Electrical Dose for Ventricular Defibrillation of Large and Small Animals Using Precordial Electrodes

Abstract

A B S T R A C T Electrical ventricular defibrillation of heavy subjects (over 100 kg body weight) is uncommon for the human or any animal species. This paper reports trans-chest ventricular defibrillation of subjects ranging in weight from 2.3 to 340 kg using conventional defibrillation current (heavily damped sine wave) of 0.3-30 ms duration. It was found that a body weight-toelectrical-shock strength relationship exists and can be expressed in terms of either electrical energy or peak current. For the duration of current pulse used clinically (3-10 ms), the relationship between energy requirement and body weight is expressed by the equation U = 0.73 W"52, where U is the energy in W s and W is the body weight in kilograms. The current relationship is I = 1.87 W0 M where I is the peak current in amperes and W is the body weight in kilograms. The energy dose is somewhat more species and weight dependent and ranges from 0.5 to 10 W s/kg (0.23-4.5 W s/lb). The data obtained indicate that the peak current dose is virtually species and weight independent and is therefore a better indicator than energy for electrical defibrillation with precordial electrodes. In the duration range of 3-10

Therapeutic indices for transchest defibrillator shocks: Effective, damaging, and lethal electrical doses

“…The percentage of animals defibrillated, damaged, or killed by shock in each dose group were plotted as functions of the current or energy dose per kilogram body weight. Normalization of dose by body weight is classically employed in experimental pharmacology and has proved of value in earlier defibrillation studies [18]. For such plots, smooth curves were fitted to experimental data by probit transformation and linear regression, using the method of Litchfield and Wilcoxon [19] and interpolated values were identified for the ED 50 , TD 50 , and LD 50 --the median effective, toxic, and lethal electrical doses.…”

T He U Se of a Utomated E Xternal D Efibrillators in C Hildren

“…One study across a wide variety of animal species showed that the energy dose required for defibrillation is somewhat weight-dependent and ranges from 0.5 to 10 J/kg. 26 Although the external defibrillation effectiveness data are too limited to draw any definitive conclusions, this study suggests that the defibrillation threshold for most patients weighing up to 50 kg is likely close to 2 J/kg. Other studies in animals and humans have shown that repeated high-energy shocks with a 360-J monophasic damped sine waveform might cause significant damage.…”

Relationship between canine transthoracic impedance and defibrillation threshold. Evidence for current-based defibrillation.

“…11 i a shock discharged at a 200-J setting will deliver more energy to a 100-X subject than to a 50-0 subject. Though the concept of defibrillation defined in terms of current has been previously introduced (16), the dose was con- 500 Rt + Ro sidered weight dependent and was therefore normalized to body weight (1 A/kg). Minimal interest in this approach developed since it would deliver 70 A to the average person and more than 100 A to large subjects, a dose far in excess of that delivered by present energy-based practice (26).…”