EAL

EE: Gas Collection Devices (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the reliability of portable calorimeters. REE was measured by two different apparatuses; one was the typical gas analyzer, the other was the portable calorimeter.
To research the necessary resting time prior to measurement in order to determine standard values.

Inclusion Criteria:

Healthy adults.

Exclusion Criteria:

Not meeting inclusion criteria.

Description of Study Protocol:

Recruitment

Procedures not specified.

Design

Diagnostic test.

Statistical Analysis

Correlation of resting metabolic rate measured with Metavine for three minutes with those obtained using the automatic gas analyzer for 20 minutes to examine the reliability of measurements performed using Metavine.

Data Collection Summary:

Timing of Measurements

Resting metabolic rate (RMR) was measured by two different apparatuses; one was the typical gas analyzer, followed immediately by the portable calorimeter.

Dependent Variables/Outcomes

Reliability of the Metavine portable calorimeter
Resting time needed prior to measurements: VO₂, VCO₂, RQ and VE were measured for 20 minutes

Independent Variables

RMR values obtained with Metavine for three RMR values obtained using automatic gas analyzer for 20 minutes.

IC type: Portable calorimeter (Metavine) and automatic gas analyzer for 20 minutes
Equipment of calibration: Not specified
Coefficient of variation using STD gases: Not described
Exercise restrictions XX-hour prior to test? Not specified
Rest before measure (state length of time rested if available): Measured while resting for 20 minutes to determine time to reach a resting state
Measurement length: 20 minutes using breath-by-breath gas analyzer method; then mask replaced and measurement taken for three minutes using Metavine calorimeter
Steady state: Evaluate if mention initial acclimatization and then continuous monitoring throughout measurement, if appropriate
Fasting length: Two hours
Exercise restrictions XX hr prior to test?
Room temp: Not mentioned
Number of measures within the measurement period: Five one-minute measures
Were some measures eliminated?
Were a set of measurements averaged?
If averaged, identify length of each measure and number of measurements.
Coefficient of variation in subjects measures? Not reported
Training of measurer? Not reported
Subject training of measuring process? Not reported
Fluctuations in RQ over time were recorded and compared with the calculated RMR from the amount of oxygen uptake and ventilation based on a fixed RQ of 0.82.

Description of Actual Data Sample:

Attrition (final N)

N=20 (four males; 16 females).

Age:

Males: 22.5±1.5 years
Females: 19.6±2.0 years.

Ethnicity

Japanese.

Anthropometrics

(Note: Measurement procedures not reported.)

	Males	Females
Height (cm)	174.3±3.7	161.3±5.9
Weight (kg)	68.5±6.8	54.8±5.3

Location

Japan.

Summary of Results:

Respiratory fluctuations were stabilized after 10 minutes as subjects entered resting state
The maximum RQ value was 0.87±0.07 in zero to three minutes and the minimum was 0.8±2+0.06 at 17 to 20 minutes. Converting these to kcal per L ingested oxygen, this difference equates to a mere 0.062kcal. The average oxygen uptake volume of the test subjects (226.7±45.2ml per minute) difference equates to 0.014kcal.
The RMR values (calculated from cumulative oxygen uptake minute volumes) are low at one and two minutes, but are nearly the same for three minutes and longer
RMR (kcal per day) per each minute of a five-minute measurement:
- Minute 1: 1450
- Minute 2: Approximately 1,456
- Minute 3: Approximately 1,480
- Minute 4: Approximately 1,478
- Minute 5: Approximately 1,476
The coefficient of correlation between the Metavine and the benchmark RMR values is 0.762 with P<0.05.

Author Conclusion:

“The portable calorimeter is a useful apparatus for measuring REE in the field”
“Unless the subjects has been exposed to severe physical activity prior to the measurement, a suitable resting time prior to the measurement of RMR is 10 minutes"
“Respiratory fluctuations vary from person to person and it is not possible to make stable measurements in one or two minutes. Therefore, a suitable measurement time for RMR is from three to six minutes.”

Funding Source:

University/Hospital:

Nippon Sport Science University, Waseda University

Reviewer Comments:

Not fully convinced by authors’ conclusions.

Strengths:

Study design was carried out very well.

Generalizability/Weaknesses:

Very small sample, men sample size does not meet study criteria
Inclusion/exclusion criteria were not described sufficiently. Generalizable only to young, healthy adults. Do not know if portable device is reliable for ill patients at clinical setting.
Limitations of the study were not discussed.
Did not account for the effect of physical activity and energy intake on RMR measurements to make recommendations on the amount of rest before measurement time.
VO₂ fluctuations may increase at different levels of physical activities. It might take more than 3-6 min to stabilize RMR and get a correct reading.
Some as indirect calorimetry procedures missing and did not report how height and weight were taken.

Analyst’s and Expert Panel members’ notes: a confounding variable in the reported measures is that ingestion of food could have occurred two hours prior to measurement in some individuals, measures were taken at an exercise testing facility and confounder of physical activity is possible; Also, the author reports resting metabolism estimation formula (page S13) using a fixed respiratory quotient(0.82): = oxygen uptake minute volume Í 4.825. This would indicate a group mean RMR of 226.7 Í 4.825= 1093 kcal/d which is below mean of males and of females. It is unclear how RMR (kcal/d) increase in 1-3 minutes when VO2 oxygen uptake decrease from minutes 1-3.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	???
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	No
	2.2.	Were criteria applied equally to all study groups?	???
	2.3.	Were health, demographics, and other characteristics of subjects described?	???
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	No
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	???
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	No
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	???
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		No
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	???
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	No
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes