CPR Coaching Device Motion Error Correction
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Solution Overview
Problem
Existing CPR devices struggle to accurately measure and provide feedback on the depth of chest compressions during cardiopulmonary resuscitation, especially in moving vehicles, due to errors from external accelerations and variations in patient anatomy, leading to inconsistent and potentially inaccurate compression depths.
Innovation Solution
A CPR coaching system that uses both an accelerometer and a force sensor to measure and correlate chest compression depth and force, with the force signal serving as a reference to correct for external motion errors, ensuring reliable feedback on compression depth and pace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accelerometer is used to measure chest compression depth, then the depth measurement can be obtained, but the measurement is inaccurate due to external accelerations and motion errors
Solution Approach 1:
The patent combines an accelerometer and a force sensor into a single CPR coaching device. The accelerometer measures compression depth while the force sensor measures compression force. By merging these two sensing mechanisms, the system can cross-validate measurements and distinguish between actual compression depth and motion artifacts, thereby improving both measurement precision and reliability simultaneously.
Solution Approach 2:
The system uses feedback from the force sensor to correct and validate the accelerometer-based depth measurements. When the force sensor detects a compression event, it provides feedback that helps the system distinguish genuine compressions from external motion, allowing the accelerometer readings to be corrected and making the depth measurement more reliable.
2Device complexity
If only force-based measurement is used, then the device complexity is reduced, but the compression depth measurement becomes inaccurate due to intra-patient variation in thoracic morphology and compliance
Solution Approach 1:
The patent merges force-based measurement (force sensor) with acceleration-based measurement (accelerometer) to create a hybrid measurement system. This combination allows the device to maintain relatively simple hardware while achieving accurate compression depth measurement by using force as a reference to validate and correct accelerometer readings, overcoming the limitations of both individual methods.
3Adaptability or versatility
If an accelerometer is used in a moving vehicle, then CPR coaching can be provided during transport, but external accelerations cause errors in the compression depth measurement
Solution Approach 1:
The force sensor acts as an intermediary that mediates between the accelerometer and the compression depth measurement. During mobile CPR in moving vehicles, the force sensor detects actual compression events and provides a reference signal that helps the system distinguish genuine compressions from vehicle motion accelerations, thereby maintaining measurement precision while enabling adaptability to mobile environments.
Solution Approach 2:
The system dynamically changes its measurement parameters by switching between relying on accelerometer data and using force sensor data based on the detection of compression events and external motion patterns. This parameter adaptation allows the system to maintain accurate compression depth measurement whether the patient is stationary or being transported in a moving vehicle.
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
The system provides accurate and reliable feedback on chest compression depth and pace, even in moving vehicles, improving the quality of CPR by minimizing errors from external accelerations and anatomical variations, thus enhancing patient care during cardiac arrest.
Implementation Method 1
an accelerometer which produces an acceleration signal which, when doubly integrated, produces a measurement of the depth of the compressions
Implementation Method 2
a force sensor which is also responsive to the compressions and produces a signal which is a measure of the force of compression
Data Source
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AI summary
A CPR coaching device is designed for placement on the chest of a patient during CPR. Chest compressions are delivered to the patient by a rescuer by pressing on the device. A force sensor and an accelerometer are located in the device and are responsive to the chest compressions. When the patient's body is stationary there will be a high correlation of a depth signal produced by doubly integrating the acceleration signal of the accelerometer and the force signal, and the depth signal is deemed reliable. When the patient's body is subject to motion such as by the motion of a vehicle transporting the patient, there will be a low correlation of the depth and force signals, with the force signal being relatively immune to this motion. In such cases, the force signal is used in association with the previously determined relationship between depth and force in the absence of motion to produce an indication of chest compression depth.