The effects of electric current applied to skin: A review for transdermal drug delivery

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1047&context=bmepubs

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

Monitoring the Chest with Impedance

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-to-electrical-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 W1.52, where U is the energy in W·s and W is the body weight in kilograms. The current relationship is I = 1.87 W0.88 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 ms, the electrical dose is very nearly 1 A/kg of body weight (0.45 A/lb).

/pdf/electrical-dose-for-ventricular-defibrillation-of-large-and-1knr3t48jl.pdf

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

Accepted, controversial, and speculative aspects of ventricular defibrillation.

Experiments were conducted in man and the dog to determine the safe levels of sinusoidal alternating current which can be passed through the thorax. The sensation current threshold was determined over a frequency range of 20 Hz to 20 kHz in 8 normal adult males for two different electrode arrangements. The thresholds for vagal stimulation and ventricular fibrillation in the frequency range of 20 Hz to 3 kHz were determined in the dog for the same electrode arrangements, and the data obtained for fibrillation was extrapolated to estimate the comparable levels for man. The results indicate that the magnitudes of the current thresholds to produce these phenomena increase with an increase in frequency. Currents higher than 5 kHz in frequency are recommended for the measurement of physiological events by electrical impedance techniques.

Hazards in the use of low frequencies for the measurement of physiological events by impedance.

The design and performance characteristics of a high-energy (5000J) defibrillator are described. The instrument was constructed for the purpose of obtaining strength duration curves for transchest defibrillation of very heavy subjects. To date, the heaviest subject that has been defibrillated is a 270 kg horse.

T. W. Coulter

Papers

Hazards in the use of low frequencies for the measurement of physiological events by impedance.

A megawatt defibrillator for transchest defibrillation of heavy subjects.

Simple versatile instrument for measuring impedance changes accompanying physiological events.