Calibrated current divider network for precision current delivery during high-voltage transthoracic defibrillation

Area of Science:

• Biomedical Engineering
• Cardiovascular Devices
• Electrical Engineering

Background:

• Transthoracic defibrillation requires precise current delivery for efficacy and safety.
• Variations in transthoracic impedance can lead to inaccurate current delivery.
• Existing methods may struggle to maintain consistent current output across different impedance levels.

Purpose of the Study:

• To design and test a calibrated resistive-network current divider for precision current delivery in transthoracic defibrillation.
• To ensure a constant pulse shape delivered by the defibrillator.
• To minimize the error between selected and delivered current during defibrillation.

Main Methods:

• A resistive-network current divider with three rheostats was designed.
• A computer-generated calibration table was used to set current levels.
• Data acquisition and display software updated the calibration table post-shock based on measured transthoracic resistance.
• Testing was performed using resistive loads and animal models.

Main Results:

• The current divider presented a constant 50-ohm load to the defibrillator.
• Root-mean-square (rms) error for delivered versus selected current was 0.48% at 45 ohms and 0.71% at 100 ohms (15-27 A range).
• Animal experiments confirmed low rms error (0.49% from 15-27 A, ≤1.5% over 8-44 A range).

Conclusions:

• The calibrated resistive-network current divider enables precise current delivery during transthoracic defibrillation.
• The system effectively compensates for variations in transthoracic resistance.
• The design offers high accuracy and reliability, validated by experimental and animal data.