Physiological measurement
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Physiological measurement · Oct 2006
Transthoracic impedance study with large self-adhesive electrodes in two conventional positions for defibrillation.
External defibrillation requires the application of high voltage electrical impulses via large external electrodes, placed on selected locations on the thorax surface. The position of the electrodes is one of the major determinants of the transthoracic impedance (TTI) which influences the intracardiac current flow during electric shock and defibrillation success. The variety of factors which influence TTI measurements raised our interest to investigate the range of TTI values and the temporal TTI variance during long-term application of defibrillation self-adhesive electrodes in two conventional positions on the patient's chest--position 1 (sub-clavicular/sub-axillar position) and position 2 (antero-posterior position). ⋯ We found that gender is important when position 1 is used because women have significantly higher TTI (111 +/- 20.3) Omega compared to the TTI of men (102.6 +/- 24) Omega (p = 0.0442). Although we found some specifics of the electrode-skin contact layer, we can conclude that because of the insignificant differences in TTI, the operator of the defibrillator paddles does not need to take into consideration the skin type and pilosity of the patients. Analysis of the correlations between TTI and the individual patient characteristics (chest size, weight, height, age) showed that these patient characteristics are unreliable factors for prediction of the TTI values and optimal defibrillation pulse parameters and energy.