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Pediatric defibrillation: importance of paddle size in determining transthoracic impedance
1Cardiovascular Center, University of Iowa, Iowa City.
Insights
Transthoracic impedance in children varies by paddle size and coupling agent. Larger adult paddles and Redux paste significantly reduce impedance, aiding defibrillation success.
Area of Science:
- Pediatric Cardiology
- Biomedical Engineering
- Electrical Safety in Medicine
Background:
- Transthoracic impedance is crucial for defibrillation/cardioversion success.
- Limited data exists on pediatric transthoracic impedance ranges and determinants.
Purpose of the Study:
- To determine the range and influencing factors of transthoracic impedance in children.
- To provide data for optimizing defibrillation/cardioversion in pediatric patients.
Main Methods:
- Measured transthoracic impedance in infants and children using a test pulse technique.
- Utilized pediatric (21 cm2) and adult (83 cm2) electrode paddles with Redux paste or creme.
- Assessed the impact of paddle size, coupling agent, body weight, and body surface area.
Main Results:
- Pediatric paddles yielded impedance of 108 ± 24 Ω; adult paddles reduced it by 47% to 57 ± 11 Ω.
- Infant impedance (pediatric paddles) was 94 ± 17 Ω.
- Redux paste reduced impedance by 13%; correlations with weight/surface area were clinically insignificant.
Conclusions:
- Larger adult electrode paddles minimize transthoracic impedance in children over approximately 10 kg.
- Optimal paddle selection is essential for effective defibrillation/cardioversion in pediatric populations.
Abstract:
Transthoracic impedance is a major determinant of successful defibrillation or cardioversion, but no data are available concerning the range and determinants of transthoracic impedance in children. Transthoracic impedance was measured in ten ambulatory infants, 6 weeks to 9 months of age, and 37 children, 1.5 to 15 years of age, using a previously validated "test pulse" technique that measures transthoracic impedance without actually delivering a shock. We used hand-held "pediatric" (21 cm2) and "adult" (83 cm2) electrode paddles coated with either Redux paste or Redux creme. Transthoracic impedance in children was 108 +/- 24 omega (range 61 to 212 omega) using pediatric paddles. Using adult paddles lowered the transthoracic resistance by 47% to 57 +/- 11 omega (range 29 to 101 omega), P less than .05. In infants, transthoracic impedance (measured only with pediatric paddles) was 94 +/- 17 omega (range 74 to 124 omega). Using Redux paste as the coupling agent reduced transthoracic impedance by 13% (P less than .05). Transthoracic impedance was significantly but poorly related to body weight and body surface areas, but the correlations were not sufficiently high to be clinically useful. These data indicate that the larger adult electrode paddles will minimize transthoracic impedance and should be used when the child's thorax is large enough to permit electrode to chest contact over the entire paddle surface. This transition occurred at an approximate weight of 10 kg.