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JP-7857298-B2 - Model-based techniques for detecting lung fluid state

JP7857298B2JP 7857298 B2JP7857298 B2JP 7857298B2JP-7857298-B2

Inventors

  • ジュヒョン・ソ
  • トニー・ジェイ・アクル

Assignees

  • アナログ ディヴァイスィズ インク

Dates

Publication Date
20260512
Application Date
20211206
Priority Date
20201211

Claims (20)

  1. A method for detecting the pulmonary fluid state of a human subject, wherein the pulmonary fluid state is represented by the pulmonary resistivity, and the method is Performing multiple impedance measurements on a region of interest using a measurement module connected to multiple electrodes to acquire measurement impedance data , wherein the multiple electrodes are configured to be in contact with the skin of the chest of the human subject . The processor connected to the measurement module compares the measured impedance data with simulated impedance data obtained from a plurality of models of the region of interest, each of which represents a different possible combination of electrode arrangement and specific anatomical features of the human subject, wherein the specific anatomical features include at least one of the relative size or location of lung tissue, cardiac tissue, soft tissue, and bone . For each of the aforementioned multiple models, the processor determines the degree of fit of the model based on a comparison between the simulated impedance data obtained from the model and the measured impedance data. The processor determines a better-fitting model and a worse-fitting model based on the model's suitability. A method comprising the processor integrating individual resistivity estimates obtained from the plurality of models such that the individual resistivity estimates from the better-fitting model are weighted more heavily in the final resistivity estimate than the individual resistivity estimates from the worse- fitting model .
  2. The method according to claim 1, wherein performing multiple impedance measurements includes performing multiple four-wire impedance measurements.
  3. The method according to claim 2, wherein up to eight electrodes are used to perform the multiple four-wire impedance measurements.
  4. The method according to any one of claims 1 to 3, wherein the final resistivity estimate is a weighted average of the individual resistivity estimates.
  5. The method according to claim 4, wherein the weights assigned to a particular model among the plurality of models are defined by the inverse value of the residual cost function value of the optimization for solving the inverse problem, and the residual cost function value corresponds to the particular model.
  6. The method according to any one of claims 1 to 3, further comprising constructing a single sample model using a weighted sum of the plurality of models based on the fitness of each of the aforementioned models.
  7. The method according to any one of claims 1 to 3, wherein the plurality of impedance measurements are performed at a single excitation frequency.
  8. The method according to any one of claims 1 to 3, wherein the plurality of impedance measurements are performed at a plurality of excitation frequencies.
  9. The method according to claim 8 , further comprising performing the comparison, determination, and integration for each of the excitation frequencies.
  10. A system for detecting the pulmonary fluid state of a human subject, wherein the pulmonary fluid state is represented by the pulmonary resistivity, and the system is Multiple electrodes on the chest of the aforementioned human subject, A chest impedance measurement module connected to the plurality of electrodes, wherein the chest impedance measurement module is configured to perform a plurality of impedance measurements on a region of interest in order to acquire measured impedance data , Connected to the aforementioned chest impedance measurement module, The measured impedance data is compared with simulated impedance data obtained from multiple models of the region of interest, each of which represents different possible combinations of electrode arrangement and specific anatomical features of the human subject, wherein the specific anatomical features include at least one of the relative size or location of lung tissue, cardiac tissue, soft tissue, and bone. For each of the aforementioned multiple models, the degree of fit of the model is determined based on a comparison between the simulated impedance data obtained from the model and the measured impedance data . Based on the degree of suitability of the aforementioned model, a better-suited model and a worse-suited model are determined, and A system comprising: a processor configured to integrate individual resistivity estimates obtained from a plurality of models such that individual resistivity estimates from the better-fitting model are weighted more heavily than individual resistivity estimates from the worse-fitting model in the final resistivity estimate .
  11. The system according to claim 10 , wherein performing multiple impedance measurements includes performing multiple four-wire impedance measurements.
  12. The system according to claim 10 or 11 , wherein the electrode is connected to an elastic chest strap for attachment around the chest of the human subject to ensure the correct position of the electrode relative to the region of interest.
  13. The system according to claim 10 or 11 , wherein the final resistivity estimate is a weighted average of the individual resistivity estimates.
  14. The system according to claim 13, wherein the weights assigned to a particular model among the plurality of models are defined by the inverse value of the residual cost function value of the optimization for solving the inverse problem, and the residual cost function value corresponds to the particular model.
  15. The system according to claim 10 or 11, wherein the chest impedance measurement module is further configured to construct a single sample model using a weighted sum of the plurality of models based on the fit of each of the models.
  16. The system according to claim 10 or 11 , wherein the plurality of electrodes include fewer than eight electrodes.
  17. The system according to claim 10 or 11 , wherein the plurality of electrodes further comprises three electrodes on the front of the chest and three of the electrodes on the left side of the chest.
  18. The system according to claim 10 or 11 , wherein the plurality of impedance measurements are performed at a single excitation frequency.
  19. The system according to claim 10 or 11 , wherein the plurality of impedance measurements are performed at a plurality of excitation frequencies.
  20. The system according to claim 19 , wherein the chest impedance measurement module is further configured to perform the comparison, determination, and integration for each of the excitation frequencies.

Description

This related application disclosure claims priority to U.S. Provisional Patent Application No. 63/124,206, titled "MODEL-BASED LUNG FLUID STATUS DETECTION," filed on 11 December 2020, the disclosure of which is incorporated in its entirety by reference. This disclosure relates generally to the field of pulmonary fluid tomography, and more specifically to a technique for model-based pulmonary fluid state detection using multiple impedance measurements in combination with prior knowledge of the area of interest. To fully understand this disclosure and its features and advantages, refer to the following description in conjunction with the attached drawings, where the same reference numerals represent the same parts. An exemplary system for model-based lung fluid state detection, according to some embodiments of this disclosure, is illustrated in an exemplary environment.This block diagram shows exemplary functional components of the system in Figure 1 according to some embodiments of the present disclosure.The operation of a four-wire impedance measurement system according to one embodiment is illustrated.An exemplary electrical impedance tomography technique for pulmonary fluid state detection is illustrated, which performs multiple four-wire impedance measurements using multiple electrodes (e.g., eight or more) distributed around a region of interest to obtain a map of resistivity estimates without using prior knowledge of the region of interest.A cross-sectional model of the human upper body is illustrated, showing various types of tissues (lungs, heart, bones, and soft tissues) and air.This flowchart illustrates the operation of a model-based liquid state detection technique using a single model of the domain of interest.Exemplary embodiments described herein illustrate a model-based lung fluid state detection system that uses multiple impedance measurements in combination with prior knowledge of the domain of interest.Exemplary embodiments described herein illustrate a model-based lung fluid state detection system that uses multiple impedance measurements in combination with prior knowledge of the domain of interest.Another exemplary embodiment described herein illustrates a model-based lung fluid state detection system that uses multiple impedance measurements in combination with prior knowledge of the domain of interest.Another exemplary embodiment described herein illustrates a model-based lung fluid state detection system that uses multiple impedance measurements in combination with prior knowledge of the domain of interest.A schematic block diagram of a system for performing chest impedance measurements on human subjects is shown. Lung resistivity is a physiological parameter that describes the electrical properties of the lungs. Lung composition changes due to changes in lung tissue, fluid, and air volume. Various diseases that can cause changes in lung composition can be monitored by measuring lung resistivity. Lung fluid status is one such change in lung composition that can be monitored by measuring lung resistivity. In certain embodiments, a chest impedance (Z) measurement system is an inexpensive, non-invasive system for evaluating lung resistivity, and therefore pulmonary fluid status, and is available in a wearable form factor to enable home use and monitoring. In some embodiments, chest impedance measurement can be achieved using four electrodes. Figure 1 shows an exemplary environment 100 illustrating an exemplary embodiment of a system 102 for performing model-based pulmonary fluid state detection in a human subject, according to several embodiments of the present disclosure. Monitoring may be performed continuously or periodically. As shown in Figure 1, according to one exemplary embodiment, the system 102 includes a four-wire chest impedance measurement module 112 and a plurality of surface electrodes/sensors 114a-114d (e.g., four surface electrodes/sensors, or any other preferred number of surface electrodes/sensors). For example, one or more of the surface electrodes may be implemented as solid gel surface electrodes or any other preferred surface electrodes. The system 102 may be configured as a substantially triangular device, or a device of any other preferred shape, capable of operating to contact one or more of the torso, upper chest, and neck, or any other preferred part or region of the body, of a human subject 104 via at least the plurality of surface electrodes/sensors 114a-114d. In various embodiments, system 102 may have a configuration that allows it to be implemented as multiple patch-like devices within a wearable vest-like structure, or as any other suitable structure or device. In one possible environment, such as environment 100, system 102 may be operable to communicate bidirectionally with a smartphone 106 via wireless communication path 116, and the smartphone 106 may then be operable to communicate bidirectionally with a communication network 108 (e.g., the Interne