Measurement Information
Will MedGem give me oxygen consumption and RMR?
Yes, the MedGem indirect calorimeter provides you with oxygen consumption measurement and performs a simple calculation to display RMR in kcal/day. When the MedGem is used in conjunction with MedGem Analyzer software, you can monitor, view, store and print patient reports containing this information.
When should I perform an RMR measurement?
When using the MedGem calorimeter to measure oxygen consumption and determine RMR in a spontaneously breathing patient, it is important that the patient is calm and relaxed.
If the patient has been active or stressed, or has recently eaten or exercised, the rate of oxygen consumption that the MedGem measures will be accurate for that condition but may not be representative of actual resting metabolic rate (RMR).
- Patient should be rested and in a comfortable sitting or reclined position. If time permits, have the patient
- Patients who are in a non-rested state (e.g., recent physical therapy treatment, respiratory treatments including medications, chest percussion procedure, stressful event, recent physical activity) should rest in a sitting or reclined position for a minimum of 15 minutes before the measurement to allow the body to stabilize.
- Parenteral and enteral nutrients are infused at a continuous rate, thus thermal effect is stable throughout the day. The feeding does not need to be turned off.
- Supplemental oxygen (i.e., nasal cannulas or mask) is not being administered to the patient.
- Measurements are made in a quiet, thermoneutral environment. With repeat testing, measurements should be taken at the same time of day under similar conditions.
Reference: Feurer ID, Mullen JL. Bedside Measurement of Resting Energy Expenditure and Respiratory Quotient via Indirect Calorimetry. Nutr. Clin. Pract. 1986; 1:43–49.
Why it is necessary to measure oxygen consumption?
Most healthcare professionals recognize that resting metabolic rate is impacted by unique characteristics such as age, obesity, body composition (muscle versus fat), recent weight changes, disease state, surgery, fever, stress and medications.
When managing a patient’s nutritional needs, knowledge of resting metabolic rate is critically important for accurately assessing a patient’s unique nutritional needs, helping the healthcare professional prevent over- or underfeeding, minimizing post-op complications and reducing length of stay.
The MedGem accurately measures patient respiratory airflow and oxygen consumption.
MedGem is a scientifically validated tool that will improve patient care through accurate, personal nutrition assessment.
How often should I perform a MedGem Metabolic Test?
In the clinical setting, a patient’s metabolic rate may increase or decrease significantly depending on clinical status. For example, when a patient develops a fever, the patient’s metabolic rate may increase.
Monitoring these changes will allow the healthcare professional to revise nutritional recommendations to meet the patient’s changing nutritional needs. In some instances, this will mean monitoring the metabolic rate daily or weekly.
Why is CO2 (Carbon Dioxide) not measured?
The intended use of MedGem is for measuring oxygen consumption and determining RMR.
RMR can be accurately determined from VO2 alone without the need for measurement of CO2.
How does the MedGem handle RQ?
The MedGem measures VO2 consumption and calculates RMR based on a constant RQ of 0.85. This is accomplished without measurement of CO2 production.
Under both normal and pathophysiologic conditions, it is extremely rare for a person to have a true metabolic RQ outside the range of 0.75 to 0.95.
Within this range of RQ’s, the use of a constant RQ of 0.85 has a maximum error of ± 2.3%.
I did two MedGem measurements and I got different results. Why?
RMR can vary each day and even within the same day. Fever, illness or stress may result in a varying metabolic rate, which is why frequent measurement is recommended in patients in clinical settings.
Monitoring changes in metabolic rate provides a more accurate means of assessing nutritional needs for better patient outcome.
Make sure that measurements are performed under similar conditions. Make sure that your patient relaxes and breathes normally during the measurement.
What does the RMR reading on the MedGem mean?
This kilocalorie (kcal/day) number represents the resting metabolic rate (RMR), or the number of calories the body burns each day at rest. (RMR is also referred to as resting energy expenditure, or REE). RMR can represent up to 100% of total metabolism in the acute patient.
The measurement captured by the MedGem accounts for stress and/or injury factors because VO2 is being measured, not calculated from a formula.
Typically, hospitalized patients have a low level of activity, thus RMR represents the majority of the total metabolism and provides the basis for accurate nutritional assessment.
The VO2 and RMR measurement provided by the MedGem will help you accurately determine patient nutritional need and monitor changes in metabolism that may impact nutritional adjustments on a regular basis.
Who can use the MedGem?
Any clinician monitoring patient nutritional needs, including dietitians, diet technicians, respiratory therapists, technicians, nurses and physicians can benefit by using MedGem on their patients for more accurate assessment of nutritional needs.
What types of patients will benefit from having their oxygen consumption measured?
There are many types of patients who can benefit from having their oxygen consumption measured to determine RMR.
Examples include patients at risk for diabetes; patients with a diagnosis of diabetes, COPD, cancer, cardiovascular and renal patients; overweight and obese patients; all patients requiring a nutritional assessment; burn patients; and geriatric patients.
Understanding individual nutritional needs typically results in greater control by the patient and better patient outcomes.
How long does it take to get a measurement result?
It takes between 5–10 minutes to get a result. Measurement time will vary depending on the time it takes for each patient to reach a steady state of breathing.
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.
What if my patient is taking medications that might affect the RMR?
If a patient is on any medications that contain stimulants or depressants, there will be a commensurate impact on RMR.
The clinician administering the measurement is best suited to determine whether the measurement should be taken when the patient is on the medication or whether the measurement should wait until medication use has been stopped for a period of time.
Thyroid medication will not impact measurement results even if the medication is taken right before a measurement as this is part of a normal regime for a patient and will be considered part of the patient’s “normal” state.
When using inhalers, it is preferred to have the patient refrain from usage immediately prior to a MedGem measurement. If the patient is unable to perform them measurement without using an inhaler, rescheduling of the test is suggested.
Will smoking affect the MedGem measurement?
Nicotine will increase resting metabolic rate because it is a stimulant. If the patient is a smoker this is the “normal” state and measurement will reflect the patient’s individual metabolic rate.
When performing a measurement, encourage the patient not to smoke immediately prior to a measurement. If a patient quits smoking, monitoring changes in RMR is recommended to adjust calorie levels.
MedGem Use
How accurate is the MedGem measurement?
The MedGem unit has been validated against the Douglas Bag method, the gold standard in metabolic Measurements, and compared to other metabolic carts.
The BodyGem unit is as accurate and reliable as any indirect calorimeter system on the market. In several studies the BodyGem has repeatedly demonstrated an accuracy of 1-3% when compared to other standard reference systems.
The MedGem’s portability makes measuring metabolism possible for most individuals and professionals.
Can I reuse the mouthpiece?
No. By FDA regulation, the disposable mouthpiece may only be used for a single measurement and should be discarded after each test.
Subsequent measurements on the same person require the use of a new breathing attachment.
The single-use breathing attachments should be discarded after a successful measurement to avoid cross-contamination.
How do I order new mouthpieces/nose clips?
You can order new BodyGem mouthpieces and MedGem mouthpieces through David Wilcoxson at 303-808-2291.
I get an error message when trying to start the measurement or warm up the device.
Refer to the MedGem Operator’s Manual for specific error code information.
When do I know the MedGem is calibrated?
After you have pressed the start button on the top of the unit, the MedGem will begin its self-calibration process and the indicator light will flash amber.
At the completion of calibration, the MedGem will beep and the indicator light will flash green. You are now ready to begin the measurement.
Measurement needs to begin within one minute of completion of the calibration.
If the measurement is not started within this time frame, the indicator light will turn amber, indicating “stand-by” mode.
How do I know the MedGem calibrated correctly?
The MedGem is designed to self calibrate. If calibration is not completed, an error code will appear in the LCD and the indicator light on top of the MedGem will turn red.
Refer to the MedGem Operator’s Manual for explanation of error codes.
I keep getting an air leak error when I take a measurement. How do I prevent this?
Make sure that the mouthpiece is firmly attached to the MedGem unit. The insert should fit snugly and be flush with the unit. The nose clip should completely close off air passage into the nose. The patient should be breathing through the mouth.
How do I clean the MedGem?
If necessary, wipe MedGem’s outside surfaces with a clean dry cloth (no cleaning agents). Do not submerge the MedGem in water or allow water or any solution to penetrate the display windows, sockets or openings on the product.
How do I store the MedGem?
The MedGem should be stored in its carrying case overnight or when not in use for prolonged periods of time.
For more information, click on MedGem