Skin burns from electrosurgical current

At 34 skin sites on anesthetized pigs, graded levels of average electrosurgical current density, J (A/cm2), at 500 kHz were delivered for specified times (t sec) to cause thermal injury. The severity of cutaneous response was determined by gross and microscopic study 56 hours later. The product J2t has been defined as the relative energy density factor, and is proportional to the delivered energy that determines skin heating. Nine of 10 sites that received low energy density factor exposure (J2t = 0.20-0.70 A2/cm4.sec-1) exhibited maximum skin temperatures of 38-47 degrees C beneath the electrodes, and subsequently has either no damage or as mild second-degree burn lying just beyond the electrode contact zone. At 9 of 11 sites exposed to a medium energy density factor (J2t = 0.70-1.60), the maximum skin temperatures below the electrodes were between 49 and 55 degrees C, with single or multiple rings of second-degree burns located just inside or beyond the rim of the electrode. At all 13 sites exposed to high energy density (J2t = 1.60-7.50), the maximum skin temperatures beneath the electrodes were 55-81 degrees C, and severe burns were produced with white to brownish, dry, firm, third-degree burns surrounded by peripheral rings of second-degree burns. No significant skin damage was produced with skin temperatures less than 45 degrees C (an energy density factor of 0.75). These data identify the temperature and energy density factor necessary to produce lesions on porcine skin.