Variable Frequency Impedance Measurement for Defibrillators
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Solution Overview
Problem
Defibrillators face challenges in accurately delivering energy to patients due to varying patient impedance, which can result in inconsistent dosages and reduced effectiveness of defibrillation shocks, as existing methods measure impedance at fixed frequencies that may not reflect the impedance during actual energy delivery.
Innovation Solution
A method where the defibrillator selects an excitation current frequency based on the intended energy or current dosage to be delivered, allowing for more accurate impedance measurement and adjustment of the energy delivery, using a processor and impedance measuring circuit to ensure precise voltage and pulse control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed frequency excitation current is used for impedance measurement, then measurement simplicity is improved, but measurement precision deteriorates because the measured impedance does not reflect the impedance during actual energy delivery
Solution Approach 1:
The patent applies dynamics by making the excitation frequency variable rather than fixed. The system dynamically adjusts the excitation frequency to match the defibrillation shock frequency, allowing the impedance measurement to accurately reflect the patient's impedance during actual energy delivery. This resolves the contradiction by sacrificing operational simplicity for measurement precision.
Solution Approach 2:
The patent changes the parameter of excitation frequency from a fixed value to a variable that matches the defibrillation shock frequency. By adjusting the excitation frequency parameter to correspond to the actual treatment frequency, the system ensures that impedance measurements are representative of the actual delivery conditions, thereby improving measurement precision.
2Measurement precision
If impedance measurement is performed at defibrillation shock frequency, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the excitation current generator to serve multiple functions: it can operate at various frequencies to match different defibrillation shock frequencies, and it integrates seamlessly with the existing defibrillator system. This multi-functionality allows accurate impedance measurement without requiring separate dedicated measurement equipment, thereby limiting the increase in device complexity.
Solution Approach 2:
The system applies self-service by using the defibrillator's own excitation current generator to perform both defibrillation and impedance measurement functions. The existing hardware is utilized for dual purposes, eliminating the need for additional specialized measurement devices and thus minimizing the increase in device complexity while achieving precise measurements.
3Manufacturing precision
If excitation current frequency is varied to match dosage, then delivery precision is improved, but control complexity increases
Solution Approach 1:
The patent applies feedback by using the measured impedance information to adjust and optimize the defibrillation shock delivery. The system measures impedance at the appropriate frequency, uses this information to determine the actual energy delivered, and can adjust subsequent shocks accordingly. This feedback mechanism improves delivery precision while using the existing control infrastructure, thereby limiting the increase in control complexity.
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
This approach enables more accurate and effective delivery of energy, ensuring the desired dosage is reached, improving the chances of successful defibrillation and reducing the risk of over or under-delivery, while also complementing other impedance-related measurements.
Implementation Method 1
measuring the impedance of the patient by observing a response to application of an excitation current
Data Source
AI summary
When a defibrillator selects a dosage of energy or current to be delivered to a patient, the defibrillator selects an excitation current frequency and applies the excitation current at the selected frequency to the patient. The frequency of the excitation current is selected as a function of the dosage to be delivered. The patient's response to the excitation current at the selected frequency will accurately reflect the impedance that the defibrillator will “see” when delivering the selected dosage of energy or current.