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The
8th Annual AIDS Meal and Nutrition Providers' Conference held in Philadelphia,
Pennsylvania this past September featured two workshops on BIA. Featured
speakers were clinical HIV specialists Cade Fields-Gardner, MS, RD, LD,
CD and Brenda Lazin, MS, RD. This article contains many of the questions
voiced by clinicians attending the sessions and answers offered by the
presenters.
Question: What
is BIA and how does it work?
Answer: BIA is
a relatively quick way to estimate fat and fat-free tissues in the
body. The BIA instrument sends a painless electric current through the
body with the use of electrodes. In addition to telling you approximately
how much muscle and organ tissue a body has, BIA helps to estimate other
lean stores and fat stores. It is important to note that BIA is much more
helpful to measure lean body tissues when disease-appropriate equations
are used. Whole-body methods of BIA cannot detect lipodystrophy or alterations
in fat distribution. Regional BIA should be able to detect increases
and decreases in fat tissues, but standardization of these methods have
not yet been accomplished.
Question: Why is
BIA important?
Answer: Body weight
may not be as good of an indicator of nutritional status. Anthropometric
measurements (such as height, weight, and other body measures) along with
BIA are the preferred way to assess weight changes and a better indicator
of functional status than body weight. BIA is helpful to follow changes
in body composition and is especially useful to check for or monitor lean
tissue wasting in people living with HIV infection. It has been recommended
that all HIV-positive individuals have a baseline BIA.
Question: What
is the correct body position when performing BIA tests?
Answer: The most
important thing to remember is consistency. Every time you perform a BIA,
your methods and procedures should always be the same. This will help reduce
operator error and allow for more accurate results. If a test is done outside
of ideal conditions, make a note of it on the report. Follow these suggestions
to properly position the client.
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The client should be laying
down flat (supine) with legs and arms slightly apart from the body so that
they don’t touch.
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Body parts should not touch
the wall or any electricity-conducting surface.
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The shoulders should be flat.
If the client is uncomfortable, a pillow may be used under the head, but
should not elevate the shoulders.
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The reading should be taken
within about five minutes of the patient lying down to prevent blood from
pooling at any of the extremities or in the central part of the body. If
it takes longer than expected, have the patient stand up and walk around
for a couple of minutes and lie down again for the test.
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