Solid-state sensor calibration

Abstract

Described herein is a method for calibrating at least one solid-state sensor coupled to an elongate body comprising an expandable member. In some variations, the method may include advancing the expandable member to a target location within a patient's blood vessel, injecting a calibration bolus into the expandable member, acquiring first sensor data from the expandable member sensor using a controller, acquiring second sensor data from the at least one solid-state sensor using the controller, and adjusting the second sensor data based on the first sensor data.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 301,475, filed January 20, 2022, which is incorporated by reference in its entirety herein.

[0002] (Government support) This invention was made with Government support under Grant Nos. FA8650-20-2-6116 and W81XWH-21-C-0058 awarded by the U.S. Air Force / Air Force Materiel Command. The Government has certain rights in this invention.

[0003] The present invention relates generally to the field of calibrating one or more solid state sensors. In particular, the present invention relates to the field of calibrating solid state sensors that may be integrated into catheters for monitoring physiological conditions during medical procedures. [Background technology]

[0004] Measuring physiological conditions at the point of intervention (e.g., during a medical procedure), particularly in real time, can provide useful data that can guide treatment decisions. For example, changes in physiological conditions during a medical procedure can provide information about the patient, such as, for example, whether the patient needs medication, the amount of medication that may be needed, whether the patient needs intravenous (IV) fluids, whether the medical procedure is adversely affecting the patient's blood flow and / or blood pressure, whether the procedure or medical device needs to be modified and / or changed, etc.

[0005] Catheters are used in conjunction with sensor devices to measure physiological conditions during medical procedures. Some existing catheters include pressure sensors that utilize a fluid column to measure blood pressure. Typically, these pressure sensors are coupled to the catheter but positioned outside the patient's body or as a stand-alone pressure sensor / device operatively connected to the catheter. Pressure within the body is transmitted to the pressure sensor through a fluid column in the catheter. In these cases, the catheter may need to be modified to accommodate the pressure sensing column. Also, the fluid column may be cumbersome to use and may result in inaccurate sensing data. For example, fluid columns are known to clot with blood. In addition, as the length of the fluid column increases, the sensor signal may begin to attenuate, which may result in inaccuracies and an inability to measure true maximum and minimum values ​​of cyclical or changing physiological conditions. In addition, movement of the fluid column and / or inadvertent contact with the fluid column may lead to excessive noise that may result in inaccurate pressure readings. Thus, the use of fluid columns can be particularly difficult, especially in situations where portability and / or field use is desirable.

[0006] In addition to the above, there is significant set-up time associated with existing catheters that utilize fluid columns. For example, during set-up, a user (e.g., surgeon, operator, etc.) may need to flush the fluid column with saline to ensure that there is no air in the fluid column. The user may also need to continue to flush the fluid column continuously and / or intermittently to ensure that blood clots do not build up in the fluid column. This can make the use of such catheters cumbersome. The use of fluid columns can be particularly challenging in situations where blood pressure measurements and / or pressure monitoring may be required quickly without significant set-up time.

[0007] More recently, the integration of solid-state sensors into catheters to measure physiological conditions in real time has been considered. However, there are several challenges associated with using solid-state sensors to measure physiological conditions. Solid-state sensors are extremely sensitive to changes in temperature and medium (e.g., air, fluid, etc.). Thus, when a catheter with a solid-state sensor is transitioned from medium to medium (air to fluid) or temperature to temperature, such as being inserted into a patient's body after being outside the body, the transition from air (e.g., outside the patient's body) to fluid (e.g., fluid inside the patient's body) can cause a rapid change in the sensor reading, thereby leading to erroneous sensor data. Furthermore, the amount of change in a sensor reading obtained from one sensor due to a transition can be different from the amount of change in a sensor reading obtained from another similar sensor. Thus, it can be difficult to uniformly calibrate solid-state sensors.

[0008] Therefore, a need exists for sophisticated systems, devices, and methods for calibrating solid-state sensors. Summary of the Invention [Means for solving the problem]

[0009] Described herein are systems, devices, and methods for calibrating solid state sensors. The method may include advancing an elongate body and an expandable member to a target location, injecting a calibration bolus into the expandable member, acquiring data (e.g., waveforms) from an expandable member sensor and one or more solid state sensors, and adjusting sensor data from at least one solid state sensor based on the data from the expandable member sensor. A negative pressure (i.e., vacuum) may be applied to the expandable member. The negative pressure may be applied before or during the process of calibrating the solid state sensor and may be used as a protective measure (e.g., a safety feature) during calibration.

[0010] In some variations, a method for calibrating at least one solid-state sensor coupled to an elongate body comprising an expandable member may include advancing the expandable member to a target location within a patient's blood vessel, injecting a fluid calibration bolus into the expandable member, acquiring first sensor data from the expandable member sensor using a controller, acquiring second sensor data from the at least one solid-state sensor using the controller, and adjusting the second sensor data based on the first sensor data. The first sensor data may represent a pressure within the expandable member.

[0011] In some variations, adjusting the second sensor data may include shifting at least one of a calibration curve and a calibration constant of the at least one solid-state sensor. In some variations, adjusting the second sensor data may further include determining a first average value of the first sensor data, determining a second average value of the second sensor data, and adjusting the second average value based on the first average value. In some variations, the first sensor data may include a first waveform and the second sensor data may include a second waveform. Adjusting the second sensor data may include adjusting the second waveform based on the first waveform.

[0012] In some variations, the second sensor data and the first sensor data may comprise data from at least one solid state sensor and data from the expandable member sensor, respectively, at a point in time. In some variations, the pressure within the expandable member may be indicative of a pressure at a target location within the blood vessel. In some variations, the method may further include determining a volume of a fluid calibration bolus prior to advancing the expandable member.

[0013] In some variations, the fluid calibration bolus may be based, at least in part, on one or more of the lengths of the elongated body. In some variations, injecting the fluid calibration bolus may further include injecting the fluid calibration bolus into the expandable member using a syringe pump. The volume of the fluid calibration bolus may be based, at least in part, on a distance between the syringe pump and the expandable member. In some variations, injecting the fluid calibration bolus may include injecting the fluid calibration bolus into the expandable member via a lumen of the elongated body. The volume of the fluid calibration bolus may be based, at least in part, on a volume of the lumen.

[0014] In some variations, the volume of the fluid calibration bolus may be about 1 ml to about 1.5 ml. In some variations, the volume of the fluid calibration bolus may be less than 5% of the volume of the expandable member. In some variations, the volume of the fluid calibration bolus may not expand the expandable member.

[0015] In some variations, acquiring the first sensor data and acquiring the second sensor data can include acquiring the first sensor data and the second sensor data a predetermined amount of time after advancing the expandable member, in some variations, the predetermined amount of time can be between about 15 seconds and about 45 seconds.

[0016] In some variations, the method may further include determining, using the controller, that the expandable member is positioned within the blood vessel. Determining that the expandable member is positioned within the blood vessel may include determining, using the controller, that the expandable member is positioned within the blood vessel based on second sensor data. The second sensor data may include a pressure waveform obtained from at least one solid-state sensor. The pressure waveform may represent an arterial pressure or a venous pressure.

[0017] In some variations, determining that the expandable member is positioned within the blood vessel may include receiving, at the controller, a user input indicating that the expandable member is positioned within the blood vessel. In some variations, the method may further include determining an initial setting point for the expandable member sensor prior to advancing the expandable member. In some variations, determining the initial setting point may further include receiving, at the controller, an air pressure from an air pressure sensor and determining, at least in part, the initial setting point based on the air pressure using the controller. In some variations, determining the initial setting point may include determining a baseline value for the expandable member sensor.

[0018] In some variations, the second sensor data from the at least one solid state sensor may include the first waveform. The method may further include determining whether a volume of the fluid calibration bolus is an undisturbed volume of fluid based at least in part on the first waveform. In some variations, the method may further include receiving a user input from a user indicating that the fluid calibration bolus has been injected into the expandable member.

[0019] In some variations, the second sensor data from the at least one solid state sensor may include the first waveform. The method may further include determining, at least in part, based on the first waveform that a volume of the fluid calibration bolus injected into the expandable member exceeds an undisturbed volume of fluid. In some variations, the at least one solid state sensor may include a first pressure sensor proximal to the expandable member and a second pressure sensor distal to the expandable member.

[0020] In some variations, adjusting the second sensor data may include adjusting sensor data from the second pressure sensor based on the first sensor data, and adjusting the sensor data from the first pressure sensor based on the first sensor data. In some variations, the second sensor data may include third sensor data from the first pressure sensor and fourth sensor data from the second pressure sensor. Adjusting the second sensor data may include adjusting fourth sensor data from the second pressure sensor based on the first sensor data, and adjusting the third sensor data from the first pressure sensor based on the fourth sensor data.

[0021] A system for measuring a physiological condition within a patient may include an elongated body comprising an expandable member and a solid-state sensor, a syringe pump in fluid communication with the expandable member, and a controller comprising an expandable member sensor in fluid communication with the expandable member. The controller may be communicatively coupled to the at least one solid-state sensor and configured to obtain first sensor data from the expandable member sensor representative of a pressure at a target location within the patient, obtain second sensor data from the solid-state sensor, and adjust the second sensor data based at least in part on the first sensor data.

[0022] In some variations, the controller may further comprise a housing with a recessed portion configured to receive a syringe pump. In some variations, the controller may further be configured to actuate the syringe pump to inject a calibration bolus into the expandable member. In other variations, a separate syringe pump may be used to inject a calibration bolus into the expandable member. In other words, a first syringe pump may be used to meter fluid into and out of the expandable member to control blood flow, and a second, different syringe pump may be used to inject a calibration bolus into the expandable member. The second syringe pump may be operated manually (e.g., actuated by hand by a user without the use of a controller) or by using a controller. In some variations, the controller may further be configured to adjust the second sensor data by shifting a calibration curve of the solid-state sensor.

[0023] In some variations, the controller may be further configured to determine a first average value of the first sensor data, determine a second average value of the second sensor data, and adjust the second average value based on the first average value. The first sensor data may include a first waveform and the second sensor data may include a second waveform. The controller may be configured to adjust the second waveform based on the first waveform.

[0024] In some variations, the second sensor data and the first sensor data may comprise data from a solid state sensor and data from an expandable member sensor, respectively, at a point in time. In some variations, the controller may be further configured to determine whether a calibration bolus has been injected into the expandable member based at least in part on at least one of the second sensor data and the first sensor data. In some variations, the volume of the calibration bolus may be based at least in part on a length of the elongated body. In some variations, the volume of the calibration bolus may be based at least in part on a distance between the syringe pump and the expandable member. In some variations, the elongated body may include a lumen connecting the syringe pump to the expandable member. The volume of the calibration bolus may be based at least in part on a volume of the lumen. In some variations, the volume of the calibration bolus may be about 1 ml to about 1.5 ml. In some variations, the volume of the calibration bolus may be less than a 5% percentage of the volume of the expandable member. In some variations, the calibration bolus may not cause the expandable member to expand.

[0025] In some variations, the controller may be configured to determine that the expandable member is positioned within the blood vessel based on second sensor data. The second sensor data may include a pressure waveform obtained from a solid-state sensor. The pressure waveform may represent an arterial or venous pressure. In some variations, the controller may include at least one user control for indicating that the expandable member is positioned within the patient's blood vessel. In some variations, the controller may be configured to determine an initial setting point for the expandable member.

[0026] In some variations, the system may further include an air pressure sensor. The controller may be further configured to receive air pressure from the air pressure sensor and determine the initial set point based at least in part on the air pressure. In some variations, the elongated body may be configured to be advanced into the aorta. In some variations, the controller may be configured to acquire first sensor data after a calibration bolus is injected into the expandable member.

[0027] A method for calibrating a first solid state sensor and a second solid state sensor coupled to an elongated body comprising an expandable member may include advancing the expandable member to a target location within a patient's blood vessel, acquiring first sensor data from the first solid state sensor using a controller, acquiring second sensor data from the second solid state sensor using a controller, determining an inherent offset between the first solid state sensor and the second solid state sensor using a controller, injecting a calibration bolus into the expandable member, acquiring third sensor data from the expandable member sensors using a controller, adjusting the first sensor data based on the third sensor data, and adjusting the second sensor data based on the first sensor data and the inherent offset after adjusting the first sensor data. The first solid state sensor may be positioned distal to the expandable member. The second solid state sensor may be positioned proximal to the expandable member. The third sensor data may represent a pressure at the target location.

[0028] A method for calibrating a first solid state sensor and a second solid state sensor coupled to an elongate body comprising an expandable member may include advancing the expandable member to a target location within a patient's blood vessel, acquiring first sensor data from the first solid state sensor using a controller, acquiring second sensor data from the second solid state sensor using a controller, determining an intrinsic offset between the first solid state sensor and the second solid state sensor using a controller, injecting a calibration bolus into the expandable member, acquiring third sensor data from the expandable member sensors using a controller, determining a difference between the first sensor data and the third sensor data using a controller to determine a proximal offset, determining a difference between the proximal offset and the intrinsic offset using a controller to determine a distal offset, adjusting a first calibration curve for the first solid state sensor based on the proximal offset, and adjusting a second calibration curve for the second solid state sensor based on the distal offset. The first solid state sensor may be positioned distal to the expandable member. The second solid state sensor may be positioned proximal to the expandable member. The third sensor data may represent pressure at the target location.

[0029] Another method may include the steps of advancing a system comprising a first solid state sensor and a second solid state sensor coupled to an elongated body having an expandable member to a target location within a patient's blood vessel, applying a first calibration protective measure to the system using a controller, acquiring first sensor data from the first solid state sensor using the controller, the first solid state sensor being positioned proximal to the expandable member, acquiring second sensor data from a second solid state sensor using the controller, the second solid state sensor being positioned distal to the expandable member, determining a unique offset between the first solid state sensor and the second solid state sensor using the controller, and calibrating by injecting a calibration bolus into the expandable member. After injecting the calibration bolus, the method may include applying a second calibration protective measure to the system using the controller, acquiring third sensor data from the expandable member sensor using the controller, the third sensor data representing pressure at the target location, acquiring a tip sensor offset using the third sensor data and data from the first solid-state sensor using the controller, and adjusting the first sensor data and the second sensor data based on the tip sensor offset and the intrinsic offset. Applying the first calibration protective measure may include applying a negative pressure to the expandable member, and applying the second calibration protective measure may include measuring pressure in the expandable member and determining that the pressure in the expandable member is at or above a threshold value. The threshold value may be zero. After calibration, the calibrated sensor of the system may be used to control blood flow in the patient. For example, blood flow may be controlled to treat one or more types of shock, such as neurogenic shock, hemorrhagic shock, hypovolemic shock, and septic shock. [Brief description of the drawings]

[0030] [Figure 1]FIG. 1 depicts exemplary sensor readings taken from the same solid-state sensor before and after acute exposure to water on three different occasions.

[0031] [Figure 2A] FIG. 2A is a block diagram illustrating an exemplary variation of a system for measuring a physiological condition.

[0032] [Figure 2B] FIG. 2B illustrates an exemplary variation of a system for measuring a physiological condition.

[0033] [Figure 2C] FIG. 2C illustrates another exemplary variation of a system for measuring a physiological condition.

[0034] [Diagram 3] FIG. 3 is a flow chart illustrating an exemplary variation of a method for calibrating a solid-state sensor.

[0035] [Figure 4] FIG. 4 is a plot containing sensor data from an expandable member sensor, a proximal solid sensor, and a distal solid sensor before, during, and after calibration from an exemplary variation of a system for calibrating solid sensors.

[0036] [Diagram 5] FIG. 5 illustrates another example variation of sensor data from the expandable member sensor, the proximal solid sensor, and the distal solid sensor before, during, and after calibration using the systems and methods described herein.

[0037] [Figure 6] FIG. 6 is a flow chart illustrating an exemplary variation of another method for calibrating a solid-state sensor.

[0038] [Figure 7]FIG. 7 provides data from the expandable member sensor, the proximal solid sensor, and the distal solid sensor before, during, and after calibration during an animal study. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Detailed Description Non-limiting examples of various aspects and variations of the present invention are described herein and illustrated in the accompanying drawings.

[0040] Described herein are systems, devices, and methods for calibrating a solid-state sensor. More specifically, described herein are systems, devices, and methods for calibrating one or more sensors coupled to (e.g., attached to, integrated with, mounted on, and / or the like) a medical device that includes an elongated body (e.g., a catheter) for monitoring a physiological condition.

[0041] Devices comprising elongated bodies may be used in a variety of medical procedures, such as, for example, cardiovascular, urological, gastrointestinal, neurovascular, ophthalmic, etc. Many of these medical procedures may be assisted by one or more sensors that provide information to a user (e.g., surgeon, operator, etc.) at the point of intervention.

[0042] Some existing sensors for providing information at the point of intervention utilize a fluid column to measure pressure, however, fluid columns suffer from several drawbacks such as, for example, excessive noise, over- and / or under-attenuation of the signal, high susceptibility to noise during any movement of the patient or arterial line, blood clots and / or blockages in the arterial line, lack of portability, etc.

[0043] To overcome the limitations of fluid columns, it may be advantageous to utilize medical devices that are coupled to or otherwise incorporate solid-state sensors to measure physiological conditions. Although solid-state sensors are known to provide accurate sensor readings despite exposure to force, movement, and vibration, they also have certain limitations. One such limitation is high sensitivity to environmental factors. For example, solid-state sensors may be susceptible to deformation due to rapid changes in temperature. Such deformation may result in erroneous changes in sensor data (e.g., rapid drops or rapid increases). This erroneous change may lead to erroneous sensor readings, thereby affecting the accuracy of the sensor data obtained from the solid-state sensor. In addition, solid-state sensors may absorb moisture as they transition from a dry medium (e.g., air) to a moist medium (e.g., fluid). Such transitions may also result in rapid changes in the sensor data, which may result in inaccurate sensor readings.

[0044] Rapid changes in sensor data may be addressed by accounting for these rapid changes (e.g., rapid changes in temperature, abrupt transitions from one medium to another, etc.). For example, determining one or more offsets that may account for these rapid changes and calibrating the solid-state sensor prior to use based on these offsets may improve the accuracy of the sensor. However, characterizing all potential offsets for all possible changes prior to use may be difficult. Furthermore, the magnitude of these offsets may be difficult to predict because these offsets may be sensor specific and may depend on various factors such as ambient temperature, humidity, sensor location, etc. For example, the same solid-state sensor may show different changes when transitioned from air to fluid at different times. FIG. 1 depicts exemplary sensor readings obtained from the same solid-state sensor before and after abrupt transitions from one medium to another, in this case water, at three different times. More specifically, FIG. 1 depicts pressure measured from a solid-state sensor over a 10 minute period on three different occasions when the solid-state sensor is suddenly exposed to water at 37 degrees Celsius, occurring at the two minute time point. After the solid-state sensor is exposed to water, the measured pressure changes suddenly, rising in two cases and falling in one case. These sudden changes resolve approximately 30 seconds after the two minute time point (e.g., 30 seconds after the sudden exposure). However, as seen in FIG. 1, the amount of change in the pressure reading is different for each of the three different occasions. Thus, it may be difficult to predict a universal offset for all solid-state sensors to account for changes in data based on environmental changes, which in turn makes it difficult to universally calibrate solid-state sensors to account for these changes. Similarly, two different solid-state sensors of the same type may exhibit different changes in the same environment, further complicating universal calibration. In addition, if the solid-state sensor was calibrated at the time of manufacture, exposing the medical device to a process such as sterilization before using the medical device clinically may change the calibration offset determined at the time of manufacture. That is, the offset determined at the time of manufacture may change from manufacture to post-sterilization when the device is used clinically.

[0045] Thus, when used in a medical device, it may be beneficial to calibrate the solid-state sensor after the medical device is inserted into the patient's body (i.e., after the solid-state sensor is exposed to an abrupt change in the environment). Described herein are systems, devices, and methods for calibrating the solid-state sensor after it is exposed to an abrupt change in the environment. More specifically, the devices, systems, and methods described herein may use sensor data from a first sensor type (e.g., a fluid column-based pressure sensor) to calibrate a sensor of a second, different sensor type (e.g., a solid-state pressure sensor). The sensor of the first sensor type may be positioned outside the patient's body and may not itself be exposed to the abrupt change in the environment and / or may not otherwise be subject to the same effects from the environmental change. The solid-state sensor may be coupled to an elongated body (e.g., a catheter) that may be advanced into the patient's body, thereby exposing the solid-state sensor (e.g., a sensor of the second sensor type) to the abrupt change in the environment. The data from the first sensor type, such as a fluid column-based pressure sensor, may then be used to calibrate the data from the solid-state pressure sensor.

[0046] For example, in variations in which a solid pressure sensor of a blood flow control device is calibrated, the elongate body may comprise an expandable member (e.g., a balloon), and a first sensor type sensor positioned outside the patient's body may be an expandable member sensor configured to measure one or more characteristics of the expandable member (e.g., pressure within the expandable member). To calibrate a solid sensor, a fluid calibration bolus (referred to herein as a "calibration bolus") may be injected into the expandable member using, for example, a pump, which may be fluidly coupled to the expandable member via a fluid column. In some variations, the calibration bolus may be saline. The volume of the calibration bolus may be at least equal to a desired volume of fluid, referred to herein as a "non-disturbing volume." The calibration process for the solid sensor may begin after at least the non-disturbing volume has been injected into the expandable member. In some variations, the non-disturbing volume of fluid may be an amount of fluid that fills the fluid column with fluid but does not expand (or minimally expands) the expandable member. For example, the undisturbed volume of fluid may be an amount of fluid that fills the fluid column with fluid but does not expand the expandable member to an extent that the expandable member can exert a significant force on the fluid within the expandable member. Because the undisturbed volume of fluid does not expand (or only minimally expands) the expandable member, the pressure outside the expandable member (e.g., blood pressure) may be the same as the pressure within the expandable member. This pressure within the expandable member may be transmitted through the fluid column to the expandable member sensor. When the volume of the calibration bolus is above the undisturbed volume but below the upper limit, the pressure within the expandable member may still be transmitted through the fluid column to the expandable member sensor as the fluid column fills with fluid, thereby allowing one or more solid state sensors to be calibrated. The sensor readings from the expandable member sensor may be used to adjust the sensor readings from the solid state sensor, thereby calibrating the solid state sensor based on the sensor data from the expandable member sensor.

[0047] Thus, described herein are systems, devices, and methods for calibrating solid-state sensors to provide accurate sensor data (e.g., pressure data), particularly accurate absolute sensor data (e.g., absolute pressure data instead of relative pressure data that may indicate the relative pressure between two or more solid-state sensors). In some variations, the absolute pressure data may incorporate the ambient pressure of the environment. In some variations, the absolute pressure data may include the pressure at a location (e.g., the location of the solid-state sensor) relative to atmospheric pressure (e.g., gauge pressure). In particular, described herein are methods for calibrating one or more solid-state sensors coupled to an elongated body comprising an expandable member. In some variations, the method may include a step of advancing the expandable member to a target location within a patient's blood vessel, at which point a calibration bolus may be injected into the expandable member. First sensor data, which may represent the pressure within the expandable member, may be obtained from the expandable member sensor using a controller, and second sensor data may be obtained from the one or more solid-state sensors using a controller. The second sensor data may be adjusted based on the first sensor data, thereby utilizing data obtained from the expandable member sensor to calibrate the solid-state sensor.

[0048] The systems, devices, and methods may also be configured to apply a vacuum to the expandable member (e.g., a balloon). The vacuum may be applied before or during the process of calibrating the solid-state sensor, or may be used as a protective measure during calibration. system

[0049] FIG. 2A is a block diagram illustrating an exemplary variation of a system 100 for measuring physiological conditions using a solid-state sensor, which may additionally be used to calibrate the solid-state sensor. FIGS. 2B and 2C illustrate exemplary variations of the system 100. The system 100 may include an elongated body 102 comprising an expandable member 110. An expandable member sensor 115 configured to measure one or more characteristics of the expandable member 110 (e.g., pressure therein) may be positioned within the controller 104. For example, the expandable member sensor 115 may be contained within, attached to, integrated with, or otherwise coupled to the controller 104. The expandable member 110 may be fluidly coupled to the expandable member sensor 115 via one or more fluid columns. One or more solid-state sensors 111 may be coupled to the elongated body 102. For example, one or more solid state sensors 111 may be attached to, integrated with, and / or otherwise mounted on the elongated body 102. For example, the elongated body 102 may include a first solid state sensor proximal to the expandable member 110, referred to as the "distal solid state sensor 111b," and a second solid state sensor distal to the expandable member 110, referred to as the "proximal solid state sensor 111a." In some variations, the system 100 may include more than one controller. For example, as seen in FIG. 2C, the system 100 may include a second controller 106, which may be operably coupled to the first controller 104. The controllers 104 and / or 106 may be communicatively coupled to the solid state sensor 111 and / or the expandable member sensor 115 and may receive and analyze sensor readings from the solid state sensor 111 and / or the expandable member sensor 115. A pump 108 (e.g., a syringe pump) may be fluidly coupled to the expandable member 110 to regulate the volume of the expandable member 110. For example, the pump may be fluidly coupled to the expandable member 110 via one or more fluid pathways (e.g., tubing, valves, lumens in the elongated body) to inject and / or remove fluid from the expandable member 110. Extension body

[0050] The devices described herein may comprise an elongated body 102 comprising one or more sensors (e.g., one, two, three, four, five, or more), and in particular, the sensors may be integrated into the elongated body 102. The elongated body 102 may comprise a shaft that is sized and shaped for placement within the patient's body (e.g., at an intervention point in a blood vessel, brain parenchyma, esophagus, stomach, small intestine, etc.). In some variations, the elongated body 102 may be steerable. For example, in some variations, the elongated body 102 may be mechanically coupled to a knob, lever, pull wire, and / or the like that may be used to steer or otherwise deflect the distal end of the shaft of the elongated body 102. In some variations, the elongated body 102 may include one or more lumens therethrough. The lumen may be a partial lumen (e.g., open on one end) or may be disposed or located within a shaft (e.g., a steerable shaft). One or more lumens (e.g., two, three, four, or more) may serve any desired purpose. For example, in some variations, the lumens may be used to transfer fluids to and from the patient's body and / or other components coupled to the elongated body, advance and / or steer a guidewire into a desired location, store other components (e.g., sensor wires, pressure sensing columns, imaging devices such as endoscopes, etc.), etc. In some variations, the lumens may include an intake lumen and an exhaust lumen for delivering fluids and / or compressed gases through the elongated body. In some variations, the elongated body 102 may include a lumen for fluidly coupling the expandable member 110 to the pump 108. The lumen fluidly coupling the expandable member 110 to the pump 108 may also serve as a fluid column fluidly coupling the expandable member 110 to the expandable member sensor 115. Additionally or alternatively, the elongated body may include another fluid column for fluidly coupling the expandable member 110 to the expandable member sensor 115. Pressure within the expandable member 110 may be communicated to the expandable member sensor 115 via the fluid column.

[0051] As mentioned above, the elongated body 102 may be sized and shaped for advancement to and at least partially placement within a target location of a patient's body. The elongated body 102 may be of any diameter and length suitable for advancement to a target location. For example, the elongated body 102 may have a diameter of about 2 mm to about 36 mm, including all values ​​and subranges therein. In some variations, the diameter may be, for example, about 3 mm to about 25 mm, about 4 mm to about 20 mm, or about 5 mm to about 15 mm, including all values ​​and subranges therein. In some variations, the diameter may be, for example, about 6 mm to about 10 mm. The elongated body 102 may have a length of about 1 cm to about 110 cm, including all values ​​and subranges therein. In some variations, the length may be, for example, from about 10 cm to about 105 cm, from about 20 cm to about 100 cm, from about 30 cm to about 90 cm, from about 40 cm to about 80 cm, or from about 50 cm to about 70 cm (including all values ​​and subranges therein).

[0052] In some variations, the elongated body 102 may comprise multiple layers. For example, one or more portions of the elongated body 102 may comprise multiple layers (e.g., two, three, four, or more), all portions of the elongated body may comprise the same layer, or the layers may vary among different portions of the elongated body 102. In other variations, the elongated body 102 may comprise a single layer, which may include one or more lumens therethrough. The elongated body 102 and / or any layer of the elongated body may be made of, for example, polytetrafluoroethylene (PTFE), polyimide, and Pebax. (R) , combinations thereof, and the like.

[0053] One or more sensors 111 (e.g., solid state sensors) may be integrated into the elongated body 102. One or more sensor wires associated with the sensor 111 may be routed through the elongated body 102. In some variations, the elongated body 102 may include an opening and / or window for receiving the sensor 111 through a sensor housing. The window and / or opening may receive the sensor 111 through the sensor housing as an inlay. In some variations, the window and / or opening may be a cavity formed with an outer layer of the elongated body 102 that may receive the sensor 111 and / or the sensor housing. In some variations, the sensor 111 may be positioned on or otherwise contact the outer surface of the elongated body 102. In some variations, the sensor 111 may be integrated into the elongated body 102 in a manner similar to that described in International Application No. PCT / US2022 / 049335, the contents of which are incorporated herein by reference in their entirety.

[0054] In variations with multiple sensors 111, the sensors 111 may be positioned along and around the elongated body in any suitable manner. For example, two or more sensors may be aligned longitudinally along the elongated body. For example, a first sensor and a second sensor may be positioned along the same longitudinal line, but the first sensor may be positioned closer to the proximal end of the elongated body, while the second sensor may be positioned closer to the distal end of the elongated body than the first sensor. In some variations, one or more sensors 111 may not be aligned longitudinally, but may instead be offset circumferentially from one or more additional sensors such that the sensor 111 is positioned around the elongated body. In some variations, the circumferential offset (e.g., the angle formed between the longitudinal axes of the sensors) may be between 15 degrees and 345 degrees, such as, for example, 90 degrees, 180 degrees, or 270 degrees. In some variations, the one or more sensors may be circumferentially offset from the one or more additional sensors but may be aligned between the proximal and distal ends of the elongate body, while in other variations, the one or more sensors may be circumferentially offset from the one or more additional sensors and may be positioned at different locations between the proximal and distal ends of the elongate body. Solid-state Sensors

[0055] As mentioned above, the elongated body 102 may include one or more sensors. In some variations, the one or more sensors on the elongated body may be solid-state sensors 111. The solid-state sensors 111 may be attached to, integrated with, and / or otherwise mounted on the elongated body 102 in any suitable manner. As discussed above, the solid-state sensors 111 may be integrated into the elongated body 102 similar to the integration described in International Application No. PCT / US2022 / 049335, the contents of which are incorporated herein by reference in their entirety.

[0056] The sensor 111 may be a pressure sensor configured to measure changes in blood pressure. In some variations, in addition to a pressure sensor, the sensor 111 may include sensors configured to measure other physiological conditions, such as heart rate, respiratory rate, intracranial pressure, cerebral oxygenation, cerebral blood flow, electroencephalography (EEG) signals, and the like. In some variations, the sensor 111 may include any sensor useful during a medical procedure, such as, for example, a temperature sensor, an electrochemical sensor, an impedance sensor, a microelectrochemical system (MEMS) sensor, a piezoelectric sensor, and / or the like. Any suitable number of sensors (e.g., one, two, three, four, or more) may be integrated into the elongated body to measure physiological conditions.

[0057] In some embodiments, the device may include two sensors, a first distal sensor 111b and a second proximal sensor 111a, integrated into or otherwise coupled to the elongated body 102. In some variations, the distal sensor 111b may be integrated proximally of the expandable member 110, while the proximal sensor 111a may be integrated distally of the expandable member 110. For example, the distal sensor 111b located on the proximal side of the expandable member 110 may be placed at a distance from the expandable member 110 such that physiological data collected from the distal sensor 111b may not be disturbed by blood flow downstream of the expandable member 110. In some variations, the distal sensor 111b may be placed at a distance of about 30 mm to about 10 mm, about 25 mm to about 15 mm, or about 22 mm to about 18 mm from the expandable member 110. For example, the distal sensor 111b may be located about 20 mm from the expandable member 110. In some variations, the proximal sensor 111a located on the distal side of the expandable member 110 may be located about 30 mm to about 10 mm, about 25 mm to about 15 mm, or about 22 mm to about 18 mm from the expandable member 110. For example, the proximal sensor 111a may be located about 20 mm from the expandable member 110. In some variations, the sensor 111 on the elongated body 102 may be mounted at a specific distance from the end of the expandable member 110 to obtain physiological data upstream and downstream of the expandable member 110.

[0058] The distal sensor 111b and the proximal sensor 111a may each measure patient physiological information at the point of intervention to determine the patient's underlying physiology and provide that information to a user. For example, in a variation in which the distal sensor 111b and the proximal sensor 111a may be blood pressure sensors, the distal sensor 111b and the proximal sensor 111a may measure the patient's local blood pressure at or around the location of the respective sensor. Data from the distal sensor 111b may be used to measure the patient's distal systolic and diastolic pressures. For example, the distal systolic and diastolic pressures may be derived from a blood pressure waveform. The distal systolic pressure may be measured by analyzing the peaks of the waveform over a given duration. The distal diastolic pressure may be measured by analyzing the troughs of the waveform over a given duration. In a similar manner, data from the proximal sensor 111a may be used to measure the patient's proximal systolic and diastolic pressures. For example, the proximal systolic and diastolic pressures may be derived from a blood pressure waveform. The proximal systolic pressure may be measured by analyzing the peaks of the waveform over a given duration. The proximal diastolic pressure may be measured by analyzing the troughs of the waveform over a given duration.

[0059] It should be noted that the terms "proximal" and "distal" as used herein in connection with sensors and / or particular localized blood pressure readings refer to the direction of blood flow from the heart. That is, "proximal" is closer to the heart while "distal" is farther from the heart. This is not to be confused with the reversed use of the terms when described in terms of a medical device such as a catheter, where the "distal end" of the medical device would generally be understood as the end with the expandable element 110 furthest from the controller 104, and the "proximal end" would be understood as the end closer to the operator.

[0060] Data from the sensors may be collected continuously or intermittently and may be collected over a defined period of time. In some variations, data from the sensors may be collected continuously, such as every 3, 4, 5, 6, 7, 8, 9, or 10 seconds (e.g., from about 3 to about 6 seconds, from about 4 to about 6 seconds, or from about 5 to about 6 seconds, etc., including all values ​​and subranges therein). In some variations, data from the sensors 118 may be collected every 5 seconds at 200 Hz. Expandable Member

[0061] The expandable member 110 may be disposed on, coupled to, integral with, attached to, and / or affixed to the shaft of the elongated body 102, and the size (e.g., volume) of the expandable member may be controllable by the controller 104 or a user. For example, the expandable member may be configured to expand and contract and / or inflate and contract such that the size (e.g., volume) of the expandable member may change during use of the blood flow control system. In some variations, the expandable member may be an inflatable / deflateable balloon, while in other variations, the expandable member may be made of a shape memory material. In still other variations, the expandable member may be connected to a mechanical linkage (e.g., wires, etc.) to change the size of the expandable member. The expandable member 110 may be made of any suitable elastomeric material (e.g., polyurethane, silicone, etc.). Additionally or alternatively, the expandable member 110 may be made of polyester, nylon, etc.

[0062] Blood flow at a target location (e.g., a target blood vessel) within the patient's body may be adjusted or otherwise controlled by varying the size of the expandable member 110. Fluid and / or compressed gas may be delivered through one or more lumens in the elongate body 102 to control and / or regulate the size (e.g., volume) of the expandable member 110. In some variations, the expandable member 110 may be strategically placed within the patient's aorta, and the size of the expandable member 110 may control blood flow through the patient's aorta such that blood flow distal to the expandable member 110 may be impeded to increase blood pressure proximal to the expandable member 110. The outer surface of the expandable member 110 may be configured to contact or otherwise interface with the wall of the patient's blood vessel (e.g., during a total occlusion). The expandable member 110 may have any suitable shape when expanded. In some variations, the expandable member 110 may have an elliptical cross-sectional shape along a longitudinal axis when expanded. In other variations, the expandable member 110 can have a spherical shape (eg, have a circular cross-sectional shape) when expanded.

[0063] 2A illustrates a system 100 with a single expandable member 110, it should be readily understood that the elongated body 102 may include any number of suitable expandable members 110. For example, the system 100 may include two, three, four, or more expandable members 110 disposed on, coupled to, integrated with, attached to, and / or affixed to the elongated body 102 in series. In variations with three or more expandable members, the distance between the expandable members may be the same, or it may be different. In some variations, the expandable members 110 may be balloons that may be positioned in series along the length of the elongated body 102 or disposed within one another. In variations with multiple balloons, the balloons may be individually expanded and contracted, or they may be expanded and contracted together.

[0064] The expandable member 110 may be fluidly coupled to an expandable member sensor 115, which may be configured to detect pressure inside the expandable member 110. For example, the expandable member 110 may be fluidly coupled to the expandable member sensor 110 via one or more fluid columns in the elongated body 102. The pressure inside the expandable member 110 may be communicated to the expandable member sensor 115 through the fluid columns. In some variations, the controller 104 may include the expandable member sensor 115 and may be configured to analyze the pressure inside the expandable member 110 via sensor readings from the expandable member sensor 115. pump

[0065] The system 100 may include a pump 108, such as a syringe pump, that may be operatively (e.g., fluidly) coupled to the expandable member 110 and facilitate adjusting its size. In some variations, the pump 108 may be contained within or otherwise carried by or coupled to the controller 104. Additionally or alternatively, the pump 108 may be communicatively coupled to the controller 104. In some variations, the pump 108 may be operated manually (e.g., manually actuated by a user without use of the controller 104) or by using the controller 104. In some variations, the pump 108 may be operated automatically using the controller 104. Additionally or alternatively, the 108 may be operated via a user interface (e.g., a button) on the controller 104. In some variations, the pump 108 may be removed or otherwise uncoupled from the controller 104 and manually operated to establish the position and initial level or volume of the expandable member 110.

[0066] The pump 108 may comprise or be otherwise coupled to an expandable member 110 that comprises a lumen (e.g., tubing), which may in turn be coupled to a lumen of the elongate body 102 of the system 100. In this manner, the pump 108 may be in fluid communication with the expandable member 110.

[0067] In some variations, one or more sets of valves may be utilized to control the flow of fluid, such as saline, and / or compressed gas, such as carbon dioxide. In some variations, the pump 108 may be fluidly coupled to a valve (e.g., a stopcock valve) that can regulate the flow of fluid and / or compressed gas to the expandable member 110.

[0068] The size (e.g., volume) of the expandable member 110 may be adjusted using the controller 104 and the pump 108. For example, the controller 104 may determine the amount of fluid and / or compressed gas to be infused into or removed from the expandable member 110 to adjust the size of the expandable member 110 and thereby affect blood flow. The controller 104 may control (e.g., move, modify, or control the position of) an actuator, which may be releasably coupled to the pump 108 (e.g., to an actuating element on the pump). The actuator may engage and move the actuating element, thereby moving a portion of the pump 108 such that the pump 108 may inject or remove fluid and / or compressed gas into or from the expandable member 110 based on instructions from the controller 104. In some variations, the removal of fluid and / or compressed gas may be activated via a screw actuation. In some variations, the pump may be coupled to a position sensor, which may provide information regarding the position of a portion of the pump 108 and therefore the amount of fluid delivered to the expandable member 110.

[0069] The pump 108 may be any suitable pump operatively and / or communicatively coupled to an actuator to inject and / or remove fluid and / or compressed gas into and / or from the expandable member 110. For example, the pump 108 may be a syringe pump, a diaphragm pump, a peristaltic pump, or other suitable pump. In some variations, the system may include multiple pumps. For example, a first pump may be used to inject a calibration bolus into the expandable member, and a second, different pump may be used to meter fluid into and out of the expandable member to control blood flow. A third pump, different from the first and second pumps, may be used to apply negative pressure to the expandable member, as discussed in more detail herein. In other variations, the same pump may be used to perform multiple functions, including injecting a calibration bolus, metering fluid into and out of the expandable member, and applying negative pressure to the expandable member. Expandable Member Sensor

[0070] The expandable member sensor 115 may be disposed on, affixed to, attached to, mounted on, coupled to, and / or otherwise contained within the controller 104. The expandable member sensor 115 may be configured to detect a property of the expandable member 110, such as, for example, the pressure of a fluid and / or compressed gas inside the expandable member 110. For example, the expandable member sensor 115 may be fluidly coupled to the expandable member 110 via one or more fluid columns (e.g., lumens, tubing within the elongated body), such as through the elongated body 102. The pressure within the expandable member 110 may be communicated via a fluid path to the expandable member sensor 115 located and / or included within the controller 104. In some variations, the expandable member sensor 115 may measure the expandable member pressure. When the expandable member 110 is not expanded, the expandable member pressure may be indicative of the pressure outside and surrounding the expandable member 110. When the expandable member is expanded, the expandable member pressure can indicate the amount of expansion of the expandable member 110. The expandable member pressure can indicate the amount of expansion and contraction of the expandable member 110.

[0071] In some variations, data may be collected from the expandable member sensor 115 continuously, such as every 3 milliseconds, 4 milliseconds, 5 milliseconds, 6 milliseconds, 7 milliseconds, 8 milliseconds, 9 milliseconds, or 10 milliseconds (e.g., from about 3 milliseconds to about 6 milliseconds, from about 4 milliseconds to about 6 milliseconds, or from about 5 milliseconds to about 6 milliseconds, etc., including all values ​​and subranges therein).

[0072] In some variations, as will be described in more detail herein, sensor readings from the expandable member sensor 115 may be used to calibrate the solid-state sensor 111. More specifically, expandable member pressure obtained from the expandable member sensor 115 when the expandable member 110 is not expanded may be used to calibrate the solid-state sensor. For example, one or more pressure waveforms indicative of pressure within the expandable member 110 obtained from the expandable member sensor 115 may be compared to one or more pressure waveforms obtained from the solid-state sensor 111. The solid-state sensor 111 may be calibrated by adjusting the pressure waveform from the solid-state sensor 111 based on the comparison with the pressure waveform obtained from the expandable member sensor 115. For example, if the pressure waveform from the expandable member sensor 115 includes an increasing slope over a first duration, the pressure waveform from the solid-state sensor 111 may be adjusted to have a similar increasing slope over a first duration. In particular, the change in slope in the pressure waveform from the solid-state sensor 111 may be adjusted to be identical and / or substantially similar (e.g., within ±10 mmHg) to the change in slope in the pressure waveform from the expandable member sensor 115. For example, the increase in slope of the pressure waveform obtained from the solid-state sensor 111 over a first duration may be adjusted to match (e.g., be the same as) the rate of increase in slope of the pressure waveform obtained from the expandable member sensor 115 over the first duration. Similarly, if the pressure waveform from the expandable member sensor 115 includes a decreasing slope over a second duration, the pressure waveform from the solid-state sensor 111 may be adjusted to have a similar or identical decreasing slope over the second duration.

[0073] In some variations, the expandable member sensor 115 may be a gauge pressure sensor. In some variations, the expandable member sensor 115 may be factory calibrated but still sensitive to atmospheric pressure and / or altitude. That is, atmospheric pressure and / or altitude at a location may affect the sensor data obtained from the expandable member sensor 115. Thus, prior to advancing the system 100 into the patient's body, an initial setting point may be determined for the expandable member sensor 115 to account for the effects of atmospheric pressure and / or altitude at the location where the medical procedure is being performed, as described further below. Additionally or alternatively, an air pressure sensor may be included within the controller (104 or 106), which can be used to compensate for changes in air pressure and / or altitude. controller

[0074] The devices and / or systems described herein may include one or more controllers (e.g., controller 104 and controller 106). For example, system 100 may include a first controller 104, which may be coupled to a base of elongated body 102. First controller 104 may be operably coupled to solid-state sensor 111 and / or expandable member sensor 115. In some variations, second controller 106 may be releasably coupled to first controller 104, as shown in FIG. 2C. In such variations, second controller 106 may be coupled to elongated body 102 via first controller 104. In some variations, system 100 may not include first controller 104, and second controller 106 may be directly coupled to elongated body 102.

[0075] A controller (e.g., controller 104 and / or controller 106) may be communicatively coupled to and receive data from sensors, such as, for example, sensors integrated into the elongated body. The controller may include a processor (e.g., a CPU) that may process data and / or other signals to control one or more components of the system. The processor may be configured to receive, process, compile, calculate, store, access, read, write, and / or transmit data and / or other signals. In some variations, the processor may be configured to access or receive data and / or other signals from one or more of a sensor and a storage medium (e.g., memory, flash drive, memory card). The processor may be configured to launch and / or execute application processes and / or other modules, processes, and / or functions associated with the device.

[0076] In some variations, data from the sensor may be analyzed in the controller over discrete time periods, for example, the data may be analyzed every 3 ms, 4 ms, 5 ms, 6 ms, 7 ms, 8 ms, 9 ms, or 10 ms (e.g., from about 3 ms to about 6 ms, from about 4 ms to about 6 ms, or from about 5 ms to about 6 ms, etc., including all values ​​and subranges therein).

[0077] In some variations, the controller may be communicatively coupled to a user interface. For example, the user interface may be a display on the controller. In some variations, the user interface may be a display on any suitable computing device (e.g., computer, smartphone, tablet, etc.) communicatively coupled to the controller, for example, via a communication device or module described herein. The user interface may comprise an input device (e.g., a touch screen) and an output device (e.g., a display device) and may be configured to receive input data from a sensor. In some variations, the input device may comprise a touch surface for an operator to provide input (e.g., finger contact on the touch surface) corresponding to a control signal. In some variations, a haptic device may be incorporated into one or more of the input and output devices to provide additional sensory output (e.g., force feedback) to the operator.

[0078] The controller 104 and / or the controller 106 may be configured to calibrate the solid-state sensor 111 based on the sensor readings from the expandable member sensor 115, as further described herein. For example, the controller 104 may be configured to calibrate the solid-state sensor 111. Additionally or alternatively, the controller 106 may be configured to calibrate the solid-state sensor 111. In some variations, the entire calibration process may be performed solely by either the controllers 104, 106. In some variations, the calibration process may be split between the controllers 104, 106. The following paragraphs discuss calibration using the controller 104. It should be readily apparent that one or more of these steps may additionally or alternatively be performed by the controller 106.

[0079] In some variations, the controller 104 may automatically calibrate the solid-state sensor 111 based on sensor readings from the expandable member sensor 115. In some variations, the controller 104 may partially automatically calibrate the solid-state sensor 111 and partially calibrate the solid-state sensor 111 based on feedback from a user (e.g., a surgeon, an operator, a physician, etc.). For example, the controller 104 may initiate a calibration process (e.g., a calibration process to calibrate the solid-state sensor) in response to and / or based on instructions and / or notifications from a user (e.g., feedback from a user). However, in some variations, the controller 104 may automatically analyze sensor readings from the expandable member sensor 115 and calibrate the solid-state sensor 111.

[0080] The solid-state sensors 111 and the expandable member sensors 115 may be initially calibrated (e.g., factory calibrated) prior to being communicatively and / or operably coupled to the controller 104. For example, calibration curves and / or calibration constants may be determined and / or set for each of the expandable member sensors 115 and the solid-state sensors 111 before the sensors are coupled to the controller 104. More specifically, because the sensors convert measurements of physical quantities (e.g., temperature, pressure, strain, light energy, etc.) into electrical signals that can be analyzed, the calibration curves may represent the relationship between the physical quantities that the sensors are configured to measure and the individual sensor outputs, such as voltage. For example, the calibration curves may show the relationship between pressure measurements and the corresponding voltage outputs. When the sensors are in use, the voltage outputs from the sensors may be analyzed by the controller 104 to determine the change in pressure as sensed and measured by each of the sensors. In some variations, the calibration curves may be linear. As an example, the calibration curve may be a straight line such as y=mx+c, where y may represent the output voltage, x may represent the change in pressure as measured and sensed by the sensor, and c may represent a calibration constant.

[0081] In some variations, after an initial calibration (e.g., a factory calibration), the solid-state sensor 111 and / or the expandable member sensor 115 may be coupled to, attached to, or otherwise integrated with the system 100. In other variations, the initial calibration described above may be performed after the solid-state sensor 111 and / or the expandable member 115 are coupled to, attached to, or otherwise integrated with the system 100. Prior to using the system 100 to monitor a physiological condition within a patient, the controller 104 may determine an initial setting point for the expandable member sensor 115. The expandable member sensor 115 may be sensitive to environmental factors, such as, for example, atmospheric pressure and / or altitude. For example, changes in atmospheric pressure and / or altitude may affect sensor readings. Thus, the controller 104 may determine an initial setting point for the expandable member sensor 115 that may take into account the effects that environmental factors may have on the sensor data. In some variations, the controller 104 may include one or more controls (e.g., a user interface with touch screen buttons, physical buttons, etc.) that a user may manipulate (e.g., press, push, pull, etc.) to indicate to the controller to determine a baseline value, such as a zero point, for the expandable member sensor 115. Additionally or alternatively, the controller 104 may automatically determine a baseline value for the expandable member sensor 115. For example, a pressure measurement and / or a sensor reading indicative of pressure from the expandable member sensor 115 may be set to zero (even if the measurement and / or reading from the expandable member sensor 115 does not indicate zero) prior to advancing the elongated body 102 into the patient's body. Additionally or alternatively, a barometer may be communicatively and / or operably coupled to the controller 104. The controller 104 may receive sensor data from the barometer (e.g., every second, every 5 milliseconds, etc.) that may be indicative of atmospheric pressure. The atmospheric pressure may be used to determine an initial setting point for the expandable member sensor 115. For example, the atmospheric pressure received from a barometer may be set as the zero point for the expandable member sensor 115 .

[0082] A user (e.g., a surgeon, operator, physician, etc.) may advance at least a portion of the system 100 into a target location within the patient's body. For example, the user may advance at least the expandable member 110 into a target location within the patient's body. When the solid-state sensor 111 transitions from air outside the patient's body to fluid inside the patient's body, the controller 104 may be configured to identify this transition. For example, the controller 104 may analyze sensor data from the solid-state sensor 111 and identify a rapid change in the sensor reading. For example, the controller 104 may identify a rapid drop or decrease and / or a rapid rise or increase in the sensor data that may indicate a transition between media. For example, a rapid change in slope in a pressure waveform (e.g., an arterial waveform, a venous waveform, etc.) obtained from the solid-state sensor 111 after a portion of the system has been advanced into a target location within the patient's body may indicate that a transition has occurred from air outside the patient's body to fluid inside the patient's body. The controller may identify this rapid change in slope and, optionally, notify the user that a transition has occurred. The change in slope (e.g., rapid rise and / or rapid fall) may range from about 15 mmHg / sec to about 1,200 mmHg / sec, including all values ​​and subranges therein. For example, the change in slope may range from about 15 mmHg / sec, about 25 mmHg / sec, about 50 mmHg / sec, about 100 mmHg / sec, about 150 mmHg / sec, about 200 mmHg / sec, about 250 mmHg / sec, about 300 mmHg / sec, about 350 mmHg / sec, about 400 mmHg / sec, about 450 mmHg / sec, about 500 mmHg / sec, about 550 mmHg / sec, about 600 mmHg / sec, about 700 mmHg / sec, about 800 mmHg / sec, about 900 mmHg / sec, about 1000 mmHg / sec, about 1200 mmHg / sec, about 1400 mmHg / sec, about 1600 mmHg / sec, about 1800 mmHg / sec, about 1900 mmHg / sec, about 2100 mmHg / sec, about 2200 mmHg / sec, about 2300 mmHg / sec, about 2400 mmHg / sec, about 250 mmHg / sec, about 300 mmHg / sec, about 350 mmHg / sec, about 400 mmHg / sec, about 450 mmHg / sec, about 500 mmHg / sec, about 550 mmHg / sec, about 600 mmHg / sec, about 2600 mmHg / sec, about 2700 mmHg / sec, about 2800 mmHg / sec, about 2900 mmHg / sec, about 3000 mm Hg / sec, about 650 mmHg / sec, about 700 mmHg / sec, about 750 mmHg / sec, about 800 mmHg / sec, about 850 mmHg / sec, about 900 mmHg / sec, about 950 mmHg / sec, about 1,000 mmHg / sec, about 1,050 mmHg / sec, about 1,100 mmHg / sec, about 1,150 mmHg / sec, or about 1,200 mmHg / sec.Additionally or alternatively, the controller 104 may include one or more controls (e.g., a user interface with touch screen buttons, physical buttons, etc.) that a user may manipulate (e.g., press, push, pull, etc.) to indicate a transition.

[0083] As discussed herein, this rapid change in sensor data may result in an inaccurate sensor reading. For example, the solid-state sensor 111 may be configured to measure a physiological condition such as blood pressure at a target location. A rapid change in slope in the pressure waveform due to a media transition may result in an inaccurate blood pressure measurement at the target location. Thus, it may be advantageous to calibrate the solid-state sensor 111 after the rapid change so that the sensor data obtained from the solid-state sensor 111 is indicative of the actual blood pressure at the target location. To that end, a calibration curve and / or calibration constants for the solid-state sensor 111 may be adjusted based on the sensor data from the expandable member sensor 115, as further described herein.

[0084] An inherent offset may exist between the sensor data from the proximal solid sensor 111a and the distal solid sensor 111b after advancement of the expandable member 110 to the target location and before delivery of any fluid to the expandable member. In some variations, this inherent offset may be due to the presence of the expandable member 110 positioned between the proximal solid sensor 111a and the distal solid sensor 111b, which may create a pressure difference between the proximal solid sensor 111a and the distal solid sensor 111b. Additionally or alternatively, this inherent offset between the proximal solid sensor 111a and the distal solid sensor 111b may be due to a rapid change in sensor data resulting from a transition from one medium to another (e.g., from air outside the patient's body to a fluid inside the patient's body) and / or the inherent offset may be an inherent difference between the two specific sensors (even though the proximal solid sensor 111a and the distal solid sensor 111b are the same type of sensor).

[0085] Thus, after advancing the expandable member 110 to a target location (e.g., a target location in a blood vessel) and before injecting fluid into the expandable member 110, the controller 104 may determine an inherent offset between the proximal solid sensor 111a and the distal solid sensor 111b. Because no fluid has yet been injected into the expandable member 110, the expandable member 110 may not affect blood flow at the target location or may not effectively and / or substantially affect blood flow at the target location (e.g., due to the difference in pressure measured by the proximal solid sensor and the distal solid sensor being no more than about 1.0 mmHg), and therefore the sensor data from the proximal solid sensor and the distal solid sensor 111b should be identical. However, the data between the two solid sensors may differ due to the inherent offset.

[0086] For example, consider sensor readings obtained from (i.e., pressures measured at) the proximal solid sensor 111a and the distal solid sensor 111b. As discussed herein, the proximal solid sensor 111a may be positioned distal to the expandable member 110. Thus, the proximal solid sensor 111a may also be referred to herein as the "tip sensor." The pressure measured at the proximal solid sensor 111a (the tip sensor) is expressed as T measured Similarly, the distal solid sensor 111b may be located proximal to the expandable member 110. Thus, the distal solid sensor 111b may be referred to as the "hub sensor." The pressure measured at the distal solid sensor 111b (hub sensor) is expressed as H measured However, the actual pressure at the proximal solid-state sensor may be expressed as T actual and the actual pressure at the distal solid-state sensor 111b may be expressed as H actual Therefore, the pressure measured at the proximal solid-state sensor 111a (T measured ) is the actual blood pressure (T actual )+ε T Similarly, the pressure measured at the distal solid sensor 111b (Hmeasured ) is the actual blood pressure (H actual )+ε H The distal solid-state sensor offset may be expressed as: [ka]

[0087] As discussed herein, T may be reached before the expandable member 110 begins to actually and / or substantially disrupt blood flow at the target location (e.g., affecting the pressure measured by the proximal and distal solid state sensors by more than about 1.0 mmHg). measured is H measured In other words, consider the pressure within the expandable member 110 to be B. [ka]

[0088] However, the pressure measured at the proximal solid sensor 111a may not be identical to the pressure measured at the distal solid sensor 111b, and therefore the inherent offset between the proximal solid sensor 111a and the distal solid sensor 111b may be determined by the controller 104 as follows: [ka] where α represents the inherent offset between the proximal solid sensor 111a and the distal solid sensor 111b.

[0089] After the inherent offset is determined, the expandable member 110 may be injected with a calibration bolus to calibrate the solid sensor. In some variations, the volume of the calibration bolus may be equal to the undisturbed volume of fluid, while in other variations, the volume of the calibration bolus may be greater than the undisturbed volume of fluid, but less than the upper volume limit. The undisturbed volume of fluid may be an amount of fluid that does not expand the expandable member 110, but ensures that the fluid column between the expandable member 110 and the pump 108 is filled. In the undisturbed volume, the expandable member 110 may not substantially and / or substantially affect blood flow at the target location (e.g., due to the difference in pressure measured by the proximal and distal solid sensors not exceeding about 1.0 mmHg), however, the fluid column is completely filled, so that pressure from inside the expandable member 110 may be transmitted to the expandable member sensor 115. More specifically, as an undisturbed volume of fluid is added, pressure from outside the expandable member 110 may begin to transmit to the expandable member sensor 115. In other words, in the undisturbed volume, the pressure outside the expandable member 110 at the target location may be the same as the pressure inside the expandable member 110. In this manner, the expandable member pressure may represent blood pressure at the target location. It should be understood that the undisturbed volume may refer to a single volume or a range of volumes, and thus, when described herein as a volume above the undisturbed volume, this may refer to volumes outside and above that range of volumes.

[0090] In some variations, the volume of the calibration bolus may be a volume above the undisturbed volume but below the upper limit volume. For example, the volume of the calibration bolus may be above the undisturbed volume such that the expandable member 110 may begin to become enlarged and blood flow at the target location may be affected by the expandable member. However, the volume of the calibration bolus may not exceed the upper limit volume. The upper limit volume may be a volume where the pressure inside the expandable member 110 is not identical to or substantially similar (e.g., not within ±5.0 mmHg) to the pressure outside the expandable member 110 at the target location, such as the pressure at the proximal solid sensor. In other words, at and above the upper limit volume, the pressure data received from the expandable member sensor may no longer represent the pressure outside the expandable member at the target location.

[0091] Thus, the volume of the calibration bolus may be such that the volume is at least an undisturbed volume at which the pressure inside the expandable member 110 may begin to transmit to the expandable member sensor 115, but is less than the volume at which the pressure inside the expandable member may not be identical to or substantially similar to (e.g., not within ±5.0 mmHg) the pressure outside the expandable member 110. For example, the volume of the calibration bolus may be such that the pressure inside the expandable member is γ lower , or at least a non-disturbing value. Thus, to calibrate the solid-state sensor 111, the expandable member pressure B is at least the pressure γ lower It should be.

[0092] As mentioned above, the volume of the calibration bolus may be greater than the undisturbed volume. However, the volume should be less than the upper volume limit where the pressure inside the expandable member is not identical to or substantially similar to (e.g., not within ±5.0 mmHg) the pressure outside the expandable member 110. For example, the volume of the calibration bolus may be greater than or equal to the pressure inside the expandable member 110, γ upper can not exceed a volume where the pressure is not the same as the pressure outside the expandable member 110. Therefore, to calibrate the solid-state sensor 111, the expandable member pressure B is upperIt should be lower than

[0093] Thus, a set of possible expandable member pressure values ​​B can be defined as follows: [ka]

[0094] In some variations, the controller 104 may be configured to adjust the pressure in the expandable member 110 to γ lower ~γ upper The method may be configured to verify whether

[0095] As discussed above, when the volume of the calibration bolus exceeds the undisturbed volume but remains below the upper volume limit such that calibration is still possible, the expandable member 110 may begin to actually and / or substantially affect the blood flow at the target location (e.g., affecting the pressure measured by the proximal and distal solid sensors by more than about 1.0 mmHg). In such a scenario, the sensor data from the distal solid sensor 111b may begin to decline. For example, when the volume of the calibration bolus exceeds the undisturbed volume, the slope in the pressure waveform from the distal solid sensor 111b may decrease. However, the slope in the pressure waveform from the proximal solid sensor 111a may increase and / or remain unchanged. More specifically, the change in slope in the pressure waveform from the distal solid sensor 111b may be different from the change in slope in the pressure waveform from the proximal solid sensor 111a. In such a scenario, a post-expansion offset between the distal solid sensor 111b and the proximal solid sensor 111a may be determined. For example, when a volume greater than the undisturbed volume is injected into the expandable member 110, the pressure disturbance caused by the expandable member 110 affecting blood flow may be represented as Ψ. A post-expansion offset β between the proximal solid sensor 111a and the distal solid sensor 111b may be determined as follows: [ka] where α represents the inherent offset between the proximal solid sensor 111a and the distal solid sensor 111b as determined in Equation 4.

[0096] In some variations, the undisturbed volume and / or the volume of the calibration bolus (to different extents) may be determined by the controller 104. Additionally or alternatively, the undisturbed volume and / or the volume of the calibration bolus may be preprogrammed into the controller 104. The undisturbed volume may be determined based on one or more of the following: the shape of the expandable member 110, the volume of the expandable member 110, the length of the elongated body 102, the volume of a fluid column fluidly coupling and / or connecting the expandable member 110 with the pump 108, the length of a fluid column coupling the expandable member 110 with the pump 102, the amount of fluid required to transition a negative pressure reading obtained from the expandable member sensor 115 to a zero pressure reading and / or a positive pressure reading, the size of the blood vessel (e.g., the size of the target location within the blood vessel), and / or combinations thereof. The volume of the calibration bolus may be determined to be equal to or based on the undisturbed volume.

[0097] In some variations, the undisturbed volume may be determined, at least in part, based on the shape of the expandable member 110. In some variations, the controller 104 may determine the undisturbed volume, at least in part, based on the shape of the expandable member 110. For example, the undisturbed volume may be determined based on whether the expandable member 110, when expanded, has an elliptical cross-sectional shape, a circular cross-sectional shape, etc.

[0098] In some variations, the undisturbed volume may be determined based at least in part on the overall volume of the expandable member 110. For example, the controller 104 may determine the undisturbed volume based at least in part on the overall volume of the expandable member 110. For example, in some variations, the undisturbed volume may be about 2% to about 5%, about 2.5% to about 5%, about 3% to about 5%, about 3.5% to about 5%, about 4% to about 5%, or about 4.5% to about 5% (including all values ​​and subranges therein) of the total volume of the expandable member 110. In some variations, the undisturbed volume may be about 5% or less, about 4.5% or less, about 4.2% or less, about 4% or less, about 3.7% or less, about 3.5% or less, about 3% or less, or about 2.5% or less of the volume of the expandable member 110.

[0099] In some variations, the undisturbed volume may be determined, at least in part, based on one or more characteristics of the elongated body 102 (e.g., length, volume of one or more lumens, etc.). For example, the undisturbed volume may be determined based on the volume of a fluid column within the elongated member 102 that fluidly couples the pump 108 (e.g., a syringe pump) to the expandable member 110. As another example, the undisturbed volume may be determined based on the length of a fluid column within the elongated member 102 that fluidly couples the pump 108 to the expandable member.

[0100] In some variations, the undisturbed volume may be determined, at least in part, based on the amount of fluid required to transition a negative pressure reading obtained from the expandable member sensor 115 to a zero pressure reading and / or a positive pressure reading. For example, when the expandable member 110 is advanced into the target vessel, a partial vacuum may be created within the expandable member 110. Thus, a pressure differential may exist between the expandable member sensor 115 and the expandable member 110. Thus, the expandable member 110 may initially result in a negative sensor reading (e.g., a negative pressure reading), indicating a partial vacuum within the expandable member 115. Injecting the undisturbed volume may overcome and / or eliminate the partial vacuum. Thus, the undisturbed volume may be an amount that may result in a zero pressure reading and / or a positive pressure reading from the expandable member sensor 115, thereby eliminating or overcoming the partial vacuum within the expandable member 110.

[0101] In some variations, the volume of the calibration bolus may be determined, at least in part, based on the size of the body cavity (e.g., blood vessel) into which the expandable member 110 is advanced. For example, the calibration bolus may be determined based on the size of the aorta or vein into which the expandable member 110 is advanced.

[0102] In some variations, the undisturbed volume may be between 100 μl and 300 ml. In some variations, the undisturbed volume may be between about 1 ml and about 1.5 ml. In some variations, the controller 104 may notify the user to inject a calibration bolus into the expandable member 110. In some variations, the controller 104 may include a user interface or display to indicate the calibration bolus and / or the time when the calibration bolus should be injected into the expandable member 110.

[0103] In some variations, the time when the calibration bolus should be injected into the expandable member 110 may be determined. For example, the controller 104 may determine the time when the calibration bolus should be injected into the expandable member 110. Additionally or alternatively, the time when the calibration bolus should be injected may be preprogrammed into the controller 104. In some variations, the time may be determined based on one or more of the length of the elongated member, the distance of the solid sensor 111 from the distal end of the elongated member, the length of a fluid column fluidly coupling and / or connecting the expandable member with the pump 108, combinations thereof, and / or the like. In some variations, the time may be determined based on sensor data from the proximal solid sensor 111a and the distal solid sensor 111b. For example, the time may be the time at or after a change in slope of the pressure waveform from the proximal solid sensor 111a matches a change in slope of the pressure waveform from the distal solid sensor 111b. As another example, the point in time may be at or after the pressure reading from the proximal solid state sensor is the same as the pressure reading from the distal solid state sensor.

[0104] During or after the calibration bolus is injected into the expandable member, the controller 104 may be configured to determine whether the volume of the calibration bolus injected into the expandable member 110 is equal to the undisturbed volume or whether the volume of the calibration bolus injected into the expandable member 110 exceeds the undisturbed volume.

[0105] When the volume of the calibration bolus is equal to the undisturbed volume, the controller 104 may be further configured to determine whether the undisturbed volume has been injected or otherwise delivered to the expandable member. In some variations, the controller 104 may be further configured to transmit a notification indicating that the undisturbed volume has been added when or after it makes the determination that the undisturbed volume has been added. Although described above in connection with the undisturbed volume, it should be understood that the controller 104 may be configured to transmit a notification that the calibration bolus has been added.

[0106] The controller 104 may analyze the sensor data from the solid state sensor 111 and / or the expandable member sensor 115 in one or more of a variety of ways to determine whether an undisturbed volume has been delivered. For example, the controller 104 may analyze the sensor data from the expandable member sensor 115 to determine whether the expandable member sensor data is zero or a positive value (e.g., a positive pressure reading). If the controller determines that the expandable member sensor data is zero or a positive value, the controller 104 may determine that an undisturbed volume has been injected and may optionally notify the user. Additionally or alternatively, if the controller 104 determines that the expandable member sensor data is a negative value, the controller 104 may determine that the amount of fluid injected into the expandable member 110 is less than the undisturbed volume. In some variations, the controller 104 may notify the user, for example, via a user interface, that the amount of fluid delivered is less than the undisturbed volume. In another example, the controller 104 may compare sensor data from the proximal solid sensor 111a with sensor data from the distal solid sensor 111b. If the change in slope in the pressure waveform (e.g., sensor data) acquired from the proximal solid sensor 111a is identical to the change in slope in the pressure waveform acquired from the distal solid sensor 111b, the controller 104 may determine that an undisturbed volume has been injected, and may optionally notify the user. More specifically, the controller may determine whether the rise or fall in pressure measured at the proximal solid sensor 111a is identical to the rise or fall in pressure measured at the distal solid sensor 111b. If the rise or fall in pressure measured at the two pressure sensors is identical, the controller 104 may determine that an undisturbed volume has been added, and may optionally notify the user. As yet another example, the controller 104 may compare sensor data received from the expandable member sensor 115 to sensor data received from one or more of the solid-state sensors 111.If the change in slope in the pressure waveform obtained from the expandable member sensor 115 is identical to the change in slope in the pressure waveform from the one or more solid state sensors 111, the controller 104 may determine that a non-disturbing volume has been injected and may optionally notify the user. More specifically, the controller 104 may determine whether the rise or fall in pressure measured from the expandable member sensor 115 is identical to the rise or fall in pressure measured at the one or more solid state sensors 111. If the rise or fall in pressure measured from the expandable member sensor 115 and the one or more solid state sensors 111 are identical, the controller 104 may determine that a non-disturbing volume has been added and may optionally notify the user. It should be understood that the controller 104 described herein may utilize any or all of the above techniques to determine whether a non-disturbing volume has been added to, injected into, or otherwise delivered to the expandable member 110.

[0107] Additionally or alternatively, the controller 104 may be configured to determine whether the volume of the calibration bolus injected into the expandable member 110 exceeds the undisturbed volume. For example, in one variation, the controller 104 may compare sensor data received from the proximal solid sensor 111a and from the distal solid sensor 111b. If a difference between the sensor data from the solid sensors 111a, 111b begins to exist, the controller 104 may determine that a volume in excess of the undisturbed volume has been added to the expandable member 110 and may optionally notify the user. For example, if the change in slope in the pressure waveform received from the proximal solid sensor 111a differs from the change in slope in the pressure waveform received from the distal solid sensor 111b, the controller 104 may determine that a volume in excess of the undisturbed volume has been added to the expandable member 110 and may optionally notify the user. More specifically, the controller 104 may determine whether the rise or fall in pressure measured at the proximal solid sensor 111a is different from the rise or fall in pressure measured at the distal solid sensor 111b. For example, if there is a fall in pressure measured at the proximal solid sensor 111a and there is no fall in pressure measured at the distal solid sensor 111b, the controller 104 may determine that a volume greater than the undisturbed volume has been added to the expandable member 110 and may optionally notify the user. When the controller 104 determines that a volume greater than the undisturbed volume has been injected into the expandable member, the controller 104 may perform one of two actions. In some variations, the controller 104 may calibrate the distal solid sensor 111b based on sensor data from the proximal solid sensor 111a, as further described herein. In other variations, the controller 104 may stop and / or terminate the calibration process, and optionally notify the user accordingly.

[0108] Prior to calibrating the solid-state sensor 111, the controller 104 may determine whether a predetermined amount of time has elapsed since advancing the elongated body 102 into a target location within the patient's body. A calibration bolus may be injected into the expandable member 110 before the predetermined amount of time has elapsed. In some variations, the predetermined time may be from about 45 seconds to about 5 seconds, about 30 seconds to about 5 seconds, about 25 seconds to about 5 seconds, about 15 seconds to about 5 seconds, about 10 seconds to about 5 seconds (including all values ​​and subranges therein) from when the expandable member 110 is advanced into the target location. In some variations, the predetermined time may be preprogrammed into the controller 104, and the controller 104 may optionally notify the user once the predetermined time has elapsed. Additionally or alternatively, the user may operate one or more controls on the controller 104 to indicate that the predetermined time has elapsed.

[0109] As discussed above, the controller 104 may indicate that the calibration bolus has been added. Additionally or alternatively, the user may manipulate one or more controls on the controller 104 to indicate that the calibration bolus has been added. For example, the controller 104 may include a display that indicates the volume of fluid injected into the expandable member 110. The user may manipulate (e.g., push, pull, press, etc.) a control on the controller 104 (e.g., a user interface with a touch screen button, a physical button, etc.) to indicate that the calibration bolus has been added. At this point, the solid state sensor 111 may be calibrated, as will be discussed in more detail herein.

[0110] To calibrate the solid sensor 111, the controller 104 may analyze sensor data from the expandable member sensor 115. For example, to calibrate the proximal solid sensor 111a, the controller 104 may analyze sensor data from the expandable member sensor 115 and the proximal solid sensor 111a. The controller 104 may shift and / or adjust the calibration curve and / or calibration constants of the proximal solid sensor 111a such that the sensor data from the proximal solid sensor 111a is identical to the sensor data from the expandable member sensor 115.

[0111] For example, when the volume of the calibration bolus is equal to the undisturbed volume, the expandable member 110 does not significantly affect blood flow at the target location. Thus, the expandable member pressure B is equal to the pressure from the proximal solid-state sensor 110a (T actual ) should be the same as [ka]

[0112] Thus, to calibrate the proximal solid sensor 110a, the controller 104 may determine a corrected proximal solid sensor offset as follows: [ka] During the ceremony, [ka] is the corrected proximal solid offset. The corrected proximal solid offset may be applied to the pressure measured at the proximal solid sensor 110a to determine a calibrated pressure value as follows: [ka] In the formula, T calibrated may be the calibrated pressure value for the proximal solid-state sensor 111a, and ε T may be the proximal solid offset in Equation 1, [ka] may be a corrected proximal solid offset. Thus, the calibration curve and / or calibration constants of the proximal solid sensor 110a may include a correction factor [ka] For example, if the calibration curve of the proximal solid sensor 111a is expressed as a straight line y=mx+c, where y may represent the output voltage and x may represent the change in pressure as measured and sensed by the distal solid sensor 111b, the controller 104 may adjust and / or vary the calibration curve such that the output voltage y of the proximal solid sensor 111a is the same as the output voltage of the expandable member sensor 115. For example, the calibration curve of the proximal solid sensor 111a may be expressed as [ka] It may be adjusted so that

[0113] When the volume of the calibration bolus exceeds the undisturbed volume, the expandable member may begin to affect blood flow at the target location. However, the expandable member pressure B′ may still be greater than the pressure (T′ actural ) may be the same as the calibration curve and / or calibration constants of the proximal solid sensor 111a when the volume of the calibration bolus exceeds the undisturbed volume. Thus, when the volume of the calibration bolus exceeds the undisturbed volume, the calibration curve and / or calibration constants of the proximal solid sensor 111a may still be adjusted in a manner similar to adjusting the calibration curve and / or calibration constants of the proximal solid sensor 111a when the volume of the calibration bolus is equal to the undisturbed volume.

[0114] The controller 104 may adjust the calibration curve and / or calibration constants of the proximal solid sensor 111a in the following manner. In some variations, the controller 104 may receive a pressure value from the expandable member sensor 115 at a specific time. The controller 104 may adjust the calibration curve and / or calibration constants of the proximal solid sensor 111a such that the pressure value from the proximal solid sensor 111a at that specific time is the same as the pressure value from the expandable member sensor 115 at that time. Additionally or alternatively, the controller 104 may receive sensor data in the form of a pressure waveform from the expandable member sensor 115. The controller may adjust the calibration curve and / or calibration constants of the proximal solid sensor 111a such that the pressure waveform from the proximal solid sensor 111a is the same as the pressure waveform from the expandable member sensor 115. In some variations, the controller 104 may determine a representative and / or average value of the sensor data (e.g., pressure values) obtained from the expandable member sensor 115 over a given duration. The controller 104 may then adjust the calibration curve and / or calibration constants of the proximal solid sensor 111a such that the sensor data (e.g., pressure values) from the proximal solid sensor 111a is the same as the representative and / or average value of the sensor data from the expandable member sensor 115.

[0115] In some variations, the distal solid sensor 111b and the proximal solid sensor 111a may be calibrated in a manner similar to that described above with respect to the proximal solid sensor 111a. In these variations, the calibration of the proximal and distal solid sensors 111a, 111b may occur simultaneously or sequentially. In some variations, the distal solid sensor 111b may be calibrated based on the proximal solid sensor 111a after the proximal solid sensor 111a has been calibrated. For example, the volume of the calibration bolus does not significantly affect blood flow at the target location, so the pressure (T actual ) is the pressure (H actual) should be the same as the offset α between the proximal solid sensor 111a and the distal solid sensor 111b, as discussed above. [ka] can therefore be determined as follows: [ka]

[0116] Distal Solid Sensor Offset Corrected [ka] is the calibrated pressure value (H calibrated ) is determined by multiplying the pressure (H measured ) can be applied. [ka] In the formula, H calibrated may be the calibrated pressure value for the distal solid-state sensor 111b, and H actual may be the actual pressure value at the distal solid-state sensor 111b, [ka] may be the distal solid-state sensor offset, [ka] may be a corrected distal solid sensor offset. Thus, the calibration curve and / or calibration constants of the distal solid sensor 110b may include a correction factor [ka] Therefore, the calibration curve of the distal solid-state sensor 111b may be adjusted by applying [ka] where y may represent the output voltage, x may represent the change in pressure as measured and sensed by the distal solid-state sensor 111b, and c may represent a calibration constant for the distal solid-state sensor; [ka] may represent a constant that accounts for the pressure difference between the distal solid sensor 111b and the proximal solid sensor 111a. To calibrate the distal solid sensor 111b, the controller 104 may adjust and / or vary the calibration curve such that the output voltage y of the distal solid sensor 111b is the same as the output voltage of the proximal solid sensor 111a. Thus, the controller 104 may adjust the calibration curve and / or calibration constant of the distal solid sensor 111b to also account for the inherent pressure difference α between the proximal solid sensor 111a and the distal solid sensor 111b.

[0117] In some variations, the distal solid sensor 111b may be calibrated based on the proximal solid sensor 111a and an additional correction factor (e.g., post-inflation offset β). For example, in some variations, when the expandable member 110 is injected with a volume greater than the undisturbed volume, the sensor data from the proximal solid sensor 111a may differ from the sensor data from the distal solid sensor 111b. This is because the expandable member 110 may begin to affect blood flow at the target location when the volume exceeds the undisturbed volume. For example, when a calibration bolus having a volume greater than the undisturbed volume is injected into the expandable member 110, the pressure proximal or upstream of the expandable member 110 (e.g., the pressure from the distal solid sensor 111b) may drop and / or become lower than the pressure within the expandable member 110. However, the pressure distal or downstream of the expandable member 110 (e.g., from the proximal solid sensor 111a) may be the same as the pressure within the expandable member 110. Because the expandable member 110 perturbs the pressure, the post-inflation offset β discussed above as representing the offset between the proximal solid sensor 111a and the distal solid sensor 111b when the volume of the calibration bolus exceeds the unperturbed volume may be used to calibrate the distal solid sensor 111b. Thus, the calibration curve of the distal solid sensor 111b may be similar to the calibration curve of the proximal solid sensor 111b, with the additional post-inflation offset β representing the corrected difference in pressure measurement between the proximal solid sensor 111a and the distal solid sensor 111b.

[0118] Thus, to calibrate the distal solid sensor 111b in this variation, the controller 104 may determine a corrected distal solid sensor offset as follows: [ka]

[0119] Distal Solid Sensor Offset Corrected [ka] is the calibrated pressure value (H′) for the distal solid-state sensor 111b as follows: calibrated ) is determined by measuring the pressure (H′ measured ) can be applied. [ka] In the formula, H′ calibrated may be the calibrated pressure value for the distal solid-state sensor 111b, and H′ actual may be the actual pressure value at the distal solid-state sensor 111b, [ka] may be the distal solid-state sensor offset, [ka] may be a corrected distal solid sensor offset. Thus, the calibration curve and / or calibration constants of the distal solid sensor 110b may include a correction factor [ka] Therefore, the calibration curve of the distal solid-state sensor 111b may be adjusted by applying [ka] where y may represent the output voltage, x may represent the change in pressure as measured and sensed by the distal solid-state sensor 111b, and c may represent a calibration constant for the distal solid-state sensor; [ka] may represent a constant that accounts for the pressure difference between the distal solid sensor 111b and the proximal solid sensor 111a. To calibrate the distal solid sensor 111b, the controller 104 may adjust and / or vary the calibration curve such that the output voltage y of the distal solid sensor 111b is the same as the output voltage of the proximal solid sensor 111a. Thus, the controller 104 may adjust the calibration curve and / or calibration constant of the distal solid sensor 111b to also account for the inherent pressure difference between the proximal solid sensor 111a and the distal solid sensor 111b.

[0120] In this manner, the controller 104 may be configured to calibrate the solid-state sensors 111 to accurately measure absolute values ​​(eg, absolute pressure) from the proximal solid-state sensor 111a and the distal solid-state sensor 111b. How to calibrate a sensor

[0121] In general, a method for calibrating a solid-state sensor may include advancing an elongate body and an expandable member to a target location, injecting a calibration bolus into the expandable member, acquiring data (e.g., waveforms) from the expandable member sensor and one or more solid-state sensors, and adjusting sensor data from at least one solid-state sensor based on the data from the expandable member sensor. In some variations, a vacuum may be applied to the expandable member (e.g., a balloon). A vacuum may be applied before or during the process of calibrating a solid-state sensor (e.g., between any steps) and may be used as a protective measure during calibration.

[0122] 3 is a flow chart illustrating an example variation of a method 200 for calibrating a solid-state sensor. The method 200 may include initially calibrating the expandable member sensor and / or the at least one solid-state sensor prior to coupling the expandable member sensor and the at least one solid-state sensor to a system (e.g., system 100 of FIGS. 2A, 2B, and 2C). For example, the expandable member sensor and / or the at least one solid-state sensor may be factory calibrated. For example, initially calibrating the expandable member sensor and the at least one solid-state sensor may include determining and / or setting a calibration curve and / or calibration constants for each of the expandable member sensor and the at least one solid-state sensor, as discussed herein.

[0123] Following the initial calibration, the method 200 may include coupling the sensor to a system for measuring physiological conditions (e.g., system 100 of FIGS. 2A, 2B, and 2C), which may also be used to calibrate one or more solid-state sensors. For example, the expandable member sensor may be coupled to, contained within, attached to, or otherwise positioned within a controller, such as controller 104 of FIGS. 2A, 2B, and 2C. At least one solid-state sensor may be coupled to (e.g., attached to, mounted on, affixed to, or otherwise integrated with) an elongated body (e.g., elongated body 102 of FIGS. 2A, 2B, and 2C). The elongated body may include an expandable member (e.g., expandable member 104 of FIGS. 2A, 2B, and 2C). The expandable member sensor may be fluidly coupled to the expandable member. For example, a fluid column within the elongated body may fluidly connect an expandable member sensor positioned in the controller to the expandable member. The at least one solid-state sensor may include two solid-state sensors, such as a distal solid-state sensor (e.g., distal solid-state sensor 111b in FIG. 2B), which may be positioned proximal to the expandable member, and a proximal solid-state sensor (e.g., proximal solid-state sensor 111a in FIG. 2B), which may be positioned distal to the expandable member.

[0124] The method 200 may include determining an initial setting point for the expandable member sensor prior to using the system to monitor a patient or to calibrate one or more solid state sensors (e.g., prior to advancing a portion of the system into the patient's body). For example, determining the initial setting point may include determining a baseline value, such as a zero point, for the expandable member sensor. For example, a sensor reading measured from the expandable member sensor prior to advancing a portion of the system may be set to zero (even if the reading itself does not indicate zero). Additionally or alternatively, determining the initial setting point may include determining a zero point for the expandable member sensor based on atmospheric pressure measured from a barometer.

[0125] The method 200 may include, at 202, advancing a portion of the system (e.g., a portion of the elongated body and the expandable member) to a target location within the patient's body. In some variations, the elongated body or a portion thereof (e.g., a tip or end portion) may be advanced to a target location within a blood vessel. For example, the elongated body and the expandable member may be advanced to and inserted into the aorta via a suitable intravascular route. For example, the method may include inserting an end portion of the elongated body into the aorta through a femoral artery. In some variations, the elongated body may be inserted into the aorta through a radial or brachial access. The elongated body may be advanced such that the expandable member is positioned at a desired location within the aorta. For example, the elongated body may be advanced until the expandable member is positioned within segment 1 of the aorta (e.g., the descending aorta above the celiac artery), segment 2 of the aorta (e.g., the abdominal aorta between the celiac artery and the lowest renal artery), or segment 3 of the aorta (e.g., the abdominal aorta between the lowest renal artery and the aortic bifurcation). Alternatively, the elongate body may be inserted into the iliac artery and not advanced into the aorta.

[0126] When a portion of the elongate body and the expandable member are advanced to a target location within the patient's body, the at least one solid sensor (e.g., the proximal solid sensor and the distal solid sensor) may be exposed to a fluid (e.g., a bodily fluid such as blood) within the patient's body. More specifically, the at least one solid sensor may transition from a dry state (e.g., due to exposure to air outside the patient's body) to a wet state (e.g., due to exposure to a fluid inside the patient's body). The transition may result in a rapid change in sensor readings from the at least one solid sensor. For example, a change in medium, a change in temperature, and / or other change in ambient conditions (surrounding the at least one solid sensor) may result in a rapid rise or fall in sensor data. In some variations, the method may include determining that the transition has occurred and notifying a user (e.g., a surgeon, operator, physician, etc.) of the transition. For example, the method may include determining that the transition has occurred by receiving sensor data from the at least one solid sensor and identifying a rapid change in the sensor data as described in more detail herein. For example, the method may include analyzing a pressure waveform (e.g., arterial waveform, venous waveform, etc.) received from at least one solid-state sensor, identifying an abrupt change in slope in the waveform, and determining that a transition has occurred. The method may further include notifying a user (e.g., via a user interface and / or display on the controller) of the transition based on the determination, e.g., automatically in response to the determination. Additionally or alternatively, the user may analyze the sensor data displayed on a user interface, such as a display on the controller. In response to observing a rapid rise or rapid fall in the sensor data, the user may manipulate (e.g., press, push, pull, etc.) one or more controls on the controller (e.g., a user interface with a touch screen button, a physical button, etc.) to indicate to the controller that a transition has occurred. In some variations, determining that a transition has occurred may include determining that the expandable member is positioned within the target vessel.In some variations, determining that the expandable member is positioned within the target vessel may include analyzing the sensor data, such as determining Euclidean distance, performing dynamic time warping, performing root mean square similarity between the sensor data from the proximal solid sensor and the distal solid sensor, etc. Identifying that the sensor data from the proximal solid sensor is substantially similar (e.g., within ±10 mmHg based on the analysis) to the sensor data from the distal solid sensor may indicate that the expandable member is positioned within the target vessel.

[0127] The method 200 may include determining a specific offset between the proximal solid sensor and the distal solid sensor after advancing the expandable member to the target location. At 204, the method 200 may include injecting a calibration bolus into the expandable member. The calibration bolus may be injected via a pump (e.g., syringe pump 108 of FIGS. 2A and 2C). The pump may be fluidly coupled to the expandable member via a fluid column in the elongated body. In some variations, injecting a volume of the calibration bolus may include injecting a non-disturbing volume of fluid that does not expand the expandable member but ensures that the fluid fills the fluid column between the expandable member and the pump. In such variations, the expandable member may not substantially and / or substantially affect blood flow at the target location (e.g., due to the difference in pressure measured by the proximal solid sensor and the distal solid sensor being no more than about 1.0 mmHg). The pressure at the target location outside the expandable member may be transmitted to the expandable member sensor via the fluid column. In some variations, injecting the calibration bolus may include injecting a fluid volume above the undisturbed volume but below the upper volume limit. Thus, the calibration bolus may begin to disturb blood flow at the target location. However, the calibration bolus may not result in a pressure application at the target location such that the pressure inside the expandable member may still be the same as or substantially similar to (e.g., within ±10 mmHg) the pressure outside the expandable member at the target location. In some variations, when the volume of the calibration bolus is above the undisturbed volume (but below the upper volume limit), the method may further include determining a post-expansion offset β between the proximal solid sensor and the distal solid sensor, as discussed in detail above. In some variations, the volume of the calibration bolus, and in some variations the undisturbed volume, may be about 1 ml to about 1.5 ml.

[0128] Prior to injecting the calibration bolus, the method 200 may also include determining an undisturbed volume. The undisturbed volume may be determined based on one or more of the size of the expandable member 110, the shape of the expandable member 110, the volume of the expandable member 110, the length of the elongated body 102, the volume of a fluid column fluidly coupling and / or connecting the expandable member 110 with the pump 108, the length of a fluid column coupling the expandable member 110 with the pump 108, the amount of fluid required to transition a negative pressure reading obtained from the expandable member sensor 115 to a zero pressure reading and / or a positive pressure reading, and the size of the target vessel (including combinations thereof), as described in more detail above.

[0129] The method 200 may also include determining a time when the calibration bolus should be injected into the expandable member. The time may be determined based on one or more of the length of the elongated member, the distance of the solid sensor 111 from the distal end of the elongated member, the length of a fluid column fluidly coupling and / or connecting the expandable member with the pump 108, sensor data (e.g., waveforms) from the proximal solid sensor and the distal solid sensor (including one or more thereof).

[0130] The method 200 may also include determining whether the volume of the calibration bolus is equal to an undisturbed volume or a volume greater than the undisturbed volume. For example, the method 200 may include determining whether an undisturbed volume has been injected into the expandable member and / or verifying whether an undisturbed volume has been injected into the expandable member. For example, verifying that an undisturbed volume of fluid has been injected may include analyzing sensor data from the expandable member sensor and determining whether a sensor measurement has transitioned from a negative value to a zero and / or positive value. If the sensor measurement transitions to a zero and / or positive value, the method may optionally include notifying a user that an undisturbed volume of fluid has been injected.

[0131] In some variations, verifying that an undisturbed volume of fluid has been injected into the expandable member may include comparing sensor data from each of the solid sensors to the remainder of the solid sensors. For example, where the elongated body includes a proximal solid sensor and a distal solid sensor, the method may include comparing sensor data from the proximal solid sensor to sensor data from the distal solid sensor. For example, in response to determining that a change in slope in the pressure waveform from the proximal solid sensor is identical to a change in slope in the pressure waveform from the distal solid sensor, the method may include determining that a desired volume of fluid has been injected into the expandable member. The method may optionally include notifying a user that an undisturbed volume of fluid has been added.

[0132] In some variations, verifying that an undisturbed volume of fluid has been added into the expandable member may include comparing sensor data from the expandable member sensor with sensor data from at least one solid sensor. For example, in response to determining that a change in slope in the pressure waveform from the expandable member sensor is identical to or substantially similar (e.g., within ±10 mmHg) to the change in slope in the pressure waveform from both the proximal solid sensor and the distal solid sensor, the method may include determining that an undisturbed volume of fluid has been injected into the expandable member. The method may optionally include notifying a user that an undisturbed volume of fluid has been added.

[0133] Additionally or alternatively, the method may include determining that a volume in excess of the undisturbed volume of fluid has been injected into the expandable member. For example, if a change in slope in the pressure waveform received from one of the solid state sensors is different from a change in slope in the pressure waveform received from the remaining solid state sensors, the method may include determining that a volume in excess of the undisturbed volume has been added to the expandable member. The method may optionally include notifying a user that a volume in excess of the undisturbed volume has been added. As another example, if a change in slope in the pressure waveform received from the expandable member sensor is the same as a change in slope in the pressure waveform received from the proximal solid state sensor and different from a change in slope in the pressure waveform received from the distal solid state sensor, the method may include determining that a volume in excess of the undisturbed volume has been added to the expandable member. The method may optionally include notifying a user that a volume in excess of the undisturbed volume has been added.

[0134] After determining that the calibration bolus has been injected into the expandable member, the method may include calibrating the at least one solid sensor. In some variations, the calibration may begin after a predetermined amount of time has elapsed after the elongate member has been advanced into the target location within the patient's body. The predetermined time may be preprogrammed into the controller and / or may be received by the controller from a user, for example, using a user interface. In some variations, the method may include notifying the user to indicate that the predetermined time has elapsed and / or that the controller may automatically begin calibrating the at least one solid sensor. Additionally or alternatively, the user may operate one or more controls on the controller to indicate that the predetermined time has elapsed, that a calibration bolus has been added, and / or that the controller may begin calibrating the at least one solid sensor. For example, the user may operate a button (e.g., a user interface on a touch screen and / or a physical button) to instruct the controller to begin calibrating the at least one solid sensor.

[0135] At 208, the method 200 may include adjusting the sensor data from at least one solid sensor based on the sensor data from the expandable member sensor. For example, the method may include shifting and / or adjusting a calibration curve and / or calibration constants of the proximal solid sensor such that the sensor data from the proximal solid sensor is identical to the sensor data from the expandable member sensor. In some variations, the calibration curve of the proximal solid sensor may be adjusted such that the sensor data at a particular data point or points from the proximal solid sensor is identical to the sensor data from the expandable member sensor at the same data point or points. In some variations, adjusting the calibration curve of the proximal solid sensor may include determining an average value of the sensor data from the proximal solid sensor and an average value of the sensor data from the expandable member sensor. The calibration curve of the proximal solid sensor may be adjusted such that the average value of the sensor data from the proximal solid sensor is identical to the average value of the sensor data from the expandable member sensor. In some variations, the calibration curve of the proximal solid sensor may be adjusted so that the pressure waveform from the proximal solid sensor is identical to the pressure waveform from the expandable member sensor.

[0136] In some variations, calibrating the distal solid sensor may include calibrating the distal solid sensor in a manner similar to that described above with respect to the proximal solid sensor. In these variations, the proximal and distal solid sensors may be calibrated simultaneously or sequentially. In some variations, the method may include adjusting and / or shifting a calibration curve and / or calibration constants of the distal solid sensor based on the calibrated proximal solid sensor and the inherent offset α between the proximal solid sensor and the distal solid sensor.

[0137] In some variations, the method may include adjusting and / or shifting a calibration curve and / or calibration constants of the distal solid sensor based on the calibrated proximal solid sensor and the post-expansion offset β between the proximal solid sensor and the distal solid sensor.

[0138] FIG. 4 illustrates an example variation of sensor data from the expandable member sensor, the proximal solid sensor, and the distal solid sensor before, during, and after calibration using the systems and methods described herein. In this example variation, the volume of the calibration bolus is a non-disturbing volume. At 302 (at about 3 minutes), the solid sensor may undergo a transition from air to water. A drop in pressure value from the solid sensor indicates this transition. At 304 (at about 5 minutes), an aliquot calibration bolus may be added. This aliquot may be sufficient to overcome the partial vacuum in the expandable member sensor. Thus, the pressure value from the expandable member sensor moves from a negative value to zero. At 306, a second aliquot of fluid may be added. The sum of the fluid added at 304 and the fluid added at 306 may be the calibration bolus. Thus, at 306, the solid sensor is calibrated based on the sensor data from the expandable member sensor. At 306, the sensor values ​​from both solid state sensors match the sensor value from the expandable member sensor. Excess fluid is added at 308. At this point, the pressure value from the proximal solid sensor may drop away from the pressure value from the distal solid sensor.

[0139] FIG. 5 illustrates another example variation of sensor data from the expandable member sensor, the proximal solid sensor, and the distal solid sensor before, during, and after calibration using the systems and methods described herein. In this variation, the volume of the calibration bolus exceeds the undisturbed volume. The sensor data shown is data collected after the solid sensor has undergone a media transition. After the media transition and application of negative pressure to the expandable member (as measured by the expandable member sensor BLN), but before the addition of the calibration bolus (e.g., at 402), an inherent offset α between the proximal solid sensor (i.e., tip sensor) and the distal solid sensor (i.e., hub sensor) may be determined. As shown in FIG. 5, prior to 402, an inherent offset α may exist between the pressure values ​​measured from the proximal solid sensor (T) and the distal solid sensor (H). The expandable member pressure measured by the expandable member sensor (BLN) may be negative due to a vacuum applied to the expandable member as described in more detail herein. At 402, a calibration bolus having a volume that exceeds the undisturbed volume of fluid may be added to the expandable member, as described above. Thus, at 402, the expandable member pressure (B) may rise to a positive value (B'). The change in slope in the waveform from the proximal solid sensor may be similar to the change in slope in the waveform from the expandable member sensor. However, because the volume of the calibration bolus exceeds the undisturbed volume, the pressure value from the distal solid sensor may begin to drop. That is, the change in slope in the waveform from the distal solid sensor may be different from the change in slope in the waveform from the expandable member sensor. Thus, in some variations, after 402, a post-expansion offset β between the proximal and distal solid sensors may be determined. In these variations, the post-expansion offset β may be determined based on the intrinsic offset α and the disturbed pressure Ψ due to the expandable member.

[0140] The sensor data from the expandable member sensor may be used to calibrate the proximal solid sensor. [ka] ) may be calculated such that the sensor data from the proximal solid sensor matches the sensor data from the expandable member sensor. This corrected proximal solid sensor offset may be applied at 404. As seen at 404, the sensor data from the proximal solid sensor begins to match the sensor data from the expandable member sensor due to application of the corrected proximal solid sensor offset. However, as the sensor data from the distal solid sensor begins to fall off at 402 (due to the expandable member), the corrected distal solid sensor offset (e.g., the corrected distal solid sensor offset described above) may become inaccurate. [ka] and / or corrected distal solid-state sensor offset [ka] ) may be calculated such that the inherent offset α between the proximal and distal solid sensors may be taken into account. This corrected distal solid sensor offset may be applied at 404.

[0141] In other variations, as mentioned above, the post-inflation offset β may not be calculated as part of the calibration process. In these variations, the equations are the same as those discussed hereinabove (using the same equation numbers used above), and the distal solid sensor offset may be determined directly based on the intrinsic offset and the proximal solid sensor offset, as explained above. Thus, the pressures measured at the proximal and distal solid sensors (i.e., the tip and hub sensors, respectively) are the actual pressures at the individual sensors plus an unknown amount of constant error, exemplified as follows: [ka] It could be. [ka]

[0142] The pressure (B) inside the expandable member (e.g., balloon (BLN)) is determined by the fact that the expandable member transmits upstream blood pressure (γ lower ) but the overall pressure inside the expandable member (γ upper When the proximal solid sensor is inflated with a volume of fluid that cannot affect the blood pressure at the distal sensor (T actual This set of expandable member pressures can be considered as B lowvol It may be referred to as. [ka]

[0143] When a vacuum is applied to the expandable member, it does not normally interfere with blood flow, and therefore the blood pressure at the proximal solid sensor (tip sensor) and the distal solid sensor (hub sensor) are generally the same: [ka]

[0144] Equations (1) and (2) can then be used to estimate the intrinsic sensor offsets (α) relative to each other as follows: [ka]

[0145] The balloon pressure is B lowvol If the balloon pressure is within , it can be seen from equation (8) that the balloon pressure can match the actual blood pressure at the tip. Therefore, equations (1) and (8) can be corrected using the pressure measurements at the proximal solid sensor (tip sensor) and the expandable member sensor (BLN) as follows: [ka] can be used to obtain an estimate of [ka]

[0146] Distal solid sensor (hub sensor) error [ka] Estimating {overscore (R)} can then be accomplished by combining equations (4) and (9) as follows: [ka]

[0147] The control system software then uses the tip and hub sensor error estimates to calibrate the sensors as follows: T measured and H measured A correction factor may be applied to both the [ka]

[0148] A vacuum (negative pressure) may be applied to the expandable member (e.g., balloon) before or during any step of the process of calibrating a solid-state sensor, as previously mentioned above, and may be used as a safety feature during calibration. In some variations, a vacuum may be applied to avoid introducing air bubbles into the elongate member shaft. Air bubbles may be accidentally introduced during coupling and / or decoupling of a syringe (e.g., at the stopcock coupling the syringe to the expandable member, from dead space in the stopcock, etc.). Air bubbles may adversely affect the pressure being transmitted from the expandable member, through the elongate member, to the expandable member sensor. For example, in an elongate member filled with an incompressible fluid (e.g., water, saline), pressure applied to the expandable member at one end of the elongate member generally transmits completely to the expandable member sensor at the opposite end of the elongate member. However, if an air bubble is present between the expandable member and the expandable member sensor, the air within the bubble may be compressed and ineffectively transmit pressure from the expandable member to the expandable member sensor. Thus, by applying a negative pressure to the expandable member (e.g., at the beginning of the calibration process) as a first calibration safeguard, the likelihood of having an air bubble in the elongated member when the calibration bolus is applied may be minimized, which in turn may reduce the likelihood of error in the calibration of the solid-state sensor. In some variations, the amount of negative pressure that may be applied to the expandable member may range from about -50 mmHg to about -350 mmHg, including all values ​​and subranges therein. For example, the applied negative pressure may be about -50 mmHg, about -75 mmHg, about -100 mmHg, about -125 mmHg, about -150 mmHg, about -175 mmHg, about -200 mmHg, about -225 mmHg, about -250 mmHg, about -275 mmHg, about -300 mmHg, about -325 mmHg, or about -350 mmHg. In some variations, the applied negative pressure may be about -275 mmHg.

[0149] Negative pressure may be applied to the expandable member using a syringe pump. The syringe pump may be operated manually (e.g., actuated by hand by a user without the use of a controller) or by using a controller. The syringe pump may be the same pump used to deliver the calibration bolus and / or the same pump used to modify the volume of the expandable member to control blood flow (e.g., inflate and / or deflate). Alternatively, the syringe pump used to apply negative pressure may be a different syringe pump than the pump used to deliver the calibration bolus and / or modify the volume of the expandable member (e.g., three different syringe pumps may be used, one for applying negative pressure, one for delivering the calibration bolus, and one for modifying the volume of the expandable member). The syringe pump used to apply negative pressure may be decoupled from the system and replaced with a different syringe pump that may be used to inject the calibration bolus and / or modify the volume of the expandable member. In variations in which a syringe pump is used to apply the negative pressure, the syringe pump may have a volume of about 1.0 ml to about 10 ml, including all values ​​and subranges therein. For example, the syringe pump may have a volume of about 1.0 ml, about 2.0 ml, about 3.0 ml, about 4.0 ml, about 5.0 ml, about 6.0 ml, about 7.0 ml, about 8.0 ml, about 9.0 ml, or about 10 ml. In one variation, the syringe pump has a volume of about 3.0 ml.

[0150] Additional configuration safeguards (e.g., second, third, and fourth calibration safeguards) may be included during the calibration process of the solid state sensor to prevent a user (e.g., surgeon, operator, etc.) from inadvertently progressing through the calibration steps. These calibration safeguards may be used to check the accuracy of the expandable member (e.g., balloon) pressure values ​​at different stages of the calibration process and may prevent moving to subsequent stages when predefined pressure values ​​are not met. In this case, the user (e.g., surgeon, operator, etc.) may be prompted by the system to perform the required action. Additional calibration safeguards may include application of a vacuum to the expandable member prior to measuring the intrinsic sensor offset, checking that the expandable member volume is zero (e.g., by checking that the pressure within the expandable member is less than about 5-10 mmHg), and that the values ​​at the proximal and distal solid state sensors are not affected by any expandable member fluid. Other calibration safeguards may also be included in the process prior to measuring the tip sensor offset. For example, the system may include a calibration safeguard that checks whether the expandable member pressure is at or above a threshold value, e.g., a non-negative value (zero or positive value), before measuring the tip sensor offset. This may help ensure that there is enough fluid within the expandable / extension member to transmit the physiological pressure to the expandable member sensor.

[0151] 6, an exemplary calibration process after placement of an elongate member including an expandable member in a body cavity (e.g., a blood vessel) is illustrated. After the elongate member (e.g., a catheter) is placed in step 500, a vacuum may be applied as a calibration safeguard in step 502 (vacuum protection) to ensure that the expandable member pressure is at or below zero. If insufficient vacuum is present, the user may be prompted by the system to repeat vacuum application 502 until the expandable pressure measures zero or below zero. The inherent offset between the solid sensors (e.g., proximal and distal solid sensors) may then be measured in step 504, and a calibration bolus may be injected in step 506. Prior to measuring the tip sensor offset in step 510, another calibration safeguard 508, post-inflation protection (post-inflation protection), may be included to ensure that the expandable member pressure is non-negative (e.g., zero or positive). The post-inflation safeguard may act as a check to ensure that there is enough fluid in the expandable / extension member to transmit physiological pressure to the expandable member sensor. If the expandable member pressure is found to be insufficient (e.g., negative), the user may be prompted by the system to repeat the injection 506 of the calibration bolus until the expandable member pressure is non-negative. After all calibration safeguards have been met, the system may then proceed to calibrate the solid state sensor in step 512 using the calculated intrinsic and tip sensor offsets.

[0152] Although the elongated body is described herein as including an expandable member, it should be readily understood that the elongated body need not include an expandable member. In variations in which an expandable member is not used, the sensor of the first sensor type providing sensor data that can be used to calibrate the solid-state sensor may be a fluid column-based pressure sensor integrated into the elongated body without an expandable member. For example, the fluid column may terminate at a point along the elongated body, such as, for example, near the distal end of the elongated body. The elongated body may include a non-expandable window (e.g., a hole) that is fluidly coupled to the fluid column. The window may be comprised of a thin film such that pressure surrounding and / or outside the non-expandable window can be transmitted to the fluid-based pressure sensor via the fluid column without the use of an expandable member. To calibrate the solid-state sensor, the fluid column may be filled with a calibration bolus. The pressure around the elongated body may be transmitted via the fluid column, and sensor readings from the fluid-column-based pressure sensor may be used to adjust sensor readings from the solid-state pressure sensor, thereby calibrating the solid-state sensor based on sensor data from the fluid-column-based sensor.

[0153] Although the first sensor may be any type of sensor suitable for use in calibrating a solid-state sensor, utilizing an expandable member sensor as described herein to calibrate a solid-state sensor has many advantages, especially in variations in which an expandable member is required for blood flow control during patient treatment. For example, with respect to a blood flow control device, utilizing an expandable member sensor, which may already be incorporated into a device for use during patient treatment, to calibrate a solid-state sensor allows the size of the device to remain unchanged, simplifying device construction and use, since no additional components (e.g., sensors, fluid columns, etc.) are required. In other words, utilizing an expandable member sensor to calibrate a solid-state sensor eliminates the need for additional components used only for calibration. Instead, the expandable member sensor is used both to help control blood flow and to calibrate the solid-state sensor, thus eliminating the need for calibration-specific components that may make the device larger and / or more difficult to make and / or use.

[0154] After the solid-state sensors are calibrated, the devices, systems, and methods described herein may be used to control blood flow at various locations within the body using sensor data from the calibrated solid-state sensors. Each calibrated solid-state sensor may measure patient physiological information, such as physiological information indicative of blood pressure or blood flow through a blood vessel (e.g., the aorta), to determine the patient's underlying physiological function. In some variations, the sensor data from the calibrated sensors is used to control blood flow within the patient. For example, the calibrated sensor data may be used to determine the size of the expandable member (e.g., to determine the amount of fluid and / or compressed gas to be injected into or removed from the expandable member) to adjust the size of the expandable member and thereby affect blood flow.

[0155] Although described above with respect to use in the aorta, it should be readily understood that the devices, systems, and methods described herein may be used in various vascular procedures, such as interventions on arteries, such as coronary or cerebral arteries (e.g., thrombectomy procedures for stroke patients, etc.). In some variations, the devices, systems, and methods may be used to control blood flow to treat patients suffering from shock, such as neurogenic, hemorrhagic, hypovolemic, and / or septic shock. For example, the devices, systems, and methods may utilize an expandable member to partially occlude a patient's blood vessel, which may allow continued perfusion distal to the expandable member while providing blood pressure support to the vascular bed above the expandable member. Thus, the devices, systems, and methods described herein may reduce ischemic injury to distal tissues by providing a further physiological increase in proximal blood pressure while also allowing continued perfusion distal to the expandable member. EXAMPLES

[0156] The following examples are illustrative only and are not to be construed as limiting the present disclosure in any way. EXAMPLES

[0157] Solid-state sensor calibration Data was captured during animal studies (pigs) using a catheter incorporating a balloon sensor and solid-state pressure sensors both proximal and distal to the balloon. External reference sensors were also placed inside the animal matching the locations of the proximal and distal solid-state sensors on the catheter (when the catheter was inserted into the animal) and their data recorded using an external data acquisition system (PowerLab). Data measured by the catheter was synchronized in real time with the external sensor data.

[0158] In this experiment, the volume of the calibration bolus was a non-perturbing volume of 2.0 ml. Referring to FIG. 7, at 600 (at about 60 minutes), a solid-state sensor was inserted into the pig's aorta to transition from air to blood. An increase in the pressure values ​​from the solid-state sensor (Proximal_Average_Catheter and Distal_Average_Catheter) indicated this transition. The pressure from the external reference sensor (Proximal_Average_External_Reference_Sensor and Distal_Average_External_Reference_Sensor) was measured to be about 60 mmHg. At 602 (at about 135 minutes), a calibration bolus was added. The volume of the calibration bolus was sufficient to overcome the partial vacuum in the balloon. Thus, the pressure value from the balloon sensor (Balloon_Average_Catheter) moved from a negative value (-100 mmHg) to about 60 mmHg, which matched the external reference sensor. Then, at 604, the solid state sensor was calibrated to remove uncalibrated sensor error 606 based on the sensor data from the balloon sensor such that the sensor values ​​from both solid state sensors matched the sensor values ​​from the balloon sensor.

[0159] The foregoing description, for purposes of explanation, used specific names to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required to practice the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously, many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to explain the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention and its various embodiments with various modifications as suited to the particular use envisioned. It is intended that the following claims and their equivalents define the scope of the invention.

Claims

1. 1. A method for calibrating at least one solid state sensor coupled to an elongated body comprising an expandable member, the method comprising: injecting a fluid calibration bolus into the expandable member; acquiring, using a controller, first sensor data from an expandable member sensor, the first sensor data representing a pressure within the expandable member; acquiring second sensor data from the at least one solid-state sensor using the controller; adjusting the second sensor data based on the first sensor data; A method comprising:

2. The method of claim 1 , wherein the pressure within the expandable member is indicative of pressure at a target location.

3. The method of claim 1 , wherein the controller comprises the expandable member sensor.

4. 1. A system for measuring a physiological condition in a patient, comprising: an elongate body comprising an expandable member and a solid state sensor; a syringe pump in fluid communication with the expandable member; a controller comprising an expandable member sensor in fluid communication with the expandable member, the controller communicatively coupled to the at least one solid-state sensor; acquiring first sensor data from the expandable member sensor representative of a pressure at a target location within the patient; acquiring second sensor data from the solid-state sensor; adjusting the second sensor data based at least in part on the first sensor data; a controller configured to: A system comprising:

5. The system of claim 4 , wherein the controller further comprises a housing comprising a recessed portion configured to receive the syringe pump.

6. The system of claim 4 , wherein the controller is further configured to actuate the syringe pump to inject a calibration bolus into the expandable member.

7. The system of claim 4 , wherein the controller is further configured to adjust the second sensor data by shifting a calibration curve of the solid-state sensor.

8. The controller further comprises: determining a first average value of the first sensor data; determining a second average value of the second sensor data; adjusting the second average value based on the first average value; The system of claim 4 configured to:

9. 5. The system of claim 4, wherein the first sensor data includes a first waveform and the second sensor data includes a second waveform, and the controller is configured to adjust the second waveform based on the first waveform.

10. The system of claim 4 , wherein the second sensor data and the first sensor data comprise data from the solid-state sensor and data from the expandable member sensor, respectively, at a point in time.

11. 5. The system of claim 4, wherein the controller is further configured to determine whether a calibration bolus has been injected into the expandable member based at least in part on at least one of the second sensor data and the first sensor data.

12. The system of claim 11 , wherein the volume of the calibration bolus is based at least in part on the length of the elongated body.

13. The system of claim 11 , wherein the volume of the calibration bolus is based at least in part on the distance between the syringe pump and the expandable member.

14. The system of claim 11 , wherein the elongated body includes a lumen connecting the syringe pump to the expandable member, and the volume of the calibration bolus is based at least in part on a volume of the lumen.

15. The system of claim 11, wherein the calibration bolus has a volume of about 1 ml to about 1.5 ml.

16. The system of claim 11 , wherein the volume of the calibration bolus is less than 5% of the volume of the expandable member.

17. The system of claim 11 , wherein the calibration bolus does not expand the expandable member.

18. 5. The system of claim 4, wherein the controller is configured to determine that the expandable member is positioned within a blood vessel based on the second sensor data, the second sensor data including a pressure waveform obtained from the solid-state sensor.

19. 20. The system of claim 18, wherein the pressure waveform represents arterial or venous pressure.

20. The system of claim 4 , wherein the controller comprises at least one user control for indicating that the expandable member is positioned within the patient's blood vessel.

21. The system of claim 4 , wherein the controller is configured to determine an initial setting point for the expandable member.

22. The system further includes a barometric pressure sensor, and the controller further includes: receiving air pressure from the air pressure sensor; determining the initial setting point based at least in part on the barometric pressure; 22. The system of claim 21 configured to:

23. The system of claim 4 , wherein the elongate body is configured to be advanced into a blood vessel.

24. The system of claim 4 , wherein the controller is configured to acquire the first sensor data after a calibration bolus is injected into the expandable member.

25. The system of claim 4 , wherein the controller is further configured to implement one or more calibration security measures.

26. 1. A method for calibrating a first solid-state sensor and a second solid-state sensor coupled to an elongated body comprising an expandable member, the method comprising: acquiring, using a controller, first sensor data from the first solid-state sensor, the first solid-state sensor being positioned distal to the expandable member; and acquiring second sensor data from the second solid-state sensor using the controller, the second solid-state sensor being positioned proximal to the expandable member; and determining a specific offset between the first solid state sensor and the second solid state sensor using the controller; injecting a calibration bolus into the expandable member; acquiring, using the controller, third sensor data from an expandable member sensor, the third sensor data representing a pressure at the target location; and adjusting the first sensor data based on the third sensor data; after adjusting the first sensor data, adjusting the second sensor data based on the first sensor data and the inherent offset; A method comprising:

27. A system for calibrating a solid state sensor, comprising: a first solid-state sensor and a second solid-state sensor coupled to an elongated body comprising an expandable member, the first solid-state sensor being positioned distal to the expandable member and the second solid-state sensor being positioned proximal to the expandable member; a controller comprising an expandable member sensor in fluid communication with the expandable member, the controller communicatively coupled to the first solid-state sensor and the second solid-state sensor, the controller comprising: acquiring first sensor data from the first solid-state sensor; acquiring second sensor data from the second solid-state sensor; determining a specific offset between the first solid state sensor and the second solid state sensor; determining whether a calibration bolus has been injected into the expandable member; acquiring third sensor data from an expandable member sensor after determining that the calibration bolus has been injected, the third sensor data representing a pressure at a target location; and determining a difference between the first sensor data and the third sensor data to determine a proximal offset; determining a difference between the proximal offset and the intrinsic offset to determine a distal offset; adjusting a first calibration curve for the first solid-state sensor based on the proximal offset; adjusting a second calibration curve for the second solid-state sensor based on the distal offset; and a controller configured to: A system comprising:

28. A system for calibrating a solid state sensor, comprising: a first solid-state sensor and a second solid-state sensor coupled to an elongated body, the elongated body comprising an expandable member, the first solid-state sensor positioned distal to the expandable member and the second solid-state sensor positioned proximal to the expandable member; a controller comprising an expandable member sensor in fluid communication with the expandable member, the controller communicatively coupled to the first solid-state sensor and the second solid-state sensor, the controller comprising: applying a first calibrated security measure to the system; acquiring first sensor data from the first solid-state sensor; acquiring second sensor data from the second solid-state sensor; determining a specific offset between the first solid state sensor and the second solid state sensor; determining whether a calibration bolus has been injected into the expandable member; applying a second calibration safeguard to the system after determining that the calibration bolus has been injected; acquiring third sensor data from an expandable member sensor, the third sensor data representing a pressure at the target location; and obtaining a tip sensor offset using the third sensor data and data from the first solid-state sensor; and adjusting the first sensor data and the second sensor data based on the leading edge sensor offset and the inherent offset; a controller configured to: A system comprising:

29. The system described in claim 23, wherein the blood vessel is an aorta or a vein.

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