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Energy Expenditure

EE: Benefits and Risks/Harms of Implementation (2013)

Benefits and Risks/Harms of Implementing the Recommendations

Safety issues should be considered for each recommendation. A description of the general benefits and risks associated with the implementation of this guideline must be addressed.

Failure to measure the resting metabolic rate (RMR) accurately may result in incorrect diagnosis of the energy state, inaccurate therapy for patients who want to gain or lose body weight, or overfeeding or underfeeding of critically ill patients.

Not following the guideline may result in inappropriate nutrition support due to inaccurate RMR measurement.

To view more information, select the link to the topic listed after each potential benefit/harm.

Potential Benefits

The primary goal of implementing these recommendations includes improving the percentage of individuals who are able to meet their nutritional needs and positively impact the patient’s treatment and clinical outcomes.

Risk/Harm Considerations

  • If the patient is dependent on supplemental oxygen, do not attempt to measure RMR. With supplemental oxygen, the indirect calorimeter will provide invalid measurements of RMR (Brandi et al, 1997; Matarese, 1997; and McClave and Snider, 1992). (EEU: Gas Collection Devices)
  • Moving the patient only for the measurement of indirect calorimetry may increase the risk of injury, pain, and negative health outcomes to patients (PHAMA, 2010). (EEU: Body Positions)

Technical Factors That Decrease the Accuracy of Indirect Calorimetry Measurements

  • Mechanical ventilation with FIO2 ≥ 60% or unstable FIO2 (> ±0.01)
  • Mechanical ventilation with PEEP > 12 cm H2O
  • Hyperventilation or hypoventilation
  • Sampling system leak
  • Excessive moisture in the indirect calorimetry system
  • Failure to collect all expiratory flow (e.g., bronchopleural fistula, chest tube leak, etc.)
  • Supplemental oxygen in spontaneously breathing patients
  • Hemodialysis in progress
  • Calibration errors.

Reference: Matarese LE. Indirect calorimetry: technical aspects. J Am Diet Assoc. 1997 Oct; 97 (10 Suppl 2): S154-S160. Review. PMID:9336580.

Factors to Consider Before, During and After an RMR Measurement

  • Critically ill adult patients who are intubated must be measured through the mechanical ventilator. (EE: Gas Collection Devices
  • Logistical considerations (e.g., patient comfort, injuries to the face, tubes in the nose or mouth, claustrophobia) should be taken into account when selecting a gas collection device (Brandi, 1997). (EE: Gas Collection Devices) 
  • If the patient is in a cool room, but adequately covered, impact of ambient temperature is likely minimized. (EE: Room Conditions)
  • If the ambient temperature in the ICU is too low or too high, the indirect calorimetry measurement may not reflect RMR. (EE: Room Conditions)
  • If the patient is not in a hypothermia protocol, but in a cooler environment, use of a blanket may be helpful to eliminate the impact of the a low room temperature (Claessens-van Ooijen et al, 2006). (EE: Room Conditions)
  • If the patient is in a hypothermia protocol (brain injury or cardiac) for 24 hours or less, do not measure RMR until rewarming is accomplished. If greater than 24 hours, measure RMR and then remeasure again when rewarming is accomplished. (EE: Room Conditions)
  • The RDN should inquire with the interdisciplinary team to determine if the patient's position is temporary or permanent. (EE: Body Positions)
  • Sedation might reduce the time it takes to return to rest after routine ICU care, but the effect is not known (EE: Rest Period Duration)
  • Further studies are needed to identify the optimal wait time after procedures, such as surgery and hemodialysis (EE: Rest Period Duration)
  • Coordination with other healthcare professionals (e.g., nurse, respiratory therapy) is needed to ensure a sufficient wait time. (EE: Rest Period Duration) and to schedule the measurement (s). [EE: Duration of Measurement (Steady State)]
  • If the 30-minute wait time cannot be achieved, then the measurement should be rescheduled or a measurement of TEE may be attempted. Additional costs may occur due to increased time. (EE: Rest Period Duration)
  • Early morning measurements may be most practical, when the patient is least likely to be disturbed. [EE: Duration of Measurement (Steady State)]
  • The recommendation EE: Measurement Duration If Unable to Achieve Steady State in Critically Ill may be associated with increased time cost. [EE: Duration of Measurement (Steady State)]
  • The RDN should use clinical judgment to determine if energy intake is in balance with the measured RMR, including calories from medication and IV fluids in the total energy intake calculation. (EE: Application of RQ)