CI: Impact of Environmental Factors on RMR Measurement: Noise, Lighting and Temperature 2006
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.
CI: Impact of Environmental Factors on RMR
Ensure that the room is comfortably quiet, and the light is not providing heat or discomfort for the patient. Noise and light may cause erroneous measures of RMR if the critically ill patient's state of rest is disturbed.
CI: Impact of Room Temperature on RMR
Recommend a room temperature 20 to 25 degrees Celsius (68 to 77 degrees Fahrenheit). When the room's temperature is too cold, RMR is overestimated in critically ill patients by shivering or non-shivering thermogenesis, as the body adapts.
Risks/Harms of Implementing This Recommendation
No potential risks and harms are associated with the application of this recommendation.
Conditions of Application
- Potential barrier: If the ambient temperature in the ICU is low, it will be difficult to measure RMR accurately
- It may not be possible to change environmental temperature in the ICU, but use of a light blanket may be helpful to eliminate the impact of the low room temperature.
Potential Costs Associated with Application
No obvious costs are associated with the application of this recommendation.
Resting metabolic rate is affected to variable degrees by moderate cold exposure or ambient room temperatures outside a comfortable zone (22 to 25°C or 72 to 75°F), according to one positive quality repeated-measures study (Van Ooijen et al, 2004)
In this study of 10 women and 10 men (19 to 36 years with BMI of 17kg/m2 to 32kg/m2), the individual change in RMR after three hours of exposure to moderate cold (15°C or 59°F), compared to RMR at typical ambient temperature, ranged from a decrease of 4% to an increase of 30% in winter and from a decrease of 12% to an increase of 24% in summer.
Two neutral quality narrative reviews recommend RMR measurement in a thermoneutral temperature room (Feurer and Mullen, 1987; McClave and Snider, 1992)
It is the consensus of the expert panel that at temperatures within the usual zone of comfort for humans, no changes in RMR, based on adjustment to ambient temperature, are observed.
Noise and Light
- There were no primary research studies that addressed the effects of ambient noise and lighting on RMR in healthy adults
- Two neutral quality narrative reviews, however, suggest that the room should be quiet and lighting mild when measuring RMR for patients in critical care settings (Feurer and Mullen, 1987; McClave and Snider, 1992)
- These conditions logically extend to other settings.
Recommendation Strength Rationale
CI: Impact of Environmental Factors
There was only one positive quality study available to evaluate.
- Reviews generally recommend a thermoneutral environment, but with no evidence basis
- Conclusion statement is Grade III.
CI: Impact of Room Temperature
The recommendation is based on two reviews, but no primary research studies.
- Conclusion statement is Grade IV.
- Risks/Harms of Implementing This Recommendation
The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).
Is control of noise and light changes necessary to ensure an accurate RMR measure by indirect calorimetry in ill adult patients?
Is control of temperature necessary to ensure an accurate RMR measure by indirect calorimetry in ill adult patients?
Feurer I, Mullen JL. Bedside measurement of resting energy expenditure and respiratory quotient via indirect calorimetry. Nutr Clin Prac 1986; 1: 43-49.
van Ooijen AMJ, van Marken Lichtenbelt WD, van Steenhoven AA, Westerterp KR. Seasonal changes in metabolic and temperature responses to cold air in humans. Physiology & Behavior. 2004; 82: 545-553.
References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process
Compher C, Frankenfield D, Keim N, Roth-Yousey L; Evidence Analysis Working Group. Best practice methods to apply to measurement of resting metabolic rate in adults: a systematic review. J Am Diet Assoc. 2006 Jun; 106 (6): 881-903. Review.