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Frequently Asked Questions (cont.)
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Clinical Variations
What if my patient’s protein intake is greater or less than 16%?
Although the protein assumption does make some difference in the RMR, it is very minor. The error for each
percent change in protein is about 0.12% change in RMR.
What if my patient is on continuous enteral or parenteral feedings?
If a patient has a continuous feeding tube (enteral or parenteral) you can still measure resting metabolic
rate. Although resting metabolic rate is usually measured under fasting conditions, it is acceptable to
measure a patient with a feeding tube if all other conditions mimic the resting state and a leak-free seal can
be achieved.
Will eating or receiving bolus enteral or parenteral feeding effect the MedGem
measurement?
Feeding will cause a transient increase in RMR from 1–5%.
What if my patient has a fever or injury, or is taking medication that might impact
measurement?
Measuring resting metabolic rate becomes important during times of fever, injury or other clinical situations
that may significantly impact nutritional needs. Under these conditions, more frequent measurements are
recommended to monitor changes in the metabolic rate to guide adjustments in nutritional requirements.
Do I need to add an injury or stress factor when using the MedGem?
No. The addition of stress or injury factors to the MedGem measurement result is not necessary.
Predictive equations do not incorporate injury factors, which has lead to the practice of adjusting the
equation results by adding in a measure for the severity of the disease. Oxygen consumption is impacted by
unique characteristics such as age, obesity, body composition, disease state, surgery, fever, stress and
medications. Because the MedGem Indirect Calorimeter measures oxygen consumption, each client’s
unique characteristics, underlying pre-existing conditions, and complications that can occur with the disease
are accounted for.
Why is metabolic rate unique to each individual and why does it change?
RMR can vary significantly from patient to patient, even between two people of the same age, gender,
height and weight. Metabolic rate is influenced by a number of factors, including body weight, body
composition (the amount of fat and muscle), age, gender, hormones, stress, disease state or process, and
medications. Changes in these factors can affect metabolism.
My patient has lost weight. Why is his/her metabolism lower?
Metabolism is influenced by total body mass (body weight). With weight loss, total body mass is lower and it
takes less energy for the body to maintain vital functions. A decrease in metabolism during weight loss is
normal. An increase in lean body mass can help maintain a higher resting metabolic rate and can potentially
offset the effects of lower body weight and calorie restriction.
Are there any specific age or weight requirements for using the MedGem?
There are no absolute standards based on age or weight. MedGem is programmed to a lower limit of 500
kcal/day for resting metabolic rate. A patient of any age needs to be able to sustain a measurement lasting
for up to 10 minutes.
