown depict numerous maternal tissue layers, which are similar to... Figure 4A The maternal tissue layer shown is illustrated, and the fetal probe 115E is configured to perform dual short-interval (SS) analysis of backscattered light and / or transmitted light through the abdomen of a pregnant mammal and the fetus contained therein.

[0114] The fetal probe 115E includes a first light source 105A emitting a first optical signal 420C, a small detector 455, a second light source 105B emitting a second optical signal 420, and a detector 160. A first portion 420A of the second optical signal can be detected by the small detector 455, and a second portion 420B of the second optical signal can be detected by the detector 160. The first and / or second optical signals 420C and / or 420 may include light having one or more wavelengths, and may be in, for example, red, near-infrared, and / or broadband spectra. In some cases, the wavelength of the optical signal 420C may be different from the wavelength of the optical signal 420 and / or may be projected at different times to distinguish the light projected from the two light sources when received by the detector 160 and processed according to one or more processes described herein. The small detector 455 may be similar to the detector 160, but may have a smaller size and / or reduced sensitivity. In some cases, the small detector 455 may be a small fiber optic detector. In some embodiments, the fetal probe 115E may include a filter (not shown) for the detector 160, which may be attenuated to enable the detector 160 to detect equal amounts of light from the first and second light sources 105A and 105B.

[0115] In some embodiments, the position of the first light source 105A and / or the second light source 105B can be adjusted (e.g., closer to or further away from the detector 160) to, for example, adjust the penetration depth of the light emitted from the light source as detected by the detector 160. This adjustment can be facilitated by, for example, manual operation and / or positioning of the detector and / or movement of the detector along a track or other positioning device included in and / or associated with the fetal probe 115E (not shown). In some cases, the positioning of the first light source 105A and / or the second light source 105B can be adjusted in response to the depth of the fetus 310 within the abdomen of a pregnant mammal (i.e., a measurement of the width of the maternal tissue 450 located between the fetal probe 115E and the fetus 310). Measurements of the depth of the fetus 310 within the abdomen of a pregnant mammal can be provided, for example, by an ultrasound or Doppler probe such as Doppler / ultrasound probe 135 and / or an image of the abdomen of a pregnant mammal, examples of which are shown in Figures 301 and 302.

[0116] In some embodiments, the first light source 105A may be positioned relative to the detector 160 such that light emitted from the first light source (i.e., light signal 420C) propagates only through the maternal tissue 305 and does not reach the fetus 310. The second light source 105B may be positioned away from the detector 160 (relative to the first light source 105A) such that light projected by the second light source 105B (i.e., light signal 420) penetrates deeper into the abdomen of the pregnant mammal than light signal 420C, reaching the fetus 310, whereby the backscattered light and / or transmitted through the fetus can be detected by the detector 160. A small detector 455 may be positioned between the first and second light sources 105A and 105B such that light (i.e., light signal 420) propagates only through the maternal tissue 450 and does not reach the fetus 310 before being detected by the small detector 455. The positioning of the first light source 105A facilitates the collection of a first set of short-interval (SS) measurements, and the path of the first optical signal 420C and / or the amount of the first optical signal 420C detected by the detector 160 may be referred to herein as the first SS channel. The positioning of the second light source 105B facilitates long-interval (LS) measurements, and the path of the second optical signal 420 and / or the amount of the second optical signal 420 detected by the detector 160 may be referred to herein as the LS channel. The positioning of the small detector 455 facilitates a second set of short-interval (SS) measurements, and the path of the first optical signal 420C and / or the amount of the first optical signal 420C detected by the detector 160 may be referred to herein as the second SS channel. Therefore, the fetal probe 115E provides SS measurements from the first and second light sources 105A and 105B.

[0117] Figure 5 A flowchart is provided showing a process 500 for determining fetal hemoglobin oxygen saturation levels. Process 500 can be performed by any system or system component described herein, for example.

[0118] First, the detected composite electronic signal can be received from a photodetector (e.g., detector 160) via a processor and / or a computer (e.g., computer 150) (step 505). The detected composite electronic signal can be received from, for example, a photodetector, a transceiver coupled to the photodetector, and / or a fetal hemoglobin probe, such as fetal hemoglobin probe 115.

[0119] The detected composite electronic signal may correspond to a light signal with multiple wavelengths emitted from the abdomen of a pregnant mammal and / or its fetus (through, for example, transmission, backscattering, and / or reflection). The light incident on and exiting the abdomen of the pregnant mammal may be generated by one or more light sources (such as light source 105) and may have any acceptable frequency or wavelength (e.g., near-infrared (NIR)) and / or combination of frequency and / or wavelength. In some embodiments (e.g., when multiple detectors are used), the received detected composite electronic signal may include and / or be associated with a detector identifier (e.g., a code) to indicate the location of a specific detected composite electronic signal. This location can then be used to analyze the received detected composite electronic signal to determine various factors of the detected light and / or the imaged tissue.

[0120] In step 510, the path length and / or degree of scattering and / or absorption of light emitted from the abdomen of the pregnant mammal for each wavelength can be measured and / or determined, for example, by analyzing the detected first light signal. In some embodiments, the execution of step 510 may include using a modified Beer-Lambert law, as shown in Equation 1 below. Equation 1 can be used, for example, to determine the absorption coefficient (μ) at a specific wavelength. a (λ)), the variation of the absorption coefficient, and / or the effective average path length factor (DPF) for a specific wavelength (λ).

[0121]

[0122] in:

[0123] Δμ a (λ) = the change in the absorption coefficient at a given wavelength λ;

[0124] r = distance between the light source and the detector;

[0125] DPF = Differential path length factor for a given wavelength λ;

[0126] ΔI = the actual intensity of light with a given wavelength λ as it changes during each heartbeat; and

[0127] I o = The incident intensity of light with a given wavelength λ.

[0128] Sometimes, I o It can be the average intensity measured during the tracking time (i.e., the time for measuring and / or detecting the composite electronic signal). In some cases, Δμ aThe values ​​of (λ) and / or DPF may be calibration factors used in other calculations described herein (e.g., Equations 5, 6, 7a, and / or 7b) (step 515). Sometimes, the DPF is estimated based on, for example, the characteristics of light at wavelength λ. As an addition or alternative, it may be derived from... The DPF is derived by spectral fitting of experimentally determined values. Alternatively, the DPF can be determined by measuring and / or calculating the amount of light scattered at a given wavelength. In some cases, when light is introduced, for example, into a part of the body with a non-uniform geometry (e.g., the abdomen of a pregnant mammal), the DPF may depend on, for example, the physical characteristics and / or intrinsic properties of the pregnant mammal and / or its fetus, including but not limited to fetal depth, lipid concentration in the tissue, width of the tissue layer, location of the fetus exposed to light, and melanin content of the pregnant mammal and / or fetus. Alternatively, the DPF may depend on the properties of the detector, such as the color of the detector's sensor surface and / or the detector's sensitivity.

[0129] In some embodiments, Equation 1 can be used to determine the absorption coefficients (also referred to herein as individual absorption coefficients) of different maternal tissue layers using optical properties such as tissue type and / or maternal geometry (e.g., width of tissue layer) and / or tissue density. For example, a series of absorption coefficients for different types and / or characteristics of maternal tissue can be experimentally determined and / or modeled based on the characteristics of the maternal tissue layer. Example features include, but are not limited to, tissue type, tissue density, tissue layer thickness, location of the tissue layer (e.g., DFP and / or distance between the light source and the detector (represented as r in Equation 1)), and / or optical properties (e.g., scattering and / or absorption coefficients of tissue of known width that can be modified or otherwise adjusted based on, for example, the geometry of a particular pregnant mammal and / or fetus). In some embodiments, these individual absorption coefficients can then be aggregated to generate a total absorption coefficient that more closely approximates the light absorption for a specific situation (e.g., a particular pregnant mammal, a specific location on the abdomen of a pregnant mammal, etc.).

[0130] In some embodiments, steps 505-515 may be performed on a per-pregnant-mammal basis to, for example, customize or calibrate instruments and / or calculate to take into account (among other things) individual physiology, instrument (e.g., light source and / or detector) arrangement, noise, etc. Alternatively or additionally, in other embodiments, steps 505-515 may be performed multiple times (e.g., hundreds, thousands, etc.) to determine multiple calibration factors. In some cases, these multiple determined calibration factors may be used, for example, to determine an average calibration factor for the pregnant mammal, which may or may not be associated with one or more physiological characteristics of the pregnant mammal. For example, in one embodiment, calibration factors may be determined for 10,000 pregnant women. These calibration factors may then be used to determine, for example, a universal calibration factor for all pregnant women (e.g., the average calibration factor for the 10,000 pregnant women) and / or grouped according to one or more physiological factors (including but not limited to fetal gestational age, maternal weight, maternal height, maternal melanin content, etc.).

[0131] Optionally, in step 520, one or more physiological characteristics or parameters of the pregnant mammal and / or fetus may be received and / or measured (e.g., by analyzing ultrasound information or images of the pregnant mammal, examples of which are provided by...). Figure 3A and 3B (Provided). Example physiological characteristics include, but are not limited to, the amount and / or degree of melanin in the skin of the woman and / or fetus and / or the type of skin pigmentation, fetal depth, fetal gestational age, and / or the width of one or more maternal or fetal tissue layers, abdominal wall thickness in pregnant mammals, percentage of hemoglobin concentration in the blood, and the degree of blood perfusion in the tissues (which can be obtained, for example, by DC tissue measurement). In some cases, the physiological characteristics may be grouped as intrinsic or geometric characteristics, wherein, for example, intrinsic characteristics such as blood or tissue oxygenation and / or hemoglobin concentration levels and body mass index (BMI), and abdominal wall thickness and / or the thickness of one layer of the abdominal wall may be geometric characteristics.

[0132] The calibration factor can be associated with one or more physiological characteristics of the pregnant mammal and / or fetus, for example, in an index or lookup table (step 525). In some embodiments, these associations can be used to select a calibration factor suitable for a particular pregnant mammal and / or fetus, as described below. Figure 13 As described in more detail. Next, the calibration factor, the one or more physiological characteristics of the pregnant mammal and / or fetus, and / or the associations between them can be stored in, for example, a database (such as database 170) and / or in memory residing in a computer (such as computer 150) (step 530). Sometimes, calibration factors can be aggregated and associated with physiological characteristics; thus, hypotheses / calibration factors can be determined and / or applied without calculating calibration factors separately for each pregnant mammal.

[0133] Figure 6 A flowchart is provided showing the process of determining the fetal hemoglobin oxygen saturation level using physiological characteristics of the pregnant mammal as measured by maternal detection electronic signals 600.

[0134] Process 600 may be performed by, for example, system 100 and / or its components. Process 600 may be performed in situ during, for example, fetal delivery and / or health checks of the pregnant mammal. In some cases, process 600 may be performed on a continuous, periodic and / or on-demand basis over a period of time (e.g., during fetal delivery), thereby allowing, for example, the fetal hemoglobin oxygen saturation level to be calibrated and recalibrated over time, for example, when needed and / or when the condition of the fetus and / or the pregnant mammal changes (e.g., when the fetus passes through the birth canal).

[0135] First, one or more maternal detection electronic signals corresponding to light signals emitted from the abdomen of a pregnant mammal can be received (step 605). This light signal can be generated by a light source (such as light source 105), incident on the abdomen of the pregnant mammal, passing through a portion of the maternal abdominal tissue, and being reflected or back-reflected through the maternal tissue, thereby being detected by a detector (such as detector 160). Example light signals (such as the light signals described) that can be detected by the detector and received in step 605 are shown in... Figure 3C The signals are displayed as the first and second optical signals 420A and 420B.

[0136] In step 610, the maternal detection electronic signal may be analyzed to determine one or more physiological characteristics of the pregnant mammal (step 615). This analysis may be, for example, frequency domain and / or time-of-flight analysis performed by a fetal hemoglobin probe configured to obtain time-of-flight measurements of photons projected onto the maternal abdomen. In some embodiments, in step 610, the determination of the physiological characteristic of the pregnant mammal may be performed by determining how the tissues of the pregnant mammal respond to incident light, for example, by measuring light absorption and / or scattering. In some embodiments, light absorption and / or scattering may be expressed as absorption coefficients or scattering coefficients, respectively, and may be used in one or more formulas described herein. Next, in step 620, a calibration factor for the physiological characteristic may be determined (step 620). In some cases, steps 610 and 615 may be performed to determine one or more intrinsic physiological characteristics of the pregnant mammal, which may be consistent across a portion of the pregnant mammal's abdomen. Such intrinsic physiological characteristics include, but are not limited to, the amount and / or degree of melanin in a woman's skin and / or the type of skin pigmentation, fetal depth, the width of one or more maternal or fetal tissue layers, the thickness of the abdominal wall of the pregnant mammal, hemoglobin oxygen saturation, the degree of blood perfusion in the abdominal tissues, whether the pregnant mammal is anemic, tissue oxygen saturation, and hemoglobin concentration level.

[0137] In step 620, the determination (i.e., calculation) and / or selection of the calibration factor can be performed, for example, by assessing how much light from the incident light signal is absorbed and / or scattered by the abdominal tissue of the pregnant mammal, and / or the flight time of the photons of the light signal passing through the abdominal tissue of the pregnant mammal and being detected by the detector. In some embodiments, to perform the determination / selection of the calibration factor in step 620, a database (e.g., database 170) and / or a memory residing in a computer (e.g., computer 150) can be queried to obtain the calibration factor corresponding to the physiological characteristic determined in step 615. The database can be populated with relevant physiological characteristics and calibration factors through process 500. In some embodiments, the correlation between the results of performing steps 605, 610, 615 and / or 620 can be mapped to each other (step 625), and the results of performing steps 605, 610, 615 and / or 620 can be stored in a database (step 630) (e.g., database 170) and / or a memory residing in a computer (e.g., computer 150).

[0138] In one embodiment, the physiological characteristic measured in step 615 may be the skin color, pigmentation, and / or melanin content of the pregnant mammal, which can be determined, for example, by measuring how much light incident on the abdomen of the pregnant mammal is absorbed by the skin of the pregnant mammal. The skin color of the pregnant mammal may affect how much incident light is absorbed, and thus may affect how much light incident on the abdomen of the pregnant mammal passes through the maternal tissue and onto the fetus, and may be associated with known or calculated factors, which are measured and / or selected in step 620. For example, the execution of 620 may include querying a database to obtain a calibration factor associated with how much light is absorbed by the skin of the pregnant mammal. In this example, the calibration factor may be an absorption coefficient, which may be associated with the absorption rate and / or skin color of the pregnant mammal.

[0139] In another embodiment, the maternal detection electronic signal received in step 605 can be analyzed in step 610 to determine the physiological characteristics of the concentration or thickness of myoglobin or muscle layer in the abdomen of the pregnant mammal. To perform this analysis, a fetal hemoglobin probe configured as a frequency-domain NIRS system and / or a fetal hemoglobin probe configured to obtain the time-of-flight of photons projected onto the maternal abdomen, passing through the maternal myoglobin layer, and reflecting back to the detector can be used. The myoglobin tissue of the pregnant mammal can absorb light projected onto the maternal abdomen, and measuring and / or calculating how much light is absorbed by the abdominal tissue of the pregnant mammal (e.g., not detected) can be used to determine the physiological characteristics of the thickness and / or concentration of the maternal myoglobin layer. In step 620, this physiological characteristic can be used, for example, to calculate a calibration factor and / or query a calibration factor database to find a calibration factor associated with the measured physiological characteristic of the myoglobin thickness and / or concentration in the pregnant mammal.

[0140] In another embodiment, the maternal detection electronic signal received in step 605 can be analyzed in step 610 to determine the physiological characteristics of the total thickness of the pregnant mammal's abdomen (also referred to herein as fetal depth), which may vary during pregnancy as the fetus grows. Alternatively or additionally, the thickness of the abdominal tissue of the pregnant mammal may vary during pregnancy and / or during delivery due to pre-eclampsia or eclampsia, which may cause edema, thus altering the abdominal thickness. To perform the analysis in step 610 for this example, a fetal hemoglobin probe configured as a frequency-domain NIRS system and / or a fetal hemoglobin probe configured to obtain the time-of-flight of photons projected onto the maternal abdomen, passing through the maternal abdominal layer, and reflecting back to the detector can be used. The abdominal tissue of the pregnant mammal absorbs light projected onto the maternal abdomen, and measuring and / or calculating how much light is absorbed by the abdominal tissue of the pregnant mammal (e.g., not detected) can be used to determine the physiological characteristics of the thickness of the abdominal tissue of the pregnant mammal. In step 620, this physiological characteristic can be used, for example, to calculate a calibration factor and / or query a calibration factor database to find a calibration factor associated with the physiological characteristic of the myoglobin concentration and / or thickness measured in the pregnant mammal.

[0141] In another example, the maternal detection electronic signal received in step 605 can be analyzed in step 610 to determine the physiological characteristics of the thickness of the adipose tissue in the abdomen of the pregnant mammal. To perform this analysis, a fetal hemoglobin probe configured as a frequency-domain NIRS system and / or a fetal hemoglobin probe configured to obtain the time-of-flight of photons projected into the maternal abdomen, passing through the maternal adipose tissue, and reflecting back to the detector can be used. The adipose tissue of the pregnant mammal can scatter light projected into the maternal abdomen, and measuring and / or calculating how much light is scattered by the adipose tissue of the pregnant mammal (e.g., not detected) can be used to determine the physiological characteristics of the thickness of the maternal adipose tissue. In step 620, this physiological characteristic can be used, for example, to calculate a calibration factor and / or query a calibration factor database to find a calibration factor associated with the measured physiological characteristic of the adipose tissue thickness of the pregnant mammal.

[0142] Figure 7A This is a flowchart illustrating an example procedure 700 for determining fetal depth and / or fetal hemoglobin oxygen saturation levels. Procedure 700 may be performed by, for example, system 100 and / or its components.

[0143] Optionally, in step 705, a plurality of first detection electronic signals may be received by, for example, a computer or processor (e.g., computer 150), each signal corresponding to a light signal having one or more wavelengths. This light signal is projected onto the abdomen of the pregnant mammal via, for example, one or more light sources (e.g., light source 105), and exits from the abdomen via, for example, reflection, backscattering, and / or transmission (i.e., through the maternal abdomen). Each of the plurality of first detection signals may be received from a different detector, as described above. Figure 2A , 2B The detectors 160A-160R are shown and discussed. The received first detection electronic signal can be associated with a detector identifier. Each detector may have a different light source / detector distance. For example, probes such as fetal probes 115A, 115B, 115D and / or 115E may have one light source and multiple detectors, each with a different light source / detector distance. In some embodiments, the light signal detected by a detector located away from the light source has a higher proportion of light incident on the fetus compared to a detector located close to the light source.

[0144] The optical signal corresponding to the first detection electronic signal has an example wavelength range between 600 nm and 1000 nm and may be similar to one or more optical signals 420. In some embodiments, the optical signal may be a broadband optical signal (e.g., white light and / or a series (e.g., 10, 15, or 20) wavelengths), and the received first detection signal may correspond to an optical signal having multiple wavelengths. In some embodiments, the optical signal or a portion thereof may have a set or known wavelength that, for light introduced into human tissue, is at an isoabsorption point to determine the ratio of oxyhemoglobin to deoxyhemoglobin in human blood, for example, 808 nm. Light at this wavelength is reflected from both oxyhemoglobin and deoxyhemoglobin in the same manner.

[0145] When step 705 is performed, each of the first detection electronic signals received in step 705 can be processed to separate the portion of the first detection electronic signal corresponding to the light incident on the fetus (step 710). This separated portion of each of the first detection electronic signals may be referred to herein as a first fetal signal. Step 710 may be performed using any suitable method for separating the fetal signal from the corresponding first detection electronic signal (including the methods disclosed herein). Suitable methods include, but are not limited to: reducing noise in the signal by, for example, applying filtering or amplification techniques; determining the portion of the first detection electronic signal contributed by the pregnant mammal and then subtracting or otherwise removing that portion of the first detection electronic signal from the received first detection electronic signal; and / or receiving information about the fetal heart rate and using that information to lock (by, for example, a lock-in amplifier) ​​the portion of the received first detection electronic signal generated by the fetus.

[0146] Optionally, step 710 may include preprocessing one or more of the first detection electronic signal to, for example, remove noise from the signal and / or remove the anatomical or physiological signals (e.g., respiratory signals) of the pregnant mammal from the first detection electronic signal. The preprocessing may include, but is not limited to, applying filtering techniques to the first detection electronic signal, applying amplification techniques to the first detection electronic signal, or using a lock-in amplifier on the first detection electronic signal. In some embodiments, the preprocessing may include applying filters (e.g., bandpass or Kalman filters) to one or more of the detection electronic signal to reduce noise or interference in the first detection electronic signal, such as electronic noise generated by devices that generate and / or detect the first detection electronic signal and / or, in some cases, environmental devices that may be coupled to the pregnant mammal.

[0147] Optionally, in step 715, the indication of the hemoglobin oxygen saturation level of the pregnant mammal may be received from, for example, a pulse oximetry probe (such as pulse oximetry probe 130), a maternal pulse oximetry probe (such as maternal probe 133), and / or an NIRS adult hemoglobin probe (such as NIRS adult hemoglobin probe 125), and / or determined by using, for example, the processor of the initial detection electronic signal execution process 700. Alternatively, in step 715, the indication of the tissue oxygen saturation level of the pregnant mammal may be received and / or determined. The tissue oxygen saturation level of the pregnant mammal may be received from, for example, a diffuse optical tomography (DOT) instrument and / or determined by applying DOT to the initial detection electronic signal. Alternatively, the indication of the hemoglobin and / or tissue oxygen saturation level of the pregnant mammal may be determined using one or more of the first detection electronic signals received in step 705 and, for example, the Beer-Lambert law described above with respect to Formula 1.

[0148] In some cases, the hemoglobin and / or tissue oxygen saturation levels of the pregnant mammal can be used to determine how much light is incident on the fetus, as described below.

[0149] In step 720, fetal depth can be received from, for example, a Doppler / ultrasound probe 135, and / or can be determined using, for example, the first detection electronic signal of step 705, the first fetal signal of step 710, and / or the maternal hemoglobin and / or tissue saturation level of step 715.

[0150] When determining fetal depth in step 720, the intensity change of each initial fetal signal can be measured by comparing the intensities of the initial fetal signals, thereby determining the fetal depth. In some cases, this comparison may include the positions of the detectors providing the corresponding first detection electronic signals and / or the light source / detector distance, and for detectors positioned farther from the light source, the decrease or reduction in the intensity of the fetal signal as the light source / detector distance increases can be quantified, thereby determining the fetal depth. This decrease in intensity as a function of the light source / detector distance can be used to determine the fetal depth.

[0151] Figure 7B A flowchart illustrating an example process for performing step 720 to determine fetal depth is provided. First, in step 750, a first initial detection electronic signal may be analyzed to determine whether it includes an initial fetal signal. This first initial detection electronic signal may correspond to an optical signal (e.g., first optical signal 420A) detected by a first detector (e.g., first detector 160A). This analysis in step 750 may be based on the processing / separation in step 710 and may include a yes-or-no determination regarding whether any initial fetal signal needs to be separated from the first initial detection electronic signal. When the first initial detection electronic signal includes an initial fetal signal, the intensity of the initial fetal signal may be determined (step 755).

[0152] Regardless of whether the first initial detection electronic signal includes an initial fetal signal, in step 760, it can be determined whether the second initial detection electronic signal includes an initial fetal signal. This second initial detection electronic signal may correspond to an optical signal (e.g., second optical signal 420B) detected by a second detector (e.g., second detector 160B). Step 760 can be performed in a similar manner to step 750. When the second initial detection electronic signal includes an initial fetal signal, the intensity of the initial fetal signal can be measured (step 755).

[0153] Regardless of whether the second initial detection electronic signal includes an initial fetal signal, in step 765, it can be determined whether the third initial detection electronic signal includes an initial fetal signal. This third initial detection electronic signal may correspond to a light signal (e.g., third light signal 420C) detected by a third detector (e.g., third detector 160C). Step 765 can be performed in a similar manner to steps 750 and / or 760. When the third initial detection electronic signal includes an initial fetal signal, the intensity of the initial fetal signal can be measured (step 755).

[0154] The process, similar to step 765, can be repeated N times until it is determined whether the last of the plurality of initial detection electronic signals received in step 705 includes the initial fetal signal (step 770). The Nth initial detection electronic signal may correspond to the light signal (e.g., the sixth light signal 420F) detected by the sixth detector (e.g., the third detector 160F). Step 770 can be performed in a similar manner to steps 750, 760, and / or 765. When the Nth initial detection electronic signal includes the initial fetal signal, the intensity of the initial fetal signal can be measured (step 755).

[0155] In step 775, fetal depth can be determined by analyzing the measured intensity of each of the corresponding initial fetal signals measured in step 755. In some embodiments, step 775 can be performed by plotting the intensity on a graph (e.g., using a scatter plot), which displays the fetal signal intensity as a function of the detector that detects the corresponding first to Nth fetal signals and / or as a function of the distance between the light source that generates the light signal and the detector that detects the corresponding first to Nth initial detected electronic signals. Figure 7C Example of graph 702 is provided, showing a scatter plot of the light intensity (in watts / cm) of the first to N fetal signals as a function of the light source / detector distance (in centimeters), which can be determined by the execution of step 755. Figure 7C In this case, graph 702 corresponds to the initial detection electronic signals detected by the first to sixth detectors 160A-160F and their corresponding distances from the light source 105. As shown in graph 702, the change in the percentage of light transmission of the signal detected at a certain distance from the light source (which may sometimes be related to the intensity of the signal) mainly follows an inverse relationship. Figure 7C As shown in Figure 702, the percentage of light transmitted onto the fetus and / or the light intensity may vary non-linearly, depending on the fetal depth and the light source-detector distance. In some embodiments, such as Figure 7D As shown, the change in the intensity and / or percentage of light reaching the fetus can depend on the fetal depth in an inverse relationship, including graph 703, which shows the change in the percentage of light transmission as a function of the light source-detector distance (in centimeters) for the maternal signal and / or the maternal portion of the signal.

[0156] Since the first fetal signal is detected by a third detector at a light source / detector distance of 3 cm, the sample fetal depth can be approximately 25 mm. Fetal depth can be determined by using the rate attenuation of the fetal signal intensity as the light source / detector distance increases. This rate of attenuation can correspond to the slope of a linear regression in a scatter plot.

[0157] In some embodiments, fetal depth can be determined by analyzing light with an isoabsorption point of 808 nm. Light at this wavelength is reflected from both oxygenated and deoxygenated hemoglobin in the same manner; therefore, the scattering and absorption of this light at this wavelength are identical for both oxygenated and deoxygenated hemoglobin and will not vary based on the hemoglobin oxygen saturation level in the blood of, for example, pregnant mammals and / or fetuses. Therefore, when performing step 720 using light with an isoabsorption point of 808 nm, it may not be necessary to measure the scattering and / or absorption of the light signal by maternal tissue (which can be expressed as scattering coefficients and / or absorption coefficients, respectively).

[0158] In step 725, a second detection electronic signal corresponding to the second light signal may be received. This second detection electronic signal may correspond to a second light signal exiting the abdomen of the pregnant mammal and may be similar to the first detection electronic signal received in step 705. The second detection electronic signal may then be processed to separate a portion of the signal incident on the fetus (step 730). This separated portion of the second detection electronic signal may be referred to herein as a second fetal signal. In some embodiments, the execution of step 730 may be similar to the execution of step 710.

[0159] In step 735, the fetal depth can be used to select factors for analyzing the second fetal signal to determine the fetal hemoglobin oxygen saturation level. For example, the fetal depth can be used to determine and / or select a differential path length factor (DFP) for a specific wavelength and / or to calculate a correlation factor to determine the fetal hemoglobin oxygen saturation level for each wavelength using, for example, the modified Beer-Lambert law as shown in Equation 1 above (step 740).

[0160] Next, the fetal depth measurement and / or selection of a specific wavelength of DFP can be used. The I0 value of each wavelength of light in the incident fetal light signal can be, for example, the intensity of light projected onto the abdomen of the pregnant mammal and / or the intensity of light incident on the fetus, which can be determined by the process disclosed herein. In the embodiment where the hemoglobin and / or tissue oxygen saturation level of the pregnant mammal is received and / or measured in step 715, the hemoglobin and / or tissue oxygen saturation level can be used to determine the amount and / or intensity of light emitted by the light source and introduced into the abdomen of the pregnant mammal that is absorbed by maternal tissue or hemoglobin. The correlation between the hemoglobin and / or tissue oxygen saturation level of the pregnant mammal and the amount of incident light she can absorb for each wavelength of light can be known and / or determined empirically, and these correlations can be stored in a lookup table, for example, in a database (such as database 170), so that when the hemoglobin and / or tissue oxygen saturation level of the pregnant mammal is received and / or measured in step 715, the corresponding light absorption level (e.g., percentage or ratio) of the pregnant mammal can be found using the lookup table. Next, when the light source projects light into the abdomen of the pregnant mammal, this value (the light absorption level of the pregnant mammal) can be applied (e.g., subtracted or multiplied) to the initial intensity of the light source to determine the initial intensity (I0) of the light incident on the fetus. ΔI(λ) can be the change in the measured intensity of the light incident on the fetus at wavelength λ and the intensity of the signal detected by the light at wavelength λ.

[0161] Once the absorption coefficient (or change in the absorption coefficient) is determined using Equation 1, the indication of fetal hemoglobin oxygen saturation can be determined, for example, by calculation using Equation 2 below:

[0162] Δμa(λ)=ΔcHbO*εHbO(λ)+ΔcHb*εHb (λ) Equation 2

[0163] in:

[0164] Δμ a (λ) = the change in the absorption coefficient at a given wavelength λ over a defined time period;

[0165] ΔC HbO = The change in the concentration of oxyhemoglobin (HbO) within the defined time period;

[0166] ΔC Hb = The change in the concentration of deoxyhemoglobin (Hb) within the defined time period;

[0167] ε HbO (λ) = the extinction coefficient of oxyhemoglobin (HbO) for a given wavelength; and

[0168] ε Hb(λ) = Extinction coefficient of deoxyhemoglobin (Hb) for a given wavelength.

[0169] By inputting the change in intensity I as a function of wavelength λ, Equation 1 can be solved for two or more wavelength pairs. Therefore, by inputting the known extinction coefficient ε for a specific wavelength... HbO (λ) and ε Hb (λ) (which can be found in a lookup table stored, for example, on computer 150), the change in absorption coefficient Δμ can be determined using Equation 2. a The wavelength pair used to perform the calculation in Equation 2 can be any wavelength pair included in the wavelength spectrum of the light signal incident on the abdomen of the pregnant mammal. In some embodiments, the calculation in Equation 2 can be performed multiple times (e.g., 10 seconds, 100 seconds, or 1000 seconds) with different wavelength combinations to obtain ΔC. HbO and ΔC Hb Multiple values ​​can be weighted and / or averaged according to one or more criteria to obtain ΔC. HbO and ΔC Hb The robust value (e.g., statistically valid and / or with an acceptable level of confidence and error rate). As an addition or alternative, Equation 2 can be calculated multiple times (e.g., 10 seconds, 100 seconds, or 1000 seconds) to fit multiple wavelengths to the equation simultaneously.

[0170] ΔC generated by Equation 2 HbO and ΔC Hb These values ​​are relative, rather than absolute, values ​​of the concentrations of oxygenated and deoxygenated hemoglobin in the fetal blood, which may help monitor changes in fetal hemoglobin oxygen saturation levels over time. In some embodiments, the determination in step 1235 may further include measuring the overall oxygen saturation of fetal hemoglobin by measuring the ratio of the change in the concentration of oxyhemoglobin to the change in the concentration of total hemoglobin (which may be the sum of oxygenated and deoxygenated hemoglobin). As an additional or alternative, another method disclosed herein may be used to determine fetal hemoglobin oxygen saturation.

[0171] Once the fetal hemoglobin oxygen saturation level is determined in step 740, it can be conveniently provided to the user by displaying it, for example, on a display device (such as display device 155) (step 745).

[0172] Figure 8 This is a flowchart illustrating a process 800 for determining fetal depth using the time-of-flight of photons incident on the fetus and / or the oxygen saturation level of fetal hemoglobin. Process 800 may be performed by, for example, system 100 and / or its components.

[0173] Optionally, in step 805, a plurality of first detection electronic signals may be received, for example, by a computer or processor (e.g., computer 150), each signal corresponding to a light signal having one or more wavelengths, which is projected onto the abdomen of the pregnant mammal by, for example, one or more light sources (e.g., light source 105) and exits from the abdomen by, for example, reflection, backscattering, and / or transmission (i.e., through the maternal abdomen). The first detection electronic signal received in step 805 may be similar to the first detection electronic signal received in step 705. In some embodiments, the time from when the light signal is projected onto the abdomen of the pregnant mammal to when it is received by a detector may be received in step 805. Alternatively or additionally, the plurality of first detection electronic signals may include timestamp information corresponding to, for example, the time when the light signal is projected onto the abdomen of the pregnant mammal and / or the time when the first detection electronic signal is received by the corresponding detector.

[0174] When step 805 is executed, each of the first detection electronic signals received in step 805 can be processed to separate the portion of the first detection electronic signal corresponding to the light incident on the fetus (step 810). The execution of step 810 can be similar to the execution of step 710.

[0175] In step 815, a marker regarding the time of flight of the photons of the light signal incident on the fetus may be received, or, during steps 805 and 810, it may be determined by using the time between the photons of the light signal leaving the light source and being received by the detector. This time of flight can be determined by calculating the length of time from when the light signal is projected onto the abdomen of the pregnant mammal to when it is received by the detector. When the plurality of first detection electronic signals include timestamp information corresponding to the light signal being projected onto the abdomen of the pregnant mammal and the first detection electronic signal being received by the corresponding detector, the time of flight of the photons of the light signal incident on the fetus can be determined by measuring the difference or length of time between the timestamp when the light signal is projected onto the abdomen of the pregnant mammal and the timestamp when the first detection electronic signal is received by the corresponding detector.

[0176] In step 820, fetal depth can be received from, for example, a Doppler / ultrasound probe 135, and / or can be determined using, for example, the first detection electronic signal of step 805, the first fetal signal of step 810, and / or the time of flight of step 815. When determining fetal depth in step 820, the fetal depth can be determined according to Equation 3 by calculating the distance the light signal travels from the time it is projected onto the abdomen of the pregnant mammal to the time it is received by the detector.

[0177] D = s * t (Equation 3)

[0178] in:

[0179] D = Distance traveled;

[0180] s = speed of light; and

[0181] t = the time from when the light signal is projected into the abdomen of the pregnant mammal until it is received by the detector.

[0182] The fetal distance can be calculated by dividing the distance (D) that the light travels by 2, since the distance calculated by Equation 3 is the distance that the light travels to the fetus and returns to the detector.

[0183] In step 825, a second detection electronic signal corresponding to the second optical signal may be received. This second detection electronic signal may correspond to a second optical signal exiting from the abdomen of the pregnant mammal and may be similar to the first detection electronic signal received in step 805. Next, the second detection electronic signal may be processed to separate a portion of the second detection electronic signal incident on the fetus (step 830). This separated portion of the second detection electronic signal may be referred to herein as a second fetal signal. In some embodiments, the execution of step 830 may be similar to the execution of steps 810 and / or 730.

[0184] In step 835, the fetal depth can be used to select factors for analyzing the second detection electronic signal to determine the fetal hemoglobin oxygen saturation level. For example, the fetal depth can be used to determine and / or select a differential path length factor (DFP) at a specific wavelength and / or for calculating a correlation factor to determine the fetal hemoglobin oxygen saturation level using, for example, Equations 1 and 2 provided and discussed above (step 840). In some embodiments, the execution of step 835 may be similar to the execution of step 735. Alternatively, another method disclosed herein can be used to determine fetal hemoglobin oxygen saturation.

[0185] Once the fetal hemoglobin oxygen saturation level is determined in step 840, it can be displayed on a display device (such as display device 155) to facilitate providing the user with an indication of the fetal hemoglobin oxygen saturation level (step 845).

[0186] Figure 9A flowchart is provided illustrating a process 900 for determining fetal hemoglobin oxygen saturation levels using physiological characteristics of the pregnant mammal as measured by maternal detection electronic signals. Process 900 may be performed by, for example, system 100 and / or its components. Process 900 may be performed in situ during, for example, fetal delivery and / or a health check of the pregnant mammal. In some cases, process 900 may be performed continuously, periodically, and / or on demand over a period of time (e.g., during fetal delivery), thereby allowing for the calibration and recalibration of the fetal hemoglobin oxygen saturation levels over time, for example, when needed and / or when the condition of the fetus and / or the pregnant mammal changes (e.g., when the fetus passes through the birth canal).

[0187] In step 925, a detection composite electronic signal may be received from a detector via a processor and / or a computer (such as computer 150). This detection composite electronic signal may be received from, for example, a photodetector, a transceiver coupled to the photodetector, and / or a fetal hemoglobin probe, such as fetal hemoglobin probe 115. This detection composite electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal and / or its fetus. The light incident on and exiting the abdomen of the pregnant mammal may be generated by one or more light sources, such as light source 105, and may have any acceptable frequency or wavelength (e.g., near-infrared (NIR)) and / or a combination of frequency and / or wavelength. In some embodiments, a marker indicating whether the fetal hemoglobin oxygen saturation level is pre-ductal or post-ductal may also be received in step 925, similar to, for example, receiving a marker indicating whether the fetal hemoglobin oxygen saturation level is pre-ductal or post-ductal in step 1305. Step 925 may be performed at any time after step 920. However, in many cases, step 925 may be performed immediately or soon after step 920 (e.g., 5 seconds, 30 seconds, 1 minute) to take into account, for example, the dynamic changes in the physiological characteristics of the abdomen of the pregnant mammal.

[0188] Next, the received detection composite electronic signal can be analyzed to separate the portion of the signal corresponding to the light incident on the fetus, thereby generating a fetal signal (step 930). Step 930 can be performed in a manner similar to, for example, performing steps 810 and / or 710 or any other method disclosed herein. Next, the calibration factor selected and / or measured in step 920 can be applied to the fetal signal to calibrate it (step 935). Once the fetal signal is calibrated, an indication of the fetal hemoglobin oxygen saturation level can be measured (step 940) and provided to the user (step 945). Optionally, the execution of step 945 may include providing the user with an indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-ductal in a manner similar to the execution of step 1355. The execution of steps 935-945 can be similar to the execution of steps 1345-1350 and / or steps 830-835 disclosed below. Alternatively, another method disclosed herein can be used to determine fetal hemoglobin oxygen saturation.

[0189] Figure 10 A flowchart is provided illustrating a process 1000 for determining fetal hemoglobin oxygen saturation levels using physiological characteristics of the pregnant mammal as measured by one or more maternal detection electronic signals. Process 1000 can be used to account for changes in maternal geometry and / or geometric physiological characteristics on a surface area of, for example, a fetal hemoglobin probe (e.g., fetal hemoglobin probe 115). Process 1000 can be performed by, for example, system 100 and / or its components. Process 1000 can be performed in situ during, for example, fetal delivery and / or a health check of the pregnant mammal. In some cases, process 1000 can be performed continuously, periodically, and / or on demand over a period of time (e.g., 1-24 hours), for example, during fetal delivery, thereby allowing, for example, the fetal hemoglobin oxygen saturation level to be calibrated and recalibrated over time, for example, when needed and / or when the condition of the fetus and / or the pregnant mammal changes (e.g., when the fetus passes through the birth canal).

[0190] First, in step 1005, one or more maternal detection electronic signals corresponding to one or more light signals emitted from the abdomen of a pregnant mammal can be received (step 1005). These light signals can be generated by a light source (e.g., light source 105), incident on the abdomen of the pregnant mammal, passing through portions of the maternal abdominal tissue, and being reflected or back-reflected through the maternal tissue, thereby being detected by a detector (e.g., detector 160). Each light signal can be associated with the location and / or identifier of the detector that detects the corresponding light signal. For example, each detector that detects the maternal detection electronic signal can be associated with an identifier (e.g., detector 1, detector 2, etc.), a location that can be the detector's position on the fetal hemoglobin probe 115 (e.g., coordinates) and / or its position on the maternal abdomen (e.g., 1 inch directly below the navel, 1 inch below the navel, and 1 inch to the left of the midsagittal line, etc.). Example light signals that can be detected by the detector and received in step 1005 include those where the light signal is located at, for example... Figure 3C The signals are displayed as the first and second optical signals 420A and 420B, respectively, and in... Figures 4A-4D The signal is displayed as optical signal 420.

[0191] In step 1010, the electronic signals detected by each maternal body can be analyzed to determine one or more external or geometric physiological characteristics of the pregnant mammal (step 1015). Examples of external physiological characteristics include, but are not limited to, the melanin content and / or degree and / or skin pigmentation type of the pregnant mammal's skin, the width of one or more maternal or fetal tissue layers, and the abdominal wall thickness of the pregnant mammal. The above... Figure 3A and 3B Provide example dimensions of the thickness of the abdominal wall and / or abdominal wall layer of the pregnant mammal.

[0192] In step 1020, a calibration factor may be selected and / or measured for each maternal detection electronic signal. This measurement (i.e., calculation) and / or selection of the calibration factor may be performed, for example, by assessing how much light from the incident light signal is absorbed and / or scattered by the abdominal tissue of the pregnant mammal, and / or the flight time of the photons of the light signal through the abdominal tissue of the pregnant mammal and detected by the detector. In some embodiments, to perform the selection of the calibration factor, a database (such as database 170) and / or memory residing in a computer (such as computer 150) may be queried to obtain a calibration factor corresponding to the physiological characteristic measured in step 915. The database may be populated with relevant physiological characteristics and calibration factors via process 500. In some embodiments, the results of performing steps 1005, 1010, 1015, and / or 1020 may be stored, for example, in a database (such as database 170) and / or memory residing in a computer (such as computer 150).

[0193] In step 1025, the physiological characteristic and / or calibration factor may be associated with a detector that detects each of the maternal detection electronic signals received in step 1005. Alternatively, in step 1025, the physiological characteristic and / or calibration factor may be associated with a location on the abdomen of the pregnant mammal.

[0194] In one example, a set of results from performing steps 1005-1025 is provided by the values ​​in Table 1, which provides the detector identifier, the physiological characteristic value of abdominal thickness, and the calibration factor corresponding to that physiological characteristic of abdominal thickness.

[0195] Detector identifier Abdominal thickness Calibration factor Detector 1 19.81mm C1 Detector 2 19.83mm C2 Detector 3 19.85mm C3

[0196] Table 1

[0197] In step 1030, one or more detection composite electronic signals may be received by a processor and / or a computer (such as computer 150). These one or more detection composite electronic signals may be received from a detector that provides the maternal detection electronic signal received in step 1005, and each detection composite electronic signal may be associated with the location and / or identifier of the detector that detects the respective detection composite electronic signal. In some embodiments, the indication regarding whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter may be received in step 1030 in a manner similar to, for example, receiving an indication regarding whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter in step 1305.

[0198] The detection composite electronic signal can be received by, for example, a photodetector, a transceiver coupled to the photodetector, and / or a fetal hemoglobin probe, such as fetal hemoglobin probe 115. This detection composite electronic signal can correspond to a light signal emitted from the abdomen of the pregnant mammal and / or its fetus. The light incident on and exiting the abdomen of the pregnant mammal can be generated by one or more light sources, such as light source 105, and can have any acceptable frequency or wavelength (e.g., near-infrared (NIR)) and / or combination of frequency and / or wavelength. Step 1030 can be performed at any time after step 1025. However, in many cases, step 1030 can be performed immediately or very soon after step 1025 (e.g., 5 seconds, 30 seconds, 1 minute, 1 hour) to, for example, take into account dynamic changes in the physiological characteristics of the pregnant mammal's abdomen.

[0199] Next, the received detection composite electronic signal can be analyzed to separate the portion of the corresponding composite electronic signal corresponding to the light incident on the fetus, thereby generating a corresponding number of fetal signals (step 1035). Step 1035 can be performed in a manner similar to, for example, performing steps 710 and / or 810 and / or according to other methods disclosed herein. Next, the calibration factor associated with the detector that detects each corresponding detection composite electronic signal can be applied to the fetal signal corresponding to each corresponding detection composite electronic signal (step 1040). The execution of step 1040 can be similar to the execution of step 935 as described above.

[0200] Continuing with the example above, in step 1040, the calibration factor is applied to the fetal signals received from the first, second, and third detectors corresponding to the first, second, and third fetal signals (that is, fetal signal 1, fetal signal 2, and fetal signal 3), which correspond to calibration factors P1, P2, and P3, as shown in Table 2. The calibration factors for the first, second, and third physiological characteristics correspond to the calibration factors for the first, second, and third fetal signals, as shown in Table 2.

[0201] Detector identifier Fetal signal identifiers Calibration factor Detector 1 Fetal signal 1 P1 Detector 2 Fetal signal 2 P2 Detector 3 Fetal signal 2 P3

[0202] Table 2

[0203] In some embodiments, the fetal signal and / or fetal signal 1, fetal signal 2 and / or fetal signal 3 disclosed herein may be a signal comprising light having multiple wavelengths, and a calibration factor for each of these wavelengths may be independently determined and / or applied to a single wavelength (or similar group of wavelengths) included in each fetal signal. Alternatively or additionally, the fetal signal and / or fetal signal 1, fetal signal 2 and / or fetal signal 3 disclosed herein may be detected by independent detectors and / or by the same detector at different times. For example, a fetal pulse may be extracted from multiple fetal signals (each of which may be detected by an independent detector), and the calibration of the fetal signal may be influenced by different proportions of different physical features in each detector channel, which may be determined by the following relationship: if detector 1 signal = function D1(D1, P1, P2, P3, ...), where D1 is a coefficient vector associated with the geometry, wavelength, etc., of detector 1, and P1 is a vector associated with physical feature P1, P2 is a vector associated with physical feature P2, and so on. In this example, function D1 may be considered as a tensor.

[0204] Once each fetal signal is calibrated, the indication of the fetal hemoglobin oxygen saturation level can be determined using one or more methods disclosed herein (step 1045). In some cases, to perform step 1050, the fetal hemoglobin oxygen saturation level of each fetal signal can be measured individually, and then the individually measured fetal hemoglobin oxygen saturation levels can be averaged to obtain the mean fetal hemoglobin oxygen saturation level. Alternatively or additionally, each fetal signal can be a mixture or combination of different signals originating from various concurrently occurring physical features, and in some cases, the calibration factors C1, C2, etc., can be vectors, and for the detector signal family, they will be tensor matrices.

[0205] Once the fetal hemoglobin oxygen saturation level is measured, it can be provided to the user (step 1050). Optionally, the execution of step 1050 may include providing the user with an indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter in a manner similar to the execution of step 1355. In some embodiments, the execution of steps 1045 and 1050 may be similar to the execution of steps 1345-1350, steps 830-835, and / or steps 940 and 945.

[0206] Figure 11 A flowchart is provided illustrating a process 1100 for determining the effect of physiological characteristics on the behavior (e.g., scattering, absorption, etc.) of light passing through the abdomen of a pregnant mammal and / or its fetus. Process 1100 may be performed by a combination of components, such as system 100 and / or its components. Example physiological characteristics include, but are not limited to, tissue type, tissue depth, width of tissue layers, number of tissue layers irradiated by light, skin pigmentation, density of tissue or tissue layers, depth of the fetus within the maternal abdomen, composition of tissue or tissue layers, etc.

[0207] In step 1105, physiological characteristics of a pregnant mammal and / or its fetus may be received. In some cases, these physiological characteristics can be determined, for example, by analyzing an image of the pregnant mammal and / or its fetus. The image may be generated by one or more imaging techniques, including but not limited to MRI or ultrasound imaging techniques. Illustrations of example images that can be analyzed to determine one or more physiological characteristics include... Figure 3A and 3B The illustration is provided. As an additional or alternative, the physiological characteristic may not be based on the image, such as body mass index, skin color, age, etc.

[0208] In step 1110, it can be determined how the physiological characteristic affects the behavior of light introduced and / or passed through the maternal abdomen and / or fetus. The light introduced and / or passed through the maternal abdomen and / or fetus may have single or multiple (e.g., wide or narrow range) wavelengths, and the determination may be based on and / or consider one or more wavelengths of interest. Generally, the behavior of light (e.g., scattering) depends on tissue morphology and the particle size / density of substances within the tissue (e.g., water, lipids, etc.). Different tissue layers typically have different morphologies, particle sizes, and / or particle densities. For example, when the physical characteristic of a tissue layer is that the amount of fat within the tissue is higher than average (i.e., high lipid count), one might expect a higher-than-average amount of light scattering due to the higher-than-average lipid content. In some embodiments, this effect can be measured by the scattering coefficient (e.g., μ). s (λ)), absorption coefficient (e.g., μ) a The scattering coefficient (λ) and / or absorption coefficient are used to describe this behavior, which can be input into formulas that describe and / or include the behavior of light as it passes through one or more media, such as the Beer-Lambert law and / or a modified Beer-Lambert law.

[0209] The determination in step 1110 can be accomplished using, for example, experimental observations collected from one or more pregnant mammals and / or physiological characteristics of mathematical modeling and / or theoretical simulations performed on multiple hypothetical pregnant mammals. For example, experimental observations can be used to correlate the observed light signal behavior (which may be detected as the pregnant mammal leaves the abdomen of the mammal under study (by, for example, reflection, backscattering, and / or transmission)) with the physiological characteristics of that pregnant mammal / pregnant mammal's abdomen. Alternatively or additionally, the detection light scattering and / or detection light signals of a group of pregnant mammals can be analyzed to determine how various physiological characteristics of the pregnant mammals in that group might affect light scattering. For example, light scattering and / or detection light signals can be analyzed together with physiological characteristics (e.g., the width of the subcutaneous fat layer of each pregnant mammal in the group) to determine whether the width of the subcutaneous fat layer affects the behavior of the detection light, and if so, how and to what extent. This process can be repeated, for example, for multiple physiological characteristics of a pregnant mammal in a population, for multiple tissue layers of the abdomen of each pregnant mammal in the population, individually (i.e., one at a time) and / or in combination (i.e., determining how multiple physiological characteristics affect the behavior of light), for multiple physiological characteristics of the pregnant mammal in the population. In some embodiments, the determination in step 1110 may depend on the frequency / wavelength of the light being observed or measured. In some cases, the determination in step 1110 may take into account how different intrinsic and / or tissue properties and geometric properties of the pregnant mammal and / or fetus affect different wavelengths. For example, a particular physiological characteristic may affect the behavior of light with a first wavelength (e.g., 700 nm) in a different way than light with a second wavelength (e.g., 800 nm), for example, having greater / less scattering and / or absorption of light with a first wavelength compared to light with a second wavelength. Therefore, the effect of physiological characteristics can be determined for different frequencies / wavelengths and / or different frequency / wavelength ranges of light.

[0210] As an addition or alternative, when performing step 1110 using mathematical modeling, one or more known, understood, estimated, and / or hypothetical behaviors of light as it passes through materials (e.g., skin, water, water with a known lipid count, skeletal muscle, fat, smooth muscle, water with a known electrolyte count, etc.) can be used to mathematically model the behavior of light as it passes through that material and / or multiple materials (e.g., skin, fat, muscle, etc.) in a physiological context (e.g., passing through the abdomen of a pregnant mammal). Example programs that can be used to perform this mathematical modeling include, but are not limited to, Monte Carlo simulations and NIRFAST for finite element modeling.

[0211] In one embodiment, the physiological characteristic received in step 1105 may be skin color, pigmentation, and / or melanin content, input by, for example, a clinician or physician. In some embodiments, skin color may be quantified using a Fitzpatrick scale, which may be input by the clinician into a processor or computer performing process 1100. In step 1110, it may be determined how the quantified skin color of the pregnant mammal affects the behavior of light incident on and / or emitted from the skin of the pregnant mammal. Based on known or calculated factors (determined in step 1110), the skin color of the pregnant mammal may affect how much of the incident light is absorbed, and thus may affect how much of the light incident on the abdomen of the pregnant mammal passes through the maternal tissue and onto the fetus.

[0212] In another embodiment, the physiological characteristic received in step 1105 may be the density, concentration, and / or thickness (collectively referred to herein as myoglobin concentration) of the myoglobin or muscle layer in the abdomen of the pregnant mammal. This myoglobin tissue of the pregnant mammal absorbs light projected onto the maternal abdomen, and measuring the concentration of the myoglobin layer can be used to determine how much light is absorbed by the myoglobin tissue of the pregnant mammal (e.g., not detected). In step 620, this physiological characteristic can be used, for example, to calculate a calibration factor and / or query a calibration factor database to find a calibration factor associated with the physiological characteristic of the measured myoglobin concentration in the pregnant mammal.

[0213] In another embodiment, the physiological characteristic received in step 1105 may be the total thickness of the abdomen of the pregnant mammal (also referred to herein as fetal depth), which may vary during pregnancy as the fetus grows. In some cases, the thickness of the abdomen of the pregnant mammal may be determined by, for example, body mass index (BMI) calculation, image analysis (examples of which are shown in Figures 301 and 302), and / or ultrasound image analysis. Alternatively or additionally, the thickness of the abdominal tissue of the pregnant mammal may vary during pregnancy and / or during fetal delivery due to preeclampsia or eclampsia. The abdominal tissue of the pregnant mammal may absorb light projected onto the maternal abdomen, and measuring and / or calculating how much light is absorbed by the abdominal tissue of the pregnant mammal (e.g., undetected) can be used to determine the physiological characteristic of the thickness of the abdominal tissue of the pregnant mammal. In step 1115, this physiological characteristic may be used, for example, to determine a calibration factor, and / or to query a calibration factor database to find a calibration factor associated with the measured physiological characteristic of the abdominal thickness of the pregnant mammal.

[0214] In yet another example, the physiological characteristic received in step 1105 could be the thickness of the adipose tissue in the abdomen of the pregnant mammal. This adipose tissue in the pregnant mammal can scatter light projected onto the maternal abdomen, and measuring and / or calculating the thickness of the adipose tissue can be used to determine how much light the adipose tissue can scatter. In step 1115, this physiological characteristic can be used, for example, to calculate a calibration factor, and / or to query a calibration factor database to find a calibration factor associated with the physiological characteristic of the measured adipose tissue thickness in the pregnant mammal.

[0215] In one different example, the physiological characteristic received in step 1105 may be the amount of hemoglobin circulating in the blood of the pregnant mammal (i.e., hemoglobin concentration). The amount of hemoglobin circulating in the blood of a pregnant mammal can be determined by blood measurements such as hemoglobin concentration measurement, hematocrit measurement, and / or total blood volume measurement to quantify the maternal hemoglobin concentration. In some cases, hemoglobin concentration can be measured using a device such as Masimo's SpHb device, which is configured to measure hemoglobin concentration in a non-invasive manner.

[0216] Anemia is a condition that causes a decrease in the concentration of hemoglobin in the blood of pregnant mammals, while conditions such as polycythemia vera cause an increase in the concentration of hemoglobin in the blood of pregnant mammals. The concentration of hemoglobin in the blood of a pregnant mammal can absorb light incident on the mother's abdomen, and the hemoglobin concentration value can be used to determine how much light the mother's hemoglobin can absorb. Anemic pregnant mammals will not absorb as much light as pregnant mammals with normal hemoglobin concentrations, which may affect how much light reaches the fetus. Similarly, the increased hemoglobin concentration in pregnant mammals with polycythemia vera may absorb more light than pregnant mammals with normal hemoglobin concentrations, which may also affect how much light reaches the fetus. In step 1115, this physiological characteristic can be used, for example, to calculate a calibration factor and / or query a calibration factor database to find a calibration factor associated with the physiological characteristic of the measured fat thickness in the pregnant mammal.

[0217] In another example, the physiological characteristic received in step 1105 could be a measurement of the hemoglobin oxygen saturation of the pregnant mammal, which can be measured, for example, by analysis of a direct arterial blood sample (using an approximation of a venous blood sample), a pulse oximeter (such as pulse oximeter 130), and / or an NIRS adult hemoglobin probe (such as an NIRS adult hemoglobin probe). Diseases that may affect blood oxygen saturation, such as pneumonia, asthma, COVID-19, cardiovascular disease, and high altitude, can cause a decrease in maternal hemoglobin oxygen saturation. This hemoglobin oxygen saturation in the blood of the pregnant mammal can determine how much light is absorbed by oxygenated and / or deoxygenated hemoglobin, and the value of this hemoglobin oxygen saturation in the blood of the pregnant mammal can be used to determine how much light is absorbed by the mother's oxygenated / deoxygenated hemoglobin, which may affect how much light is incident on the fetus.

[0218] In step 1120, the effect of one or more physiological characteristics and / or combinations of physiological characteristics on the behavior of light may be stored in a database, such as database 170. Sometimes, physiological characteristics may be indexed within this database to corresponding decisions regarding the effect of that physiological characteristic on light or a specific wavelength of light. For example, physiological characteristics that remain unchanged over a period of time (e.g., anemia, hypertension, respiratory disease, and / or the traditional low blood oxygen levels of the pregnant mammal) may be indexed to and / or associated with corresponding decisions (e.g., calibration factors) regarding the effect of that physiological characteristic on light or a specific wavelength of light.

[0219] Figure 12 A flowchart is provided illustrating an example process 1200 for determining fetal hemoglobin oxygen saturation levels using indicators of maternal hemoglobin oxygen saturation levels and / or fetal depth. Process 1200 may be performed by, for example, system 100 and / or its components.

[0220] In step 1205, the indication of the hemoglobin oxygen saturation level of the pregnant mammal may be received from, for example, a pulse oximetry probe (such as pulse oximetry probe 130), a maternal pulse oximetry probe (such as maternal probe 133), and / or an NIRS adult hemoglobin probe (such as NIRS adult hemoglobin probe 125), and / or determined by using, for example, the processor of the process 1200 executed by the first detection electronic signal. Alternatively or additionally, the indication of the tissue oxygen saturation level of the pregnant mammal may be received and / or determined in step 715. The tissue oxygen saturation level of the pregnant mammal may be received from, for example, a diffusion optical tomography (DOT) instrument and / or determined by applying DOT to the first detection electronic signal. In some embodiments, the execution of step 1205 may be similar to the execution of step 715.

[0221] In step 1210, the intensity value of the light signal incident on the abdomen of the pregnant mammal can be received. This intensity value can be obtained, for example, from the manufacturer of the light source used to generate the light signal, and / or can be experimentally determined. In step 1215, a portion and / or amount of the incident light signal that can be absorbed by the pregnant mammal and therefore may not incident on the fetus can be determined and / or received. This portion of the incident light signal that can incident on the fetus may be referred to herein as the incident fetal light signal. Step 1215 can be achieved using the light absorptivity of the pregnant mammal (e.g., Δμ). a The light absorbance can be determined by (λ), which may be based on the hemoglobin and / or tissue oxygenation levels of the pregnant mammal received in step 1205. In some embodiments, the determination in step 1215 may be performed similarly to step 720.

[0222] In step 1220, a detection electronic signal may be received from a photodetector (such as detector 160). This detection electronic signal may correspond to a light signal of one or more wavelengths that is incident on and exits the abdomen and fetus of a pregnant mammal over a period of time, as detected by the detector. Detection of this light signal may include counting photons of different wavelengths received by the detector and / or incident on an optical fiber coupled to the detector. In some cases, the received detection electronic signal may be similar to the detection electronic signal received in steps 705 and / or 725 of process 700 and / or steps 805 and / or 825 of process 800 described above.

[0223] Optionally, in some embodiments, fetal depth (e.g., the distance between the skin of the abdomen of the pregnant mammal and the skin of the fetus) may be received and / or measured (step 1225). This fetal depth may be received from, for example, a Doppler / ultrasound probe (e.g., Doppler / ultrasound probe 135) and / or a fetal depth probe (e.g., fetal depth probe 138). This fetal depth may be measured by, for example, by performing processes 700 and / or 800 as described above with reference to Figures 7 and 8. When fetal depth is received and / or measured in step 1225, this fetal depth may be used to determine and / or select calibration factors and / or differential path length factors (DPF) for one or more wavelengths of light included in the fetal signal and / or incident light signal.

[0224] In step 1230, a portion of the detection electronic signal incident on the fetus in step 1220 may be separated from the detection electronic signal, according to one or more methods disclosed herein, for example. This separated portion of the received detection electronic signal may be referred to herein as the fetal signal. Step 1230 may be performed using any suitable method for separating the fetal signal from the detection electronic signal. Suitable methods include, but are not limited to: reducing noise in the signal by, for example, applying filtering or amplification techniques; determining the portion of the detection electronic signal contributed by the pregnant mammal and then subtracting or otherwise removing that portion of the detection electronic signal from the received detection electronic signal; and / or receiving information about the fetal heart rate and using that information to lock (by, for example, a lock-in amplifier) ​​the portion of the received detection electronic signal generated by the fetus.

[0225] In step 1235, the fetal signal may be analyzed to determine the fetal hemoglobin oxygen saturation level using one or more of the methods disclosed herein, such as Formulas 1 and 2 above. In some embodiments, the execution of step 1235 may be similar to the execution of steps 740 and / or 840 of processes 700 and 800, respectively. Once the fetal hemoglobin oxygen saturation level is determined in step 1235, it can be conveniently displayed to the user, for example, on a display device (such as display device 155), to provide an indication of the fetal hemoglobin oxygen saturation level.

[0226] Figure 13 A flowchart is provided illustrating a process 1300 for determining fetal hemoglobin oxygen saturation levels using calibration factors and / or physiological characteristics of the pregnant mammal and / or fetus. Process 1300 may be performed by, for example, system 100 and / or its components.

[0227] First, the detected composite electronic signal can be received from a photodetector (e.g., detector 160) via a processor and / or computer (e.g., computer 150) (step 1305). The detected composite electronic signal can be received from, for example, a photodetector, a transceiver coupled to the photodetector, and / or a fetal hemoglobin probe, such as fetal hemoglobin probe 115. The detected composite electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal and / or its fetus. The light incident on and exiting the abdomen of the pregnant mammal may be generated by one or more light sources (e.g., light source 105) and may have any acceptable frequency or wavelength (e.g., near-infrared (NIR)) and / or a combination of frequency and / or wavelength. In some embodiments (e.g., when multiple detectors are used), the received detected composite electronic signal may include and / or be associated with a detector identifier, thereby indicating the location of a specific detected composite electronic signal. This location can then be used to analyze the received detected composite electronic signal to determine various factors of the detected light and / or the imaged tissue.

[0228] In some embodiments, step 1305 may also receive an indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-ductal. This indication may, in some cases, indicate from which part of the fetus the light signal was reflected, wherein a measurement from the fetal head would indicate a pre-ductal measurement (i.e., a higher fetal oxygen saturation level), while a measurement from the fetal body (e.g., the back or buttocks) would indicate a post-ductal measurement, with a lower expected fetal oxygen saturation level. This information can be provided, for example, by a user entering it after examining an image (such as an ultrasound or MRI image of the abdomen of the pregnant mammal), indicating from which part of the fetus the measurement was reflected.

[0229] Optionally, information about the fetus and / or pregnant mammal may be received (step 1310). Example information includes, but is not limited to, fetal heart rate, fetal ECG signal, maternal heart rate, maternal ECG signal, uterine contraction information of the pregnant mammal, maternal hemoglobin oxygen saturation, and / or maternal respiratory signal.

[0230] Next, the received detection composite electronic signal can be analyzed to separate the portion of the signal corresponding to the light incident on the fetus, thereby generating a fetal signal (step 1315). Step 1315 can be performed using any suitable method for separating the fetal signal from the received detection composite electronic signal. Suitable methods include, but are not limited to: applying filtering or amplification techniques, determining the portion of the detection composite electronic signal contributed by the pregnant mammal and then subtracting or otherwise removing that portion from the detection composite electronic signal, and / or receiving information about the fetal heart rate and using that information to lock (through, for example, a boxcar and / or a gated integrator and / or a lock-in amplifier) ​​the portion of the detection composite electronic signal that may be generated and / or influenced by the fetus. When information is received in step 1310, the execution of step 1315 may include using the information received in step 1310 to generate the fetal signal.

[0231] In step 1320, it can be determined whether the pregnant mammal is associated with the calibration factor. The pregnant mammal can be associated with the calibration factor, for example, by performing process 500 (whose execution is time-proximity to receiving the detection composite electronic signal in step 1305, e.g., simultaneously, within minutes, hours, days, and / or weeks)). In some cases, the calibration factor may be specific to the gestational age of the pregnant mammal and / or its fetus. When the pregnant mammal is associated with the calibration factor, process 1300 can proceed to step 1345, where the calibration factor can be received.

[0232] As an additional or alternative, one or more physiological characteristics of the pregnant mammal and / or fetus may be requested and / or determined (step 1325). Physiological characteristics may be determined, for example, by analyzing an image of the pregnant mammal's abdomen and / or measuring fetal depth. An example request may take the form of, for example, asking a question or request to the user via the fetal hemoglobin probe 115. The physiological characteristics may be received in any suitable manner, including but not limited to direct input by the user via an interface (e.g., keyboard or microphone), querying a database to obtain medical / physiological information about the pregnant mammal, etc. In some cases, the physiological characteristics will be demographic (e.g., age or skin color) and / or pregnancy-related (e.g., gestational age, fetal position in the abdomen, etc.). In step 1330, the physiological characteristics of the pregnant mammal and / or fetus may be received. The received physiological characteristics may then be used to query a database (e.g., database 170) to determine and / or select one or more calibration factors suitable for the pregnant mammal and / or fetus (step 1335).

[0233] In step 1340, the queried calibration factors may be received and applied to the fetal signal to calibrate or otherwise improve the fetal signal (e.g., clarify or enhance its accuracy). The calibrated signal may then be used to determine the fetal hemoglobin oxygen saturation level, thereby generating a calibrated fetal signal (step 1345). In some embodiments, the execution of step 1345 may include using each of the calibration factors received in step 1340 to generate corresponding calibration curves (which take into account one or more physiological characteristics of the pregnant mammal and / or fetus), and then applying these calibration curves to the fetal signal to calibrate and / or improve the fetal signal.

[0234] In step 1350, the calibrated fetal signal may be analyzed to determine fetal hemoglobin oxygen saturation, and the level of fetal hemoglobin oxygen saturation may be conveniently indicated to the user via, for example, a computer 150 and / or a display device (step 1355). Optionally, the execution of step 1355 may include indicating to the user whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter. This indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter can help clinicians determine whether the fetal hemoglobin oxygen saturation level is low enough to cause concern (e.g., indicating the possibility of fetal acidosis) or requires further intervention (such as cesarean section). Further details regarding the execution of step 1340 are provided below in connection with the discussion of process 1400, particularly the execution of steps 1425 and 1430.

[0235] Figure 14A flowchart is provided illustrating a process 1400 for determining fetal hemoglobin oxygen saturation levels using the physiological characteristics of the pregnant mammal and / or fetus. Process 1400 may be performed by, for example, system 100 and / or its components.

[0236] First, the detected composite electronic signal can be received from a photodetector (e.g., detector 160) via a processor and / or a computer (e.g., computer 150) (step 1405). The detected composite electronic signal can be received from, for example, a photodetector, a transceiver coupled to the photodetector, and / or a fetal hemoglobin probe (e.g., fetal hemoglobin probe 115). In some embodiments, similar to receiving an indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter in step 1405, the indication may also be received in step 1405.

[0237] The detection composite electronic signal may correspond to a light signal emitted from the abdomen of the pregnant mammal and / or its fetus. The light incident on and exiting the abdomen of the pregnant mammal may be generated by one or more light sources (such as light source 105) and may have any acceptable frequency or wavelength (e.g., near-infrared (NIR)) and / or combination of frequency and / or wavelength. In some embodiments (e.g., when using multiple detectors), the received detection composite electronic signal may include and / or be associated with a detector identifier, thereby revealing the location of reception of a specific detection composite electronic signal. This location can then be used to analyze the received detection composite electronic signal to determine various factors of the detected light and / or the imaged tissue.

[0238] In step 1410, physiological characteristics of the pregnant mammal and / or its fetus may be received. Examples of physiological characteristics include, but are not limited to, fetal depth within the abdomen, fetal position, skin pigmentation of the fetus and / or the pregnant mammal, uterine thickness, skin thickness, fetal tissue type, fetal tissue thickness, and density and / or thickness of various tissue layers included in the maternal abdomen (e.g., skin, fat, uterus, subcutaneous fat, amniotic fluid, fetus, etc.). In some embodiments, this physiological characteristic may be determined by analyzing, for example, images of the maternal abdomen (e.g., ultrasound or MRI). Figure 3A and 3B Examples are provided in the illustrations. As an additional or alternative, the physiological characteristic can be directly input by, for example, a doctor, user, and / or operator, by measuring, for example, an image of the abdomen of the pregnant mammal and / or a sample of the image.

[0239] In step 1415, a database (e.g., database 170) may be queried to obtain information on how this physiological characteristic may affect the behavior of light passing through the abdomen of the pregnant mammal and / or its fetus. This determination may be the result of performing procedures 500, 1300, and / or 1100.

[0240] In step 1420, the signal received in step 1405 may be analyzed to determine how the physiological characteristics may affect the behavior of light as it enters, passes through, and / or leaves the abdomen of the pregnant mammal.

[0241] Next, the received detection composite electronic signal can be analyzed to separate the portion of the signal corresponding to the light incident on the fetus (step 1425). In some cases, this separated portion of the signal may be referred to herein as the "fetal signal". Step 1425 can be performed using any suitable method for separating the fetal signal from the received detection composite electronic signal. Typically, the fetal signal is associated with a fetal pulsation signal, which can be used to separate the fetal signal from the composite electronic signal because the fetal signal (which is optical and included in the light signal) corresponds temporally to the fetal pulsation signal. This correspondence can be used to extract the fetal signal from the composite electronic signal. Suitable methods include, but are not limited to: reducing noise in the signal by, for example, applying filtering or amplification techniques; determining the portion of the detection composite electronic signal contributed by the pregnant mammal and then subtracting or otherwise removing that portion from the detection composite electronic signal; and / or receiving information about the fetal heart rate and using that information to lock (by, for example, a lock-in amplifier) ​​the portion of the detection composite electronic signal that may be generated and / or influenced by the fetus.

[0242] In step 1430, the fetal signal may be analyzed to determine the fetal hemoglobin oxygen saturation level. In some embodiments, two (or more) different detection composite electronic signals (also referred to herein as a first detection composite electronic signal and a second detection composite electronic signal) may be received in step 1405. The first and second detection composite electronic signals may have two different wavelengths and / or wavelength ranges and may be analyzed in step 1425 to create a first fetal signal and a second fetal signal. The first and second fetal signals may be analyzed and processed to determine the PPD pulse amplitude value of each fetal signal at enddiastole, thereby determining the first and second PPD pulse amplitudes at enddiastole, which may be referred to herein as ID1 and ID2, respectively. In some cases, the PPD pulse amplitude at enddiastole may be understood and / or referred to as the AC signal or value. Next, the first and second fetal signals can be analyzed and processed to determine the PPD pulse amplitude value of each fetal signal during systole, thereby determining the first and second PPD pulse amplitudes during systole, which are referred to herein as IS1 and IS2, respectively. In some cases, the PPD pulse amplitude during systole can be understood and / or referred to as the DC signal or value.

[0243] Next, the ratio (also known as "R") can be determined by performing calculations using the following formulas 4a and / or 4b, where:

[0244]

[0245] R = f(I) s ,I D Formula 4b

[0246] In some cases, R can be the average value, which is obtained by measuring I. D1 I D2 I S1 and I S2 Multiple values ​​and then calculate I D1 I D2 I S1 and I S2 The average value is used to determine R, and this value can be entered into equations 5a, 5b and / or 5C discussed below. Alternatively, to determine R, calculations can be performed multiple times (e.g., 70, 110, 120, etc.) using equations 4a and / or 4b to determine multiple R values, and then averaged to determine the average R value.

[0247] In some cases, the R value measured / calculated by performing process 1400 can be performed individually for each pregnant mammal or fetus to tailor or personalize the R value for each situation or fetus. In some embodiments, the R value may be correlated with the intrinsic saturated SpO2 value measured from independent control data. This uniqueness can be clinically significant because it provides a more accurate R measurement compared to R values ​​measured by the pulse oximeter or DOT manufacturer as an average across all situations. In some cases, the R value is provided by the pulse oximeter manufacturer and is based on an assessment of the results of experimental measurements. The problem with using this method is that it assumes that the conditions under which the pulse oximeter is used will be relatively consistent across different patients or situations, as is the case with fingers or earlobes, which are traditional locations for pulse oximetry on the human body. However, in the case of pregnant mammals and their fetuses, such an assumption cannot be adequately measured, as it does not present the predictability or consistency required to have sufficient confidence in the generalized R value measured by the manufacturer under average conditions. Sometimes, R may be measured multiple times during a monitoring session on, for example, on a continuous, periodic, or on-demand basis, so that the R value is specific to a particular point in time or situation. For example, during fetal labor, R-value measurements may be performed hourly, half-hourly, or minutely to adjust for changes in fetal and / or uterine movement and / or muscle expansion / contraction. Alternatively, R-values ​​may be measured (independent) quantities that may not be provided by the manufacturer of the pulse oximetry device. Calibration curves associated with these R-values ​​may be correlated with actual SpO2 values, empirically derived and incorporated by the manufacturer.

[0248] Sometimes, determining the fetal hemoglobin oxygen saturation level may include measuring the extinction coefficients (ε0) of oxyhemoglobin and (εd) of deoxyhemoglobin in the first and second fetal signals. The hemoglobin extinction coefficient can be understood as the absorption coefficient of the tissue in the study (e.g., μ). a (λ) is divided by the hemoglobin concentration. This absorption coefficient can be received and / or understood, for example, by performing process 1100 and / or step 1415. Once the extinction coefficients are determined (by looking them up, for example, in a table and / or database (such as database 170), they can be inserted into the following formula (Formula 5a) to determine fetal hemoglobin oxygen saturation (SpO2):

[0249]

[0250] in:

[0251] ε d1 =Extinction coefficient of deoxyhemoglobin with respect to λ1;

[0252] ε d2 =Extinction coefficient of deoxyhemoglobin with respect to λ2;

[0253] ε 01 = Extinction coefficient of oxyhemoglobin with respect to λ1;

[0254] ε 02 = Extinction coefficient of oxyhemoglobin with respect to λ2;

[0255] l1 = path length with respect to λ1; and

[0256] l2 = Path length with respect to λ2.

[0257] One or more of the calibration factor can be incorporated into this calculation using Equation 5b and / or Equation 5c, wherein:

[0258] SpO2=g(l1,l2,ε 01 ,ε 02 (P1, P2….) Equation 5b

[0259] SpO2=h(g,C 1, C2….) Equation 5c

[0260] in:

[0261] ε 01 = Extinction coefficient of oxyhemoglobin with respect to λ1;

[0262] ε 02 = Extinction coefficient of oxyhemoglobin with respect to λ2;

[0263] l1 = Path length with respect to λ1;

[0264] l2 = Path length with respect to λ2;

[0265] P1 = Calibration factor for the first physiological characteristic;

[0266] P2 = Calibration factor for the second physiological characteristic;

[0267] g = general formula, dependent on parameters: l1 l2, ε d1 ε d2 C1, C2, C3, etc.;

[0268] C1 = First detected electronic signal;

[0269] C2 = Second detection electronic signal; and

[0270] h = used to correlate physical features and measurement signals C i Empirical parameterization formulas.

[0271] Equation 5b allows the application of one or more calibration factors for one or more physiological characteristics in the calculation of fetal SpO2. Equation 5c allows the application of one or more calibration factors for one or more physiological characteristics for one or more detected electronic signals in the calculation of fetal SpO2.

[0272] Once measured, the fetal hemoglobin oxygen saturation (SpO2) value can be readily provided to the user (e.g., a doctor, nurse, or patient) (step 1435) by providing the indication, for example, to a display device (e.g., display device 155), or a computer (e.g., computer 150) screen or a device (e.g., fetal hemoglobin probe 115) screen.

[0273] Optionally, the execution of step 1435 may include indicating to the user, in a manner similar to the execution of step 1355, whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter. This indication of whether the fetal hemoglobin oxygen saturation level is pre- or post-catheter can help clinicians determine whether the fetal hemoglobin oxygen saturation level is low enough to cause concern (e.g., indicating the possibility of fetal acidosis) or requires further intervention (such as a cesarean section). Further details regarding the execution of step 1340 are provided below in connection with the discussion of process 1400, particularly the execution of steps 1425 and 1430.

[0274] As an addition or alternative, the execution of steps 1425 and / or 1430 may include the influence of one or more physiological characteristics, measured in step 1420, on the detection composite electronic signal, in the form of adjustments, such as to the scattering coefficient and / or absorption coefficient. For example, the detection composite electronic signal received in step 1405 may be the result of light with two different wavelengths being incident on the mother's abdomen. An example value for the first wavelength (λ1) varies between 760 nm and 805 nm, and an example value for the second wavelength (λ2) varies between 808 nm and 830 nm. Typically, the light with λ1 and λ2 will be monochromatic or within a narrow band of the electromagnetic spectrum. The light with both wavelengths may be incident on the abdomen of the pregnant mammal, collected via an optical fiber, and transmitted to one or more detectors (such as detector 160) and / or may be directly detected by detector 160. Next, the data collected by the detector can be interpreted and / or processed using Equations 6, 7a and 7b to determine the changes in absorption coefficient, oxyhemoglobin saturation (Δ[HbO]), and deoxyhemoglobin saturation (Δ[Hb]), respectively.

[0275]

[0276] Δμ can be used, for example, in Equation 6 above. aThe value of (λ) is used to determine the extinction coefficient (ε0) of oxyhemoglobin and / or the extinction coefficient (εd) of deoxyhemoglobin at wavelength λ. These values ​​for two different wavelengths λ1 and λ2 can then be used in Equations 7a and 7b to determine the relative change in oxyhemoglobin saturation (Δ[HbO]) and the relative change in deoxyhemoglobin saturation (Δ[Hb]).

[0277] The reconstruction algorithm can be used to consider, for example, the difference in path length between the light source and detector positions, fetal depth, etc., and can be used to reconstruct the predicted change Δμa of the absorption coefficient at the detector. Then, equations 7a and 7b can be solved to determine the changes in fetal oxyhemoglobin saturation (Δ[HbO]) and deoxyhemoglobin saturation (Δ[Hb]). In one example embodiment, these values ​​(Δ[HbO] and Δ[Hb]) can be used to determine the relative fetal hemoglobin oxygen levels. Alternatively or additionally, the values ​​of Δ[HbO] and Δ[Hb] can be used to generate a two-dimensional or three-dimensional map of the abdomen of the pregnant mammal to show the relative changes in oxyhemoglobin saturation (Δ[HbO]) and deoxyhemoglobin saturation (Δ[Hb]). Changes in oxyhemoglobin saturation (Δ[HbO]) and deoxyhemoglobin saturation (Δ[Hb]) can be displayed using, for example, grayscale or color coding, and these images can be topographic, profile, and / or volumetric images. Although this process does not provide an absolute value of fetal hemoglobin oxygen saturation, it provides a relative value, which can be used to monitor fetal hemoglobin oxygen saturation over time to determine its changes, which may indicate fetal distress, as seen in cases where fetal hemoglobin oxygen saturation levels decline rapidly or slowly.

[0278] Figure 15 provides a flowchart illustrating a process 1500 for determining a composite fetal hemoglobin oxygen saturation level using physiological characteristics of the pregnant mammal and / or fetus. Process 1500 may be performed by, for example, system 100 and / or its components. In some embodiments, process 1500 may be performed using a fetal hemoglobin probe (such as fetal hemoglobin probe 115 disclosed herein).

[0279] In step 1505, a first maternal detection electronic signal may be received by a processor. This first maternal detection electronic signal may be received from a first detector communicatively coupled to the processor. This first maternal detection electronic signal may correspond to a first light signal emitted from a first location on the abdomen of the pregnant mammal, which is detected and converted into the first maternal detection electronic signal by a first detector positioned adjacent to (at the top) the first location on the abdomen of the pregnant mammal. This first emitted light signal may be a portion of the light projected onto the abdomen of the pregnant mammal by a first light source. In some embodiments, the execution of step 1505 may be similar to the execution of step 905.

[0280] In step 1510, the first maternal detection electronic signal may be analyzed to optionally determine physiological characteristics (step 1515). Then, in response to the analysis, a first calibration factor may be determined for the first light signal emitted from the pregnant mammal at the first location (step 1520). In some embodiments, the execution of steps 1510, 1515, and / or 1520 may be similar to the execution of steps 910, 915, and / or 920, respectively.

[0281] In step 1525, a first maternal detection electronic signal may be received by a processor. This first maternal detection electronic signal may be received from a first detector communicatively coupled to the processor. This first maternal detection electronic signal may correspond to a first light signal emitted from a first location on the abdomen of the pregnant mammal, which is detected and converted into the first maternal detection electronic signal by a first detector positioned adjacent to (at the top) the first location on the abdomen of the pregnant mammal. This first emitted light signal may be a portion of the light projected onto the abdomen of the pregnant mammal by a first light source. In some embodiments, the execution of step 1525 may be similar to the execution of step 1505, but for a different maternal detection electronic signal (i.e., a second maternal detection electronic signal).

[0282] In step 1530, the first maternal detection electronic signal may be analyzed to optionally determine physiological characteristics (step 1535). Then, in response to the analysis, a first calibration factor may be determined for the first light signal emitted from the pregnant mammal at the first location (step 1540). In some embodiments, the execution of steps 1510, 1515, and / or 1520 may be similar to the execution of steps 1510, 1515, and / or 1520, respectively, but for a different maternal detection electronic signal (i.e., a second maternal detection electronic signal).

[0283] In some embodiments, the first and / or second physiological characteristics and / or the first and / or second calibration factors of the pregnant mammal may be stored in a database. Sometimes, an association may be established between the first physiological characteristic and the first calibration factor of the pregnant mammal and / or between the second physiological characteristic and the second calibration factor of the pregnant mammal, and this association may be stored in the database.

[0284] In step 1545, a first composite detection electronic signal may be received from the first detector. The first detector may be located adjacent to the first position on the abdomen of the pregnant mammal. In some embodiments (e.g., when the pregnant mammal wears a fetal hemoglobin probe for a period of time), the first composite detection electronic signal is received shortly after performing step 1505 (e.g., 0.5 seconds, 1 second, 1 minute, etc.). The first composite detection electronic signal may correspond to a third light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein, which is detected by the first detector and converted into the first composite detection electronic signal. The third emitted light signal may be a portion of the light projected onto the abdomen of the pregnant mammal and the fetus contained therein by, for example, the first and / or third light source.

[0285] The first composite signal can be analyzed or processed using one or more of the processes described herein to separate portions of the first composite electronic signal corresponding to the light incident on the fetus, thereby generating a first fetal signal using one or more of the methods disclosed herein (step 1550). Next, a first calibrated fetal signal can be generated by applying the first calibration factor to the first fetal signal (step 1555), and then the first calibrated fetal signal can be used to determine the first fetal hemoglobin oxygen saturation level (step 1560). The first fetal hemoglobin oxygen saturation level can be determined using any of the methods disclosed herein.

[0286] In step 1565, a second composite detection electronic signal may be received from the second detector. The second detector may be located adjacent to the second position on the abdomen of the pregnant mammal. In some embodiments (e.g., when the pregnant mammal wears a fetal hemoglobin probe for a period of time), the second composite detection electronic signal is received shortly after performing step 1505 (e.g., 0.5 seconds, 1 second, 1 minute, etc.). The second composite detection electronic signal may correspond to a third light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein, which is detected by the second detector and converted into the second composite detection electronic signal. The third emitted light signal may be a portion of the light projected onto the abdomen of the pregnant mammal and the fetus contained therein by, for example, the second and / or third light source.

[0287] The second composite signal can be analyzed or processed using one or more of the processes described herein to separate portions of the second composite electronic signal corresponding to the light incident on the fetus, thereby generating a second fetal signal using one or more of the methods disclosed herein (step 1570). Next, a second calibrated fetal signal can be generated by applying the two calibration factors to the second fetal signal (step 1575), and then the second calibrated fetal signal can be used to determine the second fetal hemoglobin oxygen saturation level (step 1580). This second fetal hemoglobin oxygen saturation level can be determined using any of the methods disclosed herein.

[0288] In step 1585, a composite fetal hemoglobin oxygen saturation level can be determined using the first and second fetal hemoglobin oxygen saturation levels. Step 1585 can be performed, for example, by taking the average of the first and second fetal hemoglobin oxygen saturation levels. In some embodiments, processes 1500 and / or steps 1545-1580 can be repeated continuously, periodically, and / or on demand, thereby allowing multiple fetal hemoglobin oxygen saturation levels to be measured over time. In these embodiments, the composite fetal hemoglobin oxygen saturation level may include more fetal hemoglobin oxygen saturation levels than the first and second fetal hemoglobin oxygen saturation levels measured in steps 1560 and 1580, and in some cases, these values ​​may be averaged, and / or the composite fetal hemoglobin oxygen saturation level may be a time-weighted average of all fetal hemoglobin oxygen saturation levels measured over a given time period (e.g., 5 minutes, 15 minutes, 1 hour, etc.). In step 1590, an indication of the composite fetal hemoglobin oxygen saturation level can be communicated to the user. In some cases, the indication of the first and / or second fetal hemoglobin oxygen saturation level may also be provided in step 1590. Alternatively, the indication of whether the fetal blood used to determine the fetal hemoglobin oxygen saturation level was pre- or post-ductal may also be provided in step 1590.

[0289] In the embodiments described herein, the light introduced into the abdomen and fetus of the pregnant mammal may have at least two independent wavelengths and / or frequencies (e.g., red, infrared, near-infrared, etc.), and the received detection electronic signals may correspond to light having these different wavelengths.

[0290] Therefore, systems, apparatus, and methods for measuring fetal oxygen levels are disclosed herein. In some embodiments, the use of the systems, apparatus, and methods described herein may be particularly useful during fetal delivery (e.g., during the first and / or second stages of labor) because it is difficult to assess fetal health during delivery.

[0291] In some embodiments, two or more of these processes, or portions thereof, may be combined and executed together in any order.

Claims

1. A method for performing transabdominal fetal oxygenation measurement or pulse oximetry, the method comprising: The processor receives physiological characteristics of a pregnant mammal, wherein the received physiological characteristics are measurements of hemoglobin oxygen saturation in the blood of the pregnant mammal received from a pulse oximetry probe. The processor measures how much light signal is absorbed by the oxygenated and deoxygenated hemoglobin of the pregnant mammal, indicated by the hemoglobin oxygen saturation, thereby determining the effect of this physiological characteristic on the behavior of the light signal projected onto the abdomen of the pregnant mammal; and In response to this effect, the calibration factor of the optical signal is determined by the processor.

2. The method of claim 1, further comprising: The processor receives a composite detection electronic signal from a detector that is communicatively coupled to the processor. The composite detection electronic signal corresponds to a light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein. The light signal is detected by the detector and converted into the composite detection electronic signal. The emitted light signal is a portion of the light projected by a light source onto the abdomen of the pregnant mammal and the fetus contained therein. The processor generates a fetal signal by separating a portion of the composite detection electronic signal that corresponds to the light incident on the fetus. The processor generates a calibrated fetal signal by applying the calibration factor to the fetal signal; The processor uses the calibrated fetal signal to determine the fetal hemoglobin oxygen saturation level; as well as This processor facilitates the provision of information about the fetal hemoglobin oxygen saturation level to the user.

3. The method of claim 1 or 2, wherein, The calibration factor used to measure the optical signal in response to this effect includes: The processor queries the database to obtain the calibration factor corresponding to the physiological characteristic.

4. The method of claim 2, further comprising: The processor receives a label indicating whether the fetal signal corresponds to pre- or post-ductal blood. as well as When it is convenient to provide the user with the fetal hemoglobin oxygen saturation level, the processor provides an indication of whether the fetal signal corresponds to pre- or post-ductal blood.

5. The method of claim 1, further comprising: The processor receives maternal detection electronic signals from a detector that is communicatively coupled to the processor. The maternal detection electronic signals correspond to light signals emitted from the abdomen of the pregnant mammal. The light signals are detected by the detector and converted into maternal detection electronic signals. The emitted light signals are the portion of light projected from a light source into the abdomen of the pregnant mammal. The processor analyzes the maternal detection electronic signal, wherein the physiological characteristics of the pregnant mammal are determined in response to the analysis.

6. The method of claim 5, further comprising: The processor stores the physiological characteristics of the pregnant mammal and the calibration factor in the database.

7. The method of claim 1, wherein, The physiological characteristic is received by at least one of the following devices: ultrasound device, Doppler device, abdominal image of the pregnant mammal, Fresnel scale reading, manual caliper, blood measuring device, pulse oximeter, pulse oximeter, and scale.

8. The method of claim 1, wherein, This physiological characteristic is intrinsic.

9. The method of claim 1, wherein, This physiological characteristic is external.

10. The method of claim 1, wherein, The physiological characteristics are the age of the pregnant mammal, the weight of the pregnant mammal, and the body mass index of the pregnant mammal.

11. The method of claim 1, wherein, The received physiological characteristic is the skin color of the pregnant mammal, and the determination of the effect of the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is absorbed by the skin color of the pregnant mammal.

12. The method of claim 1, wherein, The physiological characteristic of the reception is the thickness of the muscle layer in the abdomen of the pregnant mammal, and wherein the determination of the effect of the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is absorbed by the muscle layer in the abdomen of the pregnant mammal.

13. The method as described in claim 1, characterized in that, The physiological characteristic received is the thickness of the fat layer in the abdomen of the pregnant mammal, and the effect of determining the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is scattered by the fat layer in the abdomen of the pregnant mammal.

14. The method of claim 1, wherein, The physiological characteristic received is the body mass index of the pregnant mammal, and the determination of the effect of the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is scattered or absorbed by the abdomen of the pregnant mammal.

15. The method of claim 1, wherein, The physiological characteristic of the received light signal is the thickness of the abdomen of the pregnant mammal, and the determination of the effect of the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is absorbed by the abdomen of the pregnant mammal.

16. The method as described in claim 1, characterized in that, The physiological characteristic received is the thickness of the abdomen of the pregnant mammal, and the determination of the effect of the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is scattered by the abdomen of the pregnant mammal.

17. The method of claim 1, wherein, The physiological characteristic received is the hemoglobin concentration in the blood of the pregnant mammal, and the effect of determining the physiological characteristic on the behavior of the light signal includes determining how much of the light signal is absorbed by the hemoglobin of the pregnant mammal.

18. A method for performing transabdominal fetal oxygenation measurement or pulse oximetry, the method comprising: The processor receives maternal detection electronic signals from a detector that is communicatively coupled to the processor. These maternal detection electronic signals correspond to light signals emitted from the abdomen of the pregnant mammal. The light signals are detected by the detector and converted into maternal detection electronic signals. The emitted light signals are the portion of light projected from a light source into the abdomen of the pregnant mammal. as well as The processor analyzes the maternal detection electronic signals to determine the physiological characteristics of the pregnant mammal, including the hemoglobin oxygen saturation of the pregnant mammal's blood; and In response to the analysis, the processor determines a calibration factor for the light signal emitted by the pregnant mammal, wherein the calibration factor is related to the amount of the light signal absorbed by the oxygenated and deoxygenated hemoglobin of the pregnant mammal.

19. The method of claim 18, further comprising: The processor associates this physiological characteristic of the pregnant mammal with the calibration factor. The processor stores the association between the physiological characteristic of the pregnant mammal and the calibration factor in the database.

20. The method of claim 18 or 19, further comprising: The processor receives a composite detection electronic signal from a detector that is communicatively coupled to the processor. The composite detection electronic signal corresponds to a light signal emitted from the abdomen of the pregnant mammal and the fetus contained therein. The light signal is detected by the detector and converted into the composite detection electronic signal. The emitted light signal is a portion of the light projected by a light source onto the abdomen of the pregnant mammal and the fetus contained therein. The processor generates a fetal signal by separating a portion of the composite detection electronic signal that corresponds to the light incident on the fetus. The processor generates a calibrated fetal signal by applying the calibration factor to the fetal signal; The processor uses the calibrated fetal signal to determine the fetal hemoglobin oxygen saturation level; as well as This processor facilitates the provision of information about the fetal hemoglobin oxygen saturation level to the user.

21. The method of claim 18, wherein, The calibration factor used in this analysis to determine the optical signal includes: The processor queries the database to obtain the calibration factor corresponding to the physiological characteristic.

22. The method of claim 18, further comprising: The processor receives a label indicating whether the fetal signal corresponds to pre- or post-ductal blood. as well as When it is convenient to provide the user with the fetal hemoglobin oxygen saturation level, the processor provides an indication of whether the fetal signal corresponds to pre- or post-ductal blood.

23. The method of claim 18, wherein, This physiological characteristic is intrinsic.

24. The method of claim 18, wherein, This physiological characteristic is external.

25. The method of claim 18, wherein, The physiological characteristic of the measurement is the skin color of the pregnant mammal, and the calibration factor is related to how much of the light signal is absorbed by the skin color of the pregnant mammal.

26. The method of claim 18, wherein, The physiological characteristic measured is the thickness of the muscle layer in the abdomen of the pregnant mammal, and the calibration factor is related to how much of the light signal is absorbed by the muscle layer in the abdomen of the pregnant mammal.

27. The method of claim 18, wherein, The physiological characteristic measured is the thickness of the fat layer in the abdomen of the pregnant mammal, and the calibration factor is related to how much of the light signal is scattered by the fat layer in the abdomen of the pregnant mammal.

28. The method as described in claim 18, characterized in that, The physiological characteristic measured is the thickness of the abdomen of the pregnant mammal, and the calibration factor is related to how much of the light signal is absorbed by the abdomen of the pregnant mammal.

29. The method as described in claim 18, characterized in that, The physiological characteristic measured is the thickness of the abdomen of the pregnant mammal, and the calibration factor is related to how much of the light signal is scattered by the abdomen of the pregnant mammal.

30. The method of claim 18, wherein, The physiological characteristic measured is the hemoglobin concentration in the blood of the pregnant mammal, and the calibration factor is related to how much of the light signal is absorbed by the hemoglobin of the pregnant mammal.

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