Figure 4

Qualitative illustration of current distribution inside patient’s body and capacitive coupling with a conductive operating table. Continuous lines draw the primary current path connecting the two electrodes. The capacity between patient’s body and the table (even if it is distributed) is depicted as concentrated capacitors. Capacitive effects are more relevant where the body closer face the table surface (i.e. head, shoulder and pelvis). The dashed lines represent alternative paths for the current generated by the electro surgical device. Note that all capacitive currents must close through the capacitance coupling of the neutral electrode (which can be opportunely reduced). Local values of the current density inside the patient’s body depends on the specific conductivity of the tissues (e.g. sacrum bone is less conductive than surrounding tissues).