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Effects of Cocaine Intoxication on the Threshold for Stun Gun Induction of Ventricular Fibrillation

Dhanunjaya Lakkireddy, MD^_*, Donald Wallick, PhD^_*, Kay Ryschon, MS^_*, Mina K. Chung, MD, FACC^_*, Jagdish Butany, MD, David Martin, MD^_*, Walid Saliba, MD, FACC^_*, William Kowalewski, BS^_*, Andrea Natale, MD, FACC^_* and Patrick J. Tchou, MD, FACC^_*,_*

^_* Cleveland Clinic Foundation, Cleveland, Ohio
Toronto General Hospital, Toronto, Ontario, Canada

View larger version (27K): [in a new window]   Figure 1 The prototype Taser X-26 stun gun and the darts. The electrical current waveform characteristics at x1, x5, x10, and x30 of the standard discharge from the Taser X-26. The waveform of the standard pulse has a duration of about 100 µs and a net delivered charge of about 100 µC. Variations of the current waveform with increased output are shown. Because of the output stage transformer effects in front of the capacitors, there is an increase in both pulse duration and peak current. The gun and darts (9 mm in length) with insulated wires that carry the charge from the gun to the darts are shown in the lower panel.

View larger version (12K): [in a new window]   Figure 2 Dart positions on the front and back of the pig. Position A = sternal notch (SN) to point of maximum cardiac impulse (PMI); Position B = SN to supraumbilical region; Position C = SN to infraumbilical region; Position D = side-to-side across the chest; Position E = upper to lower midline posterior torso.

View larger version (41K): [in a new window]   Figure 3 Differences in ventricular captures rates before and after cocaine infusion at the 5 tested positions using varying multiples of standard current strength. These 2 graphs show the mean neuromuscular incapacitating (NMI) output multiples needed to achieve 2:1 (top) and 3:1 (bottom) ventricular capture at Positions A through E. Error bars indicate 1 standard deviation. Higher output multiples were needed after cocaine infusion (blue bars) to achieve the same degree of ventricular capture as during baseline stimulation (red bars).

View larger version (61K): [in a new window]   Figure 4 Example of 3:1 ventricular capture during neuromuscular incapacitating (NMI) application. The tracings from top to bottom in each panel are surface electrocardiogram (ECG) lead II, intracardiac right ventricular bipolar electrogram, and blood pressure recording. (A) The entire 5-s burst of NMI delivered at x5 output, Position A. The stimulus artifact overwhelms the surface ECG recordings. The time scale (1,000 ms, upper right of panel) does not allow appreciation of ventricular capture on this panel. There is also a stimulus artifact on the blood pressure tracing, but an overall decrease in blood pressure can be appreciated through the artifacts. (B) The end of NMI application at an expanded time scale (100 ms). Ventricular activation on the right ventricular bipolar recording at a 3:1 ratio to the stimulus artifacts can be readily appreciated. Lower arrows point to the stimulus artifact, and upper arrows point to the right ventricular bipolar electrogram. After termination of the NMI application, normal rhythm resumes with a normal blood pressure pulse.