CI: Calorie/Energy Needs (2007)


Hise ME, Halterman K, Gajewski BJ, Parkhurst M, Moncure M, Brown JC. Feeding practices of severely ill intensive care unit patients: an evaluation of energy sources and clinical outcomes. J Am Diet Assoc. 2007;107:458-465.

PubMed ID: 17324665
Study Design:
Prospective cohort study
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To assess nutrition support energy provisions in comparison with nutrition support goal recommendations in severely ill medical ICU vs surgical ICU patients and to evaluate the impact of total energy intake (nutrition support plus additional energy sources) on clinical outcomes.
Inclusion Criteria:
  • Adult (>18 years of age)
  • Admission to either the surgical or medical ICU
  • ICU LOS > 5 days
Exclusion Criteria:
  • Discharge from the ICU within 5 days of admission
  • Initiation of oral feedings in the ICU
Description of Study Protocol:

Recruitment Consecutive admissions to the SICU and MICU over a 5 month period

Design Prospective cohort study

RDs made feeding recommendations for patients; attending MDs wrote orders. Investigators measured energy intake from EN and PN (nutritional support) as well as other sources of energy (glucose in IV solutions, Propofol, etc.) and evaluated impact on energy intake on clinical outcomes. 

Blinding used: Not applicable

Intervention: Not applicable

Statistical Analysis

  • Descriptive analyses were calculated for the complete patient population and within the surgical and medical ICU populations. Groups were compared using the Student's t test and X2 tests. A p value of <0.05 was considered significant for these analyses.
  • Regression tree analysis was used to determine the relationship among the various independent variables.
    • Primary utility is to obtain an exploratory model of the relationship between the independent and dependent variable with the comparison based on R2 values (binary recursive partioning). 
    • Data are split into two dataset groups during the analysis by the algorithm's best-fit internal comparison of an independent variable to the dependent variable that leads to the lowest R2 value in the two groups.
    • Binary partitioning divided the population into two groups by examination of every possible split in the data to determine the two groups of data that were as homogeneous as possible with respect to the target data.


Data Collection Summary:

Timing of Measurements

  • Age, sex, pre-admission weight, and BMI calculations were made at the time of hospital admisison
  • APACHE II score was calculated for ICU day 1
  • Energy intake: daily during ICU admission until discharge from ICU or initiation of oral diet
    • Enteral and parenteral sources as well as sedatives (propofol) and infusions for fluid support (glucose)
    • Actual energy intake in kcals divided by target value in kcal per day as determined by RD
  • Energy balance calculated daily
    • Total energy delivery during ICU stay minus total energy goal for ICU stay

Dependent Variables

  • Mortality (patient status at discharge as alive or dead)
  • Total hospital LOS

Independent Variables

  • Energy Intake (expressed as percent of goal calories)
energy intake for all days/target energy intake
                   (number of ICU days ) 100
  • RD recommendations and MD orders
Variables used for Multivariate Analyses:
  • BMI
  • Sex
  • Age
  • Percent feeding goal
  • Percent enteral nutrition
  • Percent parenteral nutrition
  • SICU
  • MICU
  • APACHE II scores


Description of Actual Data Sample:

Initial N: 77 (48 males/29 women) 62% male

  • SICU group: N=41 (31 males/10 females)
  • MICU group: N=36 (17 males/19 females)

Age: Years, mean±SD (range)

  • SICU: 54.5±21.1 (16-84)
  • MICU: 57.2±16.4 (17-87)

Ethnicity: not discussed

Other relevant demographics: mean±SD (range)

  • Energy recommendation (kcal/kg/day)
    • SICU: 24±5.4 (13-34)
    • MICU: 22.4±5.7 (13-36)
    • SICU: 22.7±8.1 (10-44)
    • MICU: 28.7±8.9 (12-48)
    • Significant difference, p=0.005
  • BMI
    • SICU: 30.4±9.1 (19-56)
    • MICU: 28.0±9.1 (14-53)

Location: The University of Kansas Hospital, Kansas City, Kansas


Summary of Results:

Initiation of feeding and energy delivery

Variable                   SICU (n=41)  MICU (n=36)  P value
  mean±SD Range     mean±SD Range    
Time to initiation of feeding (days) 3.9±1.8 1-10 2.6±1.5 1-6 0.005
Actual kcal/kg delivered 11.6±6.7 1.6-29.2 13.0±6.6 0-28.9 0.367
Mean percent goal (%) 50±27 9-107 56±21 0-96 0.264
% receiving parenteral nutrition 24   33   0.386

  • Enteral feeding was initiated in 89% MICU and 73% SICU patients.
  • One subject did not receive either enteral or parenteral nutrition during MICU stay.
  • Seven subjects did not receive either enteral or parenteral nutrition during SICU stay.


Relationship of Energy Intake and ICU Length of Stay for Patients Discharged Alive

Percent of Goal Intake
LOS (days)
n=number of subjects

All ICU Patients 13.7 ± 9.3
< 82%
12.0 ± 6.5
24.2 ± 15.5
MICU 13.6 ± 7.7
< 82%
12.6 ± 7.1
> 82%
25.5 ± 2.1
SICU 13.8 ± 10.2
< 67%
10.4 ± 4.7
> 67%
23.5 ± 15.1

Relationship of Energy Intake and Total Hospital Length of Stay for Patients Discharged Alive
Unit Total Hospital LOS Percent of Goal Intake
Total Hospital LOS (days)

  If % Goal < 81 If % Goal > 81
All ICU Patients 26.3 ± 17.3 22.3 ± 11.5
47.2 ± 26.9
n 63 53 10

 Other Findings

  •  Survival was not significantly correlated with BMI, sex, age, APACHE II, or route of feeding. 
Author Conclusion:
Routinely monitor all energy sources and consider limiting energy delivery to 80% of goal.
Funding Source:
University/Hospital: University of Kansas
Reviewer Comments:
Number of subjects in some of the cuts (regression tree analysis) were small (1-9). Additionally, data was not collected on hyperglycemia or other factors that could have affected outcomes. 



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? Yes
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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? Yes
  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? Yes
  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? 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? 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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? Yes
  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? N/A
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? Yes
  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? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
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