Search

EP-3852833-B1 - USE OF OPTICAL FIBER SENSOR AS A DIAGNOSTIC TOOL IN CATHETER-BASED MEDICAL DEVICES

EP3852833B1EP 3852833 B1EP3852833 B1EP 3852833B1EP-3852833-B1

Inventors

  • GANDHI, Rahul, Suresh
  • ZHANG, TAO

Dates

Publication Date
20260506
Application Date
20190920

Claims (15)

  1. A blood pump system, the system comprising: a catheter (10) having proximal and distal ends; a blood pump (50) having a motor (51) coupled to the catheter (10), wherein the motor (51) has a motor current; an optical fiber sensor (30, 60) configured to detect an optical signal during pumping operation of the blood pump (50); an optical fiber (28, 29) configured to transmit the optical signal from the optical fiber sensor (30, 60) to an evaluation device (100) communicatively coupled to the optical fiber sensor (30, 60), characterized in that the evaluation device (100) is configured to: receive as inputs the transmitted optical signal and a signal indicative of the motor current, calculate a signal to noise ratio (SNR) of the optical signal, receive a predetermined threshold for SNR, compare the calculated SNR to the predetermined threshold, and determine a mechanical failure event associated with the blood pump; and wherein the mechanical failure event associated with the blood pump (50) is determined by the evaluation device (100) to have occurred when, over a time period: (1) the motor current is greater than zero, and (2) an increase in the calculated SNR in the time period exceeds the predetermined threshold.
  2. The blood pump system of claim 1, wherein the evaluation device (100) is configured to at least one of the following: (1) generate and output, in response to determining the mechanical failure event, an indicator associated with the mechanical failure event, and (2) determine the threshold based on a baseline SNR, wherein the determined threshold is preferably double a magnitude of the baseline SNR.
  3. The blood pump system of claim 1 or 2, wherein the evaluation device (100) is configured to determine a pressure signal based on the transmitted optical signal, wherein the evaluation device (100) is preferably configured to determine the mechanical failure event based on the calculated SNR, the motor current, and the determined pressure signal.
  4. The blood pump system of any one of the preceding claims, wherein the optical fiber sensor (30, 60) is coupled to the pump housing and/or is located at the distal end of the catheter (10).
  5. The blood pump system of any one of the preceding claims, wherein the time period is between about 1 to about 5 minutes or between about 5 to about 10 minutes.
  6. The blood pump system of any one of the preceding claims further comprising: a second optical fiber sensor configured to detect a second optical signal; and a second optical fiber configured to transmit the second optical signal from the second optical fiber sensor to the evaluation device (100) communicatively coupled to the second optical fiber sensor.
  7. The blood pump system of any one of the preceding claims, wherein based on the calculated SNR the evaluation device (100) is configured to detect vibrations in any one of the pump (50), motor (51), and a cannula (10) of the pump (50).
  8. A method of determining a mechanical failure event of a blood pump (50), the method comprising: determining a motor current of a motor that is coupled to a catheter and drives the blood pump (50); detecting an optical signal at the blood pump (50); transmitting the optical signal, using an optical fiber (28, 29), from the optical fiber sensor (30, 60) to an evaluation device (100); calculating, at the evaluation device (100), a signal to noise ratio (SNR) based on the transmitted optical signal; and determining a mechanical failure event associated with the blood pump (50) based on the calculated SNR and the determined motor current, wherein the mechanical failure event associated with the blood pump (50) is determined by the evaluation device (100) to have occurred when, over a time period: (1) the motor current is greater than zero and (2) an increase in the calculated SNR in the time period exceeds a predetermined threshold.
  9. The method of claim 8, wherein in response to determining the mechanical failure event, generating and outputting an indicator associated with the mechanical failure event.
  10. The method of claim 8, further comprising determining the threshold based on a baseline SNR, wherein the determined threshold is preferably double a magnitude of the baseline SNR.
  11. The method of any one of claims 8 to 10, further comprising determining a pressure signal based on the transmitted optical signal, preferably further comprising determining the mechanical failure event based on the calculated SNR, the determined motor current, and the determined pressure signal.
  12. The method of any one of claims 8 to 11, wherein the optical fiber sensor (30, 60) is coupled to the motor (51).
  13. The method of any one of claims 8 to 12, wherein the optical fiber sensor (30, 60) is located at the distal end of the catheter (10).
  14. The method of any one of claims 8 to 13, wherein the time period is between about 1 to about 5 minutes.
  15. The method of any one of claims 8 to 13, wherein the time period is between about 5 to about 10 minutes.

Description

Related Applications This application claims the benefit of priority to U.S. Provisional Application No. 62/734,702, filed September 21, 2018, and entitled "USE OF OPTICAL FIBER SENSOR AS A DIAGNOSTIC TOOL IN CATHETER-BASED MEDICAL DEVICE". Background Catheter-based medical devices can be monitored to ensure that the device is operating normally. For example, early and reliable detection of a bearing failure in a blood pump can help prevent any sudden stop of the pump and the associated adverse effects to the patients. Some blood pumps use the motor current as a sensing signal to monitor pump performance. But motor current does not always capture the early signs of bearing failure and can be affected by other factors. Blood pumps can be integrated with a fiber optic pressure sensor to monitor the placement of the pump in the vasculature of a patient. In addition to monitoring the pressure signal, the fiber optic sensor can be used to monitoring stress/strain, temperature, and vibration. For example, as described in U.S. Patent No. 9,669,144, the fiber optic sensor can be used to monitor kinks in the catheter. But optical fiber sensors have not been adopted to detect ongoing operational characteristics of catheter-based medical devices. US 2015/290372 A1 discloses sensors for catheter pumps, wherein the catheter pump can include a catheter assembly comprising a catheter and a cannula coupled to a distal portion of the catheter and the cannula can have a proximal port for permitting the flow of blood therethrough. The catheter assembly can include a sensor to be disposed near the proximal port. A processing unit can be programmed to process a signal detected by the sensor. The processing unit can comprise a computer-readable set of rules to evaluate the signal to determine a position of the cannula relative to an aortic valve of a patient. Summary According to the invention, a blood pump system comprising the features of claim 1 and a method comprising the steps of claim 8 are provided. The systems, methods, and devices described herein provide for using an optical fiber sensor as a diagnostic tool to evaluate the performance and status, and ultimately detect potential failure, of a catheter-based medical device. Adaptations of the systems may include an optical sensor and an optical fiber connecting the sensor to a monitor or other signal processing device configured to receive input signals from the sensor and determine characteristics of the medical device. According to the invention, the tool is used to detect a mechanical failure of a blood pump. Embodiments are disclosed for a blood pump system including an optical sensor configured to detect an optical signal during pumping operation of the blood pump, and an optical fiber configured to transmit the optical signal from the optical fiber sensor to an evaluation device communicatively coupled to the optical fiber sensor. The sensor is positioned near the pump so as to detect perturbations in the blood caused by pumping action of the pump and which changes or deforms the optical sensor head. The sensor head deforms based on the pressure of the blood pressing against the sensor head. When the sensor head is deformed, light bounces around into the sensor fiber and is picked up by the evaluation device. This reflected light is compared to a reference or baseline signal and a pressure signal is extracted from the comparison. Using the reflected light, the sensor can also detect perturbations in the blood caused by vibrations in the pump housing, the rotor, the motor, or the cannula that is included in the pump system. In some adaptations, the sensor is attached to the pump housing or placed adjacent to the pump housing, or placed near the pump motor (in the case of an implanted motor). The evaluation device is configured to receive as inputs the transmitted optical signal and a signal indicative of pump motor current and determine a mechanical failure event associated with the pump based on the motor current and the optical signal. The tool may be used in combination with one or more other parameters, for example other sensor readings such as placement signal and flowrate, for enhanced detection. In a first implementation, the tool is implemented in a blood pump system including a catheter having proximal and distal ends, a blood pump having a motor coupled to the catheter, an optical sensor configured to detect an optical signal during pumping operation of the blood pump, and an optical fiber extending through the catheter and configured to transmit the optical signal from the optical sensor to an evaluation device communicatively coupled to the optical sensor. The optical sensor is positioned at or near the pump so as to detect perturbations in the blood resulting from the pumping action of the pump. The evaluation device is configured to receive the input signal and determine whether a mechanical failure event associated with the blood pump has occurred. T