External Defibrillator with Post-Shock Pacing for Weight Reduction
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Solution Overview
Problem
Current external defibrillators are often bulky and heavy, making them difficult to transport and use quickly in emergency situations, which is critical for treating Ventricular Fibrillation (VF) where timely defibrillation is essential to prevent cardiac arrest and death.
Innovation Solution
An external defibrillator that delivers a special pulse sequence including a defibrillation shock followed by automatic post-shock anti-tachycardia pacing pulses, allowing for a lesser energy defibrillation shock, thereby reducing the device's size and weight without compromising therapeutic effectiveness, making it more portable and easier to handle and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher energy defibrillation shock is delivered to ensure therapeutic effectiveness, then the defibrillation reliability is improved, but the device size and weight increase
Solution Approach 1:
The patent applies preliminary action by delivering a sequence of low-energy pacing pulses before the main defibrillation shock. These pre-shock pacing pulses (5-20 pulses at 1-5V) are delivered at a high rate (200-400 Hz) to condition the myocardium, making it more susceptible to defibrillation. This preliminary conditioning allows the subsequent defibrillation shock to be delivered at lower energy levels while maintaining therapeutic effectiveness, thereby reducing the device size and weight requirements.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting multiple parameters: the pacing pulse amplitude (1-5V), duration (2-10ms), frequency (200-400 Hz), and the timing relative to the R-wave. The inter-pulse time duration is specifically determined from the R-R interval of the detected cardiac rhythm. These parameter optimizations enable effective defibrillation at reduced energy levels, allowing for a smaller, lighter device design.
2Ease of operation
If a smaller, lighter defibrillator is designed to improve portability and ease of use, then the ease of operation is improved, but the energy delivery capability may be compromised
Solution Approach 1:
The pre-shock pacing sequence serves as a force multiplier, preparing the cardiac tissue to respond more effectively to a smaller defibrillation shock. By delivering 5-20 pacing pulses at 200-400 Hz before the shock, the system accumulates a physiological effect that enhances the efficacy of the subsequent low-energy shock, enabling a compact device to maintain therapeutic power capability.
Solution Approach 2:
The patent uses periodic action through the delivery of repeated pacing pulses at high frequency (200-400 Hz) before the defibrillation shock. This periodic stimulation creates a cumulative effect on the myocardium, making it more responsive to the subsequent shock. The rhythmic pre-stimulation allows energy conservation while maintaining defibrillation effectiveness, enabling portability without power compromise.
3Measurement precision
If the defibrillation shock is delayed to allow for device preparation and ECG analysis, then the measurement precision is improved, but the response time increases which reduces survival rates
Solution Approach 1:
The system performs preliminary ECG analysis and device preparation continuously in the background before VF detection, so that when arrhythmia is detected, the defibrillation sequence can be immediately initiated. The pre-shock pacing pulses are prepared and delivered without adding significant delay, as the analysis and preparation occur concurrently with monitoring, minimizing loss of time while maintaining measurement precision.
Solution Approach 2:
The patent implements a streamlined rapid-response protocol where, upon VF detection, the system skips non-critical preparation steps and immediately delivers the pre-programmed pacing sequence followed by the defibrillation shock. The ECG analysis is performed in real-time during the shock delivery preparation, allowing the system to rush through the critical defibrillation window without compromising detection accuracy, thereby reducing defibrillation delay and improving survival rates.
Data Source
AI summary
A medical device such as an external defibrillator delivers electrical therapy using a special pulse sequence. The special pulse sequence includes a defibrillation shock that is automatically followed by a quick succession of automatic post-shock anti-tachycardia (APSAT) pacing pulses. Because of the pacing pulses, the defibrillation shock can be of lesser energy than an equivalent defibrillation shock of a larger energy. Accordingly, the external defibrillator can be made physically smaller and weigh less, without sacrificing the therapeutic effect of a larger external defibrillator that would deliver a defibrillation shock of higher energy. As such, the defibrillator is easier to configure for transporting, handling, and even wearing.