MedGem Indirect Calorimeter

MedGem is a clinically-validated and FDA 510K-cleared, class II, medical device for measurement of patient resting metabolic rate (RMR).

The MedGem

MedGem is a clinically-validated and FDA 510K-cleared, class II, medical device for measurement of patient resting metabolic rate (RMR).

The MedGem is an easy-to-use, handheld device that accurately measures oxygen consumption (VO2) to determine resting metabolic rate (RMR)*. Measurements made with The MedGem are easy to administer and provide accurate results in only a few minutes.

MedGem Dimensions
5.5 x 5.5 x 11.5 cm ( 2.2 x 2.2 x 4.5 in)
MedGem Weight:
110 gm ( 4 oz)

Measurement Specifications
Tidal Volume:
V02 Range:
V02 Resolution:
RMR Range:
RMR Resolution:
500 to 1500 ml/min 
72 to 721 ml/min 
1 ml/min 
500 to 5000 Kcals/day 
10 Kcals/day
5-10 minutes

Operating Enviroment
Relative Humidity
-30 to 3040 meters ( - 100 to 10,000 feet) 
15° to 30° C ( 59° to 86° F)  
10% to 88% RH Non-condensing

Storage Enviroment
Relative Humidity
10° to 50° C ( 14° to 122° F)  
5% to 95% RH Non-condensing

Data Port
RS-232 Serial Port
Accuracy / Reliability*                               ± 99% /  r = 0.91
There are no user serviceable parts in the MedGem device, please return to Microlife Medical Home Solutions, Inc. for servicing.

"The MedGem may be a useful clinical tool when the Delta-Trac indirect calorimeter is not available....5 predictive equations compared to the MedGem measurement found none of the equations had acceptable bias and precision among overweight and obese adults." 

Ziegler et al. 2010


"The portable MedGem may assist research dietitians in determining energy needs of racially diverse populations of middle-aged overweight and obese women."

Spears et al. 2009


"The use of the MedGem may provide clinicians a diagnostic tool for tailoring a nutrition message specific to each client."

McDoniel et al. 2008


"Cardiac output determinations made with the MedGem's measurements of oxygen uptake are clinically acceptable."

Shepherd et al. 2007


 "The MedGem hand-held indirect calorimeter has potential application in clinical evaluations in which typical metabolic carts or other standard methods  are not practical. 

Fields et al. 2006


The MedGem can be used to accurately measure oxygen consumption and  RMR in capacities where a traditional metabolic cart would not be practical or cost-effective.    

Stewart et al. 2005


"The MedGem provides a quick and convenient estimate of RMR in children that  is accurate and reliable, and should facilitate the process of pediatric weight management counseling.     

Nieman et al. 2005

MedGem Analyzer is a companion software application used with the MedGem® indirect calorimeter. Healthcare professionals can provide patients and clients with a more accurate nutritional assessment and medical nutrition therapy. Individual Metabolic FingerprintTM measurements can be viewed, stored and utilized to develop personalized calorie budgets for clients and patients. Detailed professional and individual take-home reports are conveniently provided by MedGem Analyzer.


What do the VO2 and RMR values on the MedGem device mean?

The VO2 value displayed on the MedGem device LCD screen indicates the volume of oxygen a patient consumes at rest in milliliters per minute. This value is not needed when providing nutritional assessments. Resting VO2 is sometimes used by healthcare professionals such as cardiologists and respiratory therapists. The RMR value displayed on the MedGem device LCD screen indicates the number of calories the body burns each day at rest. RMR is synonymous with resting energy expenditure or REE. RMR can represent up to 100% of total metabolism in the acute patient. Because the MedGem device measures the amount of oxygen a patient consumes rather than calculating it from a formula, stress or injury factors do not need to be added to the final, measured RMR value. The RMR measurement provided by the MedGem device will help you accurately determine patients' nutritional needs and regularly monitor changes in metabolism that may impact those needs.

Why it is necessary to measure oxygen consumption?

Resting metabolic rate is impacted by unique characteristics such as age, obesity, body composition, 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 prevent over- or underfeeding, minimizing post-op complications and reducing length of stay. The MedGem     device is a scientifically validated tool that accurately measures a patient's oxygen consumption            and will improve patient care through accurate, personal nutrition assessment.

How do I know the MedGem device is calibrated?

After you have pressed the start button on the top of the unit, the MedGem device will begin its self-calibration process and the indicator light will flash amber. At the completion of calibration, the MedGem device will beep and the indicator light will flash green. You are now ready to begin the measurement. The measurement needs to begin within one minute of the completion of the calibration. If the measurement is not started within this time frame, the indicator light will turn amber, indicating 'stand-by' mode. It is important to remember that you should not    move the device while it is calibrating.

How does the MedGem device know when the RMR reading is completed?

The MedGem device measures the volume and concentration of oxygen consumed. The RMR measurement is complete when steady state oxygen consumption is detected. The Weir equation is then applied to convert the VO2 into calories per day.

How often should I perform a measurement?

In the clinical setting, a patient's metabolic rate may increase or decrease significantly depending on their clinical status. For example, when a patient develops a fever, a corresponding rise in metabolic rate may occur. 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.

Are RMR measurements affected by a patient's medications?

If a patient is on medications that stimulate or depress the central nervous system, RMR will be             affected. The health care professional administering the RMR measurement is best suited to determine whether the measurement should be taken when the patient is on the medication or whether the measurement should be delayed until medication use has been stopped for a period    of time. It is important to note that if a patient is on a chronic medication, it is considered part of their normal physiological state and this will be reflected in their measured RMR. If a patient is on an acute regimen of medication, it may not reflect their normal physiological state and the measured RMR may not be indicative of their normal state measured with the MedGem device.

The MedGem device measures oxygen consumption and determines RMR based on a constant respiratory quotient (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 RQs, the use of a constant RQ of 0.85 has a maximum error of only ±2.2%.