Detection of cerebral hypoperfusion with bispectral index during paediatric cardiac surgery

Background. The bispectral index (BIS) may indicate changes in cerebral activity when the cerebral circulation is affected by acute hypotension. Methods. We measured BIS and cerebral haemoglobin saturation (Sr-o2) by near-infrared spectroscopy in 10 children undergoing cardiac surgery. Results. We noted 14 episodes of simultaneous decreases in Sr-o2, and BIS during acute hypotension in five children. An acute decrease in BIS, which coincided with a decrease in Sr-o2, suggesting a reduction in cerebral blood flow, was associated with acute slowing of the raw EEG waveforms. Conclusions. Our findings suggest that an acute decrease in BIS during acute hypotension indicates cerebral hypoperfusion, and that cerebral hypoperfusion caused by hypotension may occur frequently during paediatric cardiac surgery.