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Investigation into voltage breakdown in glyceryl trinitrate patches
1Resuscitation Training Unit, Wythenshawe Hospital, Manchester, UK.
Resuscitation
|August 26, 1998
Summary
Explosions during defibrillation are linked to glyceryl trinitrate (GTN) patches with metal mesh backings. The explosions are caused by electrical voltage breakdown, not the GTN itself, highlighting patch design and defibrillation technique importance.
Area of Science:
- Medical Devices
- Cardiology
- Materials Science
Background:
- Clinical reports suggest glyceryl trinitrate (GTN) patches may explode during defibrillation.
- It is recommended to remove GTN patches before defibrillation.
- The exact cause of these explosions remains unclear.
Purpose of the Study:
- To investigate the cause of explosions in GTN patches during defibrillation.
- To simulate defibrillation conditions and measure electrical parameters.
- To determine if the GTN compound or patch design is responsible.
Main Methods:
- An experimental setup simulating human defibrillation electrical conditions was created.
- Defibrillator waveform measurements were accurately taken.
- GTN patches with plastic and metal mesh backings were tested under simulated defibrillation currents.
Main Results:
- No issues were observed with GTN patches featuring a plastic backing.
- GTN patches with a metal mesh backing consistently showed an explosive effect when defibrillator current passed through the metal.
- The GTN paste remained unaffected; explosions were attributed to voltage breakdown at high defibrillator voltages (approx. 3 kV).
Conclusions:
- The observed explosions are due to electrical voltage breakdown in the metal mesh of GTN patches, not the GTN compound.
- Emphasizes the importance of proper defibrillation technique to prevent current flow through such patches.
- Findings have implications for the design of transdermal drug delivery patches.