Total Cerebral Metabolic failure occurs at cerebral blood flow of – (AIPG 2012)
a. Cerebral blood flow varies with metabolic activity. It is most commonly measured with a gammaemitting isotope such as xenon.
b. CBF parallel with metabolic activity can vary from 10 -300 mL/100mg/min. average is 50 mL/100mg/min, grey matter it is 80 mL/100mg/min white matter it is 20 mL/100mg/min. total CBF average 750 ml/min(15to 20%).
c. 20-25 mL/100mg/min- cerebral impairement starts, EEG slows
d. 15- 20 mL/100mg/min- flat EEG
e. 10 mL/100mg/min- IRREVERSIBLE DAMAGE
Ref. morgan anaesthesia-pg615.