Dynamic NIRS Filter Switching for Chest Compression Monitoring
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Solution Overview
Problem
Current methods lack effective means to objectively assess whether chest compression is being performed correctly during out-of-hospital cardiopulmonary arrest, particularly during interruptions, which affects brain oxygenation and metabolism.
Innovation Solution
A concentration measurement apparatus and method using near-infrared spectroscopy to measure temporal relative changes in oxygenated hemoglobin concentration, filtering out low-frequency components to highlight changes due to chest compression, and switching display data to show brain oxygenation state during compression interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous monitoring of oxygenated hemoglobin concentration is performed during chest compression, then the ability to assess compression effectiveness is improved, but the ability to detect low-frequency changes during interruption is lost
Solution Approach 1:
The display mode dynamically changes based on the operational state of chest compression. When compression is detected, the system displays filtered high-frequency data for real-time feedback. When interruption is detected, the system automatically switches to display unfiltered data showing low-frequency trends, thus adapting the monitoring characteristics to the current physiological state
Solution Approach 2:
The system changes the frequency filtering parameter based on the chest compression state. During active compression, a bandpass filter removes low-frequency components to highlight compression-induced changes. During interruption, the filter is adjusted or removed to preserve low-frequency information related to brain oxygenation, thus optimizing the displayed parameter for the current state
2Measurement precision
If frequency filtering is applied to remove low-frequency components, then the signal-to-noise ratio for chest compression detection is improved, but the information about brain oxygenation state is lost
Solution Approach 1:
The filtering characteristics are dynamically adjusted based on the detected chest compression state. During active compression, aggressive filtering removes low-frequency components to enhance compression signal detection. During interruption, the system automatically reduces or disables filtering to preserve low-frequency oxygenation information, thus making the filter behavior adaptive rather than static
Solution Approach 2:
The monitoring data is segmented into different frequency components, and different segments are displayed based on the operational state. High-frequency components related to chest compression are emphasized during compression, while low-frequency components related to oxygenation are preserved during interruption, thus separating the display of different physiological information based on current needs
3Ease of operation
If real-time feedback during chest compression is provided, then the ability to guide compression performance is improved, but the ability to monitor oxygenation during interruption is reduced
Solution Approach 1:
The monitoring system dynamically switches between two operational modes: during chest compression, it provides real-time feedback with filtered data to guide compression performance; during interruption, it automatically transitions to display unfiltered data for accurate oxygenation monitoring. This dynamic mode switching ensures both functions are optimized for their respective states
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables chest compression performers to objectively judge the appropriateness of chest compressions and monitor brain oxygenation during interruptions, improving the effectiveness of cardiopulmonary resuscitation efforts.
Implementation Method 1
a concentration measurement apparatus for measuring a temporal relative change amount of oxygenated hemoglobin concentration, that varies due to repetition of chest compression, in a head
Implementation Method 2
based on the intensities of the detected light components, a rate of change of the detected light amount in the direction of distance from the light incidence point is calculated. Hemoglobin oxygen saturation is calculated based on a predetermined relationship of the rate of change of the detected light amount and the light absorption coefficient
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A concentration measurement apparatus includes a probe 20, having a light incidence section making measurement light incident on the head and a light detection section detecting the measurement light that has propagated through the interior of the head, a CPU 14 determining a temporal relative change amount of oxygenated hemoglobin concentration and performing a filtering process of removing frequency components less than a predetermined frequency from frequency components contained in the relative change amount, and a display section 15 displaying first time series data indicating the filtering-processed relative change amount. The CPU 14 judges whether or not chest compression is being performed. If chest compression is not performed for a predetermined time, the display section 15 switches from displaying the first time series data to displaying second time series data indicating the relative change amount that contains frequency components less than the predetermined frequency.