To the Editor.—
Physio-Control Corporation has received reports of current arcing during defibrillation in patients who had used topical nitroglycerin ointment. Subsequently, tests of these ointments have shown them to have low electrical conductivity. For example, the resistivity of Nitrol ointment was found to be 6×108 Ω-cm as compared with 9.4 Ω-cm for Hewlett Packard Redux Electrode Paste,1 a typical defibrillation electrode contact gel. Nitro-Bid ointment resistivity was determined to be 4×109 Ω-cm. We assume that other brands of this preparation would have similar resistivity.Noting that the lanolin-petroleum-based ointments seemed to mix poorly with electrode gels, we conducted tests on anesthetized dogs. After applying the ointment to shaved dog skin in the recommended manner, 200-joule shocks were delivered with a Physio-Control Lifepak 6 Defibrillator on the treated skin. Standard electrode gel and contact pressure were used.The results demonstrated the effects of defibrillation through an insulator.
Parke JD, Higgins SE. Hazards Associated With Chest Application of Nitroglycerin Ointments. JAMA. 1982;248(4):427. doi:10.1001/jama.1982.03330040021016
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