Elevations in Resting Energy Expenditure (REE) Following ABI

Author/Year/ Country/Study design/ N



Weekes et al.
Case Series

Population: TBI; Mean Age=23.2yr; Gender: Male=6, Female=0; GCS Score Range=6-8.
Treatment: Continuous bedside indirect calorimetry (up to 24hr) was performed 3-5d post injury and again at 2-3wk (n=4).
Outcome Measure: REE.

  1. During the first testing period REE was 130±17% of predicted values (p<0.05) and at the second testing period, REE was only 105±11% of predicted (p<0.05). The decrease from first post-injury assessment to second post-injury assessment was significant (p<0.05).
  2. Calorimetry measurements fluctuated by up to 25% during the day.

Bruder et al.


Population: Head injury; Mean Time Post Injury=7.6d. Group 1 (n=9): Mean Age=30.8yr; Mean GCS Score=6.7. Group 2 (n=6): Mean Age=28.7yr; Mean GCS Score=5.5.
Treatment: Patients in Group 1 were weaned from sedation, while Group 2 was re-sedated based on hemodynamic changes, intracranial pressure, and uncontrollable restlessness. Indirect calorimetry was performed during and after deep sedation to assess REE.
Outcome Measure: REE, VO2.

  1. In both groups REE was close to predicted values (113-115%) at the initiation of the study when patients were all sedated. 
  2. There was no significant difference between the groups in mean or maximum REE during the recovery phase.
  3. REE increased to 143% of predicted values after 24 hr among patients in group 1 who were weaned from sedation, while REE increased to only 122% of predicted values among patients in group 2 who required additional sedation.
  4. There was a significant correlation between VO2 and mean arterial pressure value (p<0.001), but the relation was weak.

Dempsey et al. (1985)


Population: TBI; Mean Age=26.6yr; Gender: Male=6, Female=4; Mean GCS Score=5.2; Time Post Injury=2wk.
Treatment: All patients were intubated and received steroids. Concomitant barbiturate therapy was administered to those with failing Intracranial pressure. 30 measurements were made over the study period using indirect calorimetry and were compared to predicted levels.
Outcome Measure: REE.

  1. 16 measurements were taken during barbiturate use. These were significantly lower compared to the remaining 14 taken in the absence of barbiturate use (86±28% vs. 126±36% of predicted values; p<0.01).
  2. Mean REE was significantly lower during barbiturate therapy than without barbiturate therapy (p<0.01).

Young et al.
Case Series


Population: Head injury; Mean Age= 39.8yr; Gender: Male=15, Female=1; GCS Score Range=4-8.
Treatment: Indirect calorimetry was performed on 5 occasions from days 1 to 22 post-injury (0-3, 4-7, 8-14, 15-21, and 22 or more days). Each session lasted 15-30 min. Patients were assessed on admission, every 3d until day 18, and then weekly.
Outcome Measure: REE and Predicted Energy Expenditure.

  1. Compared to PEE, REE was consistently elevated: days 1-3: 151%; days 4-7: 138%; days 8-14: 137%; days 15-21: 140%; and days 22 or more: 116%.

Robertson et al. (1984)
Case Series


Population: Head injury; Gender: Male=49, Female=6; GCS<8.
Treatment: REE was measured by indirect calorimetry 188 times in patients with penetrating or non-penetrating brain injuries. Measurements were taken from day 1 following injury for 7-28d, or until patients were awake enough to eat.
Outcome Measure: REE.

  1. Patients with posturing responses to pain (GCS 4-5) had the highest REE at 168±53% of expected.
  2. REE was lowest in patients with withdrawal and localizing responses to pain (GCS 6-7) at 129±31% of expected.
  3. Patients with a GCS score of 8 had a REE of 150± 49%.
  4. Sedative use and paralysis were associated with lower REE.

Clifton et al.
Case Series


Population: Head Injury; Mean Age=27.8yr; Gender: Male=12, Female=2; GCS Score Range=3-8; Mean Time Post Injury=2hr.
Treatment: The REE of Enteral nutrition fed patients was measured by indirect calorimetry, over the first 9 d of onset (n=14), up to 28 d post injury (n=4).
Outcome Measure: REE.

  1. Mean values of REE ranged from 2135±374 Kcal on 1-3d to 2504±582 Kcal on 7-9d, which was not statistically significant.
  2. The mean REE ranged from 102%-170% of predicted values, over the 9 d of study.
  3. A single patient who received barbiturates had a REE lower than predicted (79%).
  4. Among patients who were non-sedated and non-paralyzed, REE was 138% of predicted values.
  5. There were no significant changes in REE over the 9 d and no associations were noted between GCS and REE.

Note: REE=Resting Energy Expenditure.