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Recommendations Summary

EE: Diurnal (Time of Day) Variation in Critically Ill 2013

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.

  • Recommendation(s)

    EE: Diurnal Variation in Critically Ill

    If the critically ill patient is mechanically ventilated and receiving continuous feedings, then the registered dietitian nutritionist (RDN) may conduct a measurement of resting metabolic rate (RMR) at any time of day, as long as resting conditions can be achieved. Likewise, if a measurement of total energy expenditure (TEE) is being considered, time of day does not need to be taken into account. Research indicates that there is no significant diurnal variation in either RMR or TEE in mechanically ventilated patients receiving continuous feedings. The effect of diurnal variation in critically ill patients who are not mechanically ventilated while receiving continuous feedings is unknown.

    Rating: Fair

    • Risks/Harms of Implementing This Recommendation

      There are no potential risks or harms associated with the application of this recommendation.

    • Conditions of Application

      Recommendation only applies to critically ill patients who are mechanically ventilated and receiving continuous feedings. 

    • Potential Costs Associated with Application

      There are no obvious costs associated with the application of this recommendation.

    • Recommendation Narrative

      Three studies were included in the evidence analysis for this recommendation:

      • One positive-quality non-randomized clinical trial (Frankenfield et al, 1994)
      • One neutral-quality cross-sectional study (van Lanschot et al, 1988)
      • One neutral-quality validity study (Zijlstra et al, 2007).

      Three studies provide evidence that there is no significant diurnal variation in REE or TEE in mechanically ventilated, critically ill patients receiving continuous feeding.

      Additional research is needed on critically ill patients who are spontaneously breathing, in the fasted state or being intermittently fed. Additionally, some of the existing research does not mention the level of sedation, so the effect of sedation on diurnal variation in RMR should also be clarified. Only one of three studies examined the diurnal variation in resting, as well as total energy expenditure, so new research on diurnal variation should encompass both measures of metabolic rate.

    • Recommendation Strength Rationale

      Conclusion statement is Grade II.

    • Minority Opinions