Changes in resting energy expenditure, body temperature and jugular bulb oxygen saturation after brain death

Objective

To determine the changes in resting energy expenditure (REE), body temperature and jugular bulb oxygen saturation (SjVO₂) of the patients with brain injury or brain death.

Methods

Fifty-two patients with Glasgow Coma Scale score < 6 admitted to our intensive care unit between October 2002 and November 2003 were included in the study. Among these patients Group 1 (n = 26) included patients with brain death. This group was divided into two subgroups later. Group 1a (n = 13) consisted of the patients with brain death when they were included in the study and Group 1b (n = 13) consisted of patients who progressed to brain death during their intensive care unit stay although they were initially not brain dead. Group 2 (n = 26) consisted of the patients with brain injury but no brain death. REE using indirect calorimetry, SjVO₂ and body temperature was recorded daily and simultaneously during the first 5 days of the study. REE values were expressed as the percentage of basal metabolic rate (BMR%) calculated using the Harris–Benedict equation.

Results

There were no differences in terms of age, APACHE II score at admission, reason for coma and BMR between Group 1 and Group 2 (P > 0.05). Mean body temperatures were 35.6 ± 0.9°C and 37 ± 0.6°C (P < 0.01), mean SjVO2 values were 90.3 ± 9.9% and 77.9 ± 10% (P < 0.01) and mean REE values were 1542 ± 580 kcal (97 ± 26.8% of mean BMR) and 1963 ± 600 kcal (117 ± 29.2% of mean BMR) (P < 0.05) in Group 1 and Group 2, respectively. In Group 1b, the mean body temperature was lower and the mean SjVO₂ was higher than the values before brain death (P < 0.05). In this group, although the mean REE was lower than the value before brain death, this difference was not statistically significant (P = 0.07).

Conclusion

In this study, we found that the mean value of REE was 17% higher than the BMR in the patients with brain injury. The mean REE and body temperature was lower and the mean SjVO₂ was higher in the brain-dead patients than in the patients with no brain death.