๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Electrodesiccation
Electrodesiccation
During electrocoagulation, especially when performed slowly, the more superficial tissues may dry out. This is called desiccation. This step is important because the current may decrease or stop flowing entirely, limiting the maximum depth of coagulation. When this occurs, a popping sound or sparking may occur through the dried nonconductive layer, exploding and fragmenting the dried layer. Desiccation is not guaranteed, does not always happen, and the time to onset is unpredictable. The timing at which desiccation occurs during the course of coagulation is dependent upon the rate of increase in temperature. This is determined by current density. A low current density can allow for a deeper coagulation before the onset of desiccation.6 Therefore, in the setting of deep coagulation (i.e., after curettage of a malignant lesion), a low power should be used. With no published data, a rule of thumb is to choose a power which can provide desiccation (popping sound) after 4 to 7 seconds to achieve relatively deep destruction.
There are three factors that influence the depth of coagulation: the size of the electrode tip, the power setting, and the length of time for which the electrode is in contact with the tissue. The longer the electrode is in contact with the tissue, the more heat is generated and the wider and deeper the tissue damage.
Utilizing a lower power with a longer contact duration is not preferable to adopting a higher power with longer contact duration. Longer contact time conducts more heat, leading to increased collateral tissue damage before the desired outcome is attained.18โ20 This is much the same concept as when choosing pulse duration for a
laser. Therefore, to minimize collateral tissue damage, the contact time should be minimized or divided into multiple pulses to allow the tissue to cool between pulses.