CPR Display Unit with Force Sensor Feedback

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Solution Overview

Problem

Current CPR feedback systems fail to provide accurate and intuitive feedback on both compression and ventilation activities, often leading to suboptimal performance due to high hands-off time, incorrect compression depth, and hyperventilation, and are not suitable for lay rescuers due to complexity and cost.

Innovation Solution

A system comprising a measuring unit with depth and force sensors, a processing unit that compares these measurements to predefined thresholds, and a display unit that provides real-time, intuitive feedback through visual and tactile indicators, ensuring correct compression depth and force without distracting the rescuer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If continuous measurement during CPR is performed using accelerometer and gyroscope, then compression monitoring is achieved, but measurement errors build up gradually when pressure is not relieved between compressions

Engineering Contradiction:
Improvecompression measurement accuracyVSAvoidmeasurement reliability during sustained pressure
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent extracts the harmful cumulative error from the continuous measurement system by introducing a force sensor that measures only the instantaneous compression force. This separates the depth measurement (which accumulates error) from the force measurement (which remains accurate), allowing the system to rely on force sensor data during sustained pressure periods when depth measurement becomes unreliable.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The force sensor acts as an intermediary measurement device that provides accurate compression data without suffering from the cumulative error problem. It mediates between the depth measurement system and the feedback system, providing a reliable alternative measurement that confirms whether compression depth thresholds are actually achieved.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If feedback systems provide continuous audio and visual instructions, then rescuer guidance is improved, but rescuer distraction and interference with emergency scene communication increases

Engineering Contradiction:
Improverescuer guidance qualityVSAvoidrescuer distraction and communication interference
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The feedback system uses periodic visual indicators that activate only at specific moments (when compression depth thresholds are reached or exceeded). Instead of continuous audio instructions, the system provides brief visual signals at critical points, reducing overall distraction while maintaining guidance effectiveness.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent employs color-changing LED indicators to convey different feedback states (e.g., green for adequate depth, red for excessive depth). This visual color-coding system provides intuitive guidance without requiring audio output, minimizing interference with emergency scene communication while maintaining ease of operation.

Inventive Principle:
Principle #32Color changes

3Loss of information

If advanced defibrillators with CPR assist devices are used, then compression and ventilation feedback is provided, but device cost, size, and complexity increase making them unsuitable for lay rescuers

Engineering Contradiction:
ImproveCPR performance feedback qualityVSAvoiddevice complexity and cost
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent employs simple, inexpensive sensors (force sensor and depth sensor) that can be easily replaced or are disposable. This allows lay rescuers to access feedback functionality without investing in expensive, complex defibrillators. The sensors are designed to be simple and cost-effective while still providing the necessary measurement capabilities.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The feedback system is designed to work with various CPR scenarios and can be integrated into different device platforms. The same sensor and processing architecture can serve both trained rescuers and lay rescuers, providing universal CPR monitoring capabilities without requiring specialized expensive equipment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Manufacturing precision

If compression depth thresholds are set according to guidelines, then correct compression depth is promoted, but feedback on excessive compression depth is not provided risking patient injury

Engineering Contradiction:
Improvecompression depth controlVSAvoidpatient injury from excessive compression
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary anti-action by providing feedback not only when compression depth is insufficient but also when it exceeds the recommended maximum. The force sensor and processing unit detect when compression force or depth surpasses safe thresholds and provide corrective feedback before significant injury can occur, counteracting the harmful effect of excessive compression.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements comprehensive feedback that includes both minimum and maximum compression depth thresholds. When compression exceeds the maximum recommended depth, the system provides visual or audible feedback to alert the rescuer to reduce force, preventing patient injury while maintaining the benefits of guideline-based compression depth control.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP1933114B1Display unit for chest compression signals
Publication Date: 2010.06.09 LAERDAL MEDICAL AS
  • EP1933114B1 patent drawingFigure 1
  • EP1933114B1 patent drawingFigure 2
  • EP1933114B1 patent drawingFigure 3a~3c

AI summary

Display unit comprising input means for an oscillating signal (having an amplitude and a frequency, i.e. chest compression signal from a CPR session), a first indicator adapted to be activated when the amplitude reaches a maximum value, a second indicator adapted to be activated when the amplitude reaches a minimum value, a third indicator adapted to be activated partially or fully depending on amplitude, a fourth indicator adapted to be activated by a secondary signal derived from the input signal's frequency and a fifth indicator adapted to be activated when there is no input signal during a predetermined period of time. The first and the second indicators have different states (brightness) depending on the number of occurrences of a maximum respectively minimum amplitude over a period of time. The fourth indicator comprises a central zone adapted to be activated when the signal's frequency lies within a maximum and minimum value and two sides zones activated when the signal frequency exceeds the maximum and minimum value, respectively.