EE: Application of RQ (2005)

Citation:

Brandi LS, Oleggini M, Lachi S, Frediani M, Bevilacqua S, Mosca F, Ferrannini E. Energy metabolism of surgical patients in the early postoperative period: A reappraisal. Crit Care Med. 1988;16(1):18-22.

 
Study Design:
Cases-control
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To reassess the impact of surgical trauma on energy metabolism in surgical patients in the early (24 to 48 h) postoperative period.
  2. To improve efforts to control for confounding factors such as age, body size, fever, malnutrition, and diet known to influence energy metabolism.

Definitions

  • Steady state: A 5-minute equilibration.
  • Energy production rate: Is the same definition as project’s resting metabolic rate.
Inclusion Criteria:
  1. Understand and give written consent.
  2. Surgeries performed in patients: Gall bladder disease, gastrectomy, neoplasm, colectomy, anterior resection, and pancreatic duodenectomy.
  3. Dx: Biliary tract stones, acute pancreatitis, Ca of stomach, colon or rectum.
  4. Control group had to have a stable wt during last 10 wk and age, sec, and body size indices were matched.
Exclusion Criteria:
  1. Refusal to consent.
  2. Pt were septic or febrile, had undergone a wt loss of >10% of their mean body wt during the last 10 wk preceding sx, or mechanically ventilated or having dissimenated neoplastic disease.
Description of Study Protocol:

ANTHROPOMETRIC

  • Ht measured? Yes
  • Wt measured? Yes
  • Fat-free mass measured? Yes

CLINICAL

  • Monitored heart rate? Not specified
  • Body temperature? Not specified
  • Medications administered? Yes

Resting energy expenditure

  • IC type: MMC Horizon w/canopy
  • Equipment of Calibration: Yes
  • Coefficient of variation using std gases: Yes RQ was 1.6%; Accuracy was 1.3%
  • Rest before measure (state length of time rested if available): Yes, 1 hr
  • Measurement length: 1 hr
  • Steady state: 5 mins of equilibration
  • Fasting length: ON; 12-24 h; in pt 12-72 h after surgery
  • Exercise restrictions XX hr prior to test? No specified for controls
  • Room temp: 21-24 degree C
  • No. of measures within the measurement period: one
  • Were some measures eliminated? Yes, the first 5 mins
  • Were a set of measurements averaged? No
  • Coefficient of variation in subjects measures? No
  • Training of measurer? Not specified
  • Subject training of measuring process? No

DIETARY

  • Fasted
  • Intervening factor:

 

Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2 l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
  2. Predicted RMR using: HB
  3. Independent variables of weight, height, age, BMI, and fat-free mass, fat mass

Blinding used: No

Description of Actual Data Sample:

Post-operative patients

  • N=22 pts ; Mean (±SEM)56±3 yr;
  • Range: 33-79 y
  • 12 males; 10 females

Controls

  • N=22 controls; Mean (±SEM 52±4 yr)
  • 12 males; 10 females

Statistical tests

  • Wilcoxon-Mann-Whitney test, linear regression analysis
  • Mean ±SEM
  • 95% confidence interval
Summary of Results:

ANTHROPOMETRIC

Post-op patients Mean±SEM Range

Wt, kg 

65±3        45-105
Ht, cm  167±2 140-180
BMI      23.5±0.82

Fat-free body mass, kg

46±2 XX

Controls Mean(±SEM)
Wt, kg  66±3
BMI      23.5±0.65
Fat-free body mass, kg 47±2

MEASUREMENT PROCESS

  • Number of measurements: 1
  • Length of measurements: One hour
  • Steady state: 5 min equilibration
  • RQ: Yes

INDIRECT CALORIMETRY RESULTS Patients Controls
VO2 ml/min 220±9 206±7
VO2, ml/min/kg LBM 4.89±0.17 4.42±0.12
VCO2 172±7 168±6
VCO2, ml/min/kg LBM 3.73±0.11 3.63±0.21
RQ 0.784±0.009a 0.814±0.009

a p<0.05 patients vs. controls

VO2was elevated in the surgical pt compared to the controls when expressed per kg of body weight or per kg of LBM, while VCO2was not different. The total RQ was significantly lower in patients than in the control group.

ENERGY PRODUCTION RATE  
EE(kcal/day) 1516±61 1416±44
EE (kcal/day/kg LBM)a 32.8±0.9 30.5±0.7

a p<0.05 patients vs. controls

ENERGY MEASUREMENT VS. HARRIS-BENEDICT ESTIMATE

In both the patients and the control group, men were older and heavier than women, and had significantly higher RMR than women(P<0.05). However, when energy production was expressed per kg of LBM, sex no longer made any difference.

[Prediction vs. measured RMR not abstracted from table].

Author Conclusion:

As stated by the author in body of report:

In our study, the results indicate that surgical patients have a moderate increase in RMR; the mean rise in energy production in pat was only about 7% (or 100 kcal/d) compared to that in controls. Therefore, we conclude that the observed difference in energy production between patients in the early postoperative period and overnight fasted, resting subjects is solely a consequence of surgery itself.”

“Previous findings suggest a factor of 1.76 times Harris-Benedict predictive estimate results in a positive nitrogen balance or 1.24 times estimated metabolic rate using Harris-Benedict. Our study found that RMR was 7%, on the average, higher than that predicted by Harris-Benedict formula.”

“It is definitely clear that use of correction factors definitely overestimates energy requirements in this category of patients.”

“The current study suggestions use of Harris-Benedict equations are not satisfactory in surgical patients, in whom the actual surplus of energy need is variable and, to some extent, unpredictable, a simple, short, and nondistressing gas exchange measurement should form the basis for determinging caloric intake.”
Funding Source:
University/Hospital: CNR Institute of Clinical Physiology(Italy), University of Pisa (Italy)
Reviewer Comments:

Strengths

  • Strengths include detailed description of indirect calorimetry completion.
  • Controlled for confounding factors of age, body size, fever, malnutrition and diet-induced thermogenesis.
  • Controlled for weight changes.
  • Used appropriate statistics.

Generalizability/Weaknesses

  • Generalizable to elective postoperative abdominal surgery in patients without complications.”
  • Study biases include no specification of how control population was selected (?staff or community-residing members?).
  • An intervening variable not measured: study did not specify if asked height and weight or measured height and weight as no description is given in methods section.
  • These are important variables on REE measurement accuracy: did not specify exercise restrictions for controls.
  • “These are important variables on formula accuracy”
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? 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
2. Was the selection of study subjects/patients free from bias? Yes
  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
  2.3. 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
3. Were study groups comparable? Yes
  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? 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
  4.4. 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? Yes
  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
  6.3. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) 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
  6.8. 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? 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
  7.4. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? 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
  8.1. 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
  8.3. 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
  8.5. 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
  8.7. 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
  9.1. Is there a discussion of findings? 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
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A