EE: Gas Collection Devices (2013)

Citation:

Forse RA. Comparison of gas exchange measurements with a mouthpiece, face mask, and ventilated canopy. Journal of Parenteral and Enteral Nutrition 1993;17:388-391.

 
Study Design:
Diagnostic, Validity or Reliability Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To determine the effect of either a mask or a mouthpiece on the gas exchange collection in human subjects, with use of an accurate ventilated canopy system.

Definitions

Steady state: Equilibration of gas exchange; usually reached in about 10 minutes

Inclusion Criteria:
  1. Understand and give written consent
  2. Volunteers
  3. Adult men and women

(no other information provided)

Exclusion Criteria:
  1. Refusal to consent
Description of Study Protocol:

MEASUREMENT PROCESS

Subjects placed in the canopy and asked to breathe either 1) normally via the canopy, 2) through a mouthpiece with a noseclip, or 3) through a tight fitting anesthesia mask (still within the canopy); randomly assigned to each method Each subject used all 3 breathing apparatus.

ANTHROPOMETRIC

  • Ht measured? Yes, method not discussed
  • Wt measured? Yes, method not discussed
  • Fat-free mass measured? No

CLINICAL

  • Monitored heart rate? Not discussed
  • Body temperature? Not discussed
  • Medications administered? Not discussed

Resting energy expenditure

  • IC type: ventilated canopy
  • Equipment of Calibration: Yes daily; accuracy for measuring oxygen consumption was 98.0±0.8% and for carbon dioxide production was 100.1±1.1%
  • Coefficient of variation using std gases: Yes
  • Rest before measure: 20 min. prior to measurement
  • Measurement length: Measurements were made every tenth of a second for 20 min/ per apparatus x 3; final 10 minutes of 20 min measure was used
  • Steady state: Equilibration or steady state was reached in about 10 min and the final 10 min were used to calculate the gas exchange.
  • Fasting length: States subjects tested in the postabsorptive state; hrs. not stated
  • Exercise restrictions: Not mentioned
  • Room temp: Not mentioned
  • No. of measures within the measurement period: Specific number not stated; measurements were made every tenth of a second for 20 min/ per apparatus x 3
  • Were some measures eliminated? Yes
  • Were sets of measurements averaged? Measurements were averaged and then compared for the three methods of gas measurement.
  • Coefficient of variation in subjects’ measures? Not discussed
  • Training of measurer? Not discussed
  • Subject training of measuring process? Not discussed

DIETARY

  • Not assessed
Data Collection Summary:

Outcome(s) and other measures

  1. VO2, ml/min, VCO2 ,ml/min; & (RQ).
  2. REE (kcal/d) by using the Wier equation.
  3. Harris Benedict formula
  4. Independent variables of weight, height, age, BMI.

Blinding used: No

Description of Actual Data Sample:
  • N=30 men and women
  • N=10 women (mean age 27±1 y; range 25-34)
  • N=20 men (mean age 28±1 y; range 24-40)

Statistical tests

Analysis of variance was used to determine the significance for oxygen consumption, carbon dioxide production, respiratory quotient, and resting energy expenditure between the breathing settings; Significance set at p<0.05.

Summary of Results:

ANTHROPOMETRIC

Men

  Mean±SD Range

Wt, kg

78±2 61.0-100.7
Ht, cm 177±1 170-188
BMI not provided  

Fat-free body mass

not provided

Fat mass not provided 

Harris-Benedict(kcal/d)

1838±37 1566-2196

 

Women

  Mean±SD Range
Wt, kg  60±3 45.5-79.4
Ht, cm 165±2 155-172
BMI not provided 

Fat-free
body mass

not provided 

Fat mass

not provided 

Harris-Benedict(kcal/d)

1405±33 1245-1603

  • Steady state—Equilibration or steady state was reached in about 10 min and the final 10 min were used to calculate the gas exchange.
  • RQ—There was no difference in the RQ for either the mask or the mouthpiece compared with the canopy alone.

INDIVIDUAL CHARACTERISTICS

There was a significant (p<0.05) increase in the oxygen consumption when either the mouthpiece or the mask was used compared with the canopy alone.

There was a significant (p<0.05) 10.2% increase in the carbon dioxide production with the mouthpiece and noseclip compared with the canopy alone.

The REE was significantly (p<0.05) increased by 8.8% with the mouthpiece and 7.2% with the face mask.

In comparison with the Harris-Benedict equation values, there was no significant difference found for the canopy, but both the mouthpiece and the mask values were significantly higher. (see below)

  • REE (kcal/d)
  • Harris-Benedict=1693±46
  • Canopy=1644±60
  • Mouthpiece=1788±63*
  • Mask=1762±66*

* significantly different from HB and canopy

Author Conclusion:

As stated by the author in body of report:

  • The study indicates that the apparatus used for gas exchange measurement will significantly affect the measurements. The magnitude of the effect is a significant 7.9% increase for VO2 with a mouthpiece and a significant 7.1% increase with a face mask. VCO2 was significantly increased 10.2% with a mouthpiece and 4.1% with a face mask. There were no differences in the RQ.
  • The results demonstrate that both the mouthpiece and the mask increase the VO2 and the energy expenditure. By using the same analytical system for the gas measurements independent of the apparatus used for gas collection, we have allowed only one variable, the effect of the collecting apparatus to be tested. Because both the mask and the mouthpiece were used inside the ventilated hood, the issue of leaks was avoided.
  • The results of this study indicate that there are differences with the gas measurements depending on the apparatus used; they support earlier studies by Kinney and coworkers. Although the study by Segal concluded that there were no significant differences with the different apparatus, there were differences in the measurements obtained by using the mouthpiece, mask, and ventilated hood in that study. With use of an accurate calorimeter and the ventilated canopy, the magnitude of the effect on gas exchange of the mask or mouthpiece is approximately 8%. To produce a significant difference with a p value of less than 0.05 with an 8% difference would require about 30 subjects. The number of subjects used in the Segal study was only 18.
  • The specific purpose for collecting gas exchange measurements will determine whether these differences are of practical significance.
Funding Source:
University/Hospital: McGill University, Canada
Reviewer Comments:

Strengths

  • Good description of equipment and calibration (high accuracy of ventilated canopy)

Limitations

  • Inclusion and exclusion criteria not provided other than 30 male and female volunteers (potential confounders??)
  • With measurements only done in morning; would not assess variability in gas measurement during day
  • Methodology not clear; ex. length of fasting prior to testing, subject training prior to measurements(to minimize anxiety and there is discomfort associated with the mouthpiece and mask) and number of measurements in each measurement period
  • Resting period between different breathing apparatus not discussed
  • Did not provide reference or formula for Harris-Benedict equation
  • Discomfort of mask and mouthpiece may increase ventilation (error in measurements?)
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
  1.3. Were the target population and setting specified? N/A
  2. Was the selection of study subjects/patients free from bias? No
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? N/A
  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? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  3. Were study groups comparable? N/A
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
  3.1. 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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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%.) N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  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
  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. 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
  5.1. 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
  5.2. 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
  5.3. 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
  5.4. 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
  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? Yes
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  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? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  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
  6.7. 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
  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. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  8. Was the statistical analysis appropriate for the study design and type of outcome indicators? 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? N/A
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  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
  8.4. 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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  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? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
  10. Is bias due to study's funding or sponsorship unlikely? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A
  10.2. Was the study free from apparent conflict of interest? N/A