GENERAL FAQ'S
PERFORMING A BIA TEST
Should the test subject lie down to be tested?
Yes. All research has been performed with the subject lying flat with legs apart and arms not touching the body, therefore it is recommended that the test subject lie down to be tested.
What side of the body is used for BIA testing?
The right side of the body is commonly used for BIA testing. However, the left side of the body may be used if necessary. It is important to be consistent and use the same side on a test subject for repeatability.
Can you feel the test while it is being performed?
No, the current passed through the body is so small that it is unlikely it will be felt at all.
How long does it take to perform a BIA test on a subject?
Typically, the test will take approximately five minutes, including entering the information into the software and generating the report.
What electrodes can be used for testing?
RJL Systems, Inc. (RJL) suggests that the tests be performed using the adhesive electrodes supplied by them. RJL cannot guarantee accurate test results acquired by using other electrodes.
Do I have to use new electrodes for every test subject?
Yes, for accuracy, and above all, for sanitary reasons, new electrodes should be used for each test performed.
Can the age of electrodes affect results?
Yes, RJL electrodes have a shelf life of 14 months. Expired electrodes will produce inaccurate results. As well, if electrodes are not kept in a sealed bag or container, they can dry out and also produce inaccurate results.
Is there anything particular that the test subject should do prior to being tested with the RJL Analyzer?
The test subjects body should be dry; no fever should be present, and should not be chilled or cold. Please review “Subject Protocol” on the “Electrode Placement” card.
Could very dry or very oily skin affect the BIA readings?
Yes. Good contact between the skin and electrodes must be made for accurate results. If a person’s skin is oily, wipe the area with an alcohol swab before positioning the electrodes. If the skin is very dry, use an electrode gel.
Will jewelry affect the BIA test?
No, there will be no effect on the BIA test provided the jewelry does not interfere with electrode placement. However we recommend that all jewelry be removed.
Do pins or rods in a subject’s arms or legs affect the BIA readings?
If they are metallic and within the signal path, yes, they can impact the readings. If the person only has pins or rods on one side of the body, test the person on the opposite side. If the implants are bilateral, the person can still be tested, with the understanding that the estimated body composition values may not be accurate. HOWEVER, serial measurements would allow you to track which direction each compartment is trending, even if you didn’t have any confidence in the specific value reported.
Can people with implanted devices such as defibrillators, pacemakers, medication pumps, etc be tested with the RJL analyzers?
There are two issues to consider in attempting to answer this type of question:
- Could the other device interfere with the RJL Analyzer?
- Could the RJL Analyzer interfere with the other device? support@rjlsystems.com or contact us by phone.RJL Systems’ analyzers measure impedance using a 50 kHz sinusoidal signal that adheres to the requirements of IEC 60601-1:2007 for Patient Auxiliary Current in a Type BF applied device.
Will medication affect the reliability of the BIA test?
Changes in the results may come from medications, disease and nutritional status. BIA results quantitatively illustrate all of these factors and conditions. That’s what BIA is all about!
Can obese or emaciated test subjects be tested with the RJL analyzers?
Yes, and serial testing will reflect changes in a person’s body composition.
Can pregnant women be tested with the RJL analyzers?
No. None of the equations provided by RJL Systems have been validated for use during pregnancy, and with all of the changes that occur in the woman’s body and in the developing child, you could not be confident in the accuracy of the body composition estimates.
At what age can children be tested?
Equations were developed on children beginning at age 4. However, people of any age may be tested for resistance and reactance results.
Are medical professionals the only people that should perform the BIA test?
No, anyone that has been properly trained can perform the test. Once trained, a technician should be able to retest a patient (changing electrodes) to within a 1% difference in the resistance reading.
BIA VALIDITY
Is it possible to have too little body fat?
Yes, your body needs some fat for energy storage and normal metabolic functions.
Does RJL have software specific to race or nationality?
Our software includes several different collections of equations (called “equation sets”) to choose from, for calculating the body composition estimates. Some of these equation sets are labeled as being specific to a certain ethnicity or body type. These equation sets use equations for estimating body fat that were either developed in a study that only evaluated people of that group or were developed in a more general study but then were specifically validated for use in that group in a follow-up study.
In general, however, most people should be just fine using one of the more general-population equation sets like NHANES-III.
Have the RJL analyzers been tested on any animals?
Yes, they include: cats, dogs, fish, cows, elk, seals, polar bears, grizzly bears, orangutans, pigs, lambs, moose, deer, rats and mice, to name just a few.
That being said, please keep in mind that RJL does not provide software or equations for body composition estimates for any species other than humans.
To evaluate body composition in non-human species, you will need to find published equations that have been either developed or cross-validated for your study population and you will need to replicate the test protocol (including electrode site preparation, electrode type, and placement) used by the original researcher(s).
ANALYZERS
How will I know if my RJL Analyzer is operating correctly?
A 500-ohm resistor is included with all the RJL analyzers. This resistor allows you to check the calibration of the analyzer. For an explanation on how to test the calibration of your unit, please refer to the manual.
Is there any chance of an electrical shock while operating the RJL Analyzers?
No, all of the RJL analyzers are designed with isolation transformers that prevent any harmful current from being exposed to the subject while being tested.
Will climate affect the BIA test?
Yes, but only when the climate changes are extreme.
Is the RJL equipment FDA approved?
The Food and Drug Administration regulates all BIA devices as class II medical devices. Manufacturers must receive clearance from the FDA to market a class II device. Please visit the FDA website for more information on RJL registration and clearances. ( FDA Website – search for RJL Systems under Applicant Name or Owner Name.)
What is the life expectancy of an RJL Analyzer?
So long as you take care of your analyzer, it can last a long time. RJL has many of their customers (from as far back as 1980) using their originally purchased analyzers.