CPR Compression Depth Sensor Using Hydrostatic Pressure Measurement
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Solution Overview
Problem
Existing cardiopulmonary resuscitation (CPR) sensor devices, particularly those using accelerometers, face challenges in accurately measuring chest compression depth due to errors caused by patients being on compliant surfaces, as they measure both patient and surface compression, making it difficult to determine the absolute compression depth without prior knowledge of the surface type and weight distribution.
Innovation Solution
A compression depth sensor utilizing hydrostatic pressure measurements with liquid-filled lumens and pressure transducers, allowing for absolute compression depth measurement by differentiating between patient and surface compression, and accounting for external parameters like bed height changes during resuscitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If accelerometer based measurement is used to measure compression depth, then the device complexity is reduced and ease of operation is improved, but measurement precision deteriorates due to inability to differentiate patient compression from surface compression
Solution Approach 1:
The measurement function is segmented into two independent components: one sensor measures total compression (patient + surface), while the other measures only surface compression. By separating the measurement tasks, the system can subtract surface compression from total compression to obtain accurate patient compression depth, resolving the precision issue while maintaining operational simplicity
Solution Approach 2:
A second sensor acts as an intermediary reference that measures surface compression independently. This intermediary measurement allows the system to compensate for surface compliance effects by subtracting the surface component from the total compression measurement, thereby improving measurement precision without complicating the operation
2Measurement precision
If standard correction for compliant surface is applied, then measurement precision is improved, but adaptability deteriorates because correction factor cannot be determined without prior knowledge of surface type and weight distribution
Solution Approach 1:
The system performs self-calibration by automatically measuring surface compression during the actual CPR procedure. The second sensor continuously monitors surface deformation, and the system dynamically calculates and applies the correction factor in real-time, eliminating the need for pre-knowledge of surface characteristics and enabling automatic adaptation to any surface type
Solution Approach 2:
The system performs preliminary measurement of surface compression characteristics before actual compression measurement begins. By characterizing the surface compliance in advance during the setup phase, the system prepares the necessary correction data to improve subsequent measurement precision while maintaining adaptability to different surfaces
3Device complexity
If accelerometer based measurement is used, then device complexity is reduced, but measurement precision deteriorates because both patient and surface compression are measured together without differentiation
Solution Approach 1:
The measurement function is segmented into two independent components: one sensor measures total compression (patient + surface), while the other measures only surface compression. By separating the measurement tasks, the system can subtract surface compression from total compression to obtain accurate patient compression depth, resolving the precision issue while maintaining operational simplicity
Solution Approach 2:
Two simple accelerometer-based sensors are merged into a coordinated measurement system. By combining the total compression measurement with the surface compression measurement, the system achieves precise patient compression measurement through differential calculation, maintaining low device complexity while improving precision
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 accurate measurement of actual chest compression depth during CPR, improving the reliability of CPR performance feedback and quality assessment, especially on compliant surfaces, by providing absolute and corrected compression depth values.
Implementation Method 1
The first pressure transducer is adapted to measure the compression depth by measuring a change in hydrostatic liquid pressure in the lumen during movement of the first movable lumen end between the first position and the second position
Data Source
AI summary
According to the invention, a compression depth sensor for measuring a compression depth comprises a first pressure transducer (30), attachable to a fixed element, a first liquid filled lumen (20), having a first fixed lumen end (21) attachable to the pressure transducer and a first movable lumen end (22) being movable between a first position and a second position, a distance between the first and second position defining the compression depth, whereby the first pressure transducer is adapted to measure the compression depth by measuring a change in liquid pressure in the lumen during movement of the first movable lumen end between the first position and the second position. A CPR apparatus according to the invention comprises such a compression sensor.