1. 1 Sudden Cardiac Death, Prehospital Amiodarone Administration and Defibrillation Waveforms Tyler Cascade March 2002 tcascade@yahoo.com

2. 2 Question: Is monophasic or biphasic defibrillation better, after a 300 mg IV amiodarone bolus, for the treatment of sudden cardiac death? Hypothesis 1: Monophasic is better Hypothesis 2: Biphasic is better Null Hypotheses: The relationship between amiodarone, defibrillation threshold, and defibrillation waveforms does not affect survival after sudden cardiac death.

3. 3 Sudden Cardiac Death (SCD) Definition: –unexpected –cardiac cause –short period of time from symptom onset to cardiac arrest Mortality of Sudden Cardiac Death, USA, 1999. (Centers for Disease Control) 728,743 462,340 341,780 120,244 323,638 0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000 All Cardiac Disease Sudden Cardiac Deaths (SCD) SCD Out-of-Hospital SCD in ED or Dead on Arrival SCD Secondary to myocardial infarction

4. 4 What can we do to help these folks live longer lives, with a good quality of life?

5. 5 Early 911 and Dispatcher Assistance Early CPR Early Defibrillation Most Important Early Drugs Epinephrine, Vasopressin Amiodarone, Lidocaine Beta-Adrenergic Blockers

6. 6 Amiodarone for resuscitation after out-of-hospital cardiac arrest due to ventricular fibrillation. Kudenchuk PJ, Cobb LA, Copass MK, Cummins RO, Doherty AM, Fahrenbruch CE, Hallstrom AP, Murray WA, Olsufka M, Walsh T. New England Journal of Medicine. 1999 Sep 16;341(12):871-8. Survival to Hospital Admission (n=504) 43% Amiodarone Group 34%Placebo Group Survival to Discharge 13.4%Amiodarone Group 13.2%Placebo Group 7% Return to Independent Living or Prior Employment

7. 7 External & Internal Defibrillation Waveforms Currently In Use MTE 1 - Monophasic Truncated Exponential MDS 2 -Monophasic Damped Sine Wave BTE 3 -Biphasic Truncated Exponential RBW 4 -Rectilinear Biphasic Waveform 200, 300, 360 Joules 120, 150 Joules

8. 8 -20 0 10 20 30 40 50 04812 -10 -20 0 10 20 30 40 50 04 8 12 -10 -20 0 10 20 30 40 50 04812 -10 -20 0 10 20 30 40 50 04 8 12 -10 Time (msec) Curre nt (amps ) Biphasic Truncated Exponential Waveform Rectilinear Biphasic Waveform Low ImpedanceHigh Impedance Time (msec) 3 rd & 4 th Generation Waveforms Patient Impedance Variables include: Distance between electrodes (chest size) Volume of air in the lungs Skin properties The use of conductive gels BTE & RBW Waveforms 50 & 150 Ohms Impedance Compensation 120, 150 Joules

9. 9 Monophasic Waveforms & Impedance Monophasic Damped Sine Waveform (MDS) Comparison of Waveform with 50 & 150 Ohm Impedances 2 nd Generation Figure 8 200, 300, 360 Joules Monophasic Truncated Exponential (MTE) Waveform Comparison of Waveform with 50 & 150 Ohm Impedances 1 st Generation Figure 4

10. 10 Shortening the second phase duration of biphasic shocks: effects of class III antiarrhythmic drugs on defibrillation efficacy in humans. Merkely B; Lubinski A; Kiss O; Horkay F; Lewicka-Nowak E; Kempa M; Szabolcs Z; Nyikos G; Zima E; Swiatecka G & Geller L. Journal of Cardiovascular Electrophysiology. 12(7), 824-7 (Jul 2001). Department of Cardiovascular Surgery, Semmelweis University, Budapest, Hungary. Effects of chronic oral amiodarone on defibrillation threshold (Internal defibrillation) Findings –DFT Affected by amiodarone –amiodarone responded differently to different waveforms –Optimal phase II = 2.5 ms

11. 11 Defibrillation Threshold Minimum amount of energy needed to successfully defibrillate the heart Patient Impedance amiodarone Monophasic Waveforms Biphasic Waveforms

12. 12 Research Web Site: http://academic.evergreen.edu/c/casasp04/