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Table 2 Estimated time (in seconds) of continuous operation of ESU in cut mode needed to increase the temperature of 10°C at the sacrum (average on a volume of about 1.5 cm3)

From: Investigating the role of capacitive coupling between the operating table and the return electrode of an electrosurgery unit in the modification of the current density distribution within the patients’ body

Time to rise temperature of 10°C at sacrum 50 W 100 W 150 W 200 W 300 W
ϵr = 1 5966 (s) 2983 (s) 1989 (s) 1491 (s) 994 (s)
ϵr = 5 875 (s) 437 (s) 292 (s) 219 (s) 145 (s)
ϵr = 20 164 (s) 82 (s) 55 (s) 41 (s) 27 (s)
ϵr = 50 59 (s) 29 (s) 19 (s) 15 (s) 10 (s)
ϵr = 100 31 (s) 16 (s) 10 (s) 8 (s) 5 (s)
  1. Time was estimated by means of the Bioheat equation: the assumption of absence of heat transfer to surrounding tissues, blood perfusion and metabolic heat was held. Time was estimated for a continuous sinusoidal waveform (typical of cut-mode); if coagulation or blend waveforms are delivered by the ESU this time should multiplied by opportune factors (e.g. if a blend-mode is obtained with a duty cycle of 50% the values in the table should by multiplied by 2) The value shown in italics matches the ESU’s settings considered for the simulation.