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Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

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Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2chnique.•Knowledge of snare designs and choosing the appropriate snare are essential parts of a successful polypectomy.Navigation of the scope to an o

ptimal position and a clean environment create an optimal condition for a safe polypectomy.•The size and the shape of the polyp dictates the choice of Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

the proper technique.•Short distances (less than 2cm) between the tip of the snare and a polyp, minimal opening of the metal loop and simultaneous ad

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

vancement of the snare toward the polyp, along with tightening of the loop are the key elements of the technique.Polypectomy of a large polyp requires

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2e is the heating of the restricted area by radio-frequency alternating current (RF) without stimulation of nerves and muscles. When current alternates

up to a million times per second it does not stimulate muscle and nene membranes long enough to induce depolarization before the next alternation occ Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

urs. Cutting is produced by rapid and strong heating, which creates evaporation of intra-and extracellular fluids.Coagulation is initiated when the sp

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

eed and degree of tissue heating is slower and less intense, leading to cellular desiccation. Specific effects of different types of RF currents and h

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2required to push current through the tissue. The higher the voltage, the deeper the thermal tissue destruction.•Tissue resistance (R) or impedance (fo

r alternating current) is the force generated by tissue to resist electrical flow. It is directly proportional to the amount of tissue electrolytes.Re Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

sistance increases dramatically during tissue heating and desiccation. Normal tissue resistance is not uniform; it is lowest along blood vessels and h

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

ighest at the level of the skirl.•Time (T) is an essential factor of energy (E) regulation, which can be expressed as:E (in joules) = p (power in wans

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2Gershman. Mike Thomson. Marvin Ament. €> 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd.* Low-voltage current penetrates le

ss through desiccation tissue and has limited ability to induce deep tissue heating.** Spikes of high-voltage coagulating current allow a deeper sprea Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

d through desiccated tissue and induce more tissue destruction.Figure 8.1 Different types of alternating RF currents and specific tissue response.Alte

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

rnative RF currentTissue resistanceHeatAbove 41.5°cAbove 60°Clotrc FastAbove 200”CAbove 500°C• devitalization -irreversible death of the tissueCoagula

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2is of bigger vessels secondary to glue effect of desiccated glucose •tissue sticking to the active electrodeCabonization • tissue may become an electr

ic insulator•tissue vaporization cutting •smoke productionFigure 8.2 Temperature-related tissue destruction always induced by RF current.•Heating prod Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

uces water loss and increases resistance.•Increasing resistance shifts the distribution of current from the lowest resistance pathway.•Fluctuation of

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2

the resistance affects the power output produced by the generator.• Some of the released heat is removed from high-temperature areas by blood flow.The

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

Ebook Practical pediatric gastrointestinal endoscopy (2/E): Part 2scopy Techniques• Current density is a measure of RF current (I) which flows through a specific cross-section area (a):I I

://khothuvien.comPolypectomyGeorge GershmanKEY POINTS•Knowledge of the principles of electro-surgery Is an essential component of safe polypectomy tec

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