EE: Room Conditions 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.
EE: Room Conditions for Measuring RMR in Critically Ill Patients
The registered dietitian nutritionist (RDN) should ensure resting metabolic rate (RMR) is measured in a quiet, thermoneutral environment for the critically ill population. Cool room temperatures or drafts may generate shivering and nonshivering thermogenesis. Research is needed to define the range of thermoneutrality for the critically ill population.
Risks/Harms of Implementing This Recommendation
There are no potential risks or harms associated with the application of this recommendation.
Conditions of Application
- This recommendation does not apply to burn patients
- If the ambient temperature in the ICU is too low or too high, the indirect calorimetry measurement may not reflect RMR
- 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 a low room temperature (Claessens-van Ooijen et al, 2006)
- If the patient is in a cool room, but adequately covered, impact of ambient temperature is likely minimized
- If the patient is in a hypothermia protocol (brain injury or cardiac) for 24 hours or less, do not measure RMR until re-warming is accomplished. If greater than 24 hours, measure RMR and then remeasure again when rewarming is accomplished.
Potential Costs Associated with Application
There are no obvious costs that may be associated with the application of this recommendation.
No original studies in critically ill patients were found to support this recommendation. However, one study in healthy people and three review articles provide support to the consensus opinion expressed for this recommendation.
Two review articles (Feurer and Mullen, 1986; Matarese, 1997) recommend conducting RMR measurements in a thermoneutral environment. This recommendation seems to be drawn from research conducted in healthy people. There is little original data regarding the effect of ambient temperature on RMR in non-burn critically ill patients. However, one study of healthy participants (Claessens-van Ooijen et al, 2006) provided evidence that use of a cover (specifically a duvet) maintains a thermoneutral condition around a test subject even though the room temperature was 15 degrees centigrade. Because this study was conducted in healthy people rather than critically ill patients, its application in the critical care guideline is an extrapolation. However, it does demonstrate that blankets or similar coverings might keep the patient in a thermoneutral condition if the room temperature cannot be adjusted.
- In one study (Claessens-van Ooijen et al, 2006), healthy lean vs. overweight men (10 subjects per group) were exposed to a cold environment. For baseline measurements, subjects were rested in a 15°C (59°F) room covered with a duvet for 60 minutes; this was considered the thermoneutral condition. After one hour, the duvet was removed for exposure to cold for 60 minutes, followed by another 60 minutes of re-warming (replacement of the duvet). There were NS differences between groups at baseline, however during the exposure to cold, both groups had a significant increase in heat production from baseline, with the Lean Group having a significantly higher increase than the Overweight Group. Following re-warming, heat production returned to baseline in the Overweight Group, but it remained significantly elevated in the Lean Group.
- In a review article (McClave and Snider, 1992), a 90% increase was reported in VO2 due to shivering in hypothermic post-operative patients recovering from long surgical procedures. Patients who were allowed to re-warm themselves through shivering thermogenesis had a 90% great VO2 consumption compared to patients who were administered general anesthesia to prevent shivering. Changes in metabolic rate were not reported.
- In two technical review articles (Feurer and Mullen, 1986; Matarese, 1997), it was recommended that indirect calorimetry be performed in a thermoneutral environment (temperature range not defined) to prevent shivering and non-shivering thermogenesis. This recommendation was based on one study conducted in surgical patients.
Recommendation Strength Rationale
Both conclusion statements were Grade V and thus the recommendation is consensus.
- 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).
What are the room conditions (in terms of temperature and noise level) required for accurate RMR measurement in the critically ill population?
What are the room conditions (in terms of humidity and lighting) required for accurate RMR measurement in the critically ill population?
References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process
- Claessens-van Ooijen AM, Westerterp KR, Wouters L, Schoffelen PF, van Steenhoven AA, van Marken Lichtenbelt WD. Heat production and body temperature during cooling and rewarming in overweight and lean men. Obesity (Silver Spring), 2006; 14 (11): 1, 914-1, 920.
- Feurer I, Mullen JL. Bedside measurement of resting energy expenditure and respiratory quotient via indirect calorimetry. Nutr Clin Prac. 1986; 1: 43-49.
- Matarese LE. Indirect calorimetry: Technical aspects. J Am Diet Assoc. 1997; 97 (Suppl 2): S154-S160.
- McClave SA, Snider HL. Use of indirect calorimetry in clinical nutrition. Nutr Clin Pract. 1992; 7: 207-221.