Energy Expenditure

EE: Flowchart: Obtaining, Interpreting, and Reassessing the RMR Value (2006)

Flowchart for Carrying Out Indirect Calorimetry Measurements

Below are the instructions for using the flowchart. 

Three action steps appear on the flowchart:

Step one is to determine if the RMR should be estimated or measured. Because unexpected RMR results can occur,

Step two is to use critical thinking skills to evaluate the RMR.

Step three is to determine when the RMR should be re-evaluated. The flow chart illustrates these decision points and factors to consider when the RMR is part of the nutrition care process.

Step One: Estimating versus measuring RMR

A number of factors should be evaluated when a dietetics professional considers whether to estimate or measure RMR. The common RMR prediction equations can be easily used without any equipment. However, significant limitations do exist. New, portable, and cost-effective indirect calorimeters offer professionals an alternative to the prediction equations. Moreover, indirect calorimetry may be indicated when RMR measurement precision is important to the outcomes (e.g. a client with unexpected weight loss or medically-dangerous weight gain), the individual is from a racial or ethnic population, or > 80 years of age, measurement of RMR by .

Individuals not eligible for indirect calorimetry measurement include those who:

  • Require nasal oxygen supplementation
  • Complain of upper respiratory infection symptoms
  • Have a nasal or oral tube in place

Also, the new, portable indirect calorimeters cannot be used with patients requiring mechanical ventilation. A metabolic cart must be used to measure RMR.

Step Two: Factors to consider when measuring RMR

Whether RMR is estimated or measured, good clinical judgment is needed to evaluate any RMR value when used in the nutrition care process (2). Critical thinking, as part of a patient/client’s nutrition care, includes integrating and evaluating objective measurements and practice experience. It is necessary to interpret RMR values since

  • different factors may affect prediction and measurement (Table 4)
  • medications can affect measurement (Table 5)

In both cases, unexpected RMR results can occur, and proper interpretation of indirect calorimetry results requires critical thinking.


Step Three: Reassessing the RMR



Finally, as with any nutrition care plan, individual monitoring and evaluation for the patient/client’s response to the intervention is needed.  Re-assessment of RMR is warranted when:

  • Weight remains unchanged or the change is contrary to the desired loss or gain (this excludes changes in weight due to fluid status)
  • Medication affecting RMR has been initiated or discontinued (refer to Table 5 for more information regarding medications)
  • Change in condition that is likely to affect RMR occurs:
    • potentially decreasing RMR—for example, significant weight loss, improvement in medical status (e.g., recovery from trauma, head injury, surgery)
    • potentially increasing RMR—for example, fever, infection, surgery, wounds, initiation of rigorous therapy regimen (e.g. rehabilitation), significant increase in lean body mass

View the flowchart graphic to see how these steps fit into the larger decision-making framework.