Liposuction, after 25 years since its introduction in the
United States in 1981, remains one of the most popular
plastic surgeries for both men and women. How it works
seems simple enough...'stick a tube and suck it out' to
paraphrase what many patients say. And while it is
conceptually simple mechanical process, there is more to it
than meets the eye.
At its most basic level, liposuction is a simple two-stage
process for removing fat. A hollow tube (cannula) is put
under the skin, the tube is moved back and forth until the
fat is dislodged, and the attached vacuum source draws the
fat back through the cannula into the tubing and finally
into the plastic bottle.
Despite this apparent simplicity, there is more science to
it than that. There are three interesting components about
liposuction, all of which contribute to its safety and
effectiveness. These include tumescent fluid infiltration,
vacuum pressure, and cannula size and design.
The placing of fluid during the liposuction operation
before doing the suctioning is an integral part of the
operation. I frequently get asked by patients if I do
tumescent liposuction. Patients think that this is a
special method of liposuction, when in fact, it is used in
every liposuction procedure. Putting large amounts of fluid
into the fat areas to be suctioned beforehand is known as
tumescent infiltration. This achieves two fundamental
things, substantially reduces bleeding (from the fat being
broken up by the liposuction tube and it distends the fat
compartments which make the tube easier to pass through the
fat being suctioned. Without tumescent infiltration,
liposuction would quite bloody, give patients more pain,
and have them bruised for a month, if not longer.
The amount of suction generated by the liposuction machine,
in short, makes liposuction possible. At the accepted
amount of suction needed for liposuction (-20 cms of water
or -1 atmosphere of pressure), the pulling of fat through
the tubing certainly occurs. But it also causes the
vaporization of water. If you have ever witnessed an actual
liposuction procedure, you may have seen bubbles in the fat
or bubbling in the plastic cannister. To some degree, this
is actually water boiling....or the pressure in the system
falling to the vapor pressure of the water in the fat being
removed. It is this vaporization that makes the viscosity
(how thick it is) of fat, which is actually a combination
of fat, blood, and infiltration fluid, less to improve its
ease of flow through the tubing. From a flow standpoint,
water that is vaporized ( a gas) flows 100 times faster
than liquid water. This is also why liposuction done at
higher altitudes, where the water vapor of pressure is
less, is somewhat easier to do. (takes less suction from
the machine)
The tube (cannula) that is actually used under the skin
differs in diameter and the holes at the tip. In days gone
by, the cannulas were quite large but left a lot of
depressions in the overlying skin after due to removing too
much fat too fast and in large pieces. Today, small
cannulas are used which removes fat more carefully and in
smaller pieces, decreasing the problem of skin
irregularities after surgery. The tip of the cannula is
rounded so that it travels through the fat easier with less
chance of penetrating something you shouldn't. The holes at
the tip are where fat sticks to and then gets sucked into
the cannula. The more holes there are at the tip achieves
two effects; increases the shearing effect (like a blade)
on fat and makes more cross-sectional area through which
fat can be suctioned.
Currently, there are newer methods of liposuction or to be
accurate, methods of loosening up the fat. These include
ultrasonic and laser-assisted. While they sound quite
advanced (and they are), there is no convincing evidence at
this time that they are actually better than traditional
liposuction. Better meaning....you get more fat removed,
smoother results, and recover faster with less bruising and
pain. They are marketed by the manufactures as such but
there is no solid science to prove it. And they still
require suction to pull out much of the loosened or
liquefied fat.
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Dr Barry Eppley is a board-certified plastic surgeon in
private practice at Clarian Health in Indianapolis,
Indiana. He writes a daily blog on trends in plastic
surgery at http://www.exploreplasticsurgery.com
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