超声技术原理及在外科手中的应用-.pptVIP

* The blade vibrates longitudinally at 55,500 Hz per second. The blade travels from 50 to 100 microns per stroke. * Rapid acceleration of tissues moving with the blade breaks the hydrogen bonds that give protein structure, which results in a protein coagulum that seal coapted vessels. Deep coagulation of large vessels results when the effect is prolonged. * * The three components of the ultrasonic system are high-frequency, computer-controlled generator, a hand piece which houses the ultrasonic transducer, and a variety of interchangeable blade configurations. The handpiece contains piezo-electric ceramics which looks like a stack of 15 nickles piled on top of one another A computer-controlled electrical signal causes the piezo-electric ceramics in the ultrasonic transducer in the ultrasonic hand piece to expand and contract, converting electrical energy to mechanical motion (ultrasound). The transducer, attached to the mount, transmits the ultrasonic vibration to the attached blade. To simplify, the electric signal sent to the transducer in the ultrasonic hand piece is converted to mechanical motion. The result is vibration of 55,500 cycles per second (ultrasonic motion) at the blade tip. * Ultrasonic wave from the hand piece mount is transferred to laparoscopic blade extender. Blade extender is supported by stabilizing silicon rings positioned at nodes to direct flow of energy in a longitudinal direction and to prevent it from being dissipated on the sheath. Motion is amplified again at blade tip. * * The graph illustrates the tissue temperature range at which Ultrasonic technology, electrosurgery and laser operate. Hemostasis is achieved by denaturation of tissue protein and formation of coagulum; these effects occur at the operating tissue temperature of the Harmonic Scalpel - temperatures less than 100°C. The higher temperatures associated with electrosurgery and laser result in tissue desiccation and eschar. * Five (5) factors affecting cutting coagulat