Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jan 2001
Effects of profound anemia on brain tissue oxygen tension, carbon dioxide tension, and pH in rabbits.
This study sought to determine the maximum tolerable limit of anemia for the brain during halothane anesthesia. Using a multiparameter sensor, we continuously monitored brain tissue oxygen tension (PO2), carbon dioxide tension (PCO2), and pH during profound hemodilution and subsequent transfusion. Twelve New Zealand White rabbits were anesthetized, intubated, and mechanically ventilated at a fraction of inspired oxygen (FiO2) of 21% to produce an arterial carbon dioxide tension (PaCO2) of 35 to 40 mm Hg. ⋯ Hemodilution results in a decrease in brain tissue PO2. Increases in CBF and oxygen extraction can only partially compensate for the decreased oxygen carrying capacity of the blood. Decreases in brain tissue PO2, pH, CMRO2, and a loss of EEG amplitude suggest that the maximum tolerable limit of hemodilution was achieved in this study.