Systems and methods for blood oxygenation assessment

Abstract

Systems and methods are described for assessing arterial blood oxygen saturation concurrently with performing continuous blood pressure monitoring via a volume clip approach. Generally, the cuff system may be configured to fit to a body appendage. The cuff system may include a pressurizable balloon and a photoplethysmograph. The method may perform arterial blood oxygen saturation when the artery of the body appendage is in an unloaded state. Small fluctuations in the plethysmogram signal may be used with the calculated calibration factor to calculate arterial blood oxygen saturation.

Description

[0001] Cross-reference of related applications This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 594,899, filed October 31, 2023, entitled "System and Method for Assessing Blood Oxygenation," the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0002] This disclosure generally relates to non-invasive systems and methods for monitoring arterial oxygen saturation. Background Technology

[0003] The proper use of many life-saving medical techniques and treatments depends on the attending physician having accurate and up-to-date information about the patient's various bodily functions. Perhaps the most critical information a doctor needs, and which often tells them a great deal about what treatment should be initiated immediately, is heart rate, blood pressure, and arterial oxygen saturation.

[0004] In environments such as operating rooms and intensive care units, monitoring and recording these vital signs is especially important. For example, when an anesthetized patient is undergoing surgery, the anesthesiologist's role is typically to monitor the patient's general condition while the surgeon performs their tasks. If the anesthesiologist knows the patient's arterial oxygen saturation, heart rate, and blood pressure, they can assess the health and condition of the patient's circulatory system.

[0005] Arterial oxygen saturation is expressed as the percentage of total hemoglobin in a patient's blood that is bound to oxygen. Hemoglobin bound to oxygen is called oxyhemoglobin. In patients, an arterial oxygen saturation value above 95% is considered healthy. As blood flows through capillaries, oxygen is unloaded into the tissues, and carbon dioxide is loaded into the hemoglobin. Therefore, the oxygen saturation level in capillaries is lower than that in arteries. Furthermore, the oxygen saturation level in veins is even lower, around 75% in healthy patients. Traditionally, pulse oximetry (SpO2) has been used to approximate SaO2 due to its non-invasive nature. Summary of the Invention

[0006] This summary is intended to provide examples and is not intended to limit the scope of the invention in any way. For example, the claims do not require any features included in the examples of this summary unless those features are expressly listed in the claims. Various features and steps as described elsewhere in this disclosure may be included in the examples summarized herein, and the features and steps described herein and elsewhere may be combined in various ways.

[0007] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation.

[0008] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, comprising: transmitting light of a first wavelength and light of a second wavelength through a body appendage via a transmitter within a blood pressure cuff; wherein the first wavelength and the second wavelength are discrete.

[0009] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, comprising: sensing light signals of a first wavelength and a second wavelength via a light sensor within a blood pressure cuff.

[0010] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, comprising: receiving light signals of a first wavelength and a second wavelength using a health monitoring system.

[0011] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, wherein a health monitoring system is connected to a blood pressure cuff.

[0012] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, wherein an optical signal provides a volumetric plethysmogram for each of a first wavelength and a second wavelength of light.

[0013] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, comprising: calculating a ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light using a health monitoring system; and calibrating the calculated ratio using a calibration factor using the health monitoring system.

[0014] In some respects, the technology described herein relates to a method for continuously measuring arterial oxygen saturation, comprising: using a health monitoring system, and calculating arterial oxygen saturation using a calibrated and calculated ratio.

[0015] In some respects, the techniques described herein relate to a method in which a first wavelength of light signal is used to monitor blood pressure via a volumetric clamp method.

[0016] In some respects, the technology described herein relates to a method in which light of a first wavelength and light of a second wavelength are transmitted through a body appendage and light signals of the first and second wavelengths of light are sensed via a light sensor when an artery within the body appendage is in an unloaded state.

[0017] In some aspects, the technology described herein relates to a method in which a ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light is calculated using the following: wherein the ratio between the volumetric plethysmogram of the first wavelength of light and the volumetric plethysmogram of the second wavelength is calculated under no-load conditions; wherein the AC component of the first wavelength is represented when the artery is under no-load conditions; the AC component of the second wavelength is represented when the artery is under no-load conditions; the DC component of the first wavelength is represented when the artery is under no-load conditions; and the DC component of the second wavelength is represented when the artery is under no-load conditions.

[0018] In some respects, the technology described herein relates to a method in which a blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon applies pressure to a body appendage such that the arteries therein are in an unloaded state.

[0019] In some respects, the techniques described herein relate to a method in which a calibration factor is based on the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light, calculated when an artery in a body appendage is under load.

[0020] In some aspects, the technology described herein relates to a method in which the ratio between a volumetric profile of a first wavelength of light and a volumetric profile of a second wavelength of light is calculated using the following: where is the ratio between the volumetric profile of the first wavelength of light and the volumetric profile of the second wavelength of light; where is the AC component of the first wavelength under load; is the AC component of the second wavelength under load; is the DC component of the first wavelength under load; and is the DC component of the second wavelength under load.

[0021] In some respects, the techniques described herein relate to a method in which calibration is performed to determine a plethysmographic setpoint for blood pressure monitoring when an artery in a body appendage is under load.

[0022] In some respects, the techniques described herein relate to a method in which a calibration factor is calculated using the following: where is the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength, calculated under load, and where is the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength, calculated under unloaded conditions.

[0023] In some respects, the techniques described herein relate to a method in which the average ratio of two or more cardiac cycles is used.

[0024] In some respects, the techniques described herein relate to a method in which the average ratio of two or more cardiac cycles is used.

[0025] In some respects, the techniques described herein relate to a method in which two or more cardiac cycles include at least one cycle preceding a load cardiac cycle and at least one cycle following a load cardiac cycle; wherein the determination is made using the load cardiac cycle.

[0026] In some respects, the techniques described herein relate to a method in which a plethysmography setpoint for blood pressure monitoring is recalibrated using a loaded cardiac cycle.

[0027] In some respects, the technology described herein relates to a method that further includes using a health monitoring system to correct a calculated ratio of the trending volumetric plethysmogram signal of the second wavelength of light when the volumetric plethysmogram signal of the second wavelength of light exhibits a trend.

[0028] In some respects, the techniques described herein relate to a method that further includes using a health monitoring system to correct for a ratio calculated based on pressure changes provided by a blood pressure cuff.

[0029] In some respects, the technology described herein relates to a method in which a first wavelength of light is infrared and a second wavelength of light is red.

[0030] In some respects, the technology described herein relates to a method in which a body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0031] In some respects, the technology described herein relates to a method that further includes displaying arterial blood oxygen saturation on a monitor connected to a health monitoring system.

[0032] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, comprising: a blood pressure cuff connected to a computing system.

[0033] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein a blood pressure cuff is configured to be fitted onto a body appendage.

[0034] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the blood pressure cuff includes an inflatable balloon, a light emitter, and a light sensor.

[0035] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein a light emitter is configured to transmit light of a first wavelength and light of a second wavelength through a body appendage; wherein a light sensor is configured to sense the light signals of the first wavelength and the second wavelength.

[0036] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the computing system includes a processor and a memory.

[0037] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the memory includes one or more applications that include a set of instructions configured to instruct a processor to: instruct a light emitter to transmit light of a first wavelength and a second wavelength through a body appendage.

[0038] In some aspects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the memory includes one or more applications that include an instruction set configured to instruct a processor to: instruct a light sensor to sense light signals of a first wavelength and a second wavelength; and to receive light signals of the first wavelength and the second wavelength.

[0039] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein an optical signal provides a volumetric plethysmogram for each of a first wavelength and a second wavelength of light.

[0040] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the memory includes one or more applications that include a set of instructions configured to instruct the processor to: calculate the ratio between a volumetric plethysmogram of light at a first wavelength and a volumetric plethysmogram of light at a second wavelength.

[0041] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the memory includes one or more applications that include an instruction set configured to bootstrap the processor to calibrate the calculated ratio using a calibration factor.

[0042] In some respects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, wherein the memory includes one or more applications that include an instruction set configured to instruct the processor to: calculate arterial oxygen saturation using a calibrated and calculated ratio.

[0043] In some respects, the technology described herein relates to a health monitoring system in which a first wavelength of light signal is also used to monitor blood pressure via a volumetric clamp method.

[0044] In some respects, the technology described herein relates to a health monitoring system in which instructions configured to direct a processor to transmit light of a first wavelength and a second wavelength through a body appendage and to sense light signals of the first and second wavelengths via a light sensor are configured to be executed when an artery within the body appendage is in an unloaded state.

[0045] In some aspects, the technology described herein relates to a health monitoring system in which the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light is calculated using the following: wherein the ratio between the volumetric plethysmogram of the first wavelength of light and the volumetric plethysmogram of the second wavelength is calculated under no-load conditions; wherein the AC component of the first wavelength is represented when the artery is under no-load conditions; the AC component of the second wavelength is represented when the artery is under no-load conditions; the DC component of the first wavelength is represented when the artery is under no-load conditions; and the DC component of the second wavelength is represented when the artery is under no-load conditions.

[0046] In some respects, the technology described herein relates to a health monitoring system in which a blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to a body appendage such that the arteries therein are in an unloaded state.

[0047] In some respects, the technology described herein relates to a health monitoring system in which a calibration factor is based on the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light, calculated when an artery in a body appendage is under load.

[0048] In some aspects, the technology described herein relates to a health monitoring system in which the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength of light is calculated using the following: where is the ratio between the volumetric plethysmogram of the first wavelength of light and the volumetric plethysmogram of the second wavelength; where is the AC component of the first wavelength; is the AC component of the second wavelength; is the DC component of the first wavelength; and is the DC component of the second wavelength.

[0049] In some respects, the technology described herein relates to a health monitoring system in which an instruction set is configured to bootstrap the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring when arteries in the body appendages are under load.

[0050] In some respects, the technology described herein relates to a health monitoring system in which a calibration factor is calculated using the following: wherein the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength is calculated under load, and wherein the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength is calculated under no-load conditions.

[0051] In some respects, the technology described herein relates to a health monitoring system in which the average ratio of two or more cardiac cycles is considered.

[0052] In some respects, the technology described herein relates to a health monitoring system in which the average ratio of two or more cardiac cycles is considered.

[0053] In some respects, the technology described herein relates to a health monitoring system in which two or more cardiac cycles include at least one cycle prior to a load cardiac cycle and at least one cycle following a load cardiac cycle; wherein the determination is made using the load cardiac cycle.

[0054] In some respects, the technology described herein relates to a health monitoring system in which a load cardiac cycle is used to recalibrate a plethysmography setpoint for blood pressure monitoring.

[0055] In some respects, the technology described herein relates to a health monitoring system in which an instruction set is further configured to guide a processor to correct a calculated ratio of the trend volumetric plethysmography signal of the second wavelength of light when the volumetric plethysmography signal of the second wavelength of light exhibits a trend.

[0056] In some respects, the technology described herein relates to a health monitoring system in which an instruction set is further configured to guide a processor to correct for a ratio calculated based on pressure changes provided by a blood pressure cuff.

[0057] In some respects, the technology described herein relates to a health monitoring system in which a first wavelength of light is infrared and a second wavelength of light is red.

[0058] In some respects, the technology described herein relates to a health monitoring system in which body appendages are: arms, fingers, thumbs, wrists, ankles, legs, toes, ears, or temples.

[0059] In some respects, the technology described herein relates to a health monitoring system that further includes a display, wherein an instruction set is further configured to guide a processor to display arterial blood oxygen saturation.

[0060] In some aspects, the technology described herein relates to a method of operating a non-invasive blood characteristic sensing system, the system including a light emitter, a light sensor, and an expandable balloon, the method comprising: (a) surrounding a sensing region of a patient's appendage with the expandable balloon; (b) pressurizing the expandable balloon to a constant pressure during an open-loop calibration mode, comprising: (i) emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; (ii) emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage; (iii) sensing the light from the light emitter at the first wavelength via the patient's appendage at the light sensor; (iv) sensing the light from the light emitter at the second wavelength via the patient's appendage at the light sensor; (v) based on the sensed first wavelength... (vi) Generating a first sensed pleth signal based on light of a second wavelength; (vii) Generating a second sensed pleth signal based on light of a second sensed wavelength; (vii) Generating a pleth setpoint based on either the first or second sensed pleth signal, wherein the pleth setpoint corresponds to the resting stress-free arterial volume; (c) Generating a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on the first sensed pleth signal; (ii) deriving and based on the second sensed pleth signal; (iii) deriving an open-loop R using the following formula: open loop; (d) Modulating the inflatable balloon pressure in closed-loop control mode to partially clamp the sensed pleth signal via a closed-loop control algorithm. The measurement of arterial volume within the area includes: (i) emitting light at a first wavelength from a light emitter into the sensing area of ​​the patient's appendage; (ii) sensing light at the first wavelength from the light emitter via the patient's appendage at a light sensor; (iii) generating a third sensed pleth signal based on the sensed first wavelength light; (iv) emitting light at a second wavelength from the light emitter into the sensing area of ​​the patient's appendage; (v) sensing light at the second wavelength from the light emitter via the patient's appendage at a light sensor; (vi) generating a fourth sensed pleth signal based on the sensed second wavelength light; and (vii) comparing the third sensed pleth signal or the fourth sensed pleth signal with a pleth setpoint to generate a pleth signal. (viii) In response to the closed-loop error signal, the inflatable balloon is pressurized; (e) A closed-loop R is generated to determine the arterial oxygen saturation measurement, including: (i) deriving and based on a third sensed pleth signal; (ii) deriving and based on a fourth sensed pleth signal; (iii) deriving the closed-loop R using the following: closed loop; (f) A calibrated R is generated based on the closed-loop R and a calibration factor, including: (i) calculating the calibration factor using the following: where is the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength calculated during open-loop calibration mode, and where is the ratio between a volumetric plethysmogram of a first wavelength of light and a volumetric plethysmogram of a second wavelength calculated in the closed-loop control algorithm;(g) Calculate arterial oxygen saturation using calibrated R and pulse oximetry calibration curves.

[0061] In some respects, the techniques described herein relate to a method in which and / or the average ratio of two or more cardiac cycles.

[0062] In some respects, the techniques described herein relate to a method in which two or more cardiac cycles include at least one cycle preceding a load cardiac cycle and at least one cycle following a load cardiac cycle.

[0063] In some respects, the techniques described herein relate to a method in which determination is made using the load cardiac cycle.

[0064] In some aspects, the technology described herein relates to a health monitoring system for continuous arterial oxygen saturation measurement, comprising: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage; wherein the blood pressure cuff includes an inflatable balloon, a light emitter, and a light sensor; wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; wherein the light sensor is configured to sense the light signals of the first wavelength and the second wavelength; wherein the computing system includes a processor and a memory; wherein the memory includes one or more applications, the applications including an instruction set configured to instruct the processor to: (a) surround the sensing area of ​​the patient's appendage with the inflatable balloon; (b) in an open loop During calibration mode, the inflatable balloon is pressurized to a constant pressure, including: (i) emitting light from a light emitter at a first wavelength into a sensing area of ​​the patient's appendage at a first wavelength; (ii) emitting light from a light emitter at a second wavelength into the sensing area of ​​the patient's appendage at a second wavelength; (iii) sensing light from the light emitter at the first wavelength via the patient's appendage at a light sensor; (iv) sensing light from the light emitter at the second wavelength via the patient's appendage at a light sensor; (v) generating a first sensed pleth signal based on the sensed first wavelength light; (vi) generating a second sensed pleth signal based on the sensed second wavelength light; (vii) generating a pleth signal based on either the first sensed pleth signal or the second sensed pleth signal. (c) Generating a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on a first sensed pleth signal; (ii) deriving and based on a second sensed pleth signal; (iii) deriving an open-loop R using the following formula: open loop; (d) modulating the inflatable balloon in closed-loop control mode to partially clamp the arterial volume within the sensing area via a closed-loop control algorithm, including: (i) emitting light at a first wavelength from a light emitter into the sensing area of ​​the patient's appendage; (ii) sensing the light at the first wavelength from the light emitter at a light sensor via the patient's appendage; (iii) based on the sensed pleth signal; (iv) A third sensed pleth signal is generated from light of a first wavelength; light of a second wavelength is emitted from a light emitter to a sensing area of ​​the patient's appendage; (v) light of the second wavelength from the light emitter is sensed at the light sensor via the patient's appendage; (vi) a fourth sensed pleth signal is generated based on the sensed second wavelength light; (vii) the third sensed pleth signal or the fourth sensed pleth signal is compared with a pleth setpoint to generate a closed-loop error signal; (viii) the inflatable balloon is pressurized in response to the closed-loop error signal; (e) a closed-loop R is generated for determining the arterial oxygen saturation measurement, including: (i) deriving and based on the third sensed pleth signal.(ii) Derive and base the fourth sensed pleth signal; (iii) Derive the closed-loop R using the following: closed loop; (f) Generate a calibrated R based on the closed-loop R and a calibration factor, including: (i) Calculating the calibration factor using: where is the ratio between the volumetric plethysmogram of the first wavelength and the volumetric plethysmogram of the second wavelength calculated during open-loop calibration mode, and where is the ratio between the volumetric plethysmogram of the first wavelength and the volumetric plethysmogram of the second wavelength calculated in the closed-loop control algorithm; and (g) Calculate arterial oxygen saturation using the calibrated R and the pulse oximetry calibration curve.

[0065] In some respects, the technology described herein relates to a health monitoring system in which and / or the average ratio of two or more cardiac cycles.

[0066] In some respects, the technology described herein relates to a health monitoring system in which two or more cardiac cycles include at least one cycle prior to a load cardiac cycle and at least one cycle following a load cardiac cycle.

[0067] In some respects, the technology described herein relates to a health monitoring system in which determination is made using the load cardiac cycle.

[0068] Other features and advantages of this disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate the principles of this disclosure by way of example. Attached Figure Description

[0069] The specification and claims will be more fully understood by referring to the following figures and data diagrams, which present exemplary embodiments of the invention and should not be construed as a complete description of the scope of this disclosure.

[0070] Figure 1A and Figure 1B A view of an example of a blood pressure cuff system on a patient's finger is provided. Figure 1A A perspective view is provided. Figure 1B A cross-sectional view is provided.

[0071] Figure 2A A schematic diagram of the organization system and the light signals passing through it is provided.

[0072] Figure 2B Examples of volumetric plots depicting the DC and AC components of an optical signal are provided.

[0073] Figure 3 Examples of blood pressure charts and corresponding volumetric plethysmograms are provided.

[0074] Figure 4 An example of a method for performing continuous arterial oxygen saturation measurements is provided.

[0075] Figure 5 An example of a method for performing continuous arterial oxygen saturation measurements is provided.

[0076] Figure 6A An example of a trend volume plot is provided.

[0077] Figure 6B An example of an arterial oxygen saturation measurement graph is provided, which compares the detrended measurement with the original measurement.

[0078] Figure 7 An example of a health monitoring system is provided for simultaneously performing arterial oxygen saturation measurement and volumetric clamp blood pressure monitoring. Detailed Implementation

[0079] A continuous supply of oxygen to the body's cells is crucial for understanding a patient's health. Almost all the oxygen transported from the lungs to the rest of the body is carried by hemoglobin, stored in red blood cells. As hemoglobin releases carbon dioxide and combines with oxygen, its color changes from blue to bright red. Arterial oxygen saturation is expressed as the percentage of the maximum amount of oxygen that arterial blood can carry. In most patients, an oxygen saturation level of approximately 95%–98% is considered normal.

[0080] Pulse oximetry is the standard test for measuring the oxygen saturation of arterial blood. A classic pulse oximeter uses a clip-on device that attaches to a limb (such as a finger). The photoplethysmography (PPG) unit within the device typically emits and captures two wavelengths of light (one infrared and one red) to measure the absorbance of the light signals at both wavelengths during an arterial pulsation, thereby calculating oxygen saturation.

[0081] Another important hemodynamic measurement for understanding a patient's health status is blood pressure. One method for calculating continuous blood pressure is the volumetric clip method. The volumetric clip method typically utilizes an inflatable cuff and a PPG to measure arterial blood pressure in a body appendage (e.g., a finger). The pressure in the cuff is adjusted to maintain a constant arterial diameter (no-load state), where the diameter is determined via a light source and a light sensor of the PPG (closed loop). The pressure within the inflatable cuff represents the arterial pressure of the finger artery. In some embodiments, the pressure applied to the body appendage can be at multiple pressures at multiple times. For example, a first pressurization may be based on the blood pressure of the body appendage. In some embodiments, the blood pressure is configured to be equal to the blood pressure of the body appendage. The system can apply a second pressurization to the body appendage. The second pressurization is lower than the first pressurization. For example, in some embodiments, the second pressurization is zero or a certain nominal pressure amount.

[0082] In some implementations, the system can apply a constant pressure to a body appendage. This can be useful, for example, for calibrating a system. Calibration can help improve the accuracy and / or consistency of blood pressure and / or pulse wave measurements. Using calibration, the system can periodically adjust its baseline to account for changes in the vascular condition of the appendage, such as changes in blood volume, temperature, and / or finger movement. During such calibration, the system can monitor changes in blood pressure within the appendage, which can lead to significant changes in measurements (see, for example...). Figure 3 (Section 305b). During calibration, even minute sensor or measurement drift over time can be corrected by resetting the system's measurement baseline. Therefore, after calibration, the cuff (e.g., cuff 20) is better able to apply just enough pressure to match arterial blood pressure without causing discomfort or over-occlusion. Additionally or optionally, calibration can help the system distinguish between physiological signals and noise. Figure 3 As shown, when the cuff applies constant pressure to the appendage, the system can transmit light at multiple wavelengths through the appendage. The constant pressure applied to the body appendage can advantageously be applied for at least one complete cardiac cycle. A complete cardiac cycle can include at least systolic and diastolic blood pressure. In some embodiments, the constant pressure may not exceed atmospheric pressure or ambient pressure. For example, measuring pulse oxygen saturation can be valuable when no pressure is applied from the pump to the cuff.

[0083] Determining pulse oxygen saturation during the calibration process can be valuable. For example, a patient's pulse oxygen saturation may be critical during an emergency, and the inability to obtain pulse oxygen saturation data during the calibration process could be dangerous for the patient, representing a serious deficiency in modern systems and methods.

[0084] Classical systems and methods for simultaneously performing pulse oximetry and volumetric clip blood pressure measurements typically utilize two distinct PPG systems, each mounted on a unique body appendage. This is because the blood pressure cuff of a volumetric clip system is configured to maintain a constant arterial diameter, while the pulse oximetry system relies on changes in arterial diameter measured by the PPG to calculate oxygen saturation. In other words, classical pulse oximetry measurements cannot be reliably performed when the artery is kept unloaded.

[0085] Here, a system and method for performing both pulse oximetry and volumetric clip blood pressure measurements on a single body appendage using a single PPG system are described. The PPG system may include components for performing pulse oximetry measurements (e.g., emitters of two optical wavelengths) and may work in conjunction with components for performing volumetric clip blood pressure measurements (e.g., emitters of at least one optical wavelength and a blood pressure cuff that is continuously adjusted to maintain the arterial diameter in an unloaded state). It is now understood that, in the unloaded state, minute fluctuations in the plethysmography signal in the artery can be used to calculate oxygen saturation using a compensation factor that can be determined and continuously updated when the artery is under load (e.g., when determining the plethysmography setpoint during blood pressure measurement calibration). Some implementations of the system and method may include additional correction factors that can improve oxygen saturation measurement.

[0086] As utilized throughout this disclosure, an artery is in an unloaded state when its diameter is constant, and in a loaded state when its diameter is not constant. In some cases, when under load, a blood pressure cuff may apply some pressure to the artery without preventing changes in its volume.

[0087] Figure 1A A simplified perspective view of the sensor system 12 attached to the hand 14 is provided. Figure 1B This is a schematic diagram of a sensor system on a finger. Although the sensor is depicted as a finger, it should be understood that volumetric blood pressure measurement and arterial pulsation can be performed on any body appendage capable of receiving a blood pressure cuff. Examples of available body appendages include (but are not limited to) the arm, finger, thumb, wrist, ankle, leg, toes, ear, temple, etc.

[0088] like Figure 1A As shown, sensor system 12 is a non-invasive hemodynamic sensor capable of generating arterial blood pressure measurements through volumetric clamping and arterial oxygen saturation. Sensor system 12 may include housing 16, connector 18, cuff 20, and inflatable balloon 22. In the illustrated embodiment, cuff 20 is a loop or similar structure that wraps around or clamps the fingers 24 of hand 14, while housing 16 is a wrist-mounted device connected to cuff 20 via connector 18. However, in the most general case, sensor system 12 may be combined with… Figure 1AThe layouts shown vary considerably. For example, sensor system 12 may include multiple individual connectors 18 between elements (e.g., cuff 20) attached to finger 24, and / or housing 16 may be repositioned to other locations (e.g., integrated with cuff 20, or disposed separately in an external location). Furthermore, cuff 20 may be configured to fit onto various body appendages, including the arm, finger, thumb, wrist, ankle, leg, toe, ear, temple, etc. In the example shown, cuff 20 surrounds the sensing area of ​​finger 24 of hand 14. At least one artery 26 passes through the sensing area, and other tissues (e.g., muscle, skin, connective tissue, veins, capillaries) may typically be present. Cuff 20 also anchors a pressurizable balloon 22, which may be, for example, an expandable annular fluid balloon supplied from another source, either by a fluid line included within connector 18. Typically, the fluid used to inflate the balloon may be air. However, in the most general case, the pressurizable balloon 22 can be any kind of mechanism suitable for applying pressure to the finger 24 based on the control described below. The sensor system 12 and the hand 14 together constitute a combined physical system 10 (sometimes referred to as a plant or vegetative system) that responds to both changes in the patient and changes in the control of the sensor system 12.

[0089] like Figure 1BAs shown, the cuff 20 includes a light emitter 28 and a light sensor 30. The light emitter 28 is configured to emit light through a sensing region configured to be sensed by the light sensor 30. In some examples, one or more wavelengths of the light emitted by the light emitter 28 may fall within the visible to infrared spectrum. The light sensor 30 is configured to detect both the overall received light amplitude and a specific received light amplitude of discrete wavelengths (or discrete bands) emitted by the light emitter 28. In some implementations, the light emitter 28 includes a single emission source (e.g., a light-emitting diode (LED)) that can provide two or more discrete wavelengths of light (or bands of light). The term "discrete" refers to wavelengths having a clearly identifiable peak wavelength. In some embodiments, discrete wavelengths may have a full width at half maximum (FWHM) of less than about 200 nm, less than about 100 nm, less than about 80 nm, less than 50 nm, less than 30 nm, less than 20 nm, less than 10 nm, less than any of these values, or fall within a range having any of these values ​​as endpoints. In some implementations, the light emitter 28 includes at least two emission sources (e.g., at least two diodes) that allow the simultaneous emission of two or more discrete wavelengths of light (or bands of light). Typically, when using at least two emission sources, the light emitters can be positioned close to each other (e.g., within 0.5 mm) to produce a similar optical path, but any configuration can be used. In some implementations, the light emitter 28 and the light sensor 30 can be located on opposite sides of the cuff 20, allowing light to travel from the light emitter 28 through the sensing area of ​​the finger 24 to reach the light sensor 30. However, more generally, the scattering of light from the light emitter 28 within the tissue of the finger 24 allows the light emitter 28 and the light sensor 30 to be effective even when not positioned on opposite sides of the cuff 20, for example, when positioned close to each other.

[0090] The total light received from the transmission of the transmitter 28 at the light sensor 30 can be used to generate and / or may be referred to hereinafter as a plethysmographic signal. The plethysmographic signal can be used as a proxy for the inverse relationship of arterial volume within the sensing region, where a decrease in received light corresponds to an increase in arterial volume (see [reference]). Figure 2A (and accompanying description). During normal blood flow, the two arteries and connected capillaries in the finger pulsate, dilate (with systolic pressure), and relax (with diastolic pressure) during each heartbeat cycle. A larger arterial volume increases the absorption of emitted light, thereby reducing the proportion of emitted light received at the light sensor 30.

[0091] The light emitter 28 can emit discrete or fixed known spectra within a defined wavelength range (e.g., a range primarily from the visible to the infrared wavelengths or including the visible to the infrared wavelengths), within which detectable differences in the absorbance of different compositions of material of interest exist. In some implementations, the light emitter 28 can emit wavelengths only within the red and infrared bands (600 nm to 1000 nm). In some implementations, a wider range of light can be used, including higher-energy visible and / or microwave light (e.g., 400 nm to 1100 nm). In the most general case, the light emitter 28 produces known light amplitudes over a sufficiently wide wavelength range to distinguish absorption spectra associated with at least two parameters, including but not limited to blood oxygen saturation, total hemoglobin, methemoglobin percentage, or carboxyhemoglobin percentage.

[0092] In some embodiments, the light emitter 28 may include a single source. For example, in some embodiments, the light emitter 28 includes a light-emitting diode (LED) capable of generating one or more wavelengths of light (e.g., discrete wavelengths of light). Additionally or optionally, the light emitter 28 may transmit light of a first wavelength at a first time and light of a second wavelength at a second time. The use of a single light emitter (e.g., a single LED) may particularly help to facilitate the portability of the device and / or reduce the energy requirements of the power supply (e.g., battery) applied to the system. Tracking sequential (e.g., continuous) cardiac cycles can be advantageous. Thus, the system can cause the light emitter 28 to emit the first and second wavelengths within threshold times of each other. For example, the difference between the second and first times may be less than the entire cardiac cycle, less than half the cardiac cycle, and / or less than a quarter of the cardiac cycle.

[0093] Sensor system 12 clamps an arterial volume within a sensing area via an actuated valve (or any fluid flow metering element) through a pneumatically pressurized balloon 22, thereby modulating the air pressure supplied to balloon 22 via connector 18. Examples of valves available include, but are not limited to, servo valves or piezoelectric pumps. Sensor system 12 can clamp the arterial volume by any method that applies known pressure to the sensing area of ​​finger 24. When performing volume clamp blood pressure monitoring, the air pressure supplied to balloon 22 is modulated to counteract arterial pulsation, such that the arterial volume within the sensing area remains relatively constant. Light emitter 28 can emit light through a portion of cuff 20 (e.g., balloon 22). This portion can include a translucent material. This material can additionally or optionally be flexible, durable, and / or biocompatible. The material can include thermoplastic polyurethane (TPU), silicone, latex, nitrile rubber, polyvinyl chloride (PVC), and / or some other flexible materials. By using translucent materials, the system is able to create a more compact sensor system 12, thus improving portability and / or reducing power requirements. For further information on potential light emitters 28, balloons 22, and cuffs 20, see International Patent Application No. PCT / US2004 / 019599, the disclosure of which is incorporated herein by reference.

[0094] Figure 2A The diagram provides an illustration of the tissues of the body appendages and how light from the emitter passes through them. Body appendages consist of tissues, venous blood, and arterial blood. When in an unclamped state (e.g.) Figure 2A (As shown), arterial blood includes both non-pulsatile and pulsatile blood. For each cardiac cycle, the volume of pulsatile blood increases to its maximum during systole and decreases to its minimum during diastole. Light signals can pass through the body appendages and are absorbed by various parts of the appendages as they pass through them. Due to the increased volume of arterial blood, more light is absorbed during systole.

[0095] like Figure 2A As can be seen, the portion of the absorbed light signal is constant and independent of the timing of the cardiac cycle. In principle, the light absorbed by tissues, venous blood, and non-pulsatile arteries remains constant over time. This constant light signal is called the DC signal. The portion of the light signal will vary depending on the arterial blood pulsation associated with the cardiac cycle. Light signal absorption is greatest during systole and least during diastole. Variable light signals are called AC signals.

[0096] DC and AC signals can be used to calculate blood oxygen saturation. Figure 2BThe diagram provides a volumetric plethysmogram of two wavelengths of light. The first wavelength, 201, is absorbed more than the second wavelength, 203, and provides less light signal. Generally, longer wavelengths of light (e.g., IR light) show better transmission through tissue than shorter wavelengths (e.g., red light), but the amount of signal received will vary based on the absorption of a particular wavelength and the light intensity provided by the emitter. Using two wavelengths of light ( λ1 and λ2 The ratio of DC and AC signals can be calculated as follows () R ): (Equation 1) ratio R A calibration curve can be generated by plotting experimentally determined oxygen saturation values ​​(e.g., SpO2). This calibration curve can be used to analyze arterial oxygen saturation determined using a PPG mounted on a body appendage. Ensure ratio. R Precise determination can be valuable. Ensuring that the AC value (e.g., for a first wavelength and / or a second wavelength) is greater than some minimum threshold can be helpful. Therefore, in some implementations, the system can ensure that the AC signal is greater than a minimum threshold. For example, additional information can be found in International Patent Application No. PCT / US2024 / 011383, the disclosure of which is incorporated herein by reference.

[0097] As mentioned earlier, arterial oxygen saturation cannot be reliably determined when the artery is unloaded, such as when a body appendage is clamped to continuously measure blood pressure via a volumetric clamp method. Figure 3 An example of a hemodynamic graph depicting the plethysmography signal 301 and cuff pressure 303 is provided. A hemodynamic graph is a typical graph for continuous blood pressure measurement via a volumetric clamp method that utilizes a single wavelength (or single band) of light. The graph can be divided into three segments: a first segment 305a, depicting blood pressure measured at a first plethysmography setpoint; a second segment 305b, depicting the calibration phase used to calibrate the plethysmography setpoint; and a third segment, depicting blood pressure measured at a second plethysmography setpoint.

[0098] As can be seen in section 305b, the calibration phase (open loop) for calibrating the plethysmography setpoint maintains a constant cuff pressure 303 in a stepwise manner to determine an appropriate plethysmography setpoint. Maintaining a constant cuff pressure 303 can advantageously be applied for at least one complete cardiac cycle. This can help ensure that full and / or accurate calibration can be achieved. Additionally or alternatively, in some embodiments, the constant cuff pressure 303 may not exceed atmospheric pressure or ambient pressure. For example, measuring pulse oxygen saturation can be valuable when no pressure is applied from the pump to the cuff (e.g., when the associated pump is off or disconnected). Plethysmography setpoint recalibration can be performed repeatedly to ensure that blood pressure readings are accurate over time. During continuous blood pressure monitoring, plethysmography setpoint recalibration can be repeated based on a time window (e.g., every 5 minutes), the number of cardiac cycles (e.g., 300 cardiac cycles), a signal indicating that the plethysmography setpoint may require recalibration, or any other metric. It is worth noting that during the calibration phase, the artery is under load, meaning that the cuff pressure does not maintain a constant arterial blood volume. Therefore, the plethysmogram signal 301 has a high amplitude during the calibration phase, reflecting the pulsation of arterial blood through the sensing area. Repeated calibration phases can be used to determine arterial oxygen saturation in a continuous or sustained manner. As indicated elsewhere herein, determining pulse oxygen saturation during the calibration step can be valuable. Therefore, in some embodiments, the system can transmit light of multiple wavelengths through the appendage (e.g., through a cuff) to generate a set of corresponding plethysmograms. For more information on calibrating plethysmogram setpoints, see U.S. Patent No. 4,510,940, the disclosure of which is incorporated herein by reference.

[0099] In some cases, calibrating multiple setpoints can be valuable. Therefore, in some implementations, the cuff can transmit light during multiple time windows. For example, the cuff can transmit light at multiple wavelengths during a first time window. This light can be sensed and converted into one or more volumetric mapping signals. The volumetric mapping signals can be used to generate corresponding volumetric mappings. Based on the volumetric mappings, the system can generate a first volumetric mapping setpoint. During different time windows, the cuff can transmit light (e.g., at multiple wavelengths) during a second time window to generate additional volumetric mappings and corresponding second volumetric mapping setpoints. Figure 6AExamples of multiple plethysmograms are shown. One or more setpoints can be used to calculate one or more ratios between plethysmograms. By identifying differences between plethysmograms over time (e.g., between a first time window and a second time window), the system can calculate or otherwise determine the degree of drift (e.g., trend) between the plethysmogram setpoints. In some embodiments, such drift can be used to update the determination of arterial oxygen saturation. For example, a lower drift over time can allow the system to compensate by increasing the calculated arterial oxygen saturation (e.g., linear compensation, geometric compensation, etc.).

[0100] Figure 4 An example of a method for continuously measuring arterial blood oxygen saturation is provided. Method 400 can be performed using a sensor system configured to perform volumetric clip blood pressure measurement and further configured with a PPG to emit and sense light at two discrete wavelengths (or two discrete bands of light), such as a reference... Figure 1A and Figure 1B Example sensor system described.

[0101] Method 400 can perform (401) volumetric clip blood pressure measurement on a patient's body appendage. Therefore, a sensor system including a cuff with a pressurizable balloon and a PPG can be fitted onto the patient's body appendage. After fitting the sensor system, an initial calibration can be performed to determine the plethysmography setpoint. Using the pressurizable balloon, the artery of the body appendage can be immobilized in a no-load state, thus maintaining a constant volume. Pressure changes in the pressurizable balloon represent changes in arterial blood pressure that can be continuously monitored. Recalibration of the plethysmography setpoint can be performed iteratively.

[0102] Method 400 may additionally or optionally include (e.g., using an inflatable balloon of a cuff) applying a first pressure to a body appendage. The first pressure may be based on blood pressure in the body appendage. For example, blood pressure may be configured to be equal to the blood pressure in the body appendage. The system may apply a second pressure to the body appendage (e.g., using an inflatable balloon). The second pressure may be lower than the first pressure. For example, in some embodiments, the second pressure is zero or a certain nominal pressure amount. For example, applying different pressures may allow a practitioner to determine blood pressure and / or arterial oxygen saturation during a temporary closed state of the cuff (e.g., between readings, after the first reading, etc.). The first pressure may be applied for at least a first time duration (e.g., greater than 5 seconds, greater than 30 seconds, greater than 1 minute, etc.), and / or the second pressure may be applied for at least a second time duration.

[0103] Method 400 can further measure (403) arterial oxygen saturation while the artery is under load. Any condition under arterial load can be utilized. In some cases, the measurement of arterial oxygen saturation is performed simultaneously with the recalibration of the plethysmography setpoint. When the artery is under load, light of two discrete wavelengths (or two discrete bands) can be transmitted through a sensing area of ​​the body appendage to measure the DC and AC of each wavelength (or band). The ratio of DC to AC for each wavelength (or band) can be calculated. In some implementations, the ratio of DC to AC for each wavelength (or band) is calculated using Equation 1. The ratio of DC to AC for each wavelength (or band) and the calibration curve can be used to determine arterial oxygen saturation.

[0104] Method 400 may continuously repeat step 403 (405) to generate continuous arterial oxygen saturation measurements. In some implementations, arterial oxygen saturation is determined each time the plethysmography setpoint is recalibrated. In some implementations, arterial oxygen saturation is determined iteratively. In some implementations, arterial oxygen saturation is determined when the artery is under load, but not simultaneously with the recalibration of the plethysmography setpoint used for blood pressure monitoring.

[0105] Back Figure 3 Sections 305a and 305c show that the plethysmography signal is constrained to a setpoint (see Plethysmography setpoint 307a and Plethysmography setpoint 307c). It is noteworthy that even when the plethysmography signal is set constant, there are minute variations in the signal, which may occur due to arterial wall movement during systole. These minute variations in the plethysmography signal can be used to calculate arterial oxygen saturation, but are not very reliable because they are more prone to noise due to the small AC component and the optical path difference between the wavelength (or two bands) used to calculate the AC component, leading to larger errors between readings and between patients. However, it has been found that calibrating the AC component by calculating it when the artery is under load (e.g., during calibration at the plethysmography setpoint) and by calculating a calibration factor when the artery is under no-load can make these minute variations in the plethysmography signal reliable. The AC component is also referred to as... Δd This indicates the change in the difference in AC component signals during the cardiac cycle.

[0106] Figure 3 Several heart samples were depicted. Δd For example, the unloaded state in an artery can be calculated ( Δd Unl ) and load status ( Δd Loa (under) Δd In particular, Δd Unl 309a is an example of the difference in AC component signals during the cardiac cycle within segment 305a, and Δd Unl 309c is an example of the difference in AC components during the cardiac cycle within segment 305c. Δd Loa 309b is an example of the difference in the AC component signal during the cardiac cycle within segment 305b, which corresponds to the AC component calculated in Equation 1. In these examples, Δd Unl and Δd Loa Each is defined as the difference between the maximum and minimum values ​​of the AC component signal, but any change in the characteristics of the AC component can be utilized. Δd Unl Examples of the definitions include (but are not limited to) the difference between the maximum and minimum values ​​of the AC component signal, the difference between the set point of the volumetric plot and the minimum value of the AC component signal, the difference between the maximum value of the AC component signal and the set point of the volumetric plot, the difference between the average value of the AC component signal and the minimum value of the AC component signal, the difference between the maximum value of the AC component signal and the average value of the AC component signal, the difference between the AC component signal value before the minimum value and the minimum value of the AC component signal, the difference between the AC component signal value before the maximum value and the maximum value of the AC component signal, and so on.

[0107] Arterial oxygen saturation (AC) signals under no-load conditions rely on minute signal fluctuations. Servo gain control can be used to amplify the AC signal, but the gain cannot be excessive, or the blood pressure measurement may become inaccurate. Therefore, in many implementations, servo gain control is used to ensure that the AC signal under no-load conditions has sufficient fluctuations to calculate arterial oxygen saturation without introducing errors into continuous blood pressure monitoring. For more information on servo gain control, see U.S. Provisional Application No. 63 / 479,721, the disclosure of which is incorporated herein by reference.

[0108] Figure 5 An example of a method for continuously measuring arterial oxygen saturation is provided. Method 500 can be performed using a sensor system configured to perform volumetric clip blood pressure measurement and further configured with a PPG to emit and sense light at two discrete wavelengths (or two discrete bands of light), such as reference [reference]. Figure 1A and Figure 1B An example sensor system is described. In some implementations, continuous measurement of arterial oxygen saturation occurs simultaneously with continuous measurement of blood pressure via a volumetric clamp method.

[0109] Method 500 can calculate (501) a calibration factor considering the AC component when the artery is in an unloaded state, such as when measuring blood pressure via a volumetric clamp method. Because the AC component is less reliable when the artery is in an unloaded state, using a calibration factor determined based on the AC component when the artery is under load can be beneficial for determining arterial oxygen saturation. Therefore, Method 500 utilizes the ratio calculated when the artery is under load during plethysmography setpoint calibration. R The ratio R It can be calculated as provided by Equation 1, and can be called... R Loa Furthermore, when the artery is in an unloaded state, the ratio... R The following can be calculated: (Equation 2) in This represents the AC component of the first wavelength when the artery is in an unloaded state, and This represents the AC component of the second wavelength when the artery is in an unloaded state.

[0110] To calculate the calibration factor, the ratio R( when the artery is under load) will be used. R Loa The ratio R( when the artery is under load) to R Unl This can be compared. Any means can be used to calibrate the ratio R of the artery under load. In some implementations, the calibration factor is calculated as follows: (Equation 3) In some implementations, the ratio R( when the artery is under load) R Loa ( ) is the average ratio (or other combined ratio) of two or more cardiac cycles. For example, Figure 3 Segment 305b consists of two cardiac cycles, and therefore these two ratios can be combined using any statistical means for combined values.

[0111] In some implementations, the ratio when the artery is under no-load conditions R ( R Unl A ratio is the average ratio (or other combination ratio) of two or more cardiac cycles. Any two or more cardiac cycles when the artery is under no-load conditions can be combined. In some implementations, the two or more no-load cardiac cycles to be combined are approximate (or otherwise approximate) loaded cardiac cycles used for calculation. For example, Figure 3The ratio R of one or more cardiac cycles within segment 305a and / or segment 305c can be used together with the ratio R of one or more cardiac cycles within segment 305b to calculate the calibration factor.

[0112] In some implementations, in order to calculate the calibration factor, the ratio R( when the artery is under no-load conditions) is used. R Unl R is a combined ratio that includes one or more unloaded cardiac cycles preceding a loaded cardiac cycle. In some implementations, the ratio R( when the artery is in an unloaded state) is... R Unl R is a combined ratio that includes one or more unloaded cardiac cycles following a loaded cardiac cycle. In some implementations, the ratio R when the artery is in an unloaded state is... R Unl ) is a combination ratio that combines one or more no-load cardiac cycles before a load cardiac cycle and one or more no-load cardiac cycles after a load cardiac cycle.

[0113] In some implementations, the system for continuously measuring arterial oxygen saturation repeatedly terminates by keeping the artery in an unloaded state to recalculate the calibration factor. The calibration factor may be recalculated based on a time window (e.g., every 5 minutes), the number of cardiac cycles (e.g., 300 cardiac cycles), a signal indicating that the calibration factor may need to be recalculated, or any other indicator. Typically, the artery can transition from an unloaded state to a loaded state, and the calibration factor is calculated accordingly. In some implementations, the calibration factor is recalculated when the plethysmography setpoint is recalibrated for continuous blood pressure monitoring. In some implementations, the calibration factor is recalculated continuously. In some implementations, the calibration factor is recalculated continuously whenever the plethysmography setpoint is recalibrated for continuous blood pressure monitoring. In some implementations, the calibration factor is recalculated continuously every other plethysmography setpoint recalibration (or any other periodicity associated with plethysmography setpoint recalibration). In some cases, the calculation of the calibration factor is independent of the recalibration of the plethysmography setpoint used for continuous blood pressure monitoring. In some cases, the artery is switched from an unloaded state to a loaded state, and a calibration factor is calculated, but recalibration of the plethysmography setpoint for continuous blood pressure monitoring is not performed. Alternatively, the previously calculated calibration factor is used instead of a recalibrated calibration factor.

[0114] Method 500 further calibrates (503) the ratio R of cardiac cycles when the artery is under no-load conditions. R UnlThe means by which the ratio R used to calibrate the cardiac cycle can depend on how the calibration factor is calculated. In some implementations, when the calibration factor is calculated using Equation 3, the ratio of the unloaded cardiac cycle is calibrated by multiplying the ratio by the calibration factor.

[0115] Method 500 optionally corrects (505) the ratio of the unloaded cardiac cycle used for the trend plethysmography signal. As previously stated, continuous blood pressure monitoring requires only one wavelength of optical signal, while arterial oxygen saturation measurement utilizes two wavelengths of optical signal. By combining continuous blood pressure monitoring with arterial oxygen saturation measurement, one optical wavelength used for arterial oxygen saturation measurement can be the same as the wavelength used for continuous blood pressure monitoring. Based on the principle of continuous blood pressure monitoring via the volumetric clip method, the amplitude of the optical wavelength used for blood pressure monitoring maintains a fairly stable optical signal amplitude. The amplitude of the other optical wavelength not used for continuous blood pressure monitoring can be trending, especially at the start of signal acquisition.

[0116] Figure 6A The document provides an example of plethysmographic signals using two wavelengths of light in a dual system for performing continuous blood pressure monitoring and arterial oxygen saturation measurement. The first plethysmographic signal 601, at the light wavelength, maintains a stable amplitude because this is the wavelength used to establish a plethysmographic setpoint for continuous blood pressure monitoring. The second plethysmographic signal 603 at the light wavelength exhibits a trending amplitude, which is common when light wavelengths are not used to establish a plethysmographic setpoint for continuous blood pressure monitoring. This trend in the plethysmographic signal can impair the accuracy of arterial oxygen saturation measurement because it leads to changes in the AC component.

[0117] Method 500 optionally corrects the calculated ratio by detrending the trend volumetric plot signal. Any detrending method can be used. Examples of detrending techniques include (but are not limited to) differencing each cardiac cycle from the previous cardiac cycle, and fitting and utilizing a regression model.

[0118] Figure 6B The example provided shows the calculated blood oxygen saturation over time. Figure 6A The second volumetric imaging signal 603 is detrended. The calculated blood oxygen saturation without detrending is shown in the darker data 611, and the calculated blood oxygen saturation with detrending is shown in the brighter data 613.

[0119] In some implementations, detrending can be achieved in part by determining multiple setpoints. These setpoints can be used to recalibrate the system. For example, the system can transmit light of multiple wavelengths over multiple time windows. For each time window, light can be sensed and converted into one or more corresponding plethysmographic signals. These one or more plethysmographic signals can be used to generate a corresponding plethysmogram. Based on the plethysmograms, the system can generate a first plethysmographic setpoint. By identifying differences between plethysms over time (e.g., between a first time window and a second time window), the system can calculate or otherwise determine a trend between the plethysmographic setpoints. This trend can be used to calibrate the system's determination of arterial oxygen saturation.

[0120] Method 500 also optionally corrects (507) for changes in cuff pressure to the ratio of unloaded cardiac cycles. To maintain the artery in an unloaded state, thus ensuring a constant volume, the pressure provided by the cuff's inflatable balloon varies according to the cardiac cycle. Furthermore, a patient's blood pressure can change rapidly over time. Larger pressure quantities on the body's appendages can affect the DC component due to changes in the optical path. This effect is more pronounced when arterial oxygen saturation is below healthy levels.

[0121] To correct for the effects of pressure changes on the body's appendages, a formula can be fitted to data comparing the impact of cuff pressure on changes in arterial oxygen saturation. Based on this formula, a correction factor can be implemented to adjust the cardiac cycle ratio R.

[0122] Method 500 further utilizes a calibration curve to determine arterial oxygen saturation during an unloaded cardiac cycle using a calibrated ratio R. In some implementations, the calibrated ratio R is further corrected for changes in trend plethysmography signal and / or cuff pressure. In many implementations, the ratio R is repeatedly recalibrated (and optionally recorrected), and thus the most recently calculated calibration factor (and optionally the most recently calculated correction factor) is used to determine arterial oxygen saturation. The calibrated (and corrected) ratio R can be used to determine arterial oxygen saturation, and the calibration curve can be used to determine arterial oxygen saturation.

[0123] Arterial oxygen saturation can be continuously calculated and updated, allowing for determination and updating of arterial oxygen saturation for each cardiac cycle. When used in conjunction with hemodynamic monitors, health monitors, or other monitoring devices, arterial oxygen saturation can be continuously displayed.

[0124] The systems and methods disclosed herein can be used within health monitoring systems, such as hemodynamic monitoring systems. Typically, health monitoring systems include a blood pressure cuff and a PPG, the blood pressure cuff including an inflatable balloon, and the PPG including a transmitter capable of emitting at least two discrete wavelengths (or at least two discrete bands). Figure 7 An example of a health monitoring system 700 is provided, which will be used to monitor blood pressure and continuously (or persistently) measure an individual's arterial oxygen saturation. Fitted onto the patient's limb is a blood pressure cuff, which includes an inflatable balloon and a PPG 720, which can be connected to a pneumatic system to provide fluid pressure and further connected to the health monitoring system 700 to perform real-time continuous blood pressure monitoring and real-time continuous (or persistent) measurement of arterial oxygen saturation.

[0125] The health monitoring system 700 may include a computing system comprising a processor system 702 and an I / O interface 704 and a user interface, the I / O interface being used for inputting and outputting data, such as data communicated between the health monitoring system 70, the blood pressure cuff, and the PPG 720. It will be readily understood that the processor system 702, the I / O interface 704, and the memory system 706 may be implemented using any of a variety of components suitable for the requirements of a particular application, including (but not limited to) a CPU, GPU, ISP, DSP, wireless modem (e.g., Wi-Fi, Bluetooth modem), serial interface, volatile memory (e.g., DRAM), and / or non-volatile memory (e.g., SRAM and / or NAND flash memory).

[0126] Memory system 706 is capable of storing various data, applications, and models. It should be understood that the listed data, applications, and models are representative samples of what can be stored in memory, and various memory systems can store some or all of the listed data, applications, and models. Furthermore, any combination of data, applications, and models can be stored, and in some implementations, various data, applications, and / or models are temporarily stored.

[0127] The health monitoring system 700 can execute a set of instructions, which is stored in a memory system 706 and executed by a processor system 702, to guide the execution of various computational methods described herein. Applications that can be stored in the memory system 706 include real-time continuous blood pressure monitoring 708 and real-time measurement of arterial oxygen saturation 710. The memory system 706 can further store calibration and correction factors 712 calculated in real time, which can be utilized by the real-time measurement of arterial oxygen saturation 710 application. The various applications can be provided as individual processes or as a collection of processes, each of which can be used to provide simultaneous real-time continuous blood pressure monitoring and real-time measurement of arterial oxygen saturation. Real-time blood pressure and arterial oxygen saturation data can also optionally be stored on the memory system 706 and / or displayed on a display screen via an I / O interface 704.

[0128] Example Group 1 Example 1. A method for continuously measuring arterial oxygen saturation, comprising: transmitting light of a first wavelength and light of a second wavelength through a body appendage via a transmitter within a blood pressure cuff; wherein the first wavelength and the second wavelength are discrete; sensing optical signals of the first wavelength and the second wavelength via a light sensor within the blood pressure cuff; receiving the optical signals of the first wavelength and the second wavelength using a health monitoring system connected to the blood pressure cuff, wherein the optical signals provide a plethysmogram for each of the first wavelength and the second wavelength; calculating a ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength using the health monitoring system; calibrating the calculated ratio using the health monitoring system with a calibration factor; and calculating arterial oxygen saturation using the health monitoring system with the calibration and the calculated ratio.

[0129] Example 2. According to the method of Example 1, the optical signal of the first wavelength is used to monitor blood pressure via a volumetric clamp method.

[0130] Example 3. The method according to Example 1 or 2, wherein transmitting light of a first wavelength and light of a second wavelength through the body appendage and sensing the light signals of the first wavelength and the second wavelength via a light sensor is performed when the artery within the body appendage is in an unloaded state.

[0131] Example 4. According to the method of Example 3, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following: wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated under no-load conditions; wherein the AC component of the first wavelength is represented when the artery is under no-load conditions; the AC component of the second wavelength is represented when the artery is under no-load conditions; the DC component of the first wavelength is represented when the artery is under no-load conditions; and the DC component of the second wavelength is represented when the artery is under no-load conditions.

[0132] Example 5. According to the method of Example 3 or 4, the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon applies pressure to the body appendage such that the arteries therein are in the unloaded state.

[0133] Example 6. The method according to any one of Examples 1 to 5, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

[0134] Example 7. According to the method of Example 6, the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength light is calculated using the following: where is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength light; where is the AC component of the first wavelength under the load condition; is the AC component of the second wavelength under the load condition; is the DC component of the first wavelength under the load condition; and is the DC component of the second wavelength under the load condition.

[0135] Example 8. The method according to Example 6 or 7, wherein calibration is performed to determine a plethysmographic setpoint for blood pressure monitoring when the artery in the body appendage is under load.

[0136] Example 9. The method according to any one of Examples 6 to 8, wherein the following calibration factor is used to calculate: wherein is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated under load, and wherein is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated under unloaded conditions.

[0137] Example 10. The method described in Example 9, where is the average ratio of two or more cardiac cycles.

[0138] Example 11. The method described in Example 9 or 10, where is the average ratio of two or more cardiac cycles.

[0139] Example 12. According to the method of Example 11, the two or more cardiac cycles include at least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle; wherein the determination is made using the load cardiac cycle.

[0140] Example 13. The method according to Example 12, wherein the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

[0141] Example 14. The method according to any one of Examples 1 to 13 further includes, when the volumetric plethysmography signal of the second wavelength light exhibits a trend, using the health monitoring system to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength light.

[0142] Example 15. The method according to any one of Examples 1 to 14 further includes using the health monitoring system to correct the calculated ratio for pressure changes provided by the blood pressure cuff.

[0143] Example 16. The method according to any one of Examples 1 to 15, wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0144] Example 17. The method according to any one of Examples 1 to 16, wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0145] Example 18. The method according to any one of Examples 1 to 17 further includes displaying the arterial blood oxygen saturation on a display connected to the health monitoring system.

[0146] Example 19. A health monitoring system for continuous arterial oxygen saturation measurement includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage; wherein the blood pressure cuff includes an inflatable balloon, a light emitter, and a light sensor; wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; wherein the light sensor is configured to sense optical signals of the first wavelength and the second wavelength; wherein the computing system includes a processor and a memory; wherein the memory includes one or more applications, the applications including an instruction set configured to instruct the processor to: instruct the light emitter to transmit light of the first wavelength and light of the second wavelength through the body appendage; instruct the light sensor to sense optical signals of the first wavelength and the second wavelength; receive the optical signals of the first wavelength and the second wavelength, wherein the optical signals provide a plethysmogram of each of the first wavelength and the second wavelength; calculate a ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength; calibrate the calculated ratio using a calibration factor; and calculate arterial oxygen saturation using the calibration and the calculated ratio.

[0147] Example 20. In the health monitoring system according to Example 19, the optical signal of the first wavelength is also used to monitor blood pressure via a volumetric clamp method.

[0148] Example 21. A health monitoring system according to Example 19 or 20, wherein the instruction configured to direct the processor to transmit light of a first wavelength and light of a second wavelength through a body appendage and to sense the light signals of the first wavelength and the second wavelength via a light sensor is configured to execute when an artery within the body appendage is in an unloaded state.

[0149] Example 22. A health monitoring system according to Example 21, wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following: wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated under no-load conditions; wherein the AC component of the first wavelength is represented when the artery is under no-load conditions; the AC component of the second wavelength is represented when the artery is under no-load conditions; the DC component of the first wavelength is represented when the artery is under no-load conditions; and the DC component of the second wavelength is represented when the artery is under no-load conditions.

[0150] Example 23. A health monitoring system according to Example 21 or 22, wherein the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

[0151] Example 24. A health monitoring system according to any one of Examples 19 to 23, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

[0152] Example 25. According to the health monitoring system of Example 24, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following: where is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength; where is the AC component of the first wavelength; is the AC component of the second wavelength; is the DC component of the first wavelength; and is the DC component of the second wavelength.

[0153] Example 26. A health monitoring system according to Example 24 or 25, wherein the instruction set is configured to instruct the processor to instruct the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring of the artery in the body appendage under load.

[0154] Example 27. A health monitoring system according to any one of Examples 24 to 26, wherein a calibration factor is calculated using the following: wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated under load, and wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated under no-load conditions.

[0155] Example 28. A health monitoring system according to Example 27, wherein the ratio is the average of two or more cardiac cycles.

[0156] Example 29. A health monitoring system according to Example 27 or 28, wherein the ratio is the average of two or more cardiac cycles.

[0157] Example 30. A health monitoring system according to Example 29, wherein the two or more cardiac cycles include at least one cycle prior to the load cardiac cycle and at least one cycle following the load cardiac cycle; wherein the determination is made using the load cardiac cycle.

[0158] Example 31. A health monitoring system according to Example 30, wherein the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

[0159] Example 32. A health monitoring system according to any one of Examples 19 to 31, wherein the instruction set is further configured to instruct the processor to correct the calculated ratio of the trend volumetric plot signal of the second wavelength light when the volumetric plot signal of the second wavelength light exhibits a trend.

[0160] Example 33. A health monitoring system according to any one of Examples 19 to 32, wherein the instruction set is further configured to guide the processor to correct the calculated ratio for pressure changes provided by the blood pressure cuff.

[0161] Example 34. A health monitoring system according to any one of Examples 19 to 33, wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0162] Example 35. A health monitoring system according to any one of Examples 19 to 34, wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0163] Example 36. A health monitoring system according to any one of Examples 19 to 35 further includes a display, wherein the instruction set is further configured to instruct the processor to display the arterial blood oxygen saturation.

[0164] Example 37. A method of operating a non-invasive blood feature sensing system, the system comprising a light emitter, a light sensor, and an expandable balloon, the method comprising: (a) surrounding a sensing region of a patient's appendage with the expandable balloon; (b) pressurizing the expandable balloon to a constant pressure during an open-loop calibration mode, comprising: (i) emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; (ii) emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage; (iii) sensing light from the light emitter at the first wavelength via the patient's appendage at the light sensor; (iv) sensing light from the light emitter at the second wavelength via the patient's appendage at the light sensor. (v) Light at the second wavelength of the light emitter; (vi) Generating a first sensed pleth signal based on the sensed first wavelength light; (vii) Generating a second sensed pleth signal based on the sensed second wavelength light; (vii) Generating a pleth setpoint based on the first sensed pleth signal or the second sensed pleth signal, wherein the pleth setpoint corresponds to the resting stress-free arterial volume; (c) Generating a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on the first sensed pleth signal; (ii) deriving and based on the second sensed pleth signal; (iii) using The following formula derives the open-loop R: Open-loop; (d) Modulating the inflatable balloon in closed-loop control mode to partially clamp the arterial volume within the sensing region via a closed-loop control algorithm, comprising: (i) emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; (ii) sensing the light from the light emitter at the first wavelength via the patient's appendage at the light sensor; (iii) generating a third sensed pleth signal based on the sensed first wavelength light; (iv) emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage; (v) sensing the pleth signal via the patient's appendage at the light sensor. (vi) Light at the second wavelength from the light emitter; (vii) generating a fourth sensed pleth signal based on the sensed second wavelength light; (vii) comparing the third sensed pleth signal or the fourth sensed pleth signal with the pleth setpoint to generate a closed-loop error signal; (viii) modulating the inflatable balloon in response to the closed-loop error signal; (e) generating a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on the third sensed pleth signal; (ii) deriving and based on the fourth sensed pleth signal; (iii) deriving the closed-loop R using the following: closed loop;(f) Generating a calibrated R based on the closed-loop R and a calibration factor, comprising: (i) calculating the calibration factor using: where is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated during the open-loop calibration mode, and where is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated in the closed-loop control algorithm; and (g) calculating arterial oxygen saturation using the calibrated R and a pulse oximetry calibration curve.

[0165] Example 38. The method of claim 37, wherein and / or the average ratio of two or more cardiac cycles.

[0166] Example 39. The method of claim 38, wherein the two or more cardiac cycles include at least one cycle preceding the load cardiac cycle and at least one cycle following the load cardiac cycle.

[0167] Example 40. The method of claim 39, wherein the determination is made using the load cardiac cycle.

[0168] Example 41. A health monitoring system for continuous arterial oxygen saturation measurement, comprising: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage; wherein the blood pressure cuff includes an inflatable balloon, a light emitter, and a light sensor; wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; wherein the light sensor is configured to sense light signals of the first wavelength and the second wavelength; wherein the computing system includes a processor and a memory; wherein the memory includes one or more applications, the applications including an instruction set configured to instruct the processor to: (a) surround the inflatable balloon with... (a) Sensing area of ​​the patient's appendage; (b) Inflate the inflatable balloon to a constant pressure during open-loop calibration mode, including: (i) emitting light from the light emitter at a first wavelength into the sensing area of ​​the patient's appendage; (ii) emitting light from the light emitter at a second wavelength into the sensing area of ​​the patient's appendage; (iii) sensing light from the light emitter at the first wavelength via the patient's appendage at the light sensor; (iv) sensing light from the light emitter at the second wavelength via the patient's appendage at the light sensor; (v) generating a first sensed pleth signal based on the sensed first wavelength light; (vi) based on the sensed first wavelength light. (vii) Generate a second sensed pleth signal based on the first sensed pleth signal or the second sensed pleth signal, wherein the pleth setpoint corresponds to the resting stress-free arterial volume; (c) Generate a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on the first sensed pleth signal; (ii) deriving and based on the second sensed pleth signal; (iii) deriving the open-loop R using the following formula: open loop; (d) Modulate the pressurization of the inflatable balloon in closed-loop control mode to partially clamp the sensed pleth signal via a closed-loop control algorithm. Measuring arterial volume within the region includes: (i) emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; (ii) sensing light from the light emitter at the first wavelength via the patient's appendage at the light sensor; (iii) generating a third sensed pleth signal based on the sensed first wavelength light; (iv) emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage from the light emitter; (v) sensing light from the light emitter at the second wavelength via the patient's appendage at the light sensor; and (vi) generating a fourth sensed pleth signal based on the sensed second wavelength light.(vii) Compare the third sensed pleth signal or the fourth sensed pleth signal with the pleth setpoint to generate a closed-loop error signal; (viii) Modulate the inflatable balloon pressurization in response to the closed-loop error signal; (e) Generate a closed-loop R for determining an arterial oxygen saturation measurement, including: (i) deriving and based on the third sensed pleth signal; (ii) deriving and based on the fourth sensed pleth signal; (iii) deriving the closed-loop R using the following: closed loop; (f) Generate a calibrated R based on the closed-loop R and a calibration factor, including: (i) calculating the calibration factor using the following: where is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated during the open-loop calibration mode, and where is the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light calculated in the closed-loop control algorithm; and (g) calculating arterial oxygen saturation using the calibrated R and a pulse oximetry calibration curve.

[0169] Example 42. The health monitoring system according to Example 41, wherein and / or the average ratio of two or more cardiac cycles.

[0170] Example 43. The health monitoring system according to Example 42, wherein the two or more cardiac cycles include at least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle.

[0171] Example 44. A health monitoring system according to Example 43, wherein the determination is made using the load cardiac cycle.

[0172] Group 1 In a first example, a method for measuring arterial oxygen saturation includes: transmitting light of a first wavelength and light of a second wavelength through a body appendage using at least one transmitter of a blood pressure cuff; sensing optical signals of the first wavelength and the second wavelength using a light sensor of the blood pressure cuff; converting the optical signals of the first wavelength and the second wavelength into corresponding plethysmography signals using a health monitoring system connected to the blood pressure cuff, wherein the plethysmography signals are configured to provide plethysmography of each of the first wavelength and the second wavelength; calculating a ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength using the health monitoring system; calibrating the calculated ratio using a calibration factor using the health monitoring system; and calculating arterial oxygen saturation using the calibration factor and the calculated ratio using the health monitoring system.

[0173] In the second example, according to the method of Example 1, the light signals of sensing the first wavelength light and the second wavelength light include applying pressure to the body appendage using the blood pressure cuff, such that the arteries therein are in the unloaded state.

[0174] In the third example, the method according to any one of Examples 1 to 2 further includes using the light signal of the first wavelength or the second wavelength to determine the blood pressure of the body appendage via a volumetric clamp method.

[0175] In the fourth example, according to any one of Examples 1 to 3, wherein when the artery in the body appendage is in an unloaded state, the light signal of transmitting the first wavelength light and the second wavelength light through the body appendage and sensing the first wavelength light and the second wavelength light is performed.

[0176] In the fifth example, according to the method described in Example 4, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric plethysmogram of the first wavelength and the volumetric plethysmogram of the second wavelength when the artery is in the unloaded state; and wherein: This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0177] In the sixth example, according to the method of any one of Examples 4 to 5, the blood pressure cuff includes an inflatable balloon, and the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

[0178] In the seventh example, according to the method of any one of Examples 1 to 5, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the artery in the body appendage under load and the volumetric plethysmogram of the first wavelength of light and the second wavelength of light.

[0179] In example 8, according to the method described in example 7, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength; and wherein: It is the AC component of the first wavelength under the load condition; It is the AC component of the second wavelength under the load condition; It is the DC component of the first wavelength under the said load state; and It is the DC component of the second wavelength under the load condition.

[0180] In the 9th example, the method according to any one of Examples 7 to 8 further includes determining a plethysmography setpoint for blood pressure monitoring using a second calibration factor when the artery in the body appendage is under the load condition.

[0181] In the 10th example, the calibration factor is calculated using the method of any one of Examples 7 to 9, wherein the calibration factor is calculated using the following equation: in R Loa It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light under the load condition, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength light in the unloaded state.

[0182] In example 11, the method described in example 10 is as follows, wherein R Loa It is the ratio of the average of two or more cardiac cycles.

[0183] In the 12th example, the method according to any one of Examples 10 to 11 is as follows: R Unl It is the ratio of the average of two or more cardiac cycles.

[0184] In example 13, according to the method of example 12, the two or more cardiac cycles include at least one cycle preceding the load cardiac cycle and at least one cycle following the load cardiac cycle, and wherein... R Loa The cardiac cycle is determined based on the load.

[0185] In Example 14, the method described in Example 13 further includes recalibrating the plethysmography setpoint for blood pressure monitoring based on the said load cardiac cycle.

[0186] In Example 15, the method according to any one of Examples 1 to 14 further includes using the health monitoring system to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength light when the volumetric plethysmography signal of the second wavelength light exhibits a trend.

[0187] In Example 16, the method according to any one of Examples 1 to 15 further includes using the health monitoring system to correct the calculated ratio for pressure changes applied by the blood pressure cuff.

[0188] In the 17th example, according to the method of any one of Examples 1 to 16, the first wavelength of light is infrared and the second wavelength of light is red.

[0189] In Example 18, according to the method of any one of Examples 1 to 17, the body appendage includes at least one of the following: arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0190] In Example 19, the method according to any one of Examples 1 to 18 further includes displaying the arterial blood oxygen saturation on a display connected to the health monitoring system.

[0191] In Example 20, according to the method of any one of Examples 1 to 19, transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff.

[0192] In example 21, according to the method of example 20, the portion of the blood pressure cuff includes an inflatable balloon.

[0193] In example 22, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; a light emitter configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to direct the processor to: direct the... A light emitter transmits light of a first wavelength and light of a second wavelength through the body appendage; guides the light sensor to sense the light signals of the first wavelength and the second wavelength; converts the light signals of the first wavelength and the second wavelength into corresponding plethysmogram signals, wherein the plethysmogram signals are configured to provide a plethysmogram of each of the first wavelength and the second wavelength; calculates the ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength; calibrates the calculated ratio using a calibration factor; and calculates arterial oxygen saturation using the calibration factor and the calculated ratio.

[0194] In example 23, according to the health monitoring system of example 22, the light signal of the first wavelength or the second wavelength is also used to monitor blood pressure via a volumetric clamp method.

[0195] In the 24th example, the health monitoring system according to any one of Examples 22 to 23, wherein the instruction configured to guide the processor to transmit light of a first wavelength and light of a second wavelength through a body appendage and to sense the light signals of the first wavelength and the second wavelength is configured to be performed when the arteries in the body appendage are in an unloaded state.

[0196] In example 25, according to the health monitoring system described in example 24, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength, calculated under no-load conditions; wherein This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0197] In the 26th example, the health monitoring system according to any one of Examples 24 to 25, wherein the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

[0198] In the 27th example, according to any one of Examples 19 to 23, the health monitoring system wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

[0199] In example 28, according to the health monitoring system described in example 27, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength; wherein It is the AC component of the first wavelength; It is the AC component of the second wavelength; It is the DC component of the first wavelength; and It is the DC component of the second wavelength.

[0200] In example 29, according to any one of Examples 27 to 28, a health monitoring system wherein the instruction set is configured to instruct the processor to instruct the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring of the artery in the body appendage under load.

[0201] In example 30, according to any one of Examples 27 to 29, the health monitoring system wherein the calibration factor is calculated using the following equation: in R Loa It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength, calculated under load conditions, and wherein... R UnlIt is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength, calculated under no-load conditions.

[0202] In example 31, according to the health monitoring system described in example 30, wherein R Loa It is the average ratio of two or more cardiac cycles.

[0203] In example 32, according to the health monitoring system described in example 30 or 31, wherein R Unl It is the average ratio of two or more cardiac cycles.

[0204] In example 33, according to the health monitoring system of example 32, the two or more cardiac cycles include at least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle; wherein the load cardiac cycle is used to determine R Loa .

[0205] In example 34, according to the health monitoring system described in example 33, the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

[0206] In example 35, according to any one of Examples 22 to 34, the health monitoring system wherein the instruction set is further configured to instruct the processor to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength light when the volumetric plethysmography signal of the second wavelength light exhibits a trend.

[0207] In example 36, according to any one of examples 22 to 35, the health monitoring system wherein the instruction set is further configured to guide the processor to correct the calculated ratio in response to pressure changes provided by the blood pressure cuff.

[0208] In example 37, the health monitoring system according to any one of Examples 22 to 36, wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0209] In Example 38, the health monitoring system according to any one of Examples 22 to 37, wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0210] In example 39, the health monitoring system according to any one of examples 22 to 38 further includes a display, wherein the instruction set is further configured to instruct the processor to display the arterial blood oxygen saturation.

[0211] In Example 40, the health monitoring system according to any one of Examples 22 to 39, wherein transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff.

[0212] In example 41, according to the health monitoring system of example 40, the portion of the blood pressure cuff includes an inflatable balloon.

[0213] In Example 42, a method of operating a non-invasive blood characteristic sensing system, the system including a light emitter, a light sensor, and an expandable balloon, the method comprising: surrounding a sensing region of a patient's appendage with the expandable balloon; pressurizing the expandable balloon to a constant pressure during an open-loop calibration mode, including: emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage; sensing light from the light emitter at the first wavelength via the patient's appendage at the light sensor; sensing light from the light emitter at the second wavelength via the patient's appendage at the light sensor; generating a first sensed pleth signal based on the sensed first wavelength light; generating a second sensed pleth signal based on the sensed second wavelength light; generating a pleth setpoint based on the first sensed pleth signal or the second sensed pleth signal, wherein the pleth setpoint corresponds to a stress-free arterial volume; generating an open-loop R for determining an arterial oxygen saturation measurement, including: deriving from the first sensed pleth signal. and Based on the second sensed pleth signal, the following is derived: and ; and the open-loop R is derived using the following formula: Open loop In closed-loop control mode, modulating the inflatable balloon to partially clamp the arterial volume within the sensing region via a closed-loop control algorithm includes: emitting light from the light emitter at a first wavelength into the sensing region of the patient's appendage; sensing light from the light emitter at the first wavelength via the patient's appendage at a light sensor; generating a third sensed pleth signal based on the sensed first wavelength light; emitting light from the light emitter at a second wavelength into the sensing region of the patient's appendage; sensing light from the light emitter at the second wavelength via the patient's appendage at a light sensor; generating a fourth sensed pleth signal based on the sensed second wavelength light; comparing the third sensed pleth signal or the fourth sensed pleth signal with a pleth setpoint to generate a closed-loop error signal; and modulating the inflatable balloon in response to the closed-loop error signal; generating a closed-loop R for determining an arterial oxygen saturation measurement, including: deriving from the third sensed pleth signal. and Based on the fourth sensed pleth signal, the following is derived: and The closed-loop R is derived using the following formula: closed loop A calibrated R is generated based on the closed-loop R and the calibration factor; and arterial oxygen saturation is calculated using the calibrated R and the pulse oxygen saturation calibration curve.

[0214] In example 43, according to the method of example 42, the calibration factor is based on the R value of the pleth signal from both the first wavelength and the second wavelength measured during the open-loop calibration mode and the closed-loop calibration mode.

[0215] In example 44, according to the method described in example 43, generating the calibration R includes calculating the calibration factor using the following equation: in R Loa It is the ratio between the pleth signal of the first wavelength of light and the pleth signal of the second wavelength in the open-loop calibration mode, and wherein... R Unl It is the ratio between the pleth signal of the first wavelength light and the pleth signal of the second wavelength light in the closed-loop control algorithm.

[0216] In example 45, according to the method described in example 44, where RLoa and / or R Unl It is the average ratio of two or more cardiac cycles.

[0217] In example 46, according to the method described in example 45, where R Unl The two or more cardiac cycles mentioned include those used for calculation R Loa At least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle.

[0218] In Example 47, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; a light emitter configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a processor; and a memory, wherein the memory includes one or more applications, the applications including a set of instructions configured to direct the processor to execute the method according to any one of Examples 42 to 47.

[0219] In example 48, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; a light emitter including an LED, wherein the LED is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set is executed by the processor. The processor is configured to: direct the LED to transmit light of the first wavelength and light of the second wavelength through the body appendage; direct the light sensor to sense the light signals of the first wavelength and light of the second wavelength; convert the light signals of the first wavelength and light of the second wavelength into corresponding plethysmogram signals, wherein the plethysmogram signals are configured to provide a plethysmogram of each of the first wavelength and the second wavelength; calculate the ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength; and calculate arterial oxygen saturation using the calculated ratio.

[0220] In example 49, the health monitoring system according to example 48, wherein guiding the LED to transmit light of the first wavelength and the second wavelength through the body appendage includes a portion of the LED guiding the LED to transmit light of the first wavelength and the second wavelength through the blood pressure cuff.

[0221] In example 50, according to the health monitoring system of example 49, the portion of the blood pressure cuff includes an inflatable balloon.

[0222] In Example 51, according to any one of Examples 48 to 50, the health monitoring system wherein the second wavelength light signal is also used to monitor blood pressure via a volumetric clamp method.

[0223] In example 52, according to the health monitoring system of example 48 or 51, the instruction configured to direct the processor to transmit light of a first wavelength and light of a second wavelength through a body appendage and to sense the light signals of the first wavelength and the second wavelength via a light sensor is configured to be executed when an artery in the body appendage is in an unloaded state.

[0224] In example 53, according to the health monitoring system described in example 52, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength, calculated under no-load conditions; wherein This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0225] In example 54, according to the health monitoring system described in examples 52 to 53, the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

[0226] In example 55, according to any one of examples 48 to 54, the health monitoring system wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

[0227] In example 56, according to the health monitoring system described in example 55, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength; wherein It is the AC component of the first wavelength; It is the AC component of the second wavelength; It is the DC component of the first wavelength; and It is the DC component of the second wavelength.

[0228] In example 57, according to the health monitoring system described in example 55 or 56, the instruction set is configured to instruct the processor to instruct the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring of the artery in the body appendage under load.

[0229] In example 58, according to any one of examples 55 to 57, the health monitoring system wherein the calibration factor is calculated using the following equation: in R loa It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength, calculated under load conditions, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength, calculated under no-load conditions.

[0230] In example 59, according to the health monitoring system described in example 58, wherein R Loa It is the average ratio of two or more cardiac cycles.

[0231] In example 60, according to the health monitoring system described in example 58 or 59, wherein R Unl It is the average ratio of two or more cardiac cycles.

[0232] In example 61, according to the health monitoring system of example 60, the two or more cardiac cycles include at least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle; wherein the load cardiac cycle is used to determine R loa .

[0233] In example 62, according to the health monitoring system described in example 61, the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

[0234] In example 63, according to any one of examples 48 to 62, the health monitoring system wherein the instruction set is further configured to instruct the processor to correct the calculated ratio of the trend volumetric signal of the second wavelength light when the volumetric signal of the second wavelength light exhibits a trend.

[0235] In example 64, according to any one of examples 48 to 63, the health monitoring system wherein the instruction set is further configured to guide the processor to correct the calculated ratio in response to pressure changes provided by the blood pressure cuff.

[0236] In example 65, the health monitoring system according to any one of examples 48 to 64, wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0237] In Example 66, according to any one of Examples 48 to 65, the health monitoring system wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0238] In example 67, the health monitoring system according to any one of examples 48 to 66 further includes a display, wherein the instruction set is further configured to instruct the processor to display the arterial blood oxygen saturation.

[0239] In example 68, a method for measuring arterial oxygen saturation includes: transmitting light of a first wavelength and light of a second wavelength through a body appendage using an LED of an emitter; guiding a light sensor to sense light signals of the first wavelength and the second wavelength; converting the light signals of the first wavelength and the second wavelength into corresponding plethysmogram signals, wherein the plethysmogram signals are configured to provide a plethysmogram of each of the first wavelength and the second wavelength; calculating a ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength; and calculating arterial oxygen saturation using the calculated ratio.

[0240] In example 69, according to the method of example 68, the light signal of sensing the first wavelength light and the second wavelength light includes applying pressure to the body appendage using the blood pressure cuff, such that the arteries therein are in the unloaded state.

[0241] In the 70th example, the method according to any one of Examples 68 to 69 further includes determining the blood pressure of the body appendage based on the plethysmography signal of the first wavelength.

[0242] In example 71, according to the method of any one of examples 68 to 70, the transmission of light of the first wavelength and light of the second wavelength through the body appendage and the sensing of light signals of the first wavelength and the second wavelength are performed when the artery in the body appendage is in an unloaded state.

[0243] In example 72, according to the method described in example 71, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric plethysmogram of the first wavelength and the volumetric plethysmogram of the second wavelength when the artery is in the unloaded state; and wherein: This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0244] In example 73, according to the method of any one of examples 71 to 72, the blood pressure cuff includes an inflatable balloon, and the inflatable balloon applies pressure to the body appendage such that the arteries therein are in the unloaded state.

[0245] In example 74, according to the method of any one of examples 68 to 73, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light under load.

[0246] In example 75, according to the method described in example 74, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength; and wherein: It is the AC component of the first wavelength under the load condition; It is the AC component of the second wavelength under the load condition; It is the DC component of the first wavelength under the said load state; and It is the DC component of the second wavelength under the load condition.

[0247] In example 76, the method according to any one of examples 74 to 75 further includes determining a plethysmography setpoint for blood pressure monitoring using a second calibration factor when the artery in the body appendage is under the load condition.

[0248] In example 77, the calibration factor is calculated using the method of any one of examples 74 to 76, wherein the calibration factor is calculated using the following equation: in R loa It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light under the load condition, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength light under the no-load condition.

[0249] In example 78, the method described in example 77 is followed, where R Loa It is the ratio of the average of two or more cardiac cycles.

[0250] In example 79, the method is according to any one of examples 77 to 78, wherein R Unl It is the ratio of the average of two or more cardiac cycles.

[0251] In example 80, according to the method of example 79, the two or more cardiac cycles include at least one cycle preceding the load cardiac cycle and at least one cycle following the load cardiac cycle, and wherein... R LoaThe cardiac cycle is determined based on the load.

[0252] In example 81, the method according to example 80 further includes recalibrating the plethysmography setpoint for blood pressure monitoring based on the said load cardiac cycle.

[0253] In Example 82, the method according to any one of Examples 68 to 81 further includes using the health monitoring system to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength of light when the volumetric plethysmography signal of the second wavelength of light exhibits a trend.

[0254] In example 83, the method according to any one of examples 68 to 82 further includes using the health monitoring system to correct the calculated ratio for pressure changes applied by the blood pressure cuff.

[0255] In example 84, the method according to any one of examples 68 to 83 is wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0256] In Example 85, according to the method of any one of Examples 68 to 84, the body appendage includes at least one of the following: arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0257] In example 86, the method according to any one of examples 68 to 85 further includes displaying the arterial blood oxygen saturation on a display connected to the health monitoring system.

[0258] In example 87, according to the method of any one of examples 68 to 86, transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff.

[0259] In example 88, according to the method described in example 87, the portion of the blood pressure cuff includes an inflatable balloon.

[0260] In example 89, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; at least one light emitter configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to direct the processor to: direct the inflatable balloon... An inflatable balloon applies constant pressure to the body appendage; guides the light emitter to transmit light of a first wavelength and a second wavelength through the body appendage during the constant pressure; guides the light sensor to sense the light signals of the first wavelength and the second wavelength; converts the light signals of the first wavelength and the second wavelength into corresponding plethysmography signals, wherein the plethysmography signals are configured to provide a plethysmography of each of the first wavelength and the second wavelength; calculates the ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength; and calculates arterial oxygen saturation using the calculated ratio.

[0261] In example 90, according to the health monitoring system of example 89, applying the constant pressure to the body appendage includes applying the constant pressure for at least one full cardiac cycle.

[0262] In example 91, the health monitoring system according to any one of examples 89 to 90, wherein applying the constant pressure to the body appendage includes applying a pressure no greater than the ambient pressure.

[0263] In example 92, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; a light emitter configured to transmit light of a first wavelength at a first time and light of a second wavelength at a second time through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to instruct the processor to: The light emitter is guided to transmit light of the first wavelength at a first time and light of the second wavelength at a second time through the body appendage; the light sensor is guided to sense the light signals of the first wavelength and the second wavelength; the light signals of the first wavelength and the second wavelength are converted into corresponding plethysmogram signals, wherein the plethysmogram signals are configured to provide a plethysmogram of each of the first wavelength and the second wavelength; a ratio between the plethysmogram of the first wavelength and the plethysmogram of the second wavelength is calculated; and arterial oxygen saturation is calculated using the calibration factor and the calculated ratio.

[0264] In example 93, according to the health monitoring system described in example 92, the difference between the second time and the first time is less than a complete cardiac cycle.

[0265] In example 94, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; at least one light emitter configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to instruct the processor to: instruct the light emitter to transmit light of the first wavelength and the second wavelength through the body appendage during a first time window; instruct the light sensor to sense light signals of the first wavelength and the second wavelength; and convert the light signals of the first wavelength and the second wavelength into corresponding plethysmographic signals, wherein the plethysmographic signals are configured to provide light of the first wavelength and the second wavelength. The process includes: generating a plethysmogram for each light source; determining a first plethysmogram setpoint based on the plethysmogram signal; calculating a first ratio between the plethysmogram of the first wavelength light and the plethysmogram of the second wavelength light; guiding the light emitter to transmit the first wavelength light and the second wavelength light through the body appendage during a second time window; guiding the light sensor to sense a second light signal of the first wavelength light and the second wavelength light; converting the second light signal of the first wavelength light and the second wavelength light into a corresponding second plethysmogram signal, wherein the plethysmogram signal is configured to provide a second plethysmogram for each of the first wavelength light and the second wavelength light; determining a second plethysmogram setpoint based on the second plethysmogram signal; calculating a second ratio between the plethysmogram of the first wavelength light and the plethysmogram of the second wavelength light; determining the degree of drift between the first plethysmogram setpoint and the second plethysmogram setpoint based on the first ratio and the second ratio; and calculating arterial oxygen saturation using the calculated ratio.

[0266] In example 95, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; at least one light emitter, wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor, wherein the light sensor is configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to direct the processor to: direct the light emitter to transmit light of the first wavelength and the second wavelength. The light is transmitted through the body appendage; the light sensor is guided to sense light signals of the first wavelength and the second wavelength; the light signals of the first wavelength and the second wavelength are converted into corresponding plethysmography signals, wherein the plethysmography signals are configured to provide a plethysmography of each of the first wavelength and the second wavelength; a ratio is calculated between the plethysmography of the first wavelength and the plethysmography of the second wavelength; and arterial oxygen saturation is calculated using the calculated ratio; wherein transmitting the first wavelength and the second wavelength through the body appendage includes transmitting the first wavelength and the second wavelength through a portion of the blood pressure cuff or the inflatable balloon.

[0267] In example 96, a health monitoring system for measuring arterial oxygen saturation includes: a blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: an inflatable balloon; at least one light emitter configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and a light sensor configured to sense light signals of the first wavelength and the second wavelength; a hardware processor; and a non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to instruct the processor to: instruct the inflatable balloon to apply a first pressure to the body appendage, the first pressure being based on... Blood pressure in a body appendage; guiding the inflatable balloon to apply a second pressure to the body appendage, the second pressure being lower than the first pressure; during the second pressure, guiding the light emitter to transmit light of a first wavelength and light of a second wavelength through the body appendage; guiding the light sensor to sense the light signals of the first wavelength and the second wavelength; converting the light signals of the first wavelength and the second wavelength into corresponding plethysmography signals, wherein the plethysmography signals are configured to provide a plethysmography of each of the first wavelength and the second wavelength; calculating the ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength; and calculating blood pressure based on the plethysmography signals.

[0268] In example 97, according to any one of examples 89 to 96, the health monitoring system wherein the light signal of the first wavelength is also used to monitor blood pressure via a volumetric clamp method.

[0269] In example 98, the health monitoring system according to any one of examples 89 to 97, wherein the instruction configured to direct the processor to transmit light of a first wavelength and light of a second wavelength through a body appendage and to sense light signals of the first wavelength and the second wavelength via a light sensor is configured to be executed when an artery within the body appendage is in an unloaded state.

[0270] In example 99, according to the health monitoring system described in example 98, the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength, calculated under no-load conditions; wherein This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0271] In the 100th example, according to any one of Examples 98 to 99, the health monitoring system wherein the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to the body appendage such that the artery therein is in the unloaded state.

[0272] In Example 101, according to any one of Examples 98 to 100, the health monitoring system wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

[0273] In example 102, according to the health monitoring system of example 101, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength; wherein It is the AC component of the first wavelength; It is the AC component of the second wavelength; It is the DC component of the first wavelength; and It is the DC component of the second wavelength.

[0274] In example 103, according to any one of examples 101 to 102, the health monitoring system wherein the instruction set is configured to instruct the processor to instruct the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring of the artery in the body appendage under load.

[0275] In example 104, according to any one of Examples 101 to 103, the health monitoring system wherein the calibration factor is calculated using the following equation: in R LoaIt is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength, calculated under load conditions, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength, calculated under no-load conditions.

[0276] In example 105, according to the health monitoring system described in example 104, wherein R Loa It is the average ratio of two or more cardiac cycles.

[0277] In example 106, according to the health monitoring system described in example 104 or 105, wherein R Unl It is the average ratio of two or more cardiac cycles.

[0278] In example 107, according to the health monitoring system of example 106, the two or more cardiac cycles include at least one cycle before the load cardiac cycle and at least one cycle after the load cardiac cycle; wherein the load cardiac cycle is used to determine R Loa .

[0279] In example 108, according to the health monitoring system described in example 107, the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

[0280] In example 109, according to any one of examples 89 to 108, the health monitoring system wherein the instruction set is further configured to instruct the processor to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength light when the volumetric plethysmography signal of the second wavelength light exhibits a trend.

[0281] In example 110, according to any one of examples 89 to 109, the health monitoring system wherein the instruction set is further configured to instruct the processor to correct the calculated ratio in response to pressure changes provided by the blood pressure cuff.

[0282] In example 111, according to any one of examples 89 to 110, the health monitoring system wherein the first wavelength of light is infrared and the second wavelength of light is red.

[0283] In Example 112, the health monitoring system according to any one of Examples 89 to 111, wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0284] In example 113, the health monitoring system according to any one of examples 89 to 112 further includes a display, wherein the instruction set is further configured to instruct the processor to display the arterial blood oxygen saturation.

[0285] In example 114, the health monitoring system according to any one of examples 89 to 113, wherein transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff.

[0286] In example 115, according to the health monitoring system described in example 114, the portion of the blood pressure cuff includes an inflatable balloon.

[0287] In example 116, according to any one of examples 89 to 115, the health monitoring system wherein the instruction set is further configured to determine the plethysmography setpoint based on the plethysmography signal.

[0288] In Example 117, a method for measuring arterial oxygen saturation includes: applying a constant pressure to a body appendage; during the constant pressure, transmitting light of a first wavelength and light of a second wavelength through the body appendage using a transmitter of a blood pressure cuff; sensing optical signals of the first wavelength and the second wavelength using a light sensor of the blood pressure cuff; converting the optical signals of the first wavelength and the second wavelength into corresponding plethysmography signals using a health monitoring system connected to the blood pressure cuff, wherein the plethysmography signals are configured to provide plethysmography of each of the first wavelength and the second wavelength; calculating a ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength using the health monitoring system; and calculating arterial oxygen saturation using the health monitoring system, a calibration factor, and the calculated ratio.

[0289] In Example 118, a method for measuring arterial oxygen saturation includes: transmitting light of a first wavelength at a first time and light of a second wavelength through a body appendage at a second time using a transmitter of a blood pressure cuff; sensing optical signals of the first wavelength and the second wavelength using a light sensor of the blood pressure cuff; converting the optical signals of the first wavelength and the second wavelength into corresponding plethysmography signals using a health monitoring system connected to the blood pressure cuff, wherein the plethysmography signals are configured to provide plethysmography of each of the first wavelength and the second wavelength; calculating a ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength using the health monitoring system; and calculating arterial oxygen saturation using the calculated ratio using the health monitoring system.

[0290] In example 119, a method for measuring arterial blood oxygen saturation includes: during a first time window, transmitting light of a first wavelength and a second wavelength through a body appendage and using a transmitter of a blood pressure cuff; sensing optical signals of the first wavelength and the second wavelength using a light sensor of the blood pressure cuff; converting the optical signals of the first wavelength and the second wavelength using a health monitoring system connected to the blood pressure cuff, wherein the plethysmography signals are configured to provide plethysmography of each of the first wavelength and the second wavelength; determining a first plethysmography setpoint based on the plethysmography signals; calculating the ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength; and during a second time window, transmitting light of the first wavelength and the second wavelength through the body appendage and using the transmitter of the blood pressure cuff. A first wavelength of light and a second wavelength of light; using the light sensor of the blood pressure cuff to sense second light signals of the first wavelength of light and the second wavelength of light; using the health monitoring system to convert the second light signals of the first wavelength of light and the second wavelength of light into corresponding second plethysmography signals, wherein the plethysmography signals are configured to provide a second plethysmography of each of the first wavelength of light and the second wavelength of light; determining a second plethysmography setpoint based on the second plethysmography signals; using the health monitoring system to calculate a second ratio between the second plethysmography of the first wavelength of light and the second plethysmography of the second wavelength of light; determining the degree of drift between the first plethysmography setpoint and the second plethysmography setpoint based on the first ratio and the second ratio; and using the health monitoring system to calculate arterial oxygen saturation using the calculated ratio.

[0291] In Example 120, a method for measuring arterial oxygen saturation includes: applying a first pressure to a body appendage using an inflatable balloon, the first pressure being based on blood pressure in the body appendage; applying a second pressure to the body appendage using the inflatable balloon, the second pressure being lower than the first pressure; transmitting light of a first wavelength and light of a second wavelength through the body appendage using a transmitter of a blood pressure cuff; sensing optical signals of the first wavelength and the second wavelength using a light sensor of the blood pressure cuff; converting the optical signals of the first wavelength and the second wavelength using a health monitoring system, wherein the health monitoring system is connected to the blood pressure cuff, wherein the plethysmography signals are configured to provide a plethysmography of each of the first wavelength and the second wavelength; calculating a ratio between the plethysmography of the first wavelength and the plethysmography of the second wavelength using the health monitoring system; calibrating the calculated ratio using the health monitoring system with a calibration factor; and calculating arterial oxygen saturation using the health monitoring system with the calibration factor and the calculated ratio.

[0292] In example 121, according to the method of any one of Examples 117 to 120, the light signal of sensing the first wavelength light and the second wavelength light includes applying pressure to the body appendage using the blood pressure cuff such that the artery therein is in the unloaded state.

[0293] In example 122, the method according to any one of examples 117 to 121 further includes determining the blood pressure of the body appendage based on the plethysmography signal at the first wavelength.

[0294] In example 123, the method according to any one of examples 117 to 122 is performed in which the first wavelength of light and the second wavelength of light are transmitted through the body appendage and the light signals of the first wavelength of light and the second wavelength of light are sensed when the artery in the body appendage is in an unloaded state.

[0295] In example 124, according to the method described in example 123, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric plethysmogram of the first wavelength and the volumetric plethysmogram of the second wavelength when the artery is in the unloaded state; and wherein: This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

[0296] In example 125, according to the method of any one of examples 123 to 124, the blood pressure cuff includes an inflatable balloon, and the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

[0297] In example 126, according to the method of any one of examples 117 to 125, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the artery in the body appendage under load and the volumetric plethysmogram of the first wavelength of light and the second wavelength of light.

[0298] In example 127, according to the method described in example 126, the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength; and wherein: It is the AC component of the first wavelength under the load condition; It is the AC component of the second wavelength under the load condition; It is the DC component of the first wavelength under the said load state; and It is the DC component of the second wavelength under the load condition.

[0299] In example 128, the method according to any one of examples 126 to 127 further includes using a second calibration factor to determine a plethysmography setpoint for blood pressure monitoring when the artery in the body appendage is under load.

[0300] In example 129, the calibration factor is calculated using the method of any one of examples 126 to 128, wherein the calibration factor is calculated using the following equation: in R LoaIt is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light under the load condition, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength light in the unloaded state.

[0301] In example 130, the method described in example 129 is as follows, wherein R Loa It is the ratio of the average of two or more cardiac cycles.

[0302] In example 131, the method according to any one of examples 129 to 130 is wherein R Unl It is the ratio of the average of two or more cardiac cycles.

[0303] In example 132, according to the method of example 131, the two or more cardiac cycles include at least one cycle preceding the load cardiac cycle and at least one cycle following the load cardiac cycle, and wherein... R Loa The cardiac cycle is determined based on the load.

[0304] In example 133, the method described in example 132 further includes recalibrating the plethysmography setpoint for blood pressure monitoring based on the said load cardiac cycle.

[0305] In example 134, the method according to any one of examples 117 to 133 further includes using the health monitoring system to correct the calculated ratio of the trend volumetric plethysmography signal of the second wavelength light when the volumetric plethysmography signal of the second wavelength light exhibits a trend.

[0306] In example 135, the method according to any one of examples 117 to 134 further includes using the health monitoring system to correct the calculated ratio for pressure changes applied by the blood pressure cuff.

[0307] In example 136, according to the method of any one of examples 117 to 135, the first wavelength of light is infrared and the second wavelength of light is red.

[0308] In Example 137, according to the method of any one of Examples 117 to 136, the body appendage includes at least one of the following: arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

[0309] In example 138, the method according to any one of examples 117 to 137 further includes displaying the arterial blood oxygen saturation on a display connected to the health monitoring system.

[0310] In example 139, according to the method of any one of examples 117 to 138, transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff.

[0311] In example 140, according to the method of example 139, the portion of the blood pressure cuff includes an inflatable balloon.

[0312] In Example 141, the method according to any one of Examples 117 to 140 further includes determining a volumetric plot setpoint based on the volumetric plot signal.

Claims

1. A health monitoring system for measuring arterial blood oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; A light emitter, wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor, wherein the optical sensor is configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, which includes an instruction set, The instruction set thereon, when executed by the processor, is configured to bootstrap the processor to: The light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; The calculated ratios are calibrated using calibration factors; and Arterial oxygen saturation is calculated using the calibration factor and the calculated ratio.

2. The health monitoring system according to claim 1, wherein the optical signal of the first wavelength or the second wavelength is further used to monitor blood pressure via a volumetric clamp method.

3. The health monitoring system of claim 1, wherein the instruction configured to direct the processor to transmit light of a first wavelength and light of a second wavelength through a body appendage and to sense light signals of the first wavelength and the second wavelength via a light sensor is configured to be executed when an artery within the body appendage is in an unloaded state.

4. The health monitoring system of claim 3, wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in R Unl It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength, calculated under no-load conditions; wherein This represents the AC component of the first wavelength when the artery is in the unloaded state; This represents the AC component of the second wavelength when the artery is in the unloaded state; It is the DC component of the first wavelength when the artery is in the unloaded state; and It is the DC component of the second wavelength when the artery is in the unloaded state.

5. The health monitoring system of claim 4, wherein the blood pressure cuff includes an inflatable balloon; wherein the inflatable balloon is configured to apply pressure to the body appendage such that the arteries therein are in the unloaded state.

6. The health monitoring system of claim 1, wherein the calibration factor is based on the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light, calculated when the artery in the body appendage is under load.

7. The health monitoring system of claim 6, wherein the ratio between the volumetric plethysmogram of the first wavelength light and the volumetric plethysmogram of the second wavelength light is calculated using the following equation: in It is the ratio between the volumetric map of the first wavelength and the volumetric map of the second wavelength; wherein It is the AC component of the first wavelength; It is the AC component of the second wavelength; It is the DC component of the first wavelength; and It is the DC component of the second wavelength.

8. The health monitoring system of claim 7, wherein the instruction set is configured to instruct the processor to instruct the health monitoring system to perform calibration for determining a plethysmographic setpoint for blood pressure monitoring of the artery in the body appendage under load.

9. The health monitoring system of claim 8, wherein the calibration factor is calculated using the following equation: in R Loa It is the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength, calculated under load conditions, and wherein... R Unl It is the ratio between the volumetric profile of the first wavelength light and the volumetric profile of the second wavelength, calculated under no-load conditions.

10. The health monitoring system of claim 9, wherein R Loa is an average ratio over two or more cardiac cycles.

11. The health monitoring system of claim 9, wherein R Unl is an average ratio over two or more cardiac cycles.

12. The health monitoring system of claim 11, wherein the two or more cardiac cycles include at least one cycle before a loaded cardiac cycle and at least one cycle after the loaded cardiac cycle; wherein the determination of R Loa .

13. The health monitoring system of claim 12, wherein the load cardiac cycle is used to recalibrate the plethysmography setpoint for blood pressure monitoring.

14. The health monitoring system of claim 1, wherein the instruction set is further configured to instruct the processor to correct the calculated ratio of the trend volumetric signal of the second wavelength light when the volumetric signal of the second wavelength light exhibits a trend.

15. The health monitoring system of claim 1, wherein the instruction set is further configured to guide the processor to correct the calculated ratio in response to pressure changes provided by the blood pressure cuff.

16. The health monitoring system of claim 1, wherein the first wavelength of light is infrared and the second wavelength of light is red.

17. The health monitoring system according to claim 1, wherein the body appendage is: an arm, finger, thumb, wrist, ankle, leg, toe, ear, or temple.

18. The health monitoring system of claim 1, further comprising a display, wherein the instruction set is further configured to instruct the processor to display the arterial blood oxygen saturation.

19. The health monitoring system of claim 1, wherein transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through the portion of the blood pressure cuff.

20. The health monitoring system of claim 19, wherein the portion of the blood pressure cuff includes an inflatable balloon.

21. A health monitoring system for measuring arterial blood oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; A light emitter, comprising an LED configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor, wherein the optical sensor is configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to bootstrap the processor to: The LED is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; and The calculated ratio is used to calculate arterial oxygen saturation.

22. A health monitoring system for measuring arterial blood oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; At least one light emitter, the at least one light emitter being configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to bootstrap the processor to: The inflatable balloon is guided to apply constant pressure to the body appendage; The light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage during the constant pressure period; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; and The calculated ratio is used to calculate arterial oxygen saturation.

23. The health monitoring system of claim 22, wherein applying the constant pressure to the body appendage comprises applying the constant pressure for at least one complete cardiac cycle.

24. The health monitoring system of claim 22, wherein applying the constant pressure to the body appendage comprises applying a pressure not greater than the ambient pressure.

25. A health monitoring system for measuring arterial oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; A light emitter configured to transmit light of a first wavelength at a first time and light of a second wavelength at a second time through the body appendage; and An optical sensor configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to bootstrap the processor to: The light emitter is guided to transmit light of the first wavelength at the first time and light of the second wavelength at the second time through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; and Arterial oxygen saturation is calculated using the calibration factor and the calculated ratio.

26. The health monitoring system of claim 25, wherein the difference between the second time and the first time is less than a complete cardiac cycle.

27. A health monitoring system for measuring arterial blood oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; At least one light emitter, the at least one light emitter being configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to bootstrap the processor to: During the first time window, the light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. The first volumetric mapping setpoint is determined based on the volumetric mapping signal; Calculate a first ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; During the second time window, the light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense a second optical signal from the first wavelength of light and the second wavelength of light; The second optical signals of the first wavelength light and the second wavelength light are converted into corresponding second volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a second volumetric mapping of each of the first wavelength light and the second wavelength light; The second volumetric mapping setpoint is determined based on the second volumetric mapping signal; Calculate a second ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; Based on the first ratio and the second ratio, determine the degree of drift between the first volumetric mapping setpoint and the second volumetric mapping setpoint; and The calculated ratio is used to calculate arterial oxygen saturation.

28. A health monitoring system for measuring arterial blood oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; At least one light emitter, wherein the light emitter is configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor, wherein the optical sensor is configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, which includes an instruction set, The instruction set thereon, when executed by the processor, is configured to bootstrap the processor to: The light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; and Calculate arterial oxygen saturation using the calculated ratio; Transmitting light of the first wavelength and light of the second wavelength through the body appendage includes transmitting light of the first wavelength and light of the second wavelength through a portion of the blood pressure cuff or the inflatable balloon.

29. A health monitoring system for measuring arterial oxygen saturation, comprising: A blood pressure cuff connected to a computing system, wherein the blood pressure cuff is configured to be fitted onto a body appendage, wherein the blood pressure cuff includes: Inflatable balloon; At least one light emitter, the at least one light emitter being configured to transmit light of a first wavelength and light of a second wavelength through the body appendage; and An optical sensor configured to sense optical signals of light of the first wavelength and light of the second wavelength; Hardware processor; and Non-transitory memory, the non-transitory memory including an instruction set, wherein the instruction set, when executed by the processor, is configured to bootstrap the processor to: The inflatable balloon is directed to apply a first pressure to the body appendage, the first pressure being based on the blood pressure of the body appendage; The inflatable balloon is directed to apply a second pressure to the body appendage, the second pressure being lower than the first pressure; During the second pressurization, the light emitter is guided to transmit light of the first wavelength and light of the second wavelength through the body appendage; The optical sensor is guided to sense the optical signals of the first wavelength and the second wavelength; The optical signals of the first wavelength light and the second wavelength light are converted into corresponding volumetric mapping signals, wherein the volumetric mapping signals are configured to provide a volumetric mapping of each of the first wavelength light and the second wavelength light. Calculate the ratio between the volumetric map of the first wavelength light and the volumetric map of the second wavelength light; and Blood pressure is calculated based on the volumetric plethysmography signal.

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