Monitoring of hemodynamic status during dialysis based on oxygen signal phase shift detection

Abstract

A hemodialysis system includes: a hemodialysis machine configured to provide hemodialysis treatment to a patient, wherein the hemodialysis treatment includes circulating the patient's extracorporeal blood through an extracorporeal blood circuit; a first oxygen saturation sensor device configured to measure oxygen saturation corresponding to the patient's extracorporeal blood in the extracorporeal blood circuit; a second oxygen saturation sensor device configured to measure oxygen saturation corresponding to blood flowing within the patient's body; and at least one controller configured to determine one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to the patient based on oxygen saturation measurements from the first and second oxygen saturation sensor devices.

Description

Background Technology

[0001] Patients with kidney failure or partial kidney failure typically undergo dialysis to remove toxins and excess fluid from their blood. Hemodialysis is one of the most common forms of dialysis. To perform hemodialysis, blood is drawn from the patient through an aspiration needle or catheter, which draws blood from an arteriovenous access or vein located at a specific, accepted access site (e.g., a shunt surgically placed in the arm, or a central venous catheter placed in the superior vena cava). The needle or catheter is connected to an external tubing that feeds the blood to a peristaltic pump and subsequently to a dialyzer that cleans the blood and removes excess fluid. The cleaned blood is then returned to the patient through an additional external tubing, typically connected to another needle in the arteriovenous access or to a separate lumen of a central venous catheter. Sometimes, heparin infusion is placed in the hemodialysis circuit to prevent blood clotting.

[0002] As the drawn blood passes through the dialyzer, it travels through straw-like tubes within the dialyzer, which serve as semi-permeable channels for impure blood. Fresh dialysate solution enters the dialyzer at its downstream end. The dialysate surrounds the straw-like tubes and flows through the dialyzer in the opposite direction to the blood flowing through the tubes. The fresh dialysate collects toxins passing through the straw-like tubes by diffusion and collects excess fluid from the blood by ultrafiltration. The dialysate containing the removed toxins and excess fluid is disposed of as waste. Red blood cells remain in the straw-like tubes and do not enter the dialysate.

[0003] Optical blood monitoring systems are frequently used during hemodialysis or other treatments involving extracorporeal blood flow. These systems use optical technology to non-invasively measure hematocrit and oxygen saturation levels in real time as the blood flows through the hemodialysis system. The blood monitoring system can measure blood at a sterile blood chamber, for example, when attached online to an extracorporeal tubing.

[0004] Typically, the blood chamber, tubing, and dialyzer are replaced for each patient. The blood chamber is for single use only. The blood chamber defines an internal blood flow cavity comprising a substantially flat observation area and two opposing observation lenses. A transmitter (e.g., a light-emitting diode (LED) emitter) and a photodetector for an optical blood monitoring system are secured (e.g., by clips) to the appropriate position on the blood chamber above the lenses. By using a photodetector that detects the resulting intensity of each wavelength, multiple wavelengths of light passing through the blood chamber and the patient's blood flowing through it can be distinguished.

[0005] Preferred wavelengths for measuring hematocrit are approximately 810 nm and approximately 1300 nm, where approximately 810 nm is substantially isoabsorbable for red blood cells and approximately 1300 nm is substantially isoabsorbable for water. Ratio measurement techniques can be used to calculate a patient's hematocrit value in real time based on this light intensity information. The hematocrit value is a percentage determined by the ratio between (1) the volume of red blood cells in a given whole blood sample and (2) the total volume of the blood sample.

[0006] In a clinical setting, the actual percentage change in blood volume during hemodialysis can be determined in real time based on measured changes in hematocrit. Therefore, optical blood monitoring systems can not only non-invasively monitor a patient's hematocrit levels but also monitor changes in blood volume in real time during hemodialysis treatment. This ability to monitor real-time changes in blood volume helps promote safe and effective hemodialysis.

[0007] For real-time blood monitoring, the transmitter and photodetector can be mounted on two opposing heads of a sensor clip assembly mounted above the blood chamber. For system accuracy, the transmitter and photodetector can be positioned and oriented in a predetermined manner each time the sensor clip assembly is clamped into place above the blood chamber. This predetermined position and orientation ensures that light propagating from the transmitter to the photodetector passes through a lens within the blood chamber.

[0008] Optical blood monitoring systems can be calibrated for specific dimensions of the blood chamber and for specific positions and orientations of the sensor clip assembly relative to the blood chamber. For this purpose, the sensor clip assembly can be configured to mate with the blood chamber, such that the transmitter and photodetector are in predetermined positions and orientations relative to each other and relative to the blood chamber.

[0009] An example of an optical blood monitoring system with a sensor clip assembly entitled “SENSOR CLIP ASSEMBLY FOR AN OPTICAL MONITORING SYSTEM” is described in U.S. Patent No. 9,801,993, which is configured to measure hematocrit and oxygen saturation of extracorporeal blood flowing through a blood chamber, the entire contents of which are incorporated herein by reference.

[0010] Cardiovascular disease is very common among hemodialysis patients and is a leading cause of death in this population. Cardiac output is a hemodynamic variable corresponding to organ perfusion. With each pump of the heart, oxygen-rich arterial blood is ejected from the left ventricle and transported through the arteries, delivering oxygen bound to hemoglobin to the capillary beds of organs and tissues. The time required for oxygen to be delivered to organs and tissues is an indicator of cardiovascular function.

[0011] However, in existing hemodialysis systems, patients' cardiovascular function is not typically monitored closely. During hemodialysis treatment, a patient's blood pressure may be checked periodically (e.g., every 30 minutes), but this provides only a rough and limited indication of cardiovascular function. Summary of the Invention

[0012] In one exemplary embodiment, this application provides an extracorporeal blood therapy system (e.g., a hemodialysis system), the extracorporeal blood therapy system comprising: an extracorporeal blood therapy machine (e.g., a hemodialysis machine) configured to provide treatment (e.g., hemodialysis treatment) to a patient, wherein the treatment includes circulating the patient's extracorporeal blood through an extracorporeal blood circuit; a first oxygen saturation sensor device configured to measure oxygen saturation corresponding to the patient's extracorporeal blood in the extracorporeal blood circuit; a second oxygen saturation sensor device configured to measure oxygen saturation corresponding to blood flowing within the patient's body; and at least one controller configured to determine one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to the patient based on oxygen saturation measurements from the first oxygen saturation sensor device and the second oxygen saturation sensor device.

[0013] In another exemplary embodiment, the patient's extracorporeal blood is drawn from the patient through an access site, and wherein the second oxygen saturation sensor device is located on the same side of the access site on the patient.

[0014] In another exemplary embodiment, the access site and the second oxygen saturation sensor device are both located on the same arm of the patient.

[0015] In another exemplary embodiment, the second oxygen saturation sensor device is configured to be attached to a patient's finger as a pulse oximeter.

[0016] In another exemplary embodiment, determining one or more OSPS values ​​or one or more transcutaneous travel time values ​​includes comparing a first oxygen saturation trace corresponding to a measurement performed by the first oxygen saturation sensor device with a second oxygen saturation trace corresponding to a measurement performed by the second oxygen saturation sensor device.

[0017] In another exemplary embodiment, the first oxygen saturation sensor device and the second oxygen saturation sensor device each have a sampling rate of at least 1 Hz.

[0018] In another exemplary embodiment, the at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values, wherein the analysis includes trend analysis that identifies an upward or downward trend in the determined OSPS values ​​or determined percutaneous travel time values ​​of a patient.

[0019] In another exemplary embodiment, the at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values, wherein the analysis includes a reference-based analysis to identify whether the patient's determined OSPS value or determined percutaneous travel time value is higher or lower than one or more reference OSPS values ​​or one or more percutaneous travel time values.

[0020] In another exemplary embodiment, one or more determined percutaneous travel time values ​​each correspond to the amount of time that blood travels between the access site for drawing blood from outside the body and the location of the second oxygen saturation sensor device.

[0021] In another exemplary embodiment, the at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined transcutaneous travel time values ​​and output the results of the analysis, wherein outputting the results includes displaying the results on a display and / or transmitting the results via a communication network.

[0022] In another exemplary embodiment, the at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values ​​and perform a response operation in response to the results of the analysis, wherein the response operation includes modifying the hemodialysis treatment for the patient.

[0023] In another exemplary embodiment, the modification includes: reducing the ultrafiltration rate; pausing hemodialysis treatment; adjusting the patient's position; lowering the dialysate temperature; infusing normal saline; increasing the sodium concentration in the dialysate; and / or triggering relatively high-frequency blood pressure measurements.

[0024] In another exemplary embodiment, the at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined transcutaneous travel time values ​​and perform response operations in response to the results of the analysis, wherein the response operations include outputting alarms and / or sending messages to medical professionals.

[0025] In another exemplary embodiment, this application provides a method for monitoring the hemodynamic status of a patient during treatment, the method comprising: measuring the oxygen saturation of the patient's extracorporeal blood at a location in an extracorporeal blood circuit by a first oxygen saturation sensor device; measuring the oxygen saturation of the patient's in vivo blood at a location in the patient's body by a second oxygen saturation sensor device; determining, by at least one controller, one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to the patient based on the oxygen saturation measurements from the first oxygen saturation sensor device and the second oxygen saturation sensor device; analyzing, by the at least one controller, one or more determined OSPS values ​​or one or more determined percutaneous travel time values; and performing a response operation by the at least one controller in response to the result of the analysis.

[0026] In another exemplary embodiment, the patient's extracorporeal blood is drawn from the patient through an access site, and wherein the second oxygen saturation sensor device is located on the same side of the access site on the patient's body.

[0027] In another exemplary embodiment, one or more determined transcutaneous travel time values ​​each correspond to the amount of time that blood travels between the access site and the location of the second oxygen saturation sensor device.

[0028] In another exemplary embodiment, the response operation includes modifying the treatment.

[0029] In yet another exemplary embodiment, this application provides a non-transitory computer-readable medium having stored processor-executable instructions thereon for monitoring a patient's hemodynamic state during treatment, wherein the processor-executable instructions, when executed, facilitate: measuring the oxygen saturation of the patient's extracorporeal blood at a location in an extracorporeal blood circuit by a first oxygen saturation sensor device; measuring the oxygen saturation of the patient's in vivo blood at a location on the patient's body by a second oxygen saturation sensor device; determining, by at least one controller, one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to the patient based on the oxygen saturation measurements from the first and second oxygen saturation sensor devices; analyzing, by the at least one controller, one or more determined OSPS values ​​or one or more determined percutaneous travel time values; and performing a response operation by the at least one controller in response to the results of the analysis.

[0030] In another exemplary embodiment, the patient's extracorporeal blood is drawn from the patient through an access site, and wherein the second oxygen saturation sensor device is located on the same side of the access site on the patient's body.

[0031] In another exemplary embodiment, one or more determined percutaneous travel time values ​​each correspond to the amount of time that blood travels between the access site and the location of the second oxygen saturation sensor device.

[0032] In another exemplary embodiment, the response operation includes modifying the treatment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of an exemplary hemodialysis system having an external oxygen saturation sensor device and a transcutaneous oxygen saturation sensor device.

[0034] Figure 2 This is a block diagram showing an extracorporeal oxygen saturation sensor device positioned in an extracorporeal blood flow path and a transcutaneous oxygen saturation sensor device positioned on the patient's body to measure oxygen saturation (SaO2) corresponding to the patient's SaO2 characteristics.

[0035] Figure 3 This is a graph showing the oxygen characteristic phase shift (OSPS) between the first SaO2 trace measured by the transdermal oxygen saturation sensor device and the second SaO2 trace measured by the in vitro oxygen saturation sensor device.

[0036] Figure 4A This is a flowchart of an exemplary procedure for monitoring a patient's OSPS during dialysis.

[0037] Figure 4B This is a flowchart of an exemplary procedure for monitoring the percutaneous travel time of a patient during dialysis.

[0038] Figure 5 The hemodialysis system communicates with the Electronic Health Records (EHR) system to provide OSPS-related or TT-related information to the EHR system. transcutaneous A block diagram of an exemplary network environment for related data. Detailed Implementation

[0039] Exemplary embodiments of this application provide improved monitoring of hemodynamic status during dialysis based on the detection of one or more oxygen characteristic phase shift (OSPS) values ​​or one or more transcutaneous travel time values ​​of a patient. One or more OSPS values ​​or one or more transcutaneous travel time values ​​of the patient are determined using an extracorporeal oxygen saturation sensor device disposed in an extracorporeal blood line and a transcutaneous oxygen saturation sensor device disposed on the patient's body (e.g., a pulse oximeter clipped to the patient's finger). This determination can be performed in real time as oxygen saturation is measured via the extracorporeal oxygen saturation sensor device and the transcutaneous oxygen saturation sensor device. The determined OSPS or transcutaneous travel time values ​​provide information about the patient's hemodynamic status, which can indicate cardiovascular function, and this information can be used to detect and respond to potential problems related to hemodynamic changes that may occur in the patient during dialysis treatment.

[0040] Figure 1 This is a schematic diagram of an exemplary hemodialysis system having an external oxygen saturation sensor device and a transcutaneous oxygen saturation sensor device. Figure 1 In the provided examples, the extracorporeal oxygen saturation sensor device may be a sensor device 34 that is part of an optical blood monitoring system 14 configured to determine changes in hematocrit, oxygen saturation, and blood volume, and the transcutaneous oxygen saturation sensor device may be a pulse oximeter 40 that is attached to the patient's body (e.g., clipped to the patient's finger).

[0041] exist Figure 1 In this case, patient 10 is undergoing hemodialysis treatment using hemodialysis machine 12. An access needle or catheter 16 is inserted into patient 10's access site (e.g., arteriovenous fistula or graft (AVF / AVG)), such as in the arm, and connected to an extracorporeal tubing 18 leading to a peristaltic pump 20 and dialyzer 22 (or blood filter). Dialyzer 22 removes toxins and excess fluid from the patient's blood. Dialyzed blood is returned from dialyzer 22 via extracorporeal tubing 24 and a return needle or catheter 26. In some parts of the world, extracorporeal blood flow may be accompanied by a heparin infusion to prevent clotting. Excess fluid and toxins are removed by clean dialysate fluid supplied to dialyzer 22 via tubing 28, and waste fluid is removed via tubing 30 for disposal. In the United States, a typical hemodialysis treatment session takes approximately 3 to 5 hours.

[0042] The optical blood monitoring system 14 includes a display device 35 and a sensor device 34. The sensor device 34 may be, for example, a sensor clip assembly that clips onto a blood chamber 32, wherein the blood chamber 32 is disposed in an external blood circuit. The controller for the optical blood monitoring system 14 may be implemented in the display device 35 or the sensor clip assembly 34, or both the display device 35 and the sensor clip assembly 34 may include corresponding controllers for performing corresponding operations associated with the optical blood monitoring system.

[0043] The blood chamber 32 may be connected in series with the external tubing 18 upstream of the dialyzer 22. Blood from the peristaltic pump 20 flows into the blood chamber 32 through the tubing 18. The sensor device 34 includes an emitter that emits light of a specific wavelength and a detector for receiving the emitted light after it has passed through the blood chamber 32. For example, the emitter may include an LED emitter that emits light at approximately 810 nm (absorbed by red blood cells, etc.), approximately 1300 nm (absorbed by water, etc.), and approximately 660 nm (sensitive to oxyhemoglobin), and the detector may include a silicon photodetector for detecting light at wavelengths of approximately 660 and 810 nm, and an indium gallium arsenide photodetector for detecting light at a wavelength of approximately 1300 nm. The blood chamber 32 includes a lens or viewing window that allows light to pass through the blood chamber 32 and allows blood to flow within it.

[0044] The controller of the optical blood monitoring system 14 uses the light intensity measured by the detector to determine changes in hematocrit (HCT), oxygen saturation, and blood volume associated with the blood passing through the blood chamber 32 to which the sensor device 34 is attached, using a ratio measurement model. The intensity of the light received at each different wavelength is reduced by attenuation and scattering of the fixed intensity of visible and infrared light emitted from each LED emitter. Beer's Law describes the attenuation and scattering for each wavelength of light as follows:

[0045] Where i n = The intensity of light received at wavelength n after attenuation and scattering; I 0-n = The intensity of transmitted light at wavelength n incident on the test medium; e = the natural exponent; ε = the extinction coefficient of the test medium (p – blood chamber polycarbonate, b – blood); X = the molar concentration of the test medium (p – blood chamber polycarbonate, b – blood); and d = the distance through the test medium (pt – emitting blood chamber polycarbonate, b – blood, pr – receiving blood chamber polycarbonate).

[0046] Since the properties of the polycarbonate blood chamber remain unchanged, the first and third exponential terms in equation (1) above are constants for each wavelength. Mathematically, these constant terms are related to the initial constant term I representing the fixed radiation intensity emitted from the corresponding LED emitter. 0-nMultiply. For simplification, equation (1) can be expressed using the volume extinction coefficient and the modified initial constant I'. 0-n Rewrite it as follows:

[0047]

[0048] Where i n = The intensity of light received at wavelength "n" after attenuation and scattering, as if the detector were receiving light at the blood boundary; α = volume extinction coefficient (α b =ε b X b And I' 0-n = Equivalent transmitted light intensity at wavelength n, as applied to the boundary of transmitted blood, taking into account losses through the blood chambers. Note the term I'. 0-n It is the intensity of light incident on the blood, including blood chamber loss.

[0049] Using the method defined in equation (2) above, a wavelength of 810 nm, which is absorbed by red blood cells, and a wavelength of 1300 nm, which is absorbed by water, can be used to determine the hematocrit of a patient. The ratio of the normalized amplitude of the intensity measured at these two wavelengths yields the ratio of the composite extinction value α of the red blood cell and water components in the blood chamber, respectively. Then, a mathematical function defines the measured HCT value:

[0050]

[0051] Where i 810 It is the light intensity at 810nm of the light receiver, i 1300 It is the infrared intensity of the photodetector at 1300 nm, and I 0-810 and I 0-1300 This is a constant representing the intensity incident on the blood, taking into account losses through the blood chamber. Assuming the blood flow through blood chamber 32 is in a steady state, i.e., stable pressure and stable flow rate, then the above equation holds.

[0052] The preferred function f[] is a second-order polynomial of the following form:

[0053]

[0054] A second-order polynomial is usually sufficient, provided that the infrared radiation incident at the first and second wavelengths is substantially equally absorbed.

[0055] Oxygen saturation level or oxyhemoglobin level is determined using a ratio measurement model with the following form:

[0056]

[0057] Where i 660 It is the light intensity at 660nm of the light receiver, i 810 It is the light intensity of the photodetector at 810 nm, and I 0-660 and I 0-810 is a constant representing the intensity incident on the blood, indicating the loss through the blood chambers. The function g[] is a mathematical function determined based on experimental data to derive the oxygen saturation level, and is preferably a second-order polynomial. Using a pair of second-order polynomials may be useful based on hematocrit values ​​or separate 810nm calibrations for oxygen and hematocrit.

[0058] Display device 35 can be used to display determined values ​​of changes in hematocrit, oxygen saturation, and blood volume in a patient during hemodialysis treatment. Furthermore, display device 35 and / or sensor device 34 may include communication hardware and / or interfaces for communicating the determined values ​​of changes in hematocrit, oxygen saturation, and blood volume to one or more other devices.

[0059] Sensor device 34 provides oxygen saturation measurements corresponding to the patient's blood flowing through the extracorporeal circuit, while pulse oximeter 40 provides oxygen saturation measurements of the blood flowing through the patient's body at the location where percutaneous sampling was performed. In one exemplary embodiment, the pulse oximeter communicates with the controller of optical blood monitoring system 14 (e.g., the controller of display device 35) via a wired or wireless connection, and the controller of optical blood monitoring system 14 uses the two sets of oxygen saturation measurements from sensor device 34 and pulse oximeter 40 to determine the patient's OSPS or percutaneous travel time. In an alternative embodiment, another controller (e.g., a controller on a remote monitoring device or server (e.g., in a computing cloud or a local edge device in a clinic) communicating with both optical blood monitoring system 14 and pulse oximeter 40 may use the two sets of oxygen saturation measurements from sensor device 34 and pulse oximeter 40 to determine the patient's OSPS or percutaneous travel time.

[0060] Figure 1 The hemodialysis system described may be one of several hemodialysis systems in a dialysis clinic. Patients may visit the dialysis clinic regularly for treatment, for example, on a Monday-Wednesday-Friday schedule or a Tuesday-Thursday-Saturday schedule.

[0061] It should be understood that Figure 1The hemodialysis system described herein is merely exemplary. The principles discussed herein are applicable to other types of hemodialysis systems and medical systems in which at least one oxygen saturation sensor may be located in an extracorporeal blood line, while another oxygen saturation sensor may be located on the patient's body. For example, the principles discussed herein can also be used in the context of other systems for providing extracorporeal therapy involving arterial and venous access, such as hemodiafiltration (HDF) systems and blood therapy systems for treating systemic inflammatory response syndrome (SIRS) / sepsis or liver failure.

[0062] Figure 2 This is a block diagram showing an extracorporeal oxygen saturation sensor device positioned in an extracorporeal blood flow path and a transcutaneous oxygen saturation sensor device positioned on the patient's body to measure oxygen saturation (SaO2) corresponding to the patient's SaO2 characteristics.

[0063] As blood flows through a patient's body, for example, through the patient's arm, it carries SaO2 characteristics that correspond to changes in the patient's blood oxygen saturation level. These changes can correspond to the patient's breathing patterns. For example, SaO2 characteristics may include peaks corresponding to portions of the patient's blood with higher oxygen saturation values ​​and troughs corresponding to portions of the patient's blood with lower oxygen saturation values.

[0064] For patients undergoing hemodialysis, at the access site, blood flow along the artery in the patient's arm is split into two distinct pathways. One pathway corresponds to the arteriovenous access and the extracorporeal blood flow in the extracorporeal blood circuit, where the extracorporeal oxygen saturation sensor device (e.g., Figure 1 The sensor device 34 depicted is positioned along an extracorporeal blood flow path. Another path corresponds to the continued blood flow within the patient's arm along the patient's arteries (passing through the access site (e.g., anastomosis with an arteriovenous access)) and associated capillary bed, wherein the transcutaneous oxygen saturation sensor device (e.g., as shown in the image) is positioned along the extracorporeal blood flow path. Figure 1 The pulse oximeter 40 depicted in the text is placed on the patient's body at a location away from the access site (e.g., attached to a finger).

[0065] Both the extracorporeal blood flow path and the blood flow path within the patient's arm carry the SaO2 characteristics of the patient's blood. However, due to differences in flow path and flow rate, and the fact that the extracorporeal flow rate is not dependent on cardiac output, the SaO2 characteristics of the extracorporeal oxygen saturation sensor device (TT) vary from the access site. extracorporeal The travel time from the access site to the transcutaneous oxygen saturation sensor device (TT) transcutaneousThe travel time of the location is independent. Therefore, for the corresponding point or segment of the SaO2 characteristic, the corresponding oxygen saturation measurement by the in vitro oxygen saturation sensor device will typically be offset in time from the corresponding oxygen saturation measurement by the transdermal oxygen saturation sensor device (in some cases, the offset may coincidentally be zero or close to zero). This offset is referred to in this application as the oxygen characteristic phase shift (OSPS).

[0066] It should be understood that the time of travel from the access site discussed in this article corresponds to the time of travel from the location of the arteriovenous anastomosis for the AVF access site, and to the time of travel from the location of the AV graft attached to the artery for the AVG.

[0067] In one exemplary embodiment, oxygen saturation measurements performed by an in vitro oxygen saturation sensor device and oxygen saturation measurements performed by a transdermal oxygen saturation sensor device form corresponding SaO2 traces. The corresponding SaO2 traces detected at the in vitro and transdermal oxygen saturation sensor devices should include sufficient data to compare the traces to determine the OSPS between them. For example, a sampling rate of 1 Hz or faster (i.e., at least one data point per second) can be used for both sensor devices to collect data over a period of time, such as 5 minutes or longer. In other exemplary embodiments, other sampling rates and time periods can be used. For example, a sampling rate of 0.2 Hz or faster (i.e., at least one data point per 5 seconds) can be used.

[0068] Figure 3 This is a graph illustrating an exemplary OSPS between a first SaO2 trace detected by a transdermal oxygen saturation sensor device and a second SaO2 trace detected by an in vitro oxygen saturation sensor device. In this example, a 17-second OSPS (corresponding to TT) was determined based on certain valleys in the two SaO2 traces that were identified as corresponding to each other. transcutaneous With TT extracorporeal (Differences between them). It should be understood that, in Figure 3 In the example depicted, the sensitivity of the percutaneous oxygen saturation sensor device (in increments of 1 percentage point) is relatively lower than that of the in vitro oxygen saturation sensor device (in increments of 0.1 percentage points). In other exemplary embodiments, both devices may have a sensitivity that provides oxygen saturation measurements in increments of 0.1 percentage points (or with higher sensitivity) to improve accuracy.

[0069] It should be understood that the corresponding SaO2 traces detected by the in vitro oxygen saturation sensor device and the transdermal oxygen saturation sensor device may be different from each other, such as... Figure 3As shown. These differences may be due to variations in the equipment used for the respective measurements, and to variations in blood oxygen saturation levels as blood travels along the corresponding flow paths between the access site and the external oxygen saturation sensor device, and between the access site and the transcutaneous oxygen saturation sensor device (which may result in slightly different SaO2 characteristics of the blood at each detection site relative to the (undetectable) SaO2 characteristics in the patient's arterial blood). However, these differences do not preclude the determination of OSPS, as the overall shape of the detected SaO2 traces may still be correlated to determine differences in arrival times between different detection sites.

[0070] If at time t extracorporeal Specific characteristics of SaO2 in arterial blood were detected at an in vitro oxygen saturation sensor device, and at time t transcutaneous If the same specific characteristic of SaO2 in arterial blood is detected at the transcutaneous oxygen saturation sensor device, then OSPS can be based on t transcutaneous With t extracorporeal The difference between them is used to determine t. transcutaneous and t extracorporeal It can be determined based on the corresponding clocks of synchronized in vitro oxygen saturation sensor devices and transcutaneous oxygen saturation sensor devices.

[0071] In addition, t transcutaneous With t extracorporeal The difference between them corresponds to TT transcutaneous With TT extracorporeal The difference between them, and TT extracorporeal The volume (i.e., TT) can be determined based on the blood flow rate through the extracorporeal blood line and the volume of the portion of the extracorporeal blood line between the arterial cannula and the location of the extracorporeal oxygen saturation sensor device. extracorporeal [min] = Volume of the relevant portion of the blood vessel [mL] / Blood flow rate [mL / min]). This means TT transcutaneous It can be based on t transcutaneous t extracorporeal and TT extracorporeal To determine (e.g., TT) transcutaneous =t transcutaneous -t extracorporeal +TT extracorporeal For example, if the blood flow rate in the extracorporeal blood tubing is 400 mL / min and the volume of the relevant portion of the extracorporeal blood tubing is 100 mL, then TT extracorporeal It is 0.25 minutes (i.e., 15 seconds). Furthermore, if t transcutaneous -t extracorporeal For 17 seconds (for example, corresponding to Figure 3 The OSPS described in the text, then TT transcutaneousThe time was determined to be 32 seconds (17 seconds + 15 seconds). It should be understood that the determined difference may be an approximation or estimate of the actual difference, as the effective extracorporeal blood flow rate may not always be exactly the same as the flow rate dialed into the blood pump.

[0072] It should be understood that TT (transcutaneous transluminal oxygen saturation sensor) is affected by a variety of factors (e.g., extracorporeal blood volume between the arterial cannula and the location of the extracorporeal oxygen saturation sensor device, vascular flow rate, arterial volume between the insertion site and the location of the transcutaneous oxygen saturation sensor device, blood flow rate through the extracorporeal blood tubing, the patient's cardiac output, arteriolar tension, etc.). transcutaneous It may be longer than, equal to or shorter than TT. extracorporeal .

[0073] It should be understood that Figure 2 A simplified description of the described blood flow path is provided. For example, in the case of AVF / AVG, a short blood flow segment may exist between the AVF / AVG anastomosis and the arterial cannulation site, which means that TT... extracorporeal In practice, this might correspond to the volume [mL] of the relevant portion of the blood tubing divided by the blood flow rate [mL / min], plus the AVF / AVG transit time. However, this AVF / AVG transit time is negligible because it is negligible in magnitude (i.e., its effect on OSPS values ​​does not show a meaningful difference related to the patient's cardiac output or hemodynamic status).

[0074] exist Figure 1 In the example shown, the transcutaneous oxygen saturation sensor device (pulse oximeter 40) is positioned on the fingertip of the patient's arm where the access site is located. In other exemplary embodiments, the transcutaneous oxygen saturation sensor device may be positioned at other locations on the patient's body, and other types of transcutaneous oxygen saturation sensor devices may be used (e.g., transcutaneous oxygen saturation sensor devices that can be attached to the patient's earlobe, forehead, toes, wrist, nose, lips, cheek, or other body parts). It may be advantageous to position the transcutaneous oxygen saturation sensor device on the same side as the access site to more easily correlate oxygen saturation measurements taken by the transcutaneous oxygen saturation sensor device and the extracorporeal oxygen saturation sensor device.

[0075] Figure 4 is a flowchart of an exemplary procedure for monitoring a patient's OSPS during dialysis. In stage 401, dialysis treatment is initiated for the patient, for example, based on the operation of a hemodialysis system connected to the patient, wherein the hemodialysis system has an extracorporeal oxygen saturation sensor device and a transcutaneous oxygen saturation sensor device (e.g., as combined above). Figure 1-3(As discussed). In stages 403-1 and 403-2, the in vitro oxygen saturation sensor device and the transcutaneous oxygen saturation sensor device obtain oxygen saturation measurements at the corresponding detection sites (e.g., as described above in conjunction with...). Figure 1-3 (As discussed).

[0076] In stage 405, one or more OSPS values ​​for the patient are determined based on oxygen saturation measurements. In one exemplary embodiment, the patient's corresponding OSPS value may correspond to a sampling window, wherein corresponding SaO2 traces detected by the extracorporeal oxygen saturation sensor device and the transcutaneous oxygen saturation sensor device during the sampling window are compared with each other. Figure 3 In the example depicted, the sampling window is 8 minutes, but it should be understood that other sampling window sizes (e.g., in the range of 5-10 minutes) may be used in other exemplary embodiments.

[0077] For example, the sampling window could be a rolling window, such that a new OSPS value is repeatedly determined whenever the sampling window moves forward an increment in time. This increment can be as small as the sampling rate provided by the in vitro oxygen saturation sensor device or the transcutaneous oxygen saturation sensor device. For example, if the sampling rate provided by at least one of the sensor devices is 1 Hz, a new OSPS value can be determined every second as a new oxygen saturation measurement is obtained. In another example, new OSPS values ​​can be determined in longer increments than the sampling rate provided by the sensor device. In yet another example, instead of using a rolling window, a non-overlapping sampling window can be used (e.g., given an 8-minute sampling window, new OSPS values ​​will be determined periodically at most once every 8 minutes).

[0078] The average OSPS for each sampling window can be calculated. For example, in Figure 3 In this process, the monitoring device has multiple opportunities to determine individual OSPS values, which can then be averaged over a sampling window to obtain a more reliable point estimate for that window. The window size can be chosen to be wide enough to allow a) reliably identifying which points in one trace correspond to which points in another trace, and b) identifying multiple OSPS values ​​that can subsequently be averaged. The sampling / analysis window can then be moved forward by an amount corresponding to a clinically useful update frequency for hemodynamic monitoring (e.g., 3 minutes or 5 minutes). Some overlap with previous sampling / analysis windows can be beneficial because corresponding points between the two curves are known for the overlapping segments of the window and can be used as a reference for new sections of the current window.

[0079] OSPS can be determined from the corresponding SaO2 traces within the sampling window based on cross-correlation analysis and / or pattern recognition analysis using the corresponding SaO2 traces.

[0080] The determination at stage 405 can be made by a controller that communicates with both sensor devices (e.g., Figure 1 The display device 35 is controlled by the controller.

[0081] In stage 407, one or more OSPS values ​​determined in stage 405 can be analyzed. For example, analysis can be performed on a rolling basis when new OSPS values ​​are determined.

[0082] One aspect of the analysis in stage 407 may include determining a trend in OSPS values ​​(trend analysis). For example, if a patient's OSPS values ​​increase over time, this may indicate a problem with the patient's perfusion (e.g., due to decreased cardiac output or increased peripheral resistance). Therefore, if the current OSPS value determined for the patient is lower than a previous OSPS value (e.g., the immediately preceding OSPS value, the initial OSPS value at the start of treatment, or the previous highest OSPS value) by a threshold amount, a potential problem associated with the patient's hemodynamic status is detected. In another example, the OSPS values ​​used in the analysis may be averages (e.g., trend analysis may include comparing the average of the last three OSPS values ​​to the average of the previous three OSPS values ​​preceding the last three OSPS values). In other exemplary embodiments, other types of trend analysis may be performed to detect potential problems associated with the patient's hemodynamic status.

[0083] In another exemplary embodiment, the derivative of the OSPS value can be analyzed. For example, the derivative of the OSPS value can be used to detect whether the change in the OSPS value accelerates over time.

[0084] Although less common, a decrease in a patient's OSPS over time may indicate a problem (e.g., increased vascular stiffness). Therefore, a downward trend in a patient's OSPS can also be used to detect potential problems associated with the patient's hemodynamic status.

[0085] Another aspect of the analysis in phase 407 may include comparing the patient's current OSPS value (or the patient's average OSPS value based on multiple determined OSPS values) with one or more reference OSPS values ​​(analysis based on a reference baseline). The one or more reference OSPS values ​​may include upper or lower limits. Furthermore, the one or more reference OSPS values ​​may be based on one or more demographic categories applicable to the patient (e.g., sex, age range, ethnicity, etc.), on the patient's physical characteristics (e.g., height or weight), on the placement of the percutaneous oxygen saturation sensor device (e.g., ipsilateral hand, contralateral hand, earlobe, etc.), and / or on the patient's previous OSPS values. When a patient's OSPS value is determined to be above the upper limit or below the lower limit, a potential problem associated with the patient's hemodynamic status is detected. For example, if a patient's OSPS value is abnormally high or abnormally low, it may indicate a perfusion problem (such as low cardiac output or high peripheral resistance corresponding to high OSPS, or a stiff vascular system corresponding to low OSPS).

[0086] It should be understood that even within a specific population or population set, there may be significant hemodynamically relevant changes from patient to patient. Therefore, the upper and lower limits can be set relatively high and relatively low, respectively, to avoid false alarms in detecting potential problems associated with a patient's hemodynamic status.

[0087] The analysis in phase 407 can be alternatively based on TT. transcutaneous Instead of being based on OSPS, it is executed. For example, stage 407 may include determining TT corresponding to the OSPS value. transcutaneous Value, and use a determined TT transcutaneous The value is used to perform trend analysis in a similar manner to that discussed above regarding using OSPS values ​​to perform trend analysis or analysis based on a reference baseline (e.g., determining TT). transcutaneous Whether it increases or decreases over time (or is based on a reference baseline analysis, such as determining TT) transcutaneous (Whether it is higher than the upper limit or lower than the lower limit).

[0088] The analysis in phase 407 can be performed by a controller that communicates with the two sensor devices or by another controller (e.g., the controller of a remote monitoring device).

[0089] In stage 409, OSPS-related data can be output. OSPS-related data may include, for example, one or more OSPS values ​​determined in stage 405, one or more TT values. transcutaneous The values ​​and / or results of one or more analyses performed in phase 407. Output OSPS-related data may include one or more OSPS values ​​determined in phase 405, one or more TT values. transcutaneousThe values ​​and / or the results of one or more analyses performed in stage 407 are displayed on the monitor, for example in Figure 1 The OSPS-related data may also include one or more OSPS values ​​determined in stage 405 and one or more TT values, displayed on the display device 35 and / or the display device of the remote monitoring device. transcutaneous The values ​​and / or the results of one or more analyses performed in stage 407 are sent to healthcare professionals and / or the electronic health record (EHR) system.

[0090] In phase 411, response actions can be performed based on the results of one or more analyses performed in phase 407. For example, if the trend analysis performed in phase 407 indicates that the patient's OSPS or TT... transcutaneous The value shows an upward or downward trend, or if the reference-based analysis performed in phase 407 indicates that the patient's OSPS or TT... transcutaneous If the value is abnormally high or abnormally low, it can be controlled by the controller (e.g. Figure 1 The controller of the hemodialysis machine 12 depicted in the image. Figure 1 The controller of the display device 35 depicted herein or the controller of the remote monitoring device performs one or more of the following response operations (e.g., for increasing hemodynamic stability):

[0091] • Reduce the ultrafiltration rate of the dialysis treatment being performed on the patient. This may include using the results of the analysis in stage 407 as one of several inputs to an algorithm for determining the ultrafiltration rate used for dialysis treatment.

[0092] • Suspend dialysis treatment.

[0093] • Adjusting the patient's position (e.g., via communication with an electronically adjustable bed or chair), for example by changing the patient from a sitting position to a supine position and / or by elevating the patient's legs and / or by placing the patient in the "Trundrumbe position" (supine, upper body lowered, legs raised) to direct blood flow from the lower limbs to the central circulation (referred to as "autologous transfusion").

[0094] • Control the operation of the heater to lower the dialysate temperature.

[0095] • Control the operation of the saline pump to infuse saline solution.

[0096] • Control the dialysate mixing process to increase the sodium concentration in the dialysate.

[0097] • Trigger more frequent blood pressure measurements to provide closer monitoring of the patient’s hemodynamic status.

[0098] • Trigger alarms and / or notifications to alert healthcare professionals to provide treatment intervention.

[0099] Each of the aforementioned interventions can be performed automatically. Alternatively, alerts and / or notifications may include instructions to healthcare professionals to perform one or more of the aforementioned interventions in this list.

[0100] By providing therapeutic intervention in a timely manner at stage 409 based on real-time analysis at stage 407, exemplary embodiments of this application are able to avoid, reverse, or mitigate problematic hemodynamic changes in patients that could otherwise lead to serious (and potentially life-threatening) problems, such as decreased blood pressure and organ insufficiency. Avoiding such complications during dialysis can also reduce the risk of long-term mortality.

[0101] The SaO2 profile of a patient, including peak and trough values ​​of oxygen saturation, can be based on his or her breathing pattern. In some exemplary embodiments, it may be advantageous to induce a clearer SaO2 profile in the patient by providing supplemental oxygen, thereby triggering one or more artificially induced increases in oxygen saturation levels corresponding to the provision of supplemental oxygen. These artificially induced increases can help make the determination of OSPS at stage 405 more accurate and reliable.

[0102] Figure 4B This is a flowchart of an exemplary procedure for monitoring the percutaneous travel time of a patient during dialysis. Figure 4B Similar to Figure 4A However, instead of executing stages 405, 407, and 409, stages 405b, 407b, and 409b are executed. In stage 405b, one or more TTs of the patient are identified. transcutaneous Value. In phase 407b, (for example, based on the above analysis of TT in the context of phase 407) transcutaneous (Discussion on value) Execution of TT transcutaneous Value analysis. Phase 407b may also include TT-based analysis. transcutaneous The value determines the OSPS value and its analysis (e.g., based on the discussion above regarding analyzing OSPS values ​​in the context of stage 407). At stage 409b, the TT is output. transcutaneous Relevant data (which may be similar to the OSPS relevant data discussed above in the context of stage 409). It should be understood that, for example, in the case of changes in the in vitro flow rate during the ongoing measurement process, this corresponds to... Figure 4B The exemplary embodiment can be advantageous, which may complicate the determination of OSPS (due to the change in OSPS determined based on the offset between two time series, in this case, new OSPS values ​​need to be corrected to make them comparable to the OSPS values ​​before the change in in vitro flow rate), but does not affect TT. transcutaneous The determination (because TT) transcutaneous Based on TTextracorporeal Indeed, this changes in response to changes in the in vitro flow rate.

[0103] Figure 5 This is a block diagram of an exemplary network environment in which a hemodialysis system communicates with an electronic health record (EHR) system to provide the EHR system with OSPS-related data or TT. transcutaneous Relevant data, OSPS related or TT transcutaneous Relevant data includes, for example, one or more OSPS values ​​determined according to phase 405 discussed above, one or more TTs. transcutaneous The values ​​and / or the results of one or more analyses performed according to phase 407 discussed above. The network environment includes one or more dialysis clinics (including corresponding dialysis clinics 510) and EHR system 530.

[0104] Dialysis clinic 510 includes one or more hemodialysis systems for providing hemodialysis treatment to one or more patients (including corresponding patients 511 and corresponding hemodialysis systems 512). Each hemodialysis system communicates with gateway device 513, for example, via a wired connection (e.g., an Ethernet RJ-45 connection or a fiber optic connection) or a wireless connection (e.g., via Bluetooth or WiFi). For example, the display device or sensor device of the optical blood monitoring system of each hemodialysis system may include a communication interface and corresponding communication equipment for communicating with the gateway device via a wired or wireless connection. Gateway device 513 is configured to communicate with EHR system 530 via one or more networks (e.g., via a private computing network, via a public computing network such as the Internet, and / or via a mobile communication network). For example, EHR system 530 includes at least one application server 531 and at least one database 532 connected to said at least one application server 531. The EHR system 530 is specifically configured to store patient health information (e.g., information relating to patient 511 and other patients receiving treatment at one or more dialysis clinics) in at least one database 532, and to process and respond to requests for electronic health information via at least one application server 531. The EHR system 530 receives patient health information from various sources, including one or more dialysis clinics, and the EHR system 530 may be configured to communicate with these sources via one or more networks (e.g., via a private computing network, via a public computing network such as the Internet, and / or via a mobile communication network).

[0105] According to exemplary embodiments of this application, such as Figure 5 As shown, dialysis clinic 510 can further provide EHR system 530 with OSPS-related or TT-related data corresponding to patient 511. transcutaneous The relevant data is for storage and / or for further analysis or processing. OSPS related or TTtranscutaneous Relevant data can be sent to the EHR system 530 in real time or in batches, and the EHR system 530 can maintain OSPS-related or TT-related data for multiple patients in at least one database 532. transcutaneous Relevant historical data. In addition, OSPS-related or TT-related data for specific patients. transcutaneous Relevant historical data allows the EHR system (or another system communicating with the EHR system) to detect potential chronic problems that develop relatively slowly in patients (e.g., over multiple treatments or over months or even years), such as OSPS or TT corresponding to patients across multiple treatments. transcutaneous The value shows a slow downward trend, indicating increased stiffness in the vascular system.

[0106] The EHR system 530 (or another system communicating with the dialysis clinic 510) can be configured to remotely monitor dialysis treatments performed at the dialysis clinic 510, enabling remote triggering based on OSPS-related or TT-related procedures. transcutaneous The relevant data may be based on OSPS or TT. transcutaneous The analysis of relevant data and corresponding response actions. Furthermore, the EHR system 530 (or another system communicating with the EHR system) can utilize aggregated OSPS-related or TT data from multiple patients. transcutaneous Relevant data is used to determine one or more OSPS or TT. transcutaneous Reference values, where one or more OSPS or TT transcutaneous Reference values ​​may, for example, correspond to one or more population categories. The EHR system 530 (or another system communicating with the EHR system) can also be based on the patient's OSPS or TT. transcutaneous Historical values ​​and / or a patient's history of complications during dialysis are used to determine one or more OSPS or TT in a single patient. transcutaneous Reference value. Determined OSPS or TT. transcutaneous The reference value can be the optimal reference value (which provides a favorable sensitivity / specificity trade-off). Additionally, the determined OSPS or TT... transcutaneous Reference values ​​can be sent over the network to determine the OSPS or TT. transcutaneous Any controller that performs value analysis.

[0107] It should be understood that Figure 5 The network environment depicted herein is merely exemplary, and the principles discussed herein also apply to other types of network configurations, entities, and devices.

[0108] It should be understood that although the exemplary embodiments discussed above include a first oxygen saturation sensor device as an in vitro oxygen saturation sensor device and a second oxygen saturation sensor device as a transcutaneous oxygen saturation sensor device (e.g., a pulse oximeter), this application is not limited thereto. For example, other types of oxygen saturation sensor devices may also be used for the second oxygen saturation sensor device, such as oxygen saturation sensor devices that measure arterial blood gases using an arterial line (e.g., a small catheter inserted into an artery, typically the radial artery near the wrist) or oxygen saturation sensor devices that utilize camera-based oxygen saturation measurement technology.

[0109] Exemplary embodiments of this application provide improved cardiovascular monitoring during dialysis in a non-invasive, inexpensive, and continuous manner. By using oxygen saturation measurements performed by both an external oxygen saturation sensor device and a transcutaneous oxygen saturation sensor device, one or more OSPS or TT of the patient can be determined in real time. transcutaneous Value, thereby determining OSPS or TT transcutaneous The value indicates the patient's hemodynamic status. Therefore, based on the determined OSPS or TT... transcutaneous Analysis of values ​​can promptly detect and respond to deterioration in hemodynamic stability, and can improve patient safety and prognosis.

[0110] It should be understood that the various machine-implemented operations described herein can occur by one or more corresponding processors executing processor-executable instructions stored on a tangible, non-transitory computer-readable medium such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), and / or another electronic memory mechanism. Therefore, for example, operations performed by any of the means described herein can be performed based on instructions stored on the means and / or applications installed on the means, and via the means's software and / or hardware.

[0111] All references cited in this article, including publications, patent applications and patents, are incorporated into this article to the same extent as if each reference were individually and specifically indicated to be incorporated into this article and described in its entirety.

[0112] While the invention has been detailed and described in the accompanying drawings and foregoing description, such description should be considered illustrative or exemplary rather than restrictive. It should be understood that changes and modifications can be made by those skilled in the art within the scope of the appended claims. In particular, this application covers further embodiments having any combination of features from the various embodiments described above and below.

[0113] The terms used in the claims should be interpreted as having the broadest reasonable interpretation consistent with the foregoing description. For example, the articles “a” or “described” used when introducing an element should not be interpreted as excluding multiple elements. Similarly, references to “or” should be interpreted as inclusive, such that references to “A or B” do not exclude “A and B” unless it is clear from the context or the preceding description that only one of A and B is intentionally chosen. Furthermore, the expression “at least one of A, B, and C” should be understood as one or more of a set of elements consisting of A, B, and C, and should not be understood as requiring at least one of the listed elements A, B, and C, regardless of whether A, B, and C are related as a category or otherwise. Moreover, the expressions “A, B, and / or C” or “at least one of A, B, or C” should be interpreted as including any singular entity from the listed elements, such as A, any subset from the listed elements, such as A and B, or the entire list of elements A, B, and C.

[0114] Unless otherwise stated herein, the listing of numerical ranges herein is intended only as a shorthand method for individually referencing each individual value falling within that range, and each individual value is incorporated into the specification as if it were listed separately herein. Unless otherwise stated herein or clearly contradicted by the context, all methods described herein may be performed in any suitable order. Unless otherwise stated, the use of any and all examples or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate the invention and does not constitute a limitation on the scope of the invention. No language in the specification should be construed as indicating that any unclaimed element is essential for the practice of the invention.

Claims

1. A hemodialysis system comprising: A hemodialysis machine configured to provide hemodialysis treatment to a patient, wherein the hemodialysis treatment includes circulating the patient's extracorporeal blood through an extracorporeal blood circuit; A first oxygen saturation sensor device configured to measure the oxygen saturation corresponding to the patient's extracorporeal blood in an extracorporeal blood circuit; A second oxygen saturation sensor device configured to measure the oxygen saturation corresponding to the blood flowing within the patient's body; and At least one controller is configured to determine one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to a patient based on oxygen saturation measurements from the first oxygen saturation sensor device and the second oxygen saturation sensor device, wherein determining one or more OSPS values ​​or one or more percutaneous travel time values ​​includes comparing a first oxygen saturation trace corresponding to a measurement performed by the first oxygen saturation sensor device with a second oxygen saturation trace corresponding to a measurement performed by the second oxygen saturation sensor device.

2. The hemodialysis system according to claim 1, wherein, The patient's extracorporeal blood is drawn from the patient through the access site, and the second oxygen saturation sensor device is located on the same side of the access site on the patient.

3. The hemodialysis system according to claim 2, wherein, Both the access point and the second oxygen saturation sensor device are located on the same arm of the patient.

4. The hemodialysis system according to claim 3, wherein, The second oxygen saturation sensor device is configured to be attached to the patient's finger as a pulse oximeter.

5. The hemodialysis system according to claim 1, wherein, The first oxygen saturation sensor device and the second oxygen saturation sensor device each have a sampling rate of at least 1 Hz.

6. The hemodialysis system according to claim 1, wherein, The at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values, wherein the analysis includes trend analysis that identifies an upward or downward trend in the determined OSPS values ​​or determined percutaneous travel time values ​​of the patient.

7. The hemodialysis system according to claim 1, wherein, The at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values, wherein the analysis includes a reference-based analysis to identify whether the patient's determined OSPS value or determined percutaneous travel time value is higher or lower than one or more reference OSPS values ​​or one or more percutaneous travel time values.

8. The hemodialysis system according to claim 1, wherein, One or more defined percutaneous travel time values ​​each correspond to the amount of time that blood travels between the access site for drawing blood from outside the body and the location of the second oxygen saturation sensor device.

9. The hemodialysis system according to claim 1, wherein, The at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined transcutaneous travel time values ​​and output the results of the analysis, wherein outputting the results includes displaying the results on a display and / or transmitting the results via a communication network.

10. The hemodialysis system according to claim 1, wherein, The at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined percutaneous travel time values, and to perform a response operation in response to the results of the analysis, wherein the response operation includes modifying the hemodialysis treatment for the patient.

11. The hemodialysis system according to claim 10, wherein, The modifications include: Reduce the ultrafiltration rate; Suspend hemodialysis treatment; Adjust the patient's position; Lower the dialysate temperature; Infuse normal saline; Increase the sodium concentration in the dialysate; and / or This triggers a relatively high frequency of blood pressure measurements.

12. The hemodialysis system according to claim 1, wherein, The at least one controller is further configured to analyze one or more determined OSPS values ​​or one or more determined transcutaneous travel time values, and to perform response operations in response to the results of the analysis, wherein the response operations include outputting alarms and / or sending messages to medical professionals.

13. A non-transitory computer-readable medium storing processor-executable instructions for monitoring a patient's hemodynamic status during treatment, the processor-executable instructions, when executed, facilitate: The oxygen saturation of the patient's extracorporeal blood at a location in the extracorporeal blood circuit is measured by a first oxygen saturation sensor device. The oxygen saturation of the blood in the patient's body at a location is measured by a second oxygen saturation sensor device. Based on oxygen saturation measurements from the first oxygen saturation sensor device and the second oxygen saturation sensor device, at least one controller determines one or more oxygen saturation phase shift (OSPS) values ​​or one or more percutaneous travel time values ​​corresponding to the patient, wherein determining one or more OSPS values ​​or one or more percutaneous travel time values ​​includes comparing a first oxygen saturation trace corresponding to a measurement performed by the first oxygen saturation sensor device with a second oxygen saturation trace corresponding to a measurement performed by the second oxygen saturation sensor device. The at least one controller analyzes one or more determined OSPS values ​​or one or more determined transcutaneous travel time values; and The at least one controller performs a response operation in response to the result of the analysis.

14. The non-transitory computer-readable medium according to claim 13, wherein, The patient's extracorporeal blood is drawn from the patient through the access site, and the second oxygen saturation sensor device is located on the same side of the access site on the patient's body.

15. The non-transitory computer-readable medium according to claim 14, wherein, One or more defined percutaneous travel time values ​​each correspond to the amount of time that blood travels between the access site and the location of the second oxygen saturation sensor device.

16. The non-transitory computer-readable medium according to claim 13, wherein, The response operation includes modifying the treatment.

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