DISTRIBUTION OF HEMATOCRIT VALUES AFTER ANEURYSMAL SUBARACHNOID HEMORRHAGE

Low hematocrit values are common after subarachnoid hemorrhage and may be associated with elevated cerebral blood flow and transcranial Dopp ler ultrasound (TCD) velocities, which may confound the interpretation of velocity as an indicator of vasospasm. The exact distribution of h ematocrit among a neurosurgical population would be useful in assessin g the magnitude of this difficulty but has not. been previously report ed. A database containing hematocrit values recorded at TCD examinatio ns over a period of 7 years was reviewed. Two thousand four hundred th irteen hematocrit values were recorded for 575 patients. The distribut ion of hematocrit values was recorded among patients and among TCD stu dies. Eighteen percent of the patient population achieved a hematocrit of 26% or less at some point in their hospital stay, whereas 57% of p atients achieved a hematocrit of 30% or less. Six percent of the TCD s tudies were associated with a hematocrit of 26% or less, while 33% of the studies were associated with a hematocrit of 30% or less.