“…The effect of induced hypotension on cerebral blood flow and oxygenation has been investigated using Doppler ultrasonography 47,49,50,85 , infrared spectroscopy 82 , thermal gradient blood flow meter 6 , measurement of difference in oxygen content in arterial and venous blood samples 60,72 , clearance of intra-arterially injected xenon 133 60 and electroencephalography 82,179,186 . Most studies showed no decrease in cerebral blood flow during hypotensive anaesthesia 4-6,8, 23,24,50,82,85,94,107,116,131,142,163,181,184,186,199 and even if there were a statistically significant reduction there was no evidence of a long-term adverse outcome clinically. One study entered in the final review showed no significant difference in cognitive test scores between patients receiving normotensive and hypotensive anaesthesia 153 .…”