Anemia is a common problem among critically ill patients. Nearly two thirds of patients are anemic on admission to the intensive care unit (ICU)1 and between 70-95% of patients develop anemia by day 3.2,3 Lower hemoglobin levels decrease the oxygen carrying capacity of blood and may reduce tissue oxygenation. This is particularly detrimental for patients with subarachnoid hemorrhage (SAH) as they are subject to increased metabolic demand for oxygen from cerebral ischemia. The optimal hemoglobin concentration in patients with subarachnoid hemorrhage (SAH) is unknown. Thirty per cent of SAH patients have a hemoglobin <10 g/dl during hospitalization.4 Many patients are routinely hemodiluted as a part of hypertensive, hypervolemic, hemodilution (triple H) therapy. Hemodilution may improve blood rheology, but it has also been shown to impair brain tissue oxygenation and increase secondary brain injury.5

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