Implantable fluid pressure and flow sensor with drift compensation and methods of using the same
AssigneeShuntAware Technologies, Inc.
InventorsSteven Charles CICCARELLI, Gabriel Michel REBEIZ, Christopher Steven CICCARELLI, Terry DAGLOW
Life of this patent
Estimating the term…
Abstract
Described are systems, methods, and media for monitoring intracranial pressure (ICP) in a subject.
Claims113
An implantable system for monitoring intracranial pressure (ICP) in a subject, the system comprising:
- (a) a conduit for the flow of cerebrospinal fluid (CSF);
- (b) a hermetically sealed compartment;
- (c) a first pressure sensor configured to measure an absolute ICP and output a measurement, wherein the first pressure sensor is hermetically sealed in the compartment, and wherein the first pressure sensor comprises a surface exposed to the CSF in the conduit;
- (d) a microcontroller disposed in the hermetically sealed compartment that receives multiple inputs including at least the output of the first pressure sensor;
- and
- (e) an accelerometer disposed in the hermetically sealed compartment for monitoring a subject's positional status, and wherein the accelerometer communicates an output to the microcontroller.
An implantable system for monitoring intracranial pressure (ICP) in a subject, the system comprising:
- (a) a conduit for the flow of cerebrospinal fluid (CSF);
- (b) a hermetically sealed compartment;
- (c) a flow rate sensor disposed in the hermetically sealed compartment, mounted to an outer surface of the CSF conduit such that the sensor is hermetically isolated from the CSF, and wherein the flow rate sensor outputs a measurement;
- and
- (d) a microcontroller disposed in the hermetically sealed compartment that receives a plurality of inputs including at least the output of the flow rate sensor;
- and
- (e) an accelerometer disposed in the hermetically sealed compartment for monitoring a subject's positional status and to communicate an output to the microcontroller.
The implantable system of any one of the preceding claims, wherein the hermetically sealed compartment comprises a wireless charging circuit configured to be charged by an external charger.
The implantable system of any one of the preceding claims, wherein the implantable system and a ventriculoperitoneal (VP) shunt valve are integrated.
The implantable system of any one of the preceding claims, wherein the implantable system is proximal and connected to a VP shunt valve.
The implantable system of any one of the preceding claims, wherein electronic components of the implantable system are mounted on a printed circuit board (PCB) within the hermetically sealed compartment.
The implantable system of any one of the preceding claims, wherein the absolute ICP is the sum of ICP and atmospheric pressure.
The implantable system of any one of the preceding claims, further comprising a circuit configured to measure a common mode output voltage of the first pressure sensor, wherein the common mode output voltage is used to measure the subject's body temperature, and wherein the common mode output voltage is linearly and precisely related to temperature:
- T=aV+b, wherein a and b are constants.
The implantable system of any one of the preceding claims, wherein a drift in pressure measurement of the first pressure sensor caused by temperature is corrected from the temperature measurement obtained from the common mode voltage of the first pressure sensor.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to:
- (a) prior to pressure measurements, turn on a switch to sample a common mode output voltage from the first pressure sensor;
- (b) store the common mode output voltage;
- and
- (c) turn off the switch to output differential pressure measurements.
The implantable system of any one of the preceding claims, wherein the ICP=m*V_diff+b+TC*delta_Temp;
- TC=temp coeff, where m is a first constant, V_diff is the differential output of the first pressure sensor, b is a second constant, TC is a temperature coefficient, and delta_Temp is a change in temperature.
The implantable system of any one of the preceding claims, wherein the wireless charging circuit uses near field communication (NFC).
The implantable system of any one of the preceding claims, wherein the hermetically sealed compartment further comprises a wireless modem configured to receive and transmit data between the microcontroller and an external device.
The implantable system of any one of the preceding claims, wherein the hermetically sealed compartment further comprises an antenna for receiving and transmitting wireless signals residing within the hermetically sealed compartment.
The implantable system of any one of the preceding claims, wherein the drift in pressure measurement of the first pressure sensor is configured to be corrected by:
- (a) storing an initial pressure of the air enclosed within the hermetically sealed compartment during assembly in non-volatile memory in the microcontroller;
- (b) measuring a second pressure of the air in the hermetically sealed compartment using a second pressure sensor that comprises a membrane or surface exposed to the air within the compartment and not in contact with the CSF, wherein the second pressure sensor is configured to measure an atmospheric pressure within the compartment and output a second measurement;
- (c) calculating a difference between the initial pressure and the second measurement to determine a sensor drift;
- and
- (d) calculating a drift-corrected absolute ICP based at least in part on a difference between a first measurement ICP and the sensor drift, wherein the first measurement ICP is produced by the first pressure sensor.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to receive the atmospheric pressure from an external device.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to compute the ICP based at least in part on a difference between the absolute ICP and the atmospheric pressure.
The implantable system of any one of the preceding claims, wherein the microcontroller is configured to compute the ICP based at least in part on a difference between the drift-corrected absolute ICP and the atmospheric pressure.
The implantable system of any one of the preceding claims, wherein the external device comprises a smartphone or a tablet computer, wherein the microcontroller is further configured to transmit a plurality of measurements output by an analog-to-digital converter (ADC) to the external device, and wherein the ICP is calculated by an internal processor digital signal processor (DSP) in the external device.
The implantable system of any one of the preceding claims, wherein a subject status includes a message to be displayed on a graphical user interface of the external device including a diagnostic summary of ICP health, flow rate health, or recommendation for adjustment to flow resistance of the VP shunt valve, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to send a message to the external device for display on the graphical user interface.
The implantable system of any one of the preceding claims, wherein the external device is connected to a cloud network.
The implantable system of any one of the preceding claims, wherein the CSF flowing out of the conduit is directly input to a VP shunt.
The implantable system of any one of the preceding claims, wherein a subject positional status includes at least:
- sitting, standing, or laying down.
The implantable system of any one of the preceding claims, wherein the microcontroller is configured to exclude pressure measurements if the accelerometer indicates subject movement during the measurement, wherein data is excluded upon detection of motion, and wherein data will begin to be captured again if two conditions are met:
- (a) a programmable timer expires, and
- (b) no motion of the subject is detected.
The implantable system of any one of the preceding claims, wherein the threshold for motion detection is increased to allow for light activity.
The implantable system of any one of the preceding claims, wherein a lowpass filter time constant is applied to the ICP waveform to reduce variation resulting from a motion detection threshold.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to transmit a change in subject position to the external device if the accelerometer detects a change in the subject positional status from laying to sitting, or from sitting to laying, sitting to standing, laying to standing, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the implantable system further comprises a motor.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to control the motor to adjust the flow resistance of the VP shunt valve by one or more increments.
The implantable system of any one of the preceding claims, wherein the microcontroller is further configured to compensate for increase in CSF flow upon standing or decrease in CSF flow upon laying down, based on input from the accelerometer, by commanding a motor to adjust the flow resistance of the VP shunt valve by one or more increments.
The implantable system of any one of the preceding claims, further comprising a valve, wherein the valve comprises one or more of a ball-spring valve, a floating ball valve, a trunnion mounted ball valve, a top entry ball valve, a side entry ball valve, a three-way ball valve, a ball check valve, a flapper check valve, a disc check valve, a ball relief valve, a spring safety valve, or a spring-loaded pressure relief valve.
The implantable system of any one of the preceding claims, wherein the implantable system further comprises the controller and a shunt wireless communication device.
The implantable system of any one of the preceding claims, wherein the valve, the flow rate sensor, the first pressure sensor, the shunt wireless communication device, the controller, or any combination thereof is magnetic or non-magnetic.
The implantable system of any one of the preceding claims, wherein an opening pressure threshold of the valve is manually adjustable.
The implantable system of any one of the preceding claims, wherein the opening pressure threshold of the valve is manually adjustable by an external magnetic device.
The implantable system of any one of the preceding claims, further comprising a motor configured to adjust an opening pressure threshold of the valve.
The implantable system of any one of the preceding claims, wherein the controller is further configured to direct the motor to adjust the opening pressure threshold.
The implantable system of any one of the preceding claims, wherein the shunt wireless communication device is further configured to receive a target opening pressure threshold, and wherein the controller is further configured to control the motor based at least in part on the target opening pressure threshold.
The implantable system of any one of the preceding claims, wherein a sensor circuit detects a motor position and the controller configures the modem to transmit this position to an external wand device.
The implantable system of any one of the preceding claims, wherein the controller is further configured to adjust the opening pressure threshold of the valve based at least in part on the ICP, the first measurement, the second measurement, a third measurement, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the controller is further configured to receive a motor position from a position sensor, and wherein the shunt wireless communication device is further configured to transmit an opening pressure threshold confirmation based on the motor position.
The implantable system of any one of the preceding claims, further comprising a memory configured to store the first measurement, second measurement, ICP, sensor drift, target ICP, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the memory comprises a non-volatile memory.
The implantable system of any one of the preceding claims, wherein the controller is further configured to adjust the opening pressure threshold of the valve based on one or more of a machine learning model, artificial intelligence, and signal processing techniques.
The implantable system of any one of the preceding claims, wherein the machine learning model is configured to determine the opening pressure threshold of the valve based on the ICP, the first measurement, the second measurement, the third measurement, the CSF flow rate, or any combination thereof, and wherein the controller is configured to adjust the opening pressure threshold of the valve.
The implantable system of any one of the preceding claims, wherein the status comprises one or more of a sleeping status, an awake status, an exercising status, a standing status, a sitting status, a laying status, and a circadian status.
The implantable system of any one of the preceding claims, wherein an algorithm is trained on a history of ICP waveforms, flow rate waveforms, or a combination thereof, and used to determine the status of the subject, wherein Fourier analysis or other signal processing techniques are applied to the ICP waveforms or flow rate waveforms, or both, to generate training data for the algorithm.
The implantable system of any one of the preceding claims, wherein the controller is configured to determine a rate of number of times the valve opens per unit of time, and wherein the rate is outputted, used to train the algorithm, or a combination thereof.
The implantable system of any one of the preceding claims, wherein the first pressure sensor comprises:
- (a) a capacitive sensor;
- (b) a piezoelectric sensor;
- (c) a piezoresistive sensor;
- (d) a magnetic sensor;
- (e) a resonant sensor;
- (f) an optical sensor;
- (g) a MEMS sensor;
- or
- (h) any combination thereof.
The implantable system of any one of the preceding claims, wherein the CSF flow rate sensor comprises:
- (a) a thermal sensor;
- (b) an optical sensor;
- (c) an electromagnetic sensor;
- (d) a Lorentz force velocity sensor;
- (e) an ultrasonic sensor;
- or
- (f) any combination thereof.
The implantable system of any one of the preceding claims, further comprising an energy storage device configured to power the first pressure sensor, the flow rate sensor, the controller, the accelerometer, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the wireless charging circuit is configured to receive power to charge the energy storage device, power the controller, or both.
The implantable system of any one of the preceding claims, wherein the energy storage device comprises a battery, a capacitor, a supercapacitor, or any combination thereof.
The implantable system of any one of the preceding claims, wherein the controller is further configured to adjust the opening pressure threshold to a base opening pressure threshold if a charge of the energy storage device falls below a preset charge threshold.
The implantable system of any one of the preceding claims, further comprising a digital modulator configured to modulate a signal from the controller, and wherein the controller and the shunt wireless communication device are communicably coupled by the digital modulator.
The implantable system of any one of the preceding claims, further comprising a first analog to digital (A/D) converter communicably coupling the first pressure sensor and the controller and configured to convert an analog signal from the first pressure sensor to a digital signal.
The implantable system of any one of the preceding claims, further comprising an A/D converter communicably coupling the flow rate sensor and the controller and configured to convert an analog signal from the flow rate sensor to a digital signal.
The implantable system of any one of the preceding claims, wherein the controller comprises a digital modulator, one or more A/D converters, or any combination thereof.
The implantable system of any one of the preceding claims, wherein a P1 component and a P2 component of an ICP waveform are compared to determine if the subject's ICP is healthy or elevated, wherein an increased amplitude of the P2 component relative to the P1 component indicate that a subject has an elevated ICP.
The implantable system of any one of the preceding claims, wherein an alert is sent to the external device when a ratio of the P2 component to the P1 component of the ICP waveform exceeds a threshold indicating that the subject has an elevated ICP.
The implantable system of any one of the preceding claims, wherein an alert is sent to the external device if a difference between the P2 component and the P1 component of the ICP waveform exceeds a threshold indicating that the subject has an elevated ICP.
A platform for monitoring intracranial pressure (ICP) of cerebrospinal fluid (CSF) in a subject, the platform comprising:
- (a) the implantable system of any of the preceding claims;
- and
- (b) a wand device comprising a wand wireless communication device configured to transmit the atmospheric pressure and receive the ICP from a shunt wireless communication device.
The platform of any one of the preceding claims, wherein the first measurement includes the absolute ICP, atmospheric pressure, and sensor drift, and wherein the second measurement includes an atmospheric pressure and sensor drift, wherein the difference between the first and second measurements is the drift corrected, absolute ICP.
The platform of any one of the preceding claims, wherein the implantable system further comprises a motor configured to adjust an opening pressure threshold of the valve, wherein the wand wireless communication device is further configured to transmit a target opening pressure threshold to the implantable system, and wherein the controller is further configured to receive the target opening pressure threshold and control the motor to adjust the opening pressure threshold of the valve based at least in part on the target opening pressure threshold.
The platform of any one of the preceding claims, wherein an accelerometer is configured to output subject position data to the microcontroller, wherein upon detecting a transition between positions, the controller can direct the motor to reduce CSF flow and in so doing, act as an electronically controlled anti-siphon device (ASD).
The platform of any one of the preceding claims, wherein the controller is further configured to adjust the opening pressure threshold of the valve based at least in part on the ICP, the first measurement, the second measurement, or any combination thereof.
The platform of any one of the preceding claims, wherein the controller is further configured to receive a motor position from a motor position sensor, and wherein the shunt wireless communication device is further configured to transmit an opening pressure threshold confirmation based on the motor position.
The platform of any one of the preceding claims, wherein the wand wireless communication device is further configured to receive the opening pressure threshold confirmation.
The platform of any one of the preceding claims, wherein the controller is further configured to adjust the opening pressure threshold of the valve based on one or more of a machine learning model, artificial intelligence, or a signal processing algorithm.
The platform of any one of the preceding claims, wherein a system algorithm is configured to determine a status of the subject based on the ICP, the first measurement, the second measurement, or any combination thereof, and wherein the controller is configured to adjust the opening pressure threshold of the valve based on the status.
The platform of any one of the preceding claims, wherein the status comprises one or more of a sleeping status, an awake status, an exercising status, a standing status, a sitting status, a laying status, and a circadian status.
The platform of any one of the preceding claims, wherein a system algorithm is trained on a history of ICP waveforms, flow rate waveforms, or a combination thereof, and used to determine the status of the subject, wherein Fourier analysis or other signal processing techniques are be applied to the ICP waveforms, flow rate waveforms, or a combination thereof, to generate the training data for an algorithm.
The platform of any one of the preceding claims, wherein the controller is configured to determine a valve opening rate, and wherein the valve opening rate is outputted, used to train an algorithm, or a combination thereof.
The platform of any one of the preceding claims, wherein the implantable system further comprises a memory configured to store the first measurement, the second measurement, absolute ICP, ICP, the target ICP, or both.
The platform of any one of the preceding claims, wherein access to implantable system data, including ICP, absolute ICP, and flow rate, is restricted by a security code.
The platform of any one of the preceding claims, wherein a status of the shunt and subject is reported via a software application residing on the wand device, wherein the status comprises information including:
- shunt health, mean CSF flow rate, mean ICP, or any combination thereof.
The platform of any one of the preceding claims, wherein the memory comprises a non-volatile memory.
The platform of any one of the preceding claims, wherein the valve comprises one or more of a ball-spring valve, a floating ball valve, a trunnion mounted ball valve, a top entry ball valve, a side entry ball valve, a three-way ball valve, a ball check valve, a flapper check valve, a disc check valve, a ball relief valve, a spring safety valve, and a spring-loaded pressure relief valve.
The platform of any one of the preceding claims, wherein the first pressure sensor comprises:
- (a) a capacitive sensor;
- (b) a piezoelectric sensor;
- (c) a piezoresistive sensor;
- (d) a magnetic sensor;
- (e) a resonant sensor;
- (f) an optical sensor;
- (g) a MEMS sensor;
- or
- (h) any combination thereof.
The platform of any one of the preceding claims, wherein the implantable system further comprises an energy storage device configured to power the valve, the first pressure sensor, the second pressure sensor, the controller, or any combination thereof.
The platform of any one of the preceding claims, further comprising a wireless charging circuit configured to receive power to charge the energy storage device, power the controller, or a combination thereof.
The platform of any one of the preceding claims, wherein the energy storage device comprises a battery, a capacitor, a supercapacitor, or any combination thereof.
The platform of any one of the preceding claims, wherein the controller of the implantable system is configured to adjust the opening pressure threshold to a base opening pressure threshold if a charge of the energy storage device falls below a preset charge threshold.
The platform of any one of the preceding claims, further comprising a digital modulator, and wherein the controller and the shunt wireless communication device are communicably coupled by the digital modulator.
The platform of any one of the preceding claims, further comprising a first analog to digital (A/D) converter communicably coupling the first pressure sensor and the controller.
The platform of any one of the preceding claims, further comprising a second A/D converter communicably coupling the second pressure sensor and the controller.
The platform of any one of the preceding claims, wherein the controller comprises a digital modulator, one or more A/D converters, or any combination thereof.
The platform of any one of the preceding claims, further comprising a third A/D converter communicably coupling the flow rate sensor and the controller.
The platform of any one of the preceding claims, wherein the wand wireless communication device is further configured to transmit a target opening pressure, wherein the shunt wireless communication device is further configured to receive the target opening pressure threshold, and wherein the controller is configured to direct the motor based on the target opening pressure threshold.
The platform of any one of the preceding claims, wherein:
- (a) the wand device further comprises a display configured to show data based on the first measurement, second measurement, the ICP, or both;
- (b) the wand device further comprises a speaker configured to emit a sound based on the ICP, CSF flow rate, or both;
- or
- (c) the wand wireless communication device is further configured to transmit the first measurement, second measurement, the third measurement, the ICP, CSF flow rate, or any combination thereof to a cloud storage.
The platform of any one of the preceding claims, wherein:
- (a) the wand device further comprises a display configured to show data based on the opening pressure threshold confirmation;
- (b) the wand device further comprises a speaker configured to emit a sound based on the opening pressure threshold confirmation;
- (c) the wand wireless communication device is further configured to transmit the opening pressure threshold confirmation to a cloud storage;
- or
- (d) any combination thereof.
The platform of any one of the preceding claims, wherein:
- (a) the wand device further comprises a display configured to show data based on the target opening pressure;
- (b) the wand wireless communication device is further configured to transmit the target opening pressure to a cloud storage;
- or
- (c) both.
The platform of any one of the preceding claims, wherein:
- (a) the wand device, typically a smartphone running an app, is capable of uploading patient data to a private or hybrid cloud accessible by the patients' doctors, and
- (b) applications in the cloud can store the patient data and further process the patient data for doctors to make informed clinical diagnoses, wherein these data comprise mean ICP, mean CSF flow rate, valve opening rate, AIr, signal processing information from a system algorithm, or a combination thereof.
A computer-implemented method for monitoring intracranial pressure (ICP) of cerebrospinal fluid (CSF) in a subject, the method comprising:
- (a) measuring, by an ICP sensor, an absolute ICP plus drift of the subject as a first measurement;
- (b) measuring, by a second sensor, an atmospheric pressure plus drift as a second measurement;
- (c) receiving the atmospheric pressure from an external source as the third measurement;
- (d) calculating an absolute ICP based at least in part on a difference between the first and second measurements;
- (e) calculating the ICP based at least in part on a difference between the absolute ICP and the third measurement;
- and
- (f) transmitting the ICP.
The computer-implemented method of any one of the preceding claims, wherein the first measurement includes the absolute ICP, atmospheric pressure, and sensor drift, and wherein the second measurement includes an atmospheric pressure and the sensor drift.
The computer-implemented method of any one of the preceding claims, wherein the third measurement is from a smartphone.
The computer-implemented method of any one of the preceding claims, further comprising adjusting an opening pressure of a valve.
The computer-implemented method of any one of the preceding claims, wherein the adjustment is performed manually.
The computer-implemented method of any one of the preceding claims, wherein the adjustment is performed by a magnetic device.
The computer-implemented method of any one of the preceding claims, wherein the adjustment is performed by a motor.
The computer-implemented method of any one of the preceding claims, further comprising receiving a target opening pressure threshold, wherein the adjustment is performed based on the target opening pressure threshold.
The computer-implemented method of any one of the preceding claims, further comprising storing the target opening pressure threshold to a memory.
The computer-implemented method of any one of the preceding claims, further comprising storing the ICP, the first measurement, the second measurement, the third measurement, or any combination thereof to a memory.
The computer-implemented method of any one of the preceding claims, wherein the adjustment is performed based at least in part on the ICP, the first measurement, the second measurement, the third measurement, or any combination thereof.
The computer-implemented method of any one of the preceding claims, wherein the adjustment is performed based on an algorithm comprising one or more of a machine learning model, artificial intelligence model, a signal processing algorithm, or any combination thereof.
The computer-implemented method of any one of the preceding claims, wherein the algorithm is configured to determine a status of the subject based on the ICP, the first measurement, the second measurement, the third measurement, or any combination thereof.
The computer-implemented method of any one of the preceding claims, wherein the status of the subject comprises one or more of a sleeping status, an awake status, an exercising status, a standing status, a sitting status, a laying status, and a circadian status.
The computer-implemented method of any one of the preceding claims, wherein a system algorithm is trained on a history of ICP waveforms and used to determine the status of the subject, wherein Fourier analysis or other signal processing techniques are applied on the ICP waveforms to generate the training data for an algorithm.
The computer-implemented method of any one of the preceding claims, wherein the controller is configured to determine a rate of number of times the valve opens per unit of time, and wherein the rate is outputted, used to train an algorithm, or a combination thereof.
The computer-implemented method of any one of the preceding claims, further comprising adjusting the opening pressure threshold to a base opening pressure threshold if a charge of the energy storage device falls below a preset charge threshold.
Non-transitory computer-readable media comprising executable instructions that, when executed, cause at least one computer processor to perform the methods of any one of the preceding claims.
A computer system comprising a memory storing computer-readable instructions and at least one processor configured to execute the computer-readable instructions that are configured to perform the method of any of the preceding claims.
Dependencies are inferred from the claim text.