No abstract

No abstract

The defibrillation threshold for various wave forms of condenser discharge, using capacitors from 4 to 200 µF, has been measured. Condenser discharge alone was used, or condenser discharge 0.25 henry (20 ohms) with an iron core series inductance, or condenser discharge, 0.29 henry (27 ohms) inductance, but without the iron core. Statistical analysis of the results showed that the last of these three circuits gave the lowest threshold voltage values. Optimal parameters of inductance-altered discharges are obtained with values of 24, 32, and 50 µF. Detailed analysis of the separate physical parameters of the discharge show that optimal pulse duration is 8.5 to 16.6 msec. Further increase of duration does not decrease the voltage or current for threshold shocks, but merely increases the energy delivered. Pulse duration appears to be one of the more important parameters for successful defibrillation, and for this reason, a series inductance is also important.

With the technical assistance of 1. Blaiek, M. Rabl and E. Sladkova and the statistical evaluation of Ing. 1. Roth MethodsThe present experiments were performed under pentobarbital anaesthesia (20 to 40 mgAg body \vt iv) on mongrel dogs, weighing from 20 to 25 kg. The electronic device for synchronizing the condenser discharge with selected phases of the electrocardiogram has been described previously. 1 The methods, in general, were also the same as before except that an inductive resistance (inductance 0.29 henry and resistance 27

No abstract