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| Basic BIA |
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Ready? The first requirement is that you get a good height and good weight on the people you are testing. A height is the most important measure you will take to punch into the equations, so do it right! With adults, you only need one to get a good height once, so this is not too difficult. Keep in mind that most people really don’t know their height, and with many people the last time they were measured was in their grandparent's kitchen, complete with the requisite pencil marks on the wall. And given the way most Americans access their health care, by only going in when there is a problem, many adults haven’t ever been measured accurately.
I'm 5' 10". I think we're about the same height. How tall are you? Oh, about 6' 2". See, I think Michael Jordan and I are about the same height...
How many times have you heard that from someone you were talking with, where they said their height was something you knew was inaccurate? So let's make sure this one time you do it right--and besides, this measurement, if done correctly, will give you accurate numbers for the BIA equations. The person you measure should be standing in stocking feet as straight and as tall as possible. You will need to measure them with a non-stretchable tape measure that is mounted (with screws or even duct tape) securely to the wall. Additionally, use a triangle on top of their head and against the wall to get the real number. A ruler or pencil above the head can move enough to make your subject an inch taller or shorter.
Now you can have the person remove their socks (or stockings or whatever foot covering they still have on) and lie flat on their back on a non-conducting surface. An exam table or mat on the floor or folded-thick blanket on a table will usually do.
They should have their arms and legs spread apart enough to
make sure that they don’t touch their torso or each other (see illustration
at right). If this is not possible (click on image to see a larger view) You can then swab the areas around where the electrodes will be placed on the hand and foot. You will want to use the right hand side of the body unless something prevents that (such as amputation or injury on that side). The skin should be clean and dry. Lotion, sweat, and Vaseline-like substances can mess up your reading, so make sure that they are well cleaned off. Place the electrodes as shown in the illustration below with the correct colors that coordinate with the manufacturers instructions (yes, it will make a difference in your reading with which one goes where!). The most crucial placement is the one on the wrist and ankle. Take a look at this illustration:
Now you can turn the machine on according to the manufacturer’s instructions. You will want to record the resistance (a 3-digit number between 200 and 800) and the reactance (a 2-digit number between 20 and 100). Just a tip: have your pencil and paper (or other recording devices) handy. It is not worth making a mistake because you tried to remember these numbers when walking to the other room to record it.
If you get wacky numbers, do some trouble shooting right then and there. Otherwise, you will have to retake the reading or maybe even throw out the reading…and what use is that? Plus, if you are taking the readings at a remote site, or anywhere the patient has to come to you to have their BIA done, you may not realize you need to redo their measures until after they have left.
Once you get the numbers you can input the information, run a report, and interpret the information. Oh, and don't forget to have the patient put their shoes and socks back on (you can always tell the rookies because their patients are always walking out after being tested carrying their shoes!). You will need the following information:
Height Weight Sex Resistance Reactance
It will be helpful to estimate a frame size when you get ready to interpret the report. Though it may be painful to those rusty brain cells, you will need to know how to interpret this information. So let's take a look.
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