A Systematic Review of the Transthoracic Impedance during Cardiac Defibrillation

For cardiac defibrillator testing and design purposes, the range and limits of the human TTI is of high interest. Potential influencing factors regarding the electronic configurations, the electrode/tissue interface and patient characteristics were identified and analyzed. A literature survey based on 71 selected articles was used to review and assess human TTI and the influencing factors found. The human TTI extended from 12 to 212 Omega in the literature selected. Excluding outliers and pediatric measurements, the mean TTI recordings ranged from 51 to 112 Omega with an average TTI of 76.7 Omega under normal distribution. The wide range of human impedance can be attributed to 12 different influencing factors, including shock waveforms and protocols, coupling devices, electrode size and pressure, electrode position, patient age, gender, body dimensions, respiration and lung volume, blood hemoglobin saturation and different pathologies. The coupling device, electrode size and electrode pressure have the greatest influence on TTI.

Automated summary

Understanding the range and limits of human trans thoracic impedance (TTI) is crucial for cardiac defibrillator testing and design. A literature survey based on 71 selected articles revealed that TTI varied from 12 to 212 Ohms, with an average TTI of 76.7 Ohms. Factors such as shock waveforms and protocols, coupling devices, electrode characteristics, and patient characteristics were found to influence TTI, with coupling devices, electrode size, and pressure having the greatest impact.