Background
Indirect calorimetry is a noninvasive and reliable means of determining resting metabolic rate in humans. Barriers to obtaining an accurate measure of resting metabolic rate in hospitalized patients include the expense and the requirement of technical expertise for maintenance.
Methods
A literature search on hand-held calorimeters was conducted using PubMed and OVID. The search resulted in a total of 54 published articles; 23 of these specifically are about hand-held calorimeter devices.
Results
Results from a hand-held calorimeter were similar to those obtained from metabolic cart studies. The Douglas bag method compared to the MedGem indicated a significant agreement with a p=0.286. The hand-held device compared to metabolic carts in 9 studies with mixed results. The predictive equations (Harris-Benedict, Mifflin St. Joer and FAO/WHO equations) were found to over and underestimate RMR compared to the MedGem. The Harris-Benedict was found to overestimate the RMR by 3-11%, the Mifflin St Joer equation overestimated the RMR by 1% and the FAO/WHO equation overestimated RMR by 12%.
Conclusion
The present study examines the validity and reliability of hand-held calorimeters for measuring resting energy expenditure based on published literature. Hand-held calorimeters are more accurate than predictive equations based on gender, age and ethnicity for determining resting metabolic rate and are therefore a viable alternative for clinical evaluation of the hospitalized patient.
Background
Critical illness causes hypercatabolism, loss of lean body mass (LBM), and poor outcomes. Evaluating LBM in the critically ill is challenging, and it is uncertain whether nutrition support (NS) impacts LBM. This study measured quadriceps muscle layer thickness (QMLT) by bedside ultrasound (US) to estimate LBM changes in surgical intensive care unit (SICU) patients and healthy controls (HCs).
Methods
Trained RDNs measured QMLT via US at the midpoint and one‐third distance between the superior margin of the patella and the anterior superior iliac spine. QMLT measurements were taken upon enrollment and repeated 1–2 times over 10 days.
Results
Fifty‐two SICU patients and 15 HCs were enrolled. Average SICU percent QMLT loss per day at the midpoint and one‐third landmarks was 3.2 ± 3.8 (P < 0.001) and 2.9 ± 5.7 (P = 0.001); and QMLT loss was higher between the second and third measurements (4.0 ± 8.0, P = 0.005 and 4.3 ± 9.8, P = 0.017 at the midpoint and one‐third landmarks) compared with that at the first and second measurements (1.7 ± 9.2, P = 0.20 & 1.7 ± 9.4, P = 0.22). Changes were not associated with NS received. No significant QMLT change was found in HCs.
Conclusions
SICU patients significantly lost QMLT over 10 days, with greater losses occurring after 5 days. These results support RDNs performing USs to detect QMLT changes and suggest this technique could be valuable to evaluate LBM changes in critically ill patients.
Mechanically ventilated cardiothoracic surgical ICU patients appear to have higher energy requirements by indirect calorimetry than those determined by Penn State equations. Future studies targeting indirect calorimetry in relation to clinical outcomes are needed.
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