Research Reports - Anemia and brain oxygen after severe traumatic brain injury
Intensive Care Med. 2012 Sep;38(9):1497-504
Oddo M, Levine JM, Kumar M, Iglesias K, Frangos S, Maloney-Wilensky E, Le Roux PD
PURPOSE: To investigate the relationship between hemoglobin (Hgb) and brain
tissue oxygen tension (PbtO(2)) after severe traumatic brain injury (TBI) and to
examine its impact on outcome.
METHODS: This was a retrospective analysis of a prospective cohort of severe TBI
patients whose PbtO(2) was monitored. The relationship between Hgb-categorized
into four quartiles (≤9; 9-10; 10.1-11; >11 g/dl)-and PbtO(2) was analyzed using
mixed-effects models. Anemia with compromised PbtO(2) was defined as episodes of
Hgb ≤ 9 g/dl with simultaneous PbtO(2) < 20 mmHg. Outcome was assessed at 30 days
using the Glasgow outcome score (GOS), dichotomized as favorable (GOS 4-5) vs.
unfavorable (GOS 1-3).
RESULTS: We analyzed 474 simultaneous Hgb and PbtO(2) samples from 80 patients
(mean age 44 ± 20 years, median GCS 4 (3-7)). Using Hgb > 11 g/dl as the
reference level, and controlling for important physiologic covariates (CPP,
PaO(2), PaCO(2)), Hgb ≤ 9 g/dl was the only Hgb level that was associated with
lower PbtO(2) (coefficient -6.53 (95 % CI -9.13; -3.94), p < 0.001). Anemia with
simultaneous PbtO(2) < 20 mmHg, but not anemia alone, increased the risk of
unfavorable outcome (odds ratio 6.24 (95 % CI 1.61; 24.22), p = 0.008),
controlling for age, GCS, Marshall CT grade, and APACHE II score.
CONCLUSIONS: In this cohort of severe TBI patients whose PbtO(2) was monitored, a
Hgb level no greater than 9 g/dl was associated with compromised PbtO(2). Anemia
with simultaneous compromised PbtO(2), but not anemia alone, was a risk factor
for unfavorable outcome, irrespective of injury severity.