Packed red blood cell transfusion causes greater hemoglobin rise at a lower starting hemoglobin in patients with subarachnoid hemorrhage.
BACKGROUND
Each unit of packed red blood cells (PRBCs) is expected to raise circulating hemoglobin (HGB) by approximately 1 g/dL. There are few data on modifiers of this relationship other than gender and body mass index (BMI).


METHODS
We recorded HGB before and after PRBC transfusion in a retrospective cohort of 103 patients and a prospective cohort of 93 patients with subarachnoid hemorrhage (SAH).


RESULTS
In the retrospective cohort, 48 of 103 patients were transfused, and in the prospective cohort, 56 of 93 patients were transfused. In both groups, lower pre-transfusion HGB was associated with a larger increase in HGB (P < 0.001) after correction for the number of units of PRBCs given. In the prospective cohort, lower pre-transfusion HGB was associated with a greater rise in HGB (P < 0.001) after correction for number of units of PRBCs given, gender, and BMI in repeated measures analysis. Pre-transfusion HGB explained an additional 12% of variance in the data (P < 0.001). In both cohorts, the magnitude of the effect was similar.


CONCLUSIONS
In patients with SAH, transfusion at lower HGB leads to a greater increase in HGB. Transfusion at lower HGB may be relatively more cost-effective, and this should be balanced against any potential benefit from higher HGB in SAH. One rather than 2 units of PRBCs are likely to be sufficient for most HGB targets after SAH, especially in patients with more severe anemia.
Naidech
Andrew M
AM
Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA. a-naidech@northwestern.edu.
Kahn
Marc J
MJ
Soong
Wayne
W
Green
David
D
Batjer
H Hunt
HH
Bleck
Thomas P
TP
D000328:Adult; D000368:Aged; D000740:Anemia / Q000097:blood* / Q000628:therapy*; D015992:Body Mass Index; D003422:Critical Care / Q000379:methods; D017707:Erythrocyte Transfusion; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors; D013345:Subarachnoid Hemorrhage / Q000097:blood* / Q000628:therapy*
D006454:Hemoglobins