Efficacy and safety of transcutaneous low-impedance cardiac pacing in human volunteers using conventional polymeric defibrillation pads

Study objectives: To assess the safety and efficacy of transcutaneous cardiac pacing using low-impedance defibrillation-type, self-adhesive polymer electrode pads positioned in the same anatomic sites typical of such pad placement in emergency defibrillation attempts. Design: Prospective, randomized, single-blinded normal subject investigation. Methods: Thirty healthy unmedicated adult volunteers of both sexes were paced transcutaneously to the threshold of capture and beyond by an intensity factor of 125%. A commercial defibrillator-pacer operating in demand mode had its rate set-point higher than the subjects' base-line rate by 125%. Threshold was established as the pulse current required to effect 75% captured beats. Pacing was continued at the 125% level for two minutes, during which subjective discomfort levels were recorded on a 1-to-5 pain scale. Results: All subjects but one were able to complete the study as designed. The single exception complained of intolerable pain early in the two-minute trial. Capture current had a mean value of 80 mA while the pain assessment averaged 3.2 on our five-point scale. No subject showed any untoward cardiovascular effects either during or after the study. Conclusion: In normal human volunteers, transcutaneous cardiac pacing with low-impedance polymer pad electrodes is safe. By extrapolation from this study population, it is sufficiently effective to accommodate successfully the vast majority of clinical circumstances likely to be encountered in emergency medicine.