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Updated: May 5, 2026
Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants
Published on: March 14, 2013
Testing a novel method for measuring sleeping metabolic rate in neonates
Suzanne S Summer1, Jesse M Pratt2, Elizabeth A Koch3
1Clinical Translational Research Center suzanne.summer@cchmc.org.
Insights
A smaller hood for indirect calorimetry (IC) accurately measures sleeping metabolic rate (SMR) in healthy infants. This smaller hood may also improve SMR testing for neonates with congenital heart disease.
Area of Science:
- Neonatology
- Pediatric critical care
- Metabolic research
Background:
- Sleeping metabolic rate (SMR) is a proxy for basal metabolic rate in infants.
- Indirect calorimetry (IC) measures SMR to assess feeding adequacy in neonates.
- Standard IC hoods are not suitable for small infants.
Purpose of the Study:
- To compare SMR measurements in neonates using a standard large hood versus a nonstandard smaller hood.
- To evaluate the feasibility of using a smaller hood for SMR assessment in neonates.
Main Methods:
- SMR was measured in healthy neonates and those with single-ventricle congenital heart disease using both small and large hoods.
- Minute ventilation (V̇E) and fraction of exhaled carbon dioxide (FĒCO2) were measured to assess data quality.
- Spearman's correlations assessed the association between SMR measurements from both hoods.
Main Results:
- SMR measurements were similar between small and large hoods in healthy neonates.
- In neonates with congenital heart disease, SMR was significantly higher with the small hood compared to the large hood.
- Fraction of exhaled carbon dioxide (FĒCO2) was higher with the small hood in both groups.
Conclusions:
- A smaller IC hood provides comparable SMR measurements to a standard large hood in healthy neonates.
- The smaller hood may enhance SMR testing in compromised neonates, such as those with congenital heart disease.
- Testing time and procedure were not negatively affected by the smaller hood size.
Background:
Sleeping metabolic rate (SMR) is used as a proxy for basal metabolic rate in infants, when measurement while awake is not practical. Measuring SMR via indirect calorimetry (IC) can be useful for assessing feeding adequacy especially in compromised neonates. Standard IC equipment, including a hood placed over the head, is not designed for the smallest of patients. Our aim was to determine whether a nonstandard smaller hood measures SMR in neonates similarly compared with a standard large hood.
Methods:
SMR was measured in healthy neonates (controls) and those born with single-ventricle congenital heart disease (cases). Two measurements were performed: SMR using a standard large hood and SMR using a smaller hood. Time-to-steady state, minute ventilation (V̇E), and fraction of exhaled carbon dioxide (FĒCO2 ; an indicator of data quality) were also measured. Primary outcome was SMR using both hoods. Results are stated as median (interquartile range). Spearman's correlations measured association between the small and large hoods.
Results:
We studied 9 controls and 7 cases. SMR in controls was not different between the small and large hoods (35.7 [15.14] vs 37.8 [7.41] kcal/kg/d, respectively). In cases, SMR with the small hood was significantly greater than that with the large hood (45.5 [4.63] vs 34.2 [8] kcal/kg/d, P < .02). FĒCO2 was significantly higher with the small hood versus the large hood in both groups, and V̇E was significantly lower with the small hood versus the large hood in controls only. The SMRs with the small and large hoods were significantly correlated in the control group (r = 0.80, P < .01). Time-to-steady state was similar in both groups regardless of hood size.
Conclusions:
SMR measured with a small hood yields results similar to those measured with a large hood in healthy neonates without affecting testing time or other aspects of the IC procedure. Furthermore, results in compromised infants suggest that a smaller hood may facilitate SMR testing in this population.
