Anemia is associated with metabolic distress and brain tissue hypoxia after subarachnoid hemorrhage.
BACKGROUND
Anemia is frequently encountered in critically ill patients and adversely affects cerebral oxygen delivery and brain tissue oxygen (PbtO2). The objective of this study is to assess whether there is an association between anemia and metabolic distress or brain tissue hypoxia in patients with subarachnoid hemorrhage.


METHODS
Retrospective study was conducted in a neurological intensive care unit in a university hospital. Patients with subarachnoid hemorrhage that underwent multimodality monitoring with intracranial pressure, PbtO2 and microdialysis were analyzed. The relationships between hemoglobin (Hb) concentrations and brain tissue hypoxia (PbtO2 < or = 15 mmHg) and metabolic distress (lactate/pyruvate ratio > or =40) were analyzed with general linear models of logistic function for dichotomized outcomes utilizing generalized estimating equations.


RESULTS
A total of 359 matched neuromonitoring hours and Hb measurements were analyzed from 34 consecutive patients. The median hemoglobin was 9.7 g/dl (interquartile range 8.8-10.5). After adjusting for significant covariates, reduced hemoglobin concentration was associated with a progressively increased risk of brain tissue hypoxia (adjusted OR 1.7 [1.1-2.4]; P = 0.01 for every unit decrease). Also after adjusting for significant covariates, hemoglobin concentrations below 9 g/dl and between 9.1 and 10 g/dl were associated with an increased risk of metabolic distress as compared to concentrations between 10.1 and 11 g/dl (adjusted OR 3.7 [1.5-9.4]; P = 0.004 for Hb < or = 9 g/dl and adjusted OR 1.9 [1.1-3.3]; P = 0.03 for Hb 9.1-10 g/dl).


CONCLUSIONS
Anemia is associated with a progressively increased risk of cerebral metabolic distress and brain tissue hypoxia after subarachnoid hemorrhage.
Kurtz
Pedro
P
Division of Critical Care Neurology, Department of Neurology, Columbia University, Milstein Hospital 8 Center, New York, NY 10032, USA. pkurtz@neuro.columbia.edu
Schmidt
J Michael
JM
Claassen
Jan
J
Carrera
Emmanuel
E
Fernandez
Luis
L
Helbok
Raimund
R
Presciutti
Mary
M
Stuart
R Morgan
RM
Connolly
E Sander
ES
Badjatia
Neeraj
N
Mayer
Stephan A
SA
Lee
Kiwon
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000209:etiology*; D001921:Brain / Q000378:metabolism; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D002534:Hypoxia, Brain / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D008659:Metabolic Diseases / Q000209:etiology*; D017551:Microdialysis; D008875:Middle Aged; D009994:Osmolar Concentration; D010100:Oxygen / Q000378:metabolism; D012189:Retrospective Studies; D018570:Risk Assessment; D013345:Subarachnoid Hemorrhage / Q000097:blood / Q000150:complications*
D006454:Hemoglobins; D010100:Oxygen
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