Energy Expenditure

EE: Practitioner Instructions for Measuring RMR (2006)

Practitioner Instructions for Measuring RMR

The instructions below apply to most patient/client situations in practice. When the patient/client consents to the IC measurement:

  • Explain the measurement procedure and answer any questions.
  • Review and/or modify the Patient Instructions for Measuring RMR. Change or add any additional guidelines, as appropriate, based upon the patient/client’s situation and the IC manufacturer’s guidelines.

In Preparation for the Measurement

It is recommended that the patient/client do the following to prepare for indirect calorimetry measurement:

  • Fast overnight or for at least five (5) hours prior to RMR measurement. If a five (5) hour fast would create medical risks, then a four (4) hour fast could be adequate if a small meal (i.e., 400 kcals or less) is consumed. If a very large meal (>900 kcals) is consumed prior to measurement, a six (6) hour or longer fast is recommended.
  • Refrain from exercise the day before and the day of the measurement or for at least two (2) hours after light aerobic exercise. With higher intensity exercise of longer duration, a rest period of 24 hours is probably acceptable, but 48 hours is preferable.
  • Refrain from nicotine or alcohol use for at least two (2) hours prior to the measurement.
  • Detail the medications, herbs, vitamins, minerals, or other supplements he/she takes for further consideration after the measurement is obtained.

The Day of the Indirect Calorimetry Measurement

On the day of the indirect calorimetry measurement you should:

  • Review the device instructions provided by the manufacturer to ensure compliance with all recommended guidelines.
    1. Calibrate the machine according to manufacturer’s instructions. The equipment must be operated by a trained individual. A system to demonstrate an individual’s current competence in the use and care of IC equipment must be in place and meet the defined expectations of an organization such as the Joint Commission on Accreditation of Healthcare Organizations.
    2. Confirm that no foods or fluids containing calories have been consumed for at least five (5) hours prior to the measurement.
  • Provide a 10-20-minute rest period for the patient/client prior to the measurement. At this time, review the measurement procedure and equipment and answer any questions.
  • Determine a position for the patient/client during the measurement:
    1. The truest and most reproducible resting metabolic rate measurement will be obtained in a lying position.  The upper body can be inclined slightly (less than 30 degrees) based on patient comfort.
    2. The next best alternative posture for measurement of metabolic rate is semi-recumbent, such as would be achieved with a reclining chair.  The resulting measurement may be higher than true resting, but not significantly so.
    3. The third best posture is sitting upright.  The resulting measurement is likely to be higher than true resting, and in any given individual can be significantly higher than resting.
  • Provide a quiet environment.
  • Conduct one 10-minute measurement (discarding the first five minutes). This time frame should be sufficient for an accurate reading. If steady state is not achieved, consider remeasuring or using an alternative method for establishing a RMR.
  • Ensure that no air leaks exist during the measurement. Comparable measures can be achieved with either a face mask, mouthpiece with nose clips, or canopy.
  • Explain the measured RMR and its relationship to overall daily energy expenditure to the patient/client.  Critically assess the value of RMR as part of the nutrition assessment (e.g., usual dietary intake and physical activity).
  • Document RMR, the intervention initiated, and the monitoring plan to assess the outcomes.