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S U P P L E M E N T T O O U T P AT I E N T S U R G E R Y M A G A Z I N E O N L I N E | M O N T H 2 0 1 4
Bipolar and ultrasonic: variations on a theme
Advanced bipolar devices employ the tissue's resistance to electrical current to
generate heat within the tissue, which is used to dissect and coagulate it. The
jaws of a device's forceps are the active and return electrodes, between which
electrical current in the form of radiofrequency energy passes. Because they're
on a single instrument, the electricity flows only through the limited area of tis-
sue grasped by the device's jaws to initiate the cutting and sealing.
With ultrasonic devices, also commonly known as harmonic scalpels, the cut-
ting and sealing effect is produced by mechanical energy. An electrical source
unit is connected to a piezoceramic transducer (similar to those found in dental
plaque removers or ophthalmic cataract phacoemulsifiers) in a forceps hand-
piece. The transducer sends high-frequency vibrations to the grasping jaws,
which heats the tissue between them to make the seal.
One of the chief risks involved in the use of energy-based cutting and sealing
devices is thermal spread. In this complication, the heat and desiccation applied
to cut tissue and seal a vessel spread farther than necessary and injure adjacent
tissue. It only takes a couple of seconds, and may only affect a couple of mil-
limeters, but the resulting tissue breakdown can pose potentially fatal infection
risks. "It's something we worry quite a bit about," says William L. Barrett, MD, a
general surgeon at CaroMont Surgical Associates in Gastonia, N.C.
Dr. Barrett says that improvements to the temperature regulation system in the
ultrasonic cutting and sealing technology he relies on have improved the accuracy
of its energy delivery and curbed high temperature spikes to mitigate the risk of
thermal spread.
Safety's not the only improvement that the product category has seen, he says.
Redesigned jaws lend an additional measure of efficiency. Devices featuring
larger jaws let users seal larger vessels during open surgeries, and articulation at
the device's distal end gives laparoscopic surgeons a little more reach. The
resulting longer holds on tissue, however, have necessitated the development of
handpieces that signal users with audible tones or other warnings to ensure safe
S U R G I C A L E N E R G I E S
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