AJP - Gastrointestinal and Liver Physiology, Vol 243, Issue 6 982-G989, Copyright © 1982 by American Physiological Society
Transthoracic defibrillation in 100-kg calves with sequentially applied pulses
J. H. Gold, J. C. Schuder, H. Stoeckle, W. C. McDaniel, D. W. Moellinger and S. A. Roberts
The effectiveness of up to five 50-A, 4-ms rectangular pulses (each
nominally 50% successful) followed, when required, by up to six 70-A, 6-ms
pulses applied at 15-s intervals in reversing ventricular fibrillation in
100-kg calves was studied in 600 episodes in which 50-A, 6-ms; 70-A, 3-ms;
70-A, 6-ms; 70-A, 12-ms; or 100-A, 6-ms prefibrillation shocks had been
delivered 5 s before the induction of fibrillation and in another 600
episodes in which the prefibrillation shock was omitted. We found that 1)
there was a modest adverse influence of the prefibrillation shock upon the
outcome of the 50-A, 4-ms portion of the sequential shock effort; 2) The
50-A, 4-ms shocks remained reasonably successful throughout the five-shock
sequence; 3) when the prefibrillation shock was omitted, the time intervals
for a return of a ventricular complex and normal sinus rhythm in the
postdefibrillation electrocardiogram increased rapidly with the number of
shocks required for defibrillation; and 4) if defibrillation was not
achieved with the five-shock sequence, a single 70-A, 6-ms shock was about
94% successful and the sequence of up to six shocks was 100% successful.
