Systems and methods for monitoring multiple tissue regions

Abstract

A medical monitoring system includes a first sensor with a first light emitter to emit a first light and a first set of multiple light detectors. The medical monitoring system also includes a second sensor with a second light emitter to emit a second light and a second set of multiple light detectors. The medical monitoring system further includes a processing system with one or more processors, as well as memory storing instructions that, when executed by the processing system, cause the processing system to determine respective regional oxygen saturation values within multiple tissue regions of a patient based on signals received from the first set of multiple light detectors and the second set of multiple light detectors.

Description

SYSTEMS AND METHODS FOR MONITORING MULTIPLE TISSUE REGIONSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U. S. Provisional Patent Application Serial No. 63 / 713,934, filed October 30, 2024, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure generally relates to medical monitoring systems and methods, and more particularly to systems and methods for monitoring multiple tissue regions.BACKGROUND

[0002] Various medical monitoring devices may be used to monitor physiological characteristics of an individual. For example, various sensors may measure temperature, blood pressure, oxygen saturation, and / or other physiological characteristics of the individual. A regional oximetry sensor may utilize wavelengths of light to measure oxygen saturation levels in tissue of the individual. In certain cases, the regional oximetry sensor may include an adhesive to enable application or adherence (e.g., attachment) to skin of the individual. After the application to the skin, the regional oximetry sensor may emit the wavelengths of light through the skin to measure the oxygen saturation levels in the tissue of the individual.

[0003] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it may be understood that these statements are to be read in this light, and not as admissions of prior art.SUMMARY

[0004] Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the disclosure. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0005] In one aspect, the present disclosure provides a medical monitoring system includes a first sensor with a first light emitter to emit a first light and a first set of multiple light detectors. The medical monitoring system also includes a second sensor with a second light emitter to emit a second light and a second set of multiple light detectors. The medical monitoring system further includes a processing system with one or more processors, as well as memory storing instructions that, when executed by the processing system, cause the processing system to determine respective regional oxygen saturation values within multiple tissue regions of a patient based on signals received from the first set of multiple light detectors and the second set of multiple light detectors. The signals are based on detection of the first light at the first set of multiple light detectors and the second set of multiple light detectors and detection of the second light at the first set of multiple of light detectors and the second set of multiple light detectors.

[0006] In one aspect, the present disclosure provides a medical monitoring system that includes a processing system with one or more processors. The medical monitoring system also includes memory storing instructions that, when executed by the processing system, cause the processing system to provide a first pulsed light drive signal over a first time period to instruct a first light emitter of a first sensor to emit a first light into tissue of a patient. Additionally, the instructions, when executed by the processing system, cause the processing system to provide a second pulsed light drive signal over a second time subsequent to the first time period to instruct a second light emitter of a second sensor to emit a second light into the tissue of the patient. Further, the instructions, when executed by the processing system, cause the processing system to determine a regional oxygen saturation value of a deep tissue region that includes a mid-cerebral artery of a patient based on signals received from multiple light detectors that detect the first light and the second light after the first light and the second light pass through the tissue of the patient.

[0007] In one aspect, the present disclosure provides a method of operating a medical monitoring system, wherein the method includes providing, using one or more processors, a first pulsed light drive signal over a first time period to instruct a first light emitter of a first sensor to emit a first light into tissue of a patient. The method also includes providing, using the one or more processors, a second pulsed light drive signal over a second time period subsequent to the first time period to instruct a second light emitter of a second sensor to emit a second light into the tissue of the patient. The method further includes receiving, at the one or more processors, signals from multiple light detectors that detect the first light and the second light after the first light and the second light pass through the tissue of the patient. The method further includes determining, using the one or more processors, respective regional oxygen saturation values within multiple tissue regions of a patient based on the signals.

[0008] Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and context of embodiments of the present disclosure without limitation to the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Advantages of the disclosed techniques may become apparent upon reading the following detailed description and upon reference to the drawings in which:

[0010] FIG. 1 is a perspective view of a medical monitoring system, in accordance with an aspect of the present disclosure;

[0011] FIG. 2 is a block diagram of the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure;

[0012] FIG. 3 is an example graph of a light drive signal that may be provided by light drive circuitry to a first light emitter of a first regional oximetry sensor and a second light emitter of a second oximetry sensor, wherein the first regional oximetry sensor and the second regional oximetry sensor may be utilized as part of the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure;

[0013] FIG. 4 is a schematic diagram of the first regional oximetry sensor and the second regional oximetry sensor applied to a patient, wherein the first regional oximetry sensor and the second regional oximetry sensor may be utilized as part of the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure;

[0014] FIG. 5 is an example of a graphical user interface that may be provided via a display of the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure;

[0015] FIG. 6 is a schematic diagram of the first regional oximetry sensor and the second regional oximetry sensor incorporated into a single sensor body that is applied to the patient, wherein the first regional oximetry sensor and the second regional oximetry sensor may be utilized as part of the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure; and

[0016] FIG. 7 is a flow diagram of a method of operating a medical monitoring system, such as the medical monitoring system of FIG. 1, in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0017] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciatedthat such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0018] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” “having” and “based on” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. As used herein, numerical terms, such as “first,” “second,” “third,” and so forth are merely provided to distinguish elements from one another to facilitate discussion.

[0019] Various sensors may measure various physiological parameters of an individual. For example, a regional oximetry sensor may use wavelengths of light to measure oxygen saturation in tissue of an individual. The regional oximetry sensor may include a light emitter that emits light at two or more wavelengths (e.g., red and infrared (IR) wavelengths) into tissue of the individual and two light detectors that detect the light after the light passes through the tissue of the individual. The two light detectors are spaced apart from one another and placed at difference distances from the light emitter to enable a near light detector and a far light detector to receive the light after the light passes through different regions of the tissue of the individual. For example, the near light detector may receive the light after the light passes through a surface tissue region of the tissue of the individual, while the far light detector may receive the light after the light passes through a shallow tissue region of the tissue of the individual.

[0020] During cerebral monitoring for certain patients, such as neonates and / or other individuals with a head circumference that is small in size (e.g., less than 40, 50, or 60 centimeters (cm)) and / or other individuals under a certain age (e.g., under 3, 6, 9, or 12 months old; due to a soft and / or translucent skull), the light may penetrate or reach a deep tissue region of the tissue of the individual. Indeed, for certain patients, the light may penetrate or reach deep cerebral tissue, such as ventricular spaces and / or a mid-cerebralartery. For example, the deep cerebral tissue may include the mid-cerebral artery (e.g., include the mid-cerebral artery and / or tissue surrounding the mid-cerebral artery; include a region of tissue that encompasses at least a portion of the mid-cerebral artery). Further, a depth of the light within the tissue of the individual may vary with the head circumference of the individual, particularly for neonates and / or other individuals with a head circumference that is small in size and / or other individuals under a certain age. For example, regional oxygen saturation (rSO₂) measurements obtained via the regional oximetry sensor may be lower in neonates with a head circumference that is small in size (e.g., less than 40 cm) due to the depth of the light within the tissue of the individual reaching the ventricular spaces, although values of the rSO₂ may plateau at smallest circumferences as the depth of the light reaches deep cerebral structures.

[0021] With the foregoing in mind, it is presently recognized that it would be desirable to utilize multiple regional oximetry sensors to monitor different tissue regions of a patient. For example, the multiple regional oximetry sensors may include a first regional oximetry sensor and a second regional oximetry sensor. The first regional oximetry sensor may include a first light emitter, a first near light detector, and a first far light detector. The second regional oximetry sensor may include a second light emitter, a second near light detector, and a second far light detector. A monitor may include a light drive circuitry that provides light drive signals to operate the first light emitter and the second light emitter in a coordinated manner. For example, the light drive signals may instruct the first light emitter to emit light at a first wavelength over a first time period and to emit light at a second wavelength over a second time period. Then, the light drive signals may instruct the second light emitter to emit light at the first wavelength over a third time period and to emit light at the second wavelength over a fourth time period. The light (e.g., each light emission from the first light emitter and the second light emitter) may be received at and detected by the first near light detector and the first far light detector of the first regional oximetry sensor, and the light may also be received at and detected by the second near light detector and the second far light detector of the second regional oximetry sensor.

[0022] In such cases, a portion of the light emitted by the first light emitter may reach the first near light detector after passing through a surface tissue region of the patient.Accordingly, respective signals generated by the first near light detector in response to detection of the portion of the light emitted by the first light emitter reflect oxygen saturation within the surface tissue region of the patient. Similarly, an additional portion of the light emitted by the first light emitter may reach the first far light detector after passing through a shallow tissue region of the patient. Accordingly, respective signals generated by the first far light detector in response to detection of the additional portion of the light emitted by the first light emitter reflect oxygen saturation within the shallow tissue region of the patient. Further, a further portion of the light emitted by the first light emitter may reach the second near light detector and the second far light detector after passing through a deep tissue region of the patient. Accordingly, respective signals generated by the second near light detector and the second far light detector in response to detection of the further portion of the light emitted by the first light emitter reflect oxygen saturation within the deep tissue region of the patient. It should be appreciated that similar techniques may be employed to utilize the light emitted by the second light emitter (e.g., the light emitted by the second emitter is detected at the first near light detector and the first far light detector of the first regional oximetry sensor, as well as at the second near light detector and the second far light detector of the second regional oximetry sensor).

[0023] Advantageously, embodiments disclosed herein may enable efficient monitoring of rSO₂ across multiple regions of tissue of the patient (e.g., one or more surface tissue regions, one or more shallow tissue regions, one or more deep tissue regions). Further, monitoring the rSO₂ across the multiple regions of the tissue of the patient may facilitate determining an autoregulation status of the patient (e.g., a cerebral autoregulation status, or other organ autoregulation status that may be derived from the cerebral autoregulation status). For example, in monitoring the rSO₂ across the multiple regions of the tissue of the patient, at least one of the multiple regions of the tissue of the patient may be identified to correlate to or include an indication of a mid-cerebral artery. Accordingly, the rSO₂ that is identified to correlate to or include the indication of the midcerebral artery may be utilized to determine the autoregulation status of the patient (e.g., based on a correlation between the rSO₂ and a blood pressure of the patient over a time period).

[0024] With the foregoing in mind, FIG. 1 is a perspective view of an embodiment of a medical monitoring system 10 that includes a monitor 12 (e.g., regional oximetry monitor) and multiple medical sensors 14 (e.g., regional oximetry sensors). Further, in the illustrated example, the multiple medical sensors 14 include a first regional oximetry sensor 20 with a first sensor body 22 that supports a first light emitter 24, a first near light detector 26, and a first far light detector 28. Together, the first near light detector 26 and the first far light detector 28 may be referred to as a first set of multiple light detectors. Additionally, in the illustrated embodiment, the multiple medical sensors 14 include a second regional oximetry sensor 30 with a second sensor body 32 that supports a second light emitter 34, a second near light detector 36, and a second far light detector 38.Together, the second near light detector 36 and the second far light detector 38 may be referred to as a second set of multiple light detectors.

[0025] As shown, with respect to the first regional oximetry sensor 20, the first near light detector 26 is positioned closer to the first light emitter 24 as compared to the first far light detector 28 (e.g., the first far light detector 28 is positioned further from the first light emitter 24; along a longitudinal axis of the first regional oximetry sensor 20; the first light emitter 24, the first near light detector 26, and the first far light detector 28 are stacked in a line along the longitudinal axis of the first regional oximetry sensor 20). Additionally, as shown, with respect to the second regional oximetry sensor 30, the second near light detector 36 is positioned closer to the second light emitter 34 as compared to the second far light detector 38 (e.g., the second far light detector 38 is positioned further from the second light emitter 34; along a longitudinal axis of the second regional oximetry sensor 30; the second light emitter 34, the second near light detector 36, and the second far light detector 38 are stacked in a line along the longitudinal axis of the second regional oximetry sensor 30).

[0026] Each sensor body 22, 32 may include multiple layers, such as a respective flexible circuit between a respective first layer (e.g., light blocking layer; metallized tape; plastic tape) and a respective second layer (e.g., light blocking layer; metallized tape; plastic tape). Each sensor body 22, 32 may include or be coupled to a respective patient adhesive that is utilized to couple (e.g., adhere) each sensor body 22, 32 to skin of thepatient. The first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be reusable, disposable, partially usable, or partially disposable.

[0027] As shown, the multiple medical sensors 14 may generate signals (e.g., nearinfrared spectroscopy (NIRS) signals; regional oximetry signals), and the monitor 12 may receive and process the signals to calculate regional oxygen saturation (rSO₂). In certain embodiments, the multiple medical sensors 14 may be positioned on a head of a patient; however, it should be understood that the multiple medical sensors 14 may be adapted for use at any of a variety of tissue locations, such as a foot, forehead, temple, stomach, chest, back, thigh, and / or any other suitable measurement site. Further, the medical monitoring system 10 may include additional types of sensors, such as one or more pulse oximetry sensors, one or more blood pressure sensors, and so forth. In such cases, the monitor 12 may be configured to receive and process respective signals (e.g., photoplethysmography (PPG) signals from the one or more pulse oximetry sensors; blood pressure signals from the one or more blood pressure sensors) to calculate respective physiological parameters (e.g., oxygen saturation (SpO₂); blood pressure measurements).

[0028] The multiple medical sensors 14 are communicatively coupled to the monitor 12, such as via one or more cables 35. The one or more cables 35 may interface directly with (e.g., contact; extend from; plug into) the monitor 12 and the multiple medical sensors 14. The one or more cables 35 may have any suitable structure (e.g., form, arrangement, configuration). For example, the one or more cables 35 may include a branched structure in which a single line (e.g., cable portion) extends from the monitor 12, and the single line branches into two branched lines (e.g., cable portions) that interface with a respective medical sensor of the multiple medical sensors 14. In certain embodiments, the one or more cables 35 may include separate cables (e.g., multiple cables) that separately extend from the monitor 12 (e.g., separate ports at the monitor 12) and interface with a respective medical sensor of the multiple medical sensors 14 (e.g., one cable for each of the multiple medical sensors 14). The one or more cables 35 may include multiple conductors (e.g., wires) to transmit signals and / or receive signals, as well as a cable sheath (e.g., insulator) to surround the multiple conductors. Additionally or alternatively, the multiple medical sensors 14 may communicate with the monitor 12wirelessly (e.g., the multiple medical sensors 14 and the monitor 12 include wireless transceivers configured to communicate via any suitable wireless protocol).

[0029] In operation, the monitor 12 may receive signals from the multiple medical sensors 14, and the monitor 12 may be configured to calculate one or more physiological parameters based on the signals. In particular, the monitor 12 may include a processor configured to execute code (e.g., stored in a memory of the monitor 12 or received from another device) to process the signals from the multiple medical sensors 14 to calculate the one or more physiological parameters, such as rSO₂. The monitor 12 may additionally or alternatively calculate any variety of additional physiological parameters, such as arterial blood oxygen saturation, pulse rate, respiration rate, blood pressure, autoregulation status, or any other suitable physiological parameter. For example, the monitor 12 may use the rSO₂ to calculate the autoregulation status of the patient. It should be appreciated that the autoregulation status may indicate blood pressures at which the patient is capable of autoregulating, such as via making certain physiological changes (e.g., constrict or dilate arterioles) to regulate blood flow during changes in blood pressure. For example, the autoregulation status may be intact between a lower limit of autoregulation (e.g., LLA; a first blood pressure value) and an upper limit of autoregulation (e.g., ULA; a second blood pressure value), wherein the LLA and the ULA are based on a correlation index (COx) of blood pressure values and rSO₂ values (e.g., respective rSO₂ for one or more deep tissue regions). Alternatively or additionally, the LLA and the ULA may be based on other parameters (e.g., other correlation coefficients and / or gradients).

[0030] Additionally, as illustrated in FIG. 1, the monitor 12 includes a display 37 (e.g., display screen) configured to display the one or more physiological parameters, such as rSO₂. The display 37 may also display other information, such as instructions to reposition the multiple medical sensors 14, alarm indications, settings, and so forth. In certain embodiments, the display 37 may be a touch screen display. The monitor 12 may include various input components, such as the touch screen display, knobs, switches, keys and keypads, buttons, and so forth, to provide for operation and configuration of the monitor 12. The monitor 12 may also include one or more indicator lights and / or one or more speakers. The monitor 12 may also include additional port(s) and / or wireless interfaces (e.g., channels) to connect to additional devices, such as additional sensors tomonitor additional physiological parameters of the patient and / or to monitor physiological parameters of other patients at one time.

[0031] Furthermore, one or more functions of the monitor 12 disclosed herein may also be implemented directly in the multiple medical sensors 14, or by any other suitable device. For example, in some embodiments, the multiple medical sensors 14 may include one or more processing components configured to calculate physiological parameters, such as rSO₂. The multiple medical sensors 14 may have varying levels of processing power, and may output data in various stages to the monitor 12. For example, in some embodiments, the data output to the monitor 12 may be analog signals, such as detected light signals (e.g., regional oximetry signals), or processed signals (e.g., filtered regional oxygen saturation signals; rSO₂ values).

[0032] Further, in some embodiments, each of the multiple medical sensors 14 may include a respective battery to provide power to components of the multiple medical sensors 14. For example, the multiple medical sensors 14 may be configured to operate in a wireless mode and, at times, may not receive power from the monitor 12 while operating in the wireless mode. In some embodiments, the battery may be a rechargeable battery such as, for example, a lithium ion, a lithium polymer, a nickel-metal hydride, a nickelcadmium battery, or any other suitable rechargeable battery. In other embodiments, any suitable power source may be utilized, such as, one or more capacitors or an energy harvesting power supply (e.g., a motion generated energy harvesting device, thermoelectric generated energy harvesting device, or any other suitable energy harvesting power supply).

[0033] FIG. 2 is a block diagram of an embodiment of the medical monitoring system 10. As shown, the medical monitoring system 10 includes the monitor 12 and the multiple medical sensors 14, including the first regional oximetry sensor 20 and the second regional oximetry sensor 30. With reference to the first regional oximetry sensor 20, the first light emitter 24 may include two light emitting diodes (LEDs) that are configured to emit at least two wavelengths of light, such as a first red LED 40 configured to emit wavelengths of light within the red spectrum and a first infrared (IR) LED 42 configured to emit wavelengths of light within the IR spectrum (e.g., IR or near IR spectrum). In certainembodiments, the first red LED 40 and the first IR LED 42 emit light in a range of about 600 nanometers (nm) to about 1000 nm. In certain embodiments, the first red LED 40 is configured to emit light between approximately 600 nm and 735 nm, and the first IR LED 42 is configured to emit light between approximately 800 nm and 1000 nm. It should be noted that the first light emitter 24 may include any number of LEDs and / or may be configured to transmit 3, 4, or 5 or more wavelengths of light in any suitable application.

[0034] With reference to the second regional oximetry sensor 30, the second light emitter 34 may include two light emitting diodes (LEDs) that are configured to emit at least two wavelengths of light, such as a second red LED 50 configured to emit wavelengths of light within the red spectrum and a second IR LED 52 configured to emit wavelengths of light within the IR spectrum. In certain embodiments, the second red LED 50 and the second IR LED 52 emit light in a range of about 600 nm to about 1000 nm. In certain embodiments, the second red LED 50 is configured to emit light between approximately 600 nm and 735 nm, and the second IR LED 52 is configured to emit light between approximately 800 nm and 1000 nm. It should be noted that the second light emitter 34 may also transmit 3, 4, or 5 or more wavelengths of light in any suitable application. Thus, the first red LED 40 and the second red LED 50 may both be configured to emit wavelengths of light within the red spectrum, and the first IR LED 42 and the second IR LED 52 may both be configured to emit wavelengths of light in the IR spectrum. Indeed, the first red LED 40 and the second red LED 50 may both be configured to or be specified to emit a same wavelength of light within the red spectrum (e.g., a same range of wavelengths; allowing for manufacturing tolerance), and the first IR LED 42 and the second IR LED 52 may both be configured to or specified to emit a same wavelength of light in the IR spectrum (e.g., a same range of wavelengths; allowing for manufacturing tolerance).

[0035] As discussed in more detail herein, a light drive circuitry 54 of the monitor 12 may provide respective light drive signals (e.g., drive currents) to the first red LED 40 and the first IR LED 42 of first light emitter 24, as well as to the second red LED 50 and the second IR LED 52 of the second light emitter 34 to cause respective LEDS 40, 42, 50, 52 to emit respective wavelengths of light. It should be understood that, as used herein, theterm "light" may refer to one or more of red, IR, visible, invisible light, and further that the light may have any suitable wavelength of light.

[0036] In any case, the first light emitter 24 and the second light emitter 34 emit light that passes through tissue of the patient. As described herein, the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38 detect the light as reflected and / or transmitted by the tissue of the patient. Optical density values are measured at the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38 for each wavelength of light emitted by the first light emitter 24 and the second emitter 34 (e.g., two, three, or four wavelengths of light emitted by the first light emitter 23 and the second light emitter 34 at different times or in sequence; one wavelength at a time; one light emission at a time). For example, in certain embodiments, the first light emitter 24 and the second light emitter 34 may each emit two or four different wavelengths of light, such as two or four wavelengths of light selected from λ1−Δ=690 nm, λ1=730 nm, λ2=770 nm and λ2+Δ=810 nm. With four different wavelengths of light, the wavelengths may be chosen to have a constant gap (Δ) between them, which in this exemplary embodiment is 40 nm.

[0037] In any case, for each wavelength introduced into the tissue of the patient, the optical density values of the light are detected and measured by the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. The optical density values are conveyed as electrical signals to the monitor 12, which then uses a processor 60 to process the electrical signals with one or more algorithms (e.g., stored in a memory 62) to generate useful physiological information related to rSO₂ (e.g., rSO₂ values). For example, the monitor 12 may compute and contrast the optical density values or corresponding absorption of the light at the multiple wavelengths as detected by each detector 26, 28, 36, 38 to derive rSO₂, and in particular, to derive rSO₂ within different tissue regions of the tissue of the patient. For example, to derive rSO₂ in at least the one or more surface tissue regions 130 and / or the one or more shallow tissue regions 132 using a particular sensor 20, 30, the rSO₂ may be determined based on intensity of the light detected at the light detectors 26, 28, 36, 38 (e.g., R = ln ( [ I₁(λ₁) / I₁(λ₂) ] / [ I₂(λ₁) / I₂(λ₂) ] ), wherein I₁(λ₁) is a respective intensity of a firstlight at a first wavelength at one detector, and I₁(λ₂) is a respective intensity of the first light at a second wavelength at the one detector, I₂(λ₁) is a respective intensity of a second light at the first wavelength at another detector, and I₂(λ₂) is a respective intensity of the second light at the second wavelength at the another detector). Further, the rSO₂ may be determined based on intensity of the light detected at the light detectors 26, 28, 36, 38, such as via rSO₂ = R(A*Mb(r₂- r₁)[c]) - 1 - (B / A), where r₁ and r₂ are spacings for respective light detectors (e.g., the light detectors 26, 28; the light detectors 36, 38) of the particular sensor 20, 30. A and B are constants related to extinction coefficients of oxygenated and reduced hemoglobin, and combined concentration of all hemoglobin, additionally factored by the concentration of blood in the tissue, is given by [c]. Further, Mb is an empirically determined constant relating to the mean path length of light through subdermal tissue. Further, the rSO₂ in at least the one or more deep tissue regions 134 may be derived based by accounting for the intensity of the light detected at the light detectors 26, 28, 36, 38 after the light passes through the one or more deep tissue region 134.

[0038] As shown, each of the multiple medical sensors 14 may include a respective encoder 58. For example, with respect to the first regional oximetry sensor 20, the respective encoder 58 may store information about the first regional oximetry sensor 20, such as a type of sensor, calibration information, wavelengths emitted by the first light emitter 24, spacing between optical components, first coefficients, and so forth. When accessed by the monitor 12, the information may be utilized by the monitor 12 to calculate rSO₂ and / or other physiological parameters using the signals generated by the first near light detector 26 and the first far light detector 28. For example, the monitor 12 may use the information to select and / or utilize an appropriate algorithm (e.g., first algorithm and / or with the first coefficients) to calculate rSO₂ and / or the other physiological parameters signals generated by the first near light detector 26 and the first far light detector 28.

[0039] In certain embodiments, the first regional oximetry sensor 20 may be designed for use on the patient having a head circumference of a certain size (e.g., within a certain range; below a threshold size, such as 40, 50, or 60 cm). During a patient monitoringsession, a clinician may input patient characteristics (e.g., the head circumference and / or age) at the monitor 12 and / or the monitor 12 may access the patient characteristics (e.g., from a database; based on a patient identifier that is used to identify the patient characteristics associated with the patient identifier in a lookup table). Further, the respective encoder 58 may provide the information about the first regional oximetry sensor 20 to the monitor 12, such as in response to connecting the first regional oximetry sensor 20 to the monitor 12. The monitor 12 may compare the patient characteristics to the information about the first regional oximetry sensor 20 to confirm that the patient characteristics correspond to the information about the first regional oximetry sensor 20 (e.g., to confirm that the first regional oximetry sensor 20 is appropriate for the patient; is an appropriate type, has appropriate specifications for the patient, such as appropriate spacing of the optical components). In response to confirming that the patient characteristics correspond to the information about the first regional oximetry sensor 20, the monitor 12 may take certain actions, such as provide a notification (e.g., via the display 37) to indicate that the first regional oximetry sensor 20 is appropriate for the patient and / or enable monitoring with the first regional oximetry sensor 20 (e.g., enable operation of the light drive circuitry 54 to provide the light drive signals to the first regional oximetry sensor 20, process the signals received from the first regional oximetry sensor 20 to determine rSCh, and / or display rSCh). However, in response to determining that the patient characteristics do not correspond to the information about the first regional oximetry sensor 20, the monitor 12 may take other certain actions, such as provide another notification (e.g., via the display 37) to indicate that the first regional oximetry sensor 20 is not appropriate for the patient and / or block monitoring with the first regional oximetry sensor 20 (e.g., block operation of the light drive circuitry 54 to provide the light drive signals to the first regional oximetry sensor 20, discard or do not process the signals received from the first regional oximetry sensor 20 to determine rSCh, and / or block display of rSCh).

[0040] It should be appreciated that same or similar techniques may be applied to the second regional oximetry sensor 30. For example, with respect to the second regional oximetry sensor 30, the respective encoder 58 may store information about the second regional oximetry sensor 30, such as a type of sensor, calibration information, wavelengthsemitted by the first light emitter 24, spacing between optical components, second coefficients, and so forth. When accessed by the monitor 12, the information may be utilized by the monitor 12 to calculate rSO₂ and / or other physiological parameters using the signals generated by the second near light detector 36 and the second far light detector 38. For example, the monitor 12 may use the information to select and / or utilize an appropriate algorithm (e.g., second algorithm and / or with the second coefficients) to calculate rSO₂ and / or the other physiological parameters signals generated by the second near light detector 26 and the second far light detector 28. In certain embodiments, the second medical sensor 20 may be designed for use on the patient having a head circumference of a certain size (e.g., within a certain range; below a threshold size, such as 40, 50, or 60 cm). Accordingly, the monitor 12 may be configured to determine whether the second regional oximetry sensor 30 is appropriate for the patient and carry out certain actions, as described herein with respect to the first regional oximetry sensor 20.

[0041] As shown, the monitor 12 includes a time processing unit (TPU) 56, which may be controlled by the processor 60 and is configured to provide timing control signals to the light drive circuitry 54 and optionally to other parts of the medical monitoring system 10. For example, the TPU 56 may provide timing control signals to the light drive circuitry 54 to control when the light drive circuitry 54 provides the light drive signals to cause illumination of the first red LED 40, the first IR LED 42, the second red LED 50, and the second IR LED 52. It should be appreciated that one or more functions or components of the monitor 12 disclosed herein may also be implemented directly in the multiple medical sensors 14, or by any other suitable device.

[0042] FIG. 3 is an example graph of a light drive signal 70 that may be provided by the light drive circuitry 54 of FIG. 2 to the first light emitter 24 of the first regional oximetry sensor 20 of FIGS. 1 and 2 and the second light emitter 34 of the second regional oximetry sensor 30 of FIGS. 1 and 2. In FIG. 3, the light drive signal 70 is a pulse signal with light drive pulses 72, 74, 76, 78 (e.g., high states; presence of drive current). The Light drive pulses 72, 74, 76, 78 may extend over any suitable time and cause corresponding light emission for any suitable time (e.g., less than or approximately 1, 2, 3, 4, or 5 milliseconds). It should be understood that the light drive pulses 72, 74, 76, 78 are shown as square waves merely as an illustrative example, and the light drive pulses 72, 74,76, 78 may include any other suitable waveform (e.g., shape). Further, the light drive signal 70 may include “off’ periods 80 (e.g., low states; absence of drive current) between the light drive pulses 72, 74, 76, 78. During the “off’ periods 80, the light drive circuitry 54 does not provide drive current to the first light emitter 24 and the second light emitter 34. The “off’ periods 80 may be provided, for example, to prevent overlap of the emitted light, since the LEDS 40, 42, 50, 52 may take time to turn completely on and completely off.

[0043] In certain embodiments, a first light drive pulse 72 may be provided to cause the first red LED 40 to emit light, a second light drive pulse 74 may be provided to cause the first IR LED 42 to emit light, a third light drive pulse 76 may be provided to cause the second red LED 50 to emit light, and a fourth light drive pulse 78 may be provided to cause the second IR LED 52 to emit light. As shown, red light drive pulses (e.g., the first light drive pulse 72 and the third light drive pulse 76) may have a higher amplitude than IR light drive pulses (e.g., the second light drive pulse 74 and the fourth light drive pulse 79) because the red LEDs 40, 50 may be less efficient than the IR LEDs 42, 52 at converting electrical energy into light energy, for example. However, in certain embodiments, output levels may be equal, may be adjusted for nonlinearity of emitters, may be modulated in any other suitable technique, or any combination thereof.

[0044] In FIG. 3, a period of time between a first time 82 and a second time 84 may be referred to as a drive cycle, which includes four light drive pulses, four “off’ periods, and eight total segments: the first light drive pulse 72, followed by one “off’ period 80, followed by the second light drive pulse 74, followed by another “off’ period 80, followed by the third light drive pulse 76, followed by another “off’ period 80, followed by the fourth light drive pulse 78, and followed by another “off’ period 80. After the second time 84, the drive cycle may be repeated, such as continuously or for some designated time during a patient monitoring session. It will be understood that a starting point of the drive cycle may be at any location within FIG. 3, provided the drive cycle spans four light drive pulses and four “off’ periods. The “off’ periods may also be referred to as dark periods, in that the LEDs 40, 42, 50, 52 are dark or returning to dark during the “off’ periods. It should also be understood that with use of more than two wavelengths of light, additional light drive pulses may be included in the light drive signal. For example, withfour wavelengths of light and two sensors, eight light drive pulses may be included in the light drive signal (e.g., per drive cycle; one light drive pulse for each wavelength of light per sensor; eight light drive pulses, eight “off’ periods, and sixteen total segments).

[0045] As described herein, for each wavelength introduced into the tissue of the patient (e.g., for each light emission provided according to the light drive pulses 72, 74, 76, 78), the optical density values of the light are detected and measured by the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. Thus, the detectors 26, 28, 36, 38 may generate signals while the light is being emitted from the LEDs 40, 42, 50, 52 (e.g., approximately at a same time; due to and / or in response to the light being emitted from the LEDs 40, 42, 50, 52). An amplitude of the signals generated by the detectors 26, 28, 36, 38 may be proportional to the light incident upon the detectors 26, 28, 36, 38. Further, peaks in the signals may be correlated to (e.g., synchronous or nearly synchronous; correspond) the light drive pulses 72, 74, 76, 78. For example, when the first light drive pulse 72 causes illumination of the first red LED 40, each of the detectors 26, 28, 36, 38 may generate a respective signal with a respective peak that is correlated to the fight emitted by the first red LED 40. Similarly, when the second light drive pulse 74 causes illumination of the first IR LED 42, each of the detectors 26, 28, 36, 38 may generate a respective signal with a respective peak that is correlated to the light emitted by the first IR LED 42, and so forth with respect to remaining LEDs. Additionally, the signals generated by the detectors 26, 28, 36, 38 may include valleys that may be correlated to the “off’ periods 80. It should be appreciated that the valleys may be zero or non-zero portions of the signals, such as non-zero but relatively low current due to detection of ambient light and / or factors.

[0046] FIG. 4 is a schematic diagram of an embodiment of the first regional oximetry sensor 20 and the second regional oximetry sensor 30 applied to a patient 100, such as to an exterior surface of a head 102 of the patient 100. As shown, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 are applied on generally opposite sides of the head 102 of the patient 100 (e.g., opposite temple regions of the head 102 of the patient 100). Further, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 are applied with the first light emitter 24 and the second light emitter 34 in an outside position (e.g., separated from one another by a first distance 104 acrossthe head 102 of the patient 100) and with the first far light detector 28 and the second far light detector 38 in an inside position (e.g., separated from one another by a second distance 106 across the head 102 of the patient 100, wherein the first distance 104 is greater than the second distance 106). However, it should be appreciated that the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be applied in any suitable configuration and / or at any suitable location on the patient 100. For example, the first regional oximetry sensor 20 may be applied to a front of the head 102 of the patient 100, while the second regional oximetry sensor 30 is applied to a back of the head 102 of the patient 100. As another example, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be stacked vertically on the head 102 of the patient 100 (e.g., stacked one on top of the other on a center portion of a forehead of the patient 100). It should be appreciated that additional regional oximetry sensors may be utilized together with the first regional oximetry sensor 20 and the second regional oximetry sensor 30, such as 1, 2, 3, 4, or more additional regional oximetry sensors, which may be applied in any suitable configuration and / or at any suitable location on the patient 100. For example, a third regional oximetry sensor may include a third light emitter, a third near light detector, and a third far light detector. In some such cases, the third near light detector, the third far light detector, and the detectors 26, 28, 36, 38 may detect light emitted by the first light emitter 24, the second light emitter 34, and the third light emitter to provide additional signals to monitor the patient 100.

[0047] With reference to FIG. 4, in operation, the first light emitter 24 may emit light into tissue of the patient 100. The first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38 detect the light as reflected and / or transmitted by the tissue of the patient 100. To facilitate discussion, FIG.4 includes respective lines representative of respective paths of the light from the first light emitter 24 to the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. For example, a first line 110 is representative of a first path of the light from the first light emitter 24 to the first near light detector 26, a second line 112 is representative of a second path of the light from the first light emitter 24 to the first far light detector 28, a third line 114 is representative of a third path of the light from the first light emitter 24 to the second near light detector 36, and afourth line 116 is representative of a fourth path of the light from the first light emitter 24 to the second far light detector 38. As described herein, the first light emitter 24 may be driven (e.g., via the light drive pulses 72, 74 in the light drive signal 70 of FIG. 3) to emit light at multiple wavelengths at separate times (e.g., via the first red LED 40 and the first IR LED 42 of FIG. 2).

[0048] Additionally, a fifth line 120 is representative of a fifth path of the light from the second light emitter 34 to the second near light detector 36, a sixth line 122 is representative of a sixth path of the light from the second light emitter 34 to the second far light detector 38, a seventh line 124 is representative of a seventh path of the light from the second light emitter 34 to the first near light detector 26, and a eighth line 126 is representative of an eighth path of the light from the second light emitter 34 to the first far light detector 28. As described herein, the second light emitter 34 may be driven (e.g., via the light drive pulses 76, 78 in the light drive signal 70 of FIG. 3) to emit light at multiple wavelengths at separate times (e.g., via the second red LED 50 and the second IR LED 52 of FIG. 2).

[0049] For each wavelength introduced into the tissue of the patient 100, the optical density values of the light are detected and measured by the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. Thus, for each wavelength introduced into the tissue of the patient 100, the first near light detector 26 generates respective signals indicative of the optical density values of the light as detected and measured by the first near light detector 26. Similarly, for each wavelength introduced into the tissue of the patient 100, the first far light detector 28 generates respective signals indicative of the optical density values of the light as detected and measured by the first far light detector 28. Further, for each wavelength introduced into the tissue of the patient 100, the second near light detector 36 generates respective signals indicative of the optical density values of the light as detected and measured by the second near light detector 36. Further, for each wavelength introduced into the tissue of the patient 100, the second far light detector 38 generates respective signals indicative of the optical density values of the light as detected and measured by the second far light detector 38.

[0050] Advantageously, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be operated (e.g., by the monitor 12 of FIG. 1) to enable efficient monitoring of rSO₂ across multiple regions of tissue of the patient 100. For example, the multiple regions of the tissue of the patient 100 may include one or more surface tissue regions 130 (e.g., non-cerebral tissue; skin and other tissue near a surface of the skin), one or more shallow tissue regions 132 (e.g., outer cerebral tissue), and / or one or more deep tissue regions 134 (e.g., deep cerebral tissue, including ventricular spaces and / or midcerebral artery). With reference to the first line 110, the light from the first light emitter 24 may reach the first near light detector 26 after passing through a respective surface tissue region 130. With reference to the second line 112, the light from the first light emitter 24 may reach the first far light detector 28 after passing through a respective shallow tissue region 132. With reference to the third line 114 and the fourth line 116, the light from the first light emitter 24 may reach the second near light detector 36 and the second far light detector 38 after passing through a respective deep tissue region 134 (e.g., a first deep tissue region).

[0051] Further, with reference to the fifth line 120, the light from the second light emitter 34 may reach the second near light detector 36 after passing through a respective surface tissue region 130. With reference to the sixth line 122, the light from the second light emitter 34 may reach the second far light detector 38 after passing through a respective shallow tissue region 132. With reference to the seventh line 124 and the eighth line 126, the light from the second light emitter 34 may reach the first near light detector 26 and the first far light detector 28 after passing through a respective deep tissue region 134 (e.g., the first deep tissue region and / or a second deep tissue region that is different from the first deep tissue region).

[0052] As a result, the monitor 12 may receive and process the signals from the detectors 26, 28, 36, 38 to determine the rSCh across multiple regions of tissue of the patient 100, including the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue region 134. It should be appreciated that the monitor 12 may implement any of a variety of processing techniques and utilize any of a variety of algorithms to process the signals from the detectors 26, 28, 36, 38 to determine the rSO2across multiple regions of tissue of the patient 100. For example, for aparticular sensor 20, 30, respective optical density values at the near detectors 26, 36 for each wavelength may be subtracted from respective optical density values at far detectors 26, 36 for each wavelength. As another example, for a particular sensor 20, 30, respective amount of absorption computed for the near detectors 26, 36 for each wavelength may be subtracted from respective amount of absorption computed for the far detectors 28, 38 for each wavelength. Resulting optical density values or absorptions may be used to compute the rSO2for the one or more shallow tissue regions 132, as the light passed through the one or more surface tissue regions 130 to reach the one or more shallow tissue regions 132. In other words, for a particular sensor 20, 30, because the far detectors 28, 38 receive the light that passed through the one or more shallow tissue regions 132 in addition to the one or more surface tissue regions 130, the rSO2may be computed for only the one or more shallow tissue regions 132 by subtracting out the optical density values (e.g., an amount of light) measured by the near detectors 26, 36 or corresponding absorption. Similarly, with both sensors 20, 30, the rSO2may be computed for only the one or more deep tissue regions 134 by subtracting out appropriate optical density values or corresponding absorption (e.g., representative of the optical density values or corresponding absorption in the one or more surface tissue regions 130 and the one or more shallow tissue regions 132).

[0053] Further, use of both sensors 20, 30 may enable additional processing and analysis of the patient 100. For example, it is expected or desirable for the rSO2to be consistent throughout the tissue of the patient 100, or at least across multiple surface tissue regions 130, across multiple shallow tissue regions 132, and / or across multiple deep tissue regions 134. Further, it may be expected or desirable for the rSO2to be consistent across multiple surface and shallow tissue regions 130, 132; across multiple shallow and deep tissue regions 132, 134; and / or across all regions 130, 132, 134. For example, it may be expected or desirable for a respective rSO2measured at a one region to be consistent with or correspond to a respective rSO2measured at a another region, such as varying by less than a threshold percentage, such as varying by less than 1, 2, 3, 4, or 5 percent.Accordingly, the monitor 12 may compare multiple rSO2values across multiple regions and provide an alert (e.g., notification; visible and / or audible alarm) in response to determining that the multiple rSO2values across multiple regions do not correspond to oneanother (e.g., vary by more than the threshold percentage). In certain embodiments, the monitor 12 may calculate and / or output (e.g., via the display 37) one or more variability indicators based on variability between the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue regions 134. For example, the one or more variability indicators may each include or reflect a variability percentage across any selected or designated regions (e.g., a variability indicator of three when a respective rSO2measured at a one region varies by three percent from a respective rSO2measured at a another region).

[0054] In some cases, the multiple rSO2values across multiple regions may not correspond to one another due to improper placement on the patient 100 and / or improper size and / or type of the multiple medical sensors 14. Thus, the alert may prompt the clinician to reposition the multiple medical sensors 14 and / or to confirm the type of the multiple medical sensors 14. However, the multiple rSO2values across multiple regions may not correspond to one another due to improper blood flow and / or oxygenation in the tissue of the patient 100. Thus, the alert may notify the clinician of a medical issue with respect to rSO2of the patient 100. It should be appreciated that the monitor 12 may provide an initial alert (e.g., a first alert after placement of the multiple medical sensors 14 on the patient 100 and / or within an initial period of time of initial monitoring of the patient 100 with the multiple medical sensors 14, such as within 0.5, 1, or 2 minutes) to prompt the clinician to reposition the multiple medical sensors 14 and / or to confirm the type of the multiple medical sensors 14. Subsequently, any further alerts may notify the clinician of a potential medical issue with respect to the rSO2of the patient 100. It should be appreciated that the monitor 12 may compare respective rSO2values, optical density detected at the detectors 26, 28, 36, 38, and / or corresponding absorption of the light in order to compare regions and / or identify inconsistencies across regions.

[0055] In certain embodiments, the monitor 12 may aggregate the respective rSO2values across the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue regions 134 to generate one or more aggregate rSO2values. For example, the monitor 12 may generate the one or more aggregate rSO2values as a median of the respective rSO2values, an average of the respective rSO2values, and / or a weighted average of the respective rSO2values. In theweighted average, the monitor 12 may apply a lowest weight to the one or more surface tissue regions 130, an intermediate weight the one or more shallow tissue regions 132, and / or a highest weight to the one or more deep tissue regions 134; however, any of a variety of weighting schemes are envisioned.

[0056] Additionally or alternatively, the monitor 12 may generate one or more scores based on the respective rSO2values and / or the variability across the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue regions 134. The one or more scores may be any numerical score (e.g., on a scale of 1-10), any category score (e.g., good, poor; high, medium, low), and so forth that may provide a helpful indicator of overall cerebral health with respect to rSO2. For example, the one or more scores may take in account and / or reflect both the respective rSO2values and / or the variability, so that the one or more scores indicate high cerebral health when a particular rSO2value (e.g., the aggregate rSO2; the respective rSO2for the one or more deep tissue regions) is within a respective target percentage range (e.g., over 75 percent; within 10 percent of baseline) and / or the variability is within a respective target percentage range (e.g., less than 5 percent), medium cerebral health when the particular rSO2value is within the respective target percentage range and / or the variability is not within the respective target percentage range, and a low cerebral health when the particular rSO2value is outside of the respective target percentage range regardless of the variability.

[0057] FIG. 5 is an example of a graphical user interface (GUI) 140 that may be presented for visualization by the clinician. While the example refers to the GUI 140 being presented via the display 37, it should be appreciated that the GUI 140 may be presented via any suitable device (e.g., a handheld device of the clinician, such as a mobile phone or tablet; a remote monitoring station separate from the monitor 12). As described herein, the GUI 140 may include the one or more aggregate rSO2values 142, the one or more variability indicators 144, and / or the one or more scores 146. In certain embodiments, the GUI 140 may include an indication of autoregulation status (e.g., cerebral autoregulation status), which may include a text indication (e.g., intact, impaired) and / or a graphical indication (e.g., blood pressure signal overlaid onto blood pressure ranges identified and labeled as intact or impaired).

[0058] As shown, the GUI 140 may include an image 150 (e.g., diagram; schematic) that illustrates representations of one or more tissue regions of the patient, such as representations of the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue regions 134 (in FIG. 5, the representations of the one or more tissue regions are labeled with same numerical indicators as the one or more tissue regions in FIG. 4 to facilitate understanding and relationship between these features). Further, as shown, respective rSO2values 152 may be overlaid onto the representations of the one or more tissue regions of the patient (e.g., a first rSO2value over a first surface tissue region 130, a second rSO2value over a second surface tissue region 130, and so forth). It should be appreciated that the respective rSO2values 152 may be presented proximate to (e.g., overlaid onto, adjacent to, above, below, beside) the representations of the one or more tissue regions of the patient or at any other suitable location. Additionally or alternatively, the respective rSO2values 152 may be presented in a table or list format.

[0059] The GUI 140 may enable the clinician to provide user inputs (e.g., via touchscreen and / or keyed inputs) to adjust display parameters. For example, the clinician may select one of the one or more tissue regions to obtain additional information about the selected one of the one or more tissue regions, such as a graph 154 of the respective rSO2values for the selected one of the one or more tissue regions over time. As another example, the clinician may input a preference to only display the respective rSO2values for the one or more deep tissue regions 134, and the GUI may be adjusted accordingly. As another example, the clinician may input a preference to only display an aggregate rSO2value for certain tissue regions, and the GUI 140 may be adjusted accordingly. Further, it should be appreciated that the GUI 140 may be updated over time, such as based on additional signals received during a patient monitoring session, to reflect current information (e.g., the one or more aggregate rSO2values 142, one or more variability indicators 144, the one or more scores 146, the autoregulation status 148, and / or the respective rSO2values 152).

[0060] FIG. 6 is a schematic diagram of an embodiment of the first regional oximetry sensor 20 and the second regional oximetry sensor 30 incorporated into a single sensor body 160 that is applied to the patient 100, wherein the first regional oximetry sensor 20and the second regional oximetry sensor 30 may be utilized as part of the medical monitoring system 10 of FIG. 1. The first regional oximetry sensor 20 and the second regional oximetry sensor 30 may include any of the features set forth in and described with respect to FIG. 4; however, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 are supported by the single sensor body 160. The single sensor body 160 may include or be coupled to a respective patient adhesive that is utilized to couple (e.g., adhere) the single sensor body 160 (and thus, the first regional oximetry sensor 20 and the second regional oximetry sensor 30) to skin of the patient 100.

[0061] For example, as set forth in and described with respect to FIG. 4, the single sensor body 160 may be placed such that the first regional oximetry sensor 20 and the second regional oximetry sensor 30 are applied on generally opposite sides of the head 102 of the patient 100 (e.g., opposite temple regions of the head 102 of the patient 100). Further, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be applied with the first light emitter 24 and the second light emitter 34 in an outside position and with the first far light detector 28 and the second far light detector 38 in an inside position. However, it should be appreciated that that the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be incorporated into the single sensor body 160 in any suitable configuration and / or may be applied at any suitable location on the patient 100. It should be appreciated that additional regional oximetry sensors may be utilized together with the first regional oximetry sensor 20 and the second regional oximetry sensor 30, such as 1, 2, 3, 4, or more additional regional oximetry sensors, which may be incorporated into the single sensor body 160 and / or may be separate from the single sensor body 160 (e.g., separate regional oximetry sensors and / or multiple additional regional oximetry sensors incorporated into an additional single sensor body).

[0062] In operation, the first light emitter 24 may emit light into tissue of the patient 100, and then the second light emitter 34 may emit light into the tissue of the patient 100. The first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38 detect the light as reflected and / or transmitted by the tissue of the patient 100. To facilitate discussion, FIG. 6 also includes respective lines representative of respective paths of the light from the first light emitter 24 to the first nearlight detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. Further, FIG. 6 includes respective lines representative of respective paths of the light from the second light emitter 34 to the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. As described herein, the first light emitter 24 may be driven (e.g., via the light drive pulses 72, 74 in the light drive signal 70 of FIG. 3) to emit light at multiple wavelengths at separate times (e.g., via the first red LED 40 and the first IR LED 42 of FIG. 2). Further, the second light emitter 34 may be driven (e.g., via the light drive pulses 76, 78 in the light drive signal 70 of FIG. 3) to emit light at multiple wavelengths at separate times (e.g., via the second red LED 50 and the second IR LED 52 of FIG. 2).

[0063] For each wavelength introduced into the tissue of the patient 100, the optical density values of the light are detected and measured by the first near light detector 26, the first far light detector 28, the second near light detector 36, and the second far light detector 38. Advantageously, the first regional oximetry sensor 20 and the second regional oximetry sensor 30 may be operated (e.g., by the monitor 12 of FIG. 1) to enable efficient monitoring of rSO₂ across multiple regions of tissue of the patient 100. For example, as described herein, the monitor 12 may receive and process the signals from the detectors 26, 28, 36, 38 to determine the rSCh across multiple regions of tissue of the patient 100, including the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue region 134.

[0064] In certain embodiments, the single sensor body 160 may support one or more additional emitters and / or one or more additional detectors. Further, relative spacing and / or positioning of the optical components (e.g., all emitters and detectors) may be known (e.g., stored in one or more encoders incorporated into the single sensor body 160; stored at and / or accessible by the monitor 12). In such cases, based on patient characteristics (e.g., the head circumference and / or age), the monitor 12 may drive certain emitters (e.g., only certain emitters) and / or process signals from certain detectors (e.g., only certain detectors) to target certain regions of tissue of the patient 100, such as to determine the respective rSO2values for the one or more surface tissue regions 130, the one or more shallow tissue regions 132, and / or the one or more deep tissue region 134 given the patient characteristics. For example, based on historical data (e.g., empiricaland / or modeled data), it may be determined that a first configuration (e.g., first optical components with first relative spacing) enables monitoring the certain regions given a first set of patient characteristics for a first patient (e.g., a first head circumference and / or age), while a second configuration (e.g., second optical components with second relative spacing) enables monitoring the certain regions given a second set of patient characteristics for a second patient (e.g., a second head circumference and / or age), and so forth. Thus, such techniques enable the medical monitoring system 10 to provide efficient, accurate monitoring for patients of different patient characteristics.

[0065] In certain embodiments, the single sensor body 160 may form or be part of an annular structure 162 (e.g., ring; band) that is configured to wrap circumferentially about the head 102 of the patient 100. For example, in FIG. 6, an optional band 164 is coupled to the single sensor body 160 to form the annular structure 162. A sensor 166 (e.g., strain gauge) may be incorporated into the annular structure 162, and the sensor 166 may generate an output (e.g., signal) indicative of the head circumference of the head 102 of the patient 100. When the single sensor body 160 (and thus, the first regional oximetry sensor 20 and the second regional oximetry sensor 30) is coupled to the the monitor 12, the sensor 166 may provide the output indicative of the head circumference of the head 102 of the patient 100. In this way, the annular structure 162 may enable automated detection and input of the head circumference of the head 102 of the patient 100, and then the monitor 12 may confirm that the single sensor body 160 is appropriate for the patient 100, operate certain emitters, operate and / or process signals from certain detectors, use certain algorithms, label or associate certain rSO2values with certain tissue regions of the patient 100, and so forth as appropriate for the patient 100 given the head circumference of the head 102 of the patient 100.

[0066] FIG. 7 is a flow diagram of a method 180 of operating the medical monitoring system 10 of FIG. 1, in accordance with an aspect of the present disclosure. The following description of the method 180 is described as being performed by a processing system (e.g., the processor 60 of the monitor 12), but it should be noted that any suitable processor-based device or system may be specially programmed to perform any of the methods described herein. Moreover, although the following description of the method 180 is described as including certain steps performed in a particular order, it should beunderstood that the steps of the method 180 may be performed in any suitable order, that certain steps may be omitted, and / or that certain steps may be added.

[0067] In block 182, the method 180 may begin with instructing a first light emitter to emit light (e.g., first light) into tissue of a patient. As described herein, a processing system may drive the first light emitter (e.g., via light drive pulses) to emit the light at multiple wavelengths at separate times (e.g., via a first red LED and a first IR LED of the first light emitter). The first light emitter may be supported in a first sensor body of a first regional oximetry sensor, which is applied (e.g., adhered) to skin of the patient.

[0068] In block 184, the method 180 may continue with receiving signals indicative of the light detected by multiple detectors. The multiple detectors may include multiple sets of multiple detectors. For example, the multiple detectors may include a first near light detector and a first far light detector, which may be supported in the first sensor body of the first regional oximetry sensor. Similarly, the multiple detectors may include a second near light detector and a second far light detector, which may be supported in a second sensor body of a second regional oximetry sensor. Each of the multiple detectors may generate a respective signal indicative of optical density of the light, and each of the multiple detectors may provide the respective signal to the processing system.

[0069] In block 186, the method 180 may continue with instructing a second light emitter to emit additional light (e.g., second light) into the tissue of the patient. As described herein, the processing system may drive the second light emitter (e.g., via light drive pulses) to emit the additional light at multiple wavelengths at separate times (e.g., via a second red LED and a second IR LED of the second light emitter). The second light emitter may be supported in the second sensor body of the second regional oximetry sensor, which is applied (e.g., adhered) to skin of the patient.

[0070] In block 188, the method 180 may continue with receiving additional signals indicative of the additional light detected by the multiple detectors. The multiple detectors may include the multiple sets of multiple detectors. For example, the multiple detectors may include the first near light detector and the first far light detector, as well as the second near light detector and the second far light detector. Each of the multiple detectorsmay generate a respective additional signal indicative of optical density of the additional light, and each of the multiple detectors may provide the respective additional signal to the processing system.

[0071] In block 190, the method 180 may continue with determining rSO2based on the signals and the additional signals. In particular, the rSO2may include respective rSO2values for multiple tissue regions of the patient, such as one or more surface tissue regions, one or more shallow tissue regions, and / or one or more deep tissue regions. Further, the one or more deep tissue regions may include deep cerebral tissue, such as ventricular spaces and / or mid-cerebral artery. It should be appreciated that the processing system may employ any of a variety of processing techniques and any of a variety of algorithms to process the signals and the additional signals to determine the respective rSO2values for the multiple tissue regions of of the patient, as well as to determine other metrics, such as one or more aggregate rSO2values, one or more variability indicators, one or more scores, autoregulation status, and so forth.

[0072] In block 192, the method 180 may continue with providing an indication of the rSO2, such as on a display. For example, the method 180 may include generating a GUI and / or providing instructions to display the GUI that includes the one or more aggregate rSO2values, the one or more variability indicators, and / or the one or more scores. The GUI may include an indication of autoregulation status (e.g., cerebral autoregulation status), which may include a text indication (e.g., intact, impaired) and / or a graphical indication (e.g., blood pressure signal overlaid onto blood pressure ranges identified and labeled as intact or impaired). The GUI may include an image (e.g., diagram; schematic) that illustrates representations of the one or more tissue regions of the patient, and the respective rSO2values may be positioned proximate to the representations of the one or more tissue regions of the patient. However, the GUI may include any of a variety of other formats and information to facilitate monitoring the patient (e.g., the respective rSO2values in a table or list format).

[0073] While the disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood thatthe embodiments provided herein are not intended to be limited to the particular forms disclosed. Rather, the various embodiments may cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the following appended claims. It should be appreciated that any features shown or described herein, such as with reference to FIGS. 1-7, may be combined in any suitable manner.

[0074] Features may be further described by reference to the following examples:

[0075] Example 1: A medical monitoring system, comprising: a first sensor, comprising a first light emitter to emit a first light and a first plurality of light detectors; a second sensor, comprising a second light emitter to emit a second light and a second plurality of light detectors; a processing system comprising one or more processors; and memory storing instructions that, when executed by the processing system, cause the processing system to determine respective regional oxygen saturation values within a plurality of tissue regions of a patient based on signals received from the first plurality of light detectors and the second plurality of light detectors, wherein the signals are based on detection of the first light at the first plurality of light detectors and the second plurality of light detectors and detection of the second light at the first plurality of light detectors and the second plurality of light detectors

[0076] Example 2: The medical monitoring system of example 1, wherein the plurality of tissue regions comprises one or more surface tissue regions, one or more shallow tissue regions, and one or more deep tissue regions

[0077] Example 3: The medical monitoring system of any of examples 1 or 2, wherein at least one tissue region of the plurality of tissue regions comprises a mid-cerebral artery.

[0078] Example 4: The medical monitoring system of any of examples 1 to 3, wherein the instructions, when executed by the processing system, cause the processing system to drive the first light emitter to emit the first light and the second light emitter to emit the second light in sequence.

[0079] Example 5: The medical monitoring system of any of examples 1 to 4, wherein the instructions, when executed by the processing system, cause the processing system todrive a respective first light emitting diode of the first light emitter to emit the first light within a first wavelength range over a first time period, drive a respective second light emitting diode of the first light emitter to emit the first light within a second wavelength range over a second time period, drive a respective first light emitting diode of the second light emitter to emit the second light within the first wavelength range over a third time period, and drive a respective second light emitting diode of the second light emitter to emit the second light within the second wavelength range over a fourth time period.

[0080] Example 6: The medical monitoring system of any of examples 1 to 5, wherein the instructions, when executed by the processing system, cause the processing system to determine an aggregate regional oxygen saturation value based on the respective regional oxygen saturation values within the plurality of tissue regions of the patient.

[0081] Example 7: The medical monitoring system of example 6, wherein the instructions, when executed by the processing system, cause the processing system to determine the aggregate regional oxygen saturation value based on a median, an average, or a weighted average of the respective regional oxygen saturation values within the plurality of tissue regions of the patient.

[0082] Example 8: The medical monitoring system of any of examples 1 to 7, wherein the instructions, when executed by the processing system, cause the processing system to determine a score indicative of cerebral health of the patient based on a variability between the respective regional oxygen saturation values within the plurality of tissue regions of the patient.

[0083] Example 9: The medical monitoring system of example 8, wherein the instructions, when executed by the processing system, cause the processing system to determine the score indicative of cerebral health of the patient based on the variability and the respective regional oxygen saturation values within the plurality of tissue regions of the patient.

[0084] Example 10: The medical monitoring system of any of examples 1 to 9, wherein the instructions, when executed by the processing system, cause the processing system to instruct display of an image of the plurality of tissue regions of the patient andthe respective regional oxygen saturation values that correspond to the plurality of tissue regions of the patient.

[0085] Example 11: The medical monitoring system of any of examples 1 to 10, wherein the instructions, when executed by the processing system, cause the processing system to determine an autoregulation status of the patient based on at least one of the respective regional oxygen saturation values of the plurality of tissue regions of the patient.

[0086] Example 12: The medical monitoring system of any of examples 1 to 11, wherein the instructions, when executed by the processing system, cause the processing system to determine that a type of the first sensor is inappropriate for the patient based on a head circumference of the patient, and instruct output of a notification to indicate that the type of the first sensor is inappropriate for the patient.

[0087] Example 13: The medical monitoring system of any of examples 1 to 12, comprising a single sensor body that supports the first sensor and the second sensor.

[0088] Example 14: A medical monitoring system, comprising: a processing system comprising one or more processors; and memory storing instructions that, when executed by the processing system, cause the processing system to: provide a first pulsed light drive signal over a first time period to instruct a first light emitter of a first sensor to emit a first light into tissue of a patient; provide a second pulsed light drive signal over a second time subsequent to the first time period to instruct a second light emitter of a second sensor to emit a second light into the tissue of the patient; and determine a regional oxygen saturation value of a deep tissue region that comprises a mid-cerebral artery of the patient based on signals received from a plurality of light detectors that detect the first light and the second light after the first light and the second light pass through the tissue of the patient.

[0089] Example 15: The medical monitoring system of example 14, wherein the instructions, when executed by the processing system, cause the processing system to determine additional respective regional oxygen saturation values of one or more surface tissue regions, one or more shallow tissue regions, or any combination thereof.

[0090] Example 16: The medical monitoring system of any of examples 14 or 15, wherein the instructions, when executed by the processing system, cause the processing system to determine that a type of the first sensor is inappropriate for the patient based on a head circumference of the patient, and instruct output of a notification to indicate that the type of the first sensor is inappropriate for the patient.

[0091] Example 17: A method of operating a medical monitoring system, the method comprising: providing, using one or more processors, a first pulsed light drive signal over a first time period to instruct a first light emitter of a first sensor to emit a first light into tissue of a patient; providing, using the one or more processors, a second pulsed light drive signal over a second time period subsequent to the first time period to instruct a second light emitter of a second sensor to emit a second light into the tissue of the patient; receiving, at the one or more processors, signals from a plurality of light detectors that detect the first light and the second light after the first light and the second light pass through the tissue of the patient; and determining, using the one or more processors, respective regional oxygen saturation values within a plurality of tissue regions of the patient based on the signals.

[0092] Example 18: The method of example 17, wherein the plurality of tissue regions comprises a deep tissue region that comprises a mid-cerebral artery of the patient.

[0093] Example 19: The method of example 18, comprising determining, using the one or more processors, an autoregulation status of the patient based on the regional oxygen saturation value of the deep tissue region.

[0094] Example 20: The method of any of examples 17 to 19, comprising instructing, using the one or more processors, display of an image of the plurality of tissue regions of the patient and the respective regional oxygen saturation values that correspond to the plurality of tissue regions of the patient.

Claims

CLAIMSWhat is claimed is:

1. A medical monitoring system (10), comprising:a first sensor (20), comprising:a first light emitter (24) to emit a first light; anda first plurality of light detectors (26, 28);a second sensor (30), comprising:a second light emitter (34) to emit a second light; anda second plurality of light detectors (36, 38);a processing system comprising one or more processors (60); andmemory (62) storing instructions that, when executed by the processing system, cause the processing system to:determine respective regional oxygen saturation values within a plurality of tissue regions (130, 132, 134) of a patient (100) based on signals received from the first plurality of light detectors (26, 28) and the second plurality of light detectors (36, 38), wherein the signals are based on detection of the first light at the first plurality of light detectors (26, 28) and the second plurality of light detectors (36, 38) and detection of the second light at the first plurality of light detectors (26, 28) and the second plurality of light detectors (36, 38).

2. The medical monitoring system (10) of claim 1, wherein the plurality of tissue regions (130, 132, 134) comprises one or more surface tissue regions (130), one or more shallow tissue regions (132), and one or more deep tissue regions (134).

3. The medical monitoring system (10) of any of claims 1 or 2, wherein at least one tissue region of the plurality of tissue regions (130, 132, 134) comprises a mid-cerebral artery.

4. The medical monitoring system (10) of any of claims 1 to 3, wherein the instructions, when executed by the processing system, cause the processing system to drive the first light emitter (24) to emit the first light and the second light emitter (34) to emit the second light in sequence.

5. The medical monitoring system (10) of any of claims 1 to 4, wherein the instructions, when executed by the processing system, cause the processing system to drive a respective first light emitting diode (40) of the first light emitter (24) to emit the first light within a first wavelength range over a first time period, drive a respective second light emitting diode (42) of the first light emitter (24) to emit the first light within a second wavelength range over a second time period, drive a respective first light emitting diode (50) of the second light emitter (34) to emit the second light within the first wavelength range over a third time period, and drive a respective second light emitting diode (52) of the second light emitter (34) to emit the second light within the second wavelength range over a fourth time period.

6. The medical monitoring system (10) of any of claims 1 to 5, wherein the instructions, when executed by the processing system, cause the processing system to determine an aggregate regional oxygen saturation value (142) based on the respective regional oxygen saturation values (152) within the plurality of tissue regions (130, 132, 134) of the patient (100).

7. The medical monitoring system (10) of claim 6, wherein the instructions, when executed by the processing system, cause the processing system to determine the aggregate regional oxygen saturation value (142) based on a median, an average, or a weighted average of the respective regional oxygen saturation values (152) within the plurality of tissue regions (130, 132, 134) of the patient (100).

8. The medical monitoring system (10) of any of claims 1 to 7, wherein the instructions, when executed by the processing system, cause the processing system to determine a score (146) indicative of cerebral health of the patient (100) based on avariability (144) between the respective regional oxygen saturation values (152) within the plurality of tissue regions (130, 132, 134) of the patient (100).

9. The medical monitoring system (10) of claim 8, wherein the instructions, when executed by the processing system, cause the processing system to determine the score (146) indicative of cerebral health of the patient (100) based on the variability (144) and the respective regional oxygen saturation values (152) within the plurality of tissue regions (130, 132, 134) of the patient (100).

10. The medical monitoring system (10) of any of claims 1 to 9, wherein the instructions, when executed by the processing system, cause the processing system to instruct display of an image (150) of the plurality of tissue regions (130, 132, 134) of the patient (100) and the respective regional oxygen saturation values (152) that correspond to the plurality of tissue regions (130, 132, 134) of the patient (100).

11. The medical monitoring system (10) of any of claims 1 to 10, wherein the instructions, when executed by the processing system, cause the processing system to determine an autoregulation status (148) of the patient (100) based on at least one of the respective regional oxygen saturation values (152) of the plurality of tissue regions (130, 132, 134) of the patient (100).

12. The medical monitoring system (10) of any of claims 1 to 11, wherein the instructions, when executed by the processing system, cause the processing system to determine that a type of the first sensor (20) is inappropriate for the patient (100) based on a head circumference of the patient (100), and instruct output of a notification to indicate that the type of the first sensor (20) is inappropriate for the patient (100).

13. The medical monitoring system (10) of any of claims 1 to 12, comprising a single sensor body (160) that supports the first sensor (20) and the second sensor (30).

14. A method of operating a medical monitoring system (10), the method comprising: providing, using one or more processors (60), a first pulsed light drive signal over a first time period to instruct a first light emitter (24) of a first sensor (20) to emit a first light into tissue of a patient (100);providing, using the one or more processors (60), a second pulsed light drive signal over a second time period subsequent to the first time period to instruct a second light emitter (34) of a second sensor (30) to emit a second light into the tissue of the patient (100);receiving, at the one or more processors (60), signals from a plurality of light detectors (26, 28, 36, 38) that detect the first light and the second light after the first light and the second light pass through the tissue of the patient (100); anddetermining, using the one or more processors (60), respective regional oxygen saturation values (152) within a plurality of tissue regions (130, 132, 134) of the patient (100) based on the signals.

15. The method of claim 14, comprising determining, using the one or more processors (60), an autoregulation status (148) of the patient (100) based on the respective regional oxygen saturation value (152) of a deep tissue region (134) of the plurality of tissue regions (130, 132, 134).

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