Ultrasonically Activated Coagulating Scalpel And Shears

The ultrasonically activated coagulating scalpel cuts and coagulates by using lower temperatures than those used by electrosurgery or lasers. This technology controls bleeding by coaptive coagulation at low temperatures ranging from 50 to 100°C. Vessels are coapted (tam-ponaded) and sealed by a protein coagulum. Coagulation occurs by means of protein denaturation when the blade, vibrating at 55,500 Hz couples with protein, denaturing it to form a coagulum that seals small coapted vessels. When the effect is prolonged, secondary heat is produced, which seals larger vessels. In contrast, electrosurgery and lasers coagulate by burning (obliterative coagulation) at higher temperatures (150 to 400° C). Blood and tissue are desiccated and oxidised (charred), forming eschar that covers and seals the bleeding area. Re-bleeding can occur when blades removed during electro-surgery stick to tissue and disrupt the eschar (Fig. 1).

Ultrasonic energy is an efficient alternative to electrosurgery. Lower temperatures are used with the ultrasonically activated

Fig. 1 Harmonic Scalpel™ (A) Generator and (B) Scalpel (Ethicon Endosurgery, Cincinnati, OH, USA).

Fig. 1 Harmonic Scalpel™ (A) Generator and (B) Scalpel (Ethicon Endosurgery, Cincinnati, OH, USA).

coagulating scalpel, than with electrosurgery. No electricity goes to or through the patient. The surgeon controls the precision of cutting and coagulation by adjusting the power level, blade edge, tissue traction, and blade pressure.

The ultrasonically activated scalpel25 has led to the development of the ultrasonically activated coagulating shears (CS or LCS). The scissors-like devise has a blunt blade, which oscillates at 55 kHz. This produces heat and vibration and solubilises the collagen in vessels up to 6 mm. CS has simplified operative procedures, reducing operating time.34 It is useful in controlling intrahepatic vessels. A disadvantage of the technique is that at a power level of three, it may take 5 to 30 seconds for coagulation to be complete. This may seem tedious compared with simple ligation, in open surgery. CS applied directly to liver parenchyma without the forceps fracture method is also unfeasible as the ultrasonic energy is easily dispersed and not adequately concentrated, resulting in poor coagulation. As long as the blood vessel has enough coagulum material, vessels up to 6 mm may be coagulated.25 Therefore, it should be able to coagulate most intra-hepatic vessels. CS is not good at controlling bleeds from small tributaries or pinholes, however, it is comparable to the forceps fracture method.

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