Clinical implication of orbital ultrasound monitoring during selective cerebral perfusion

Background. We evaluated clinical relevance of orbital ultrasound (OUS) mon itoring to neurological events in aortic surgery associated with selective cerebral perfusion (SCP). Methods. In 24 consecutive cases, blood now was monitored at central retina l artery (CRA) and retrobulbar vessels. The threshold perfusion pressure fo r detecting CRA flow in the color Doppler mode (BPt) was determined in indi vidual eyes. Results. The BPt ranged from 25 to 71 mm Hg. Events (infarction, anisocoria , delirium) occurred in 8 cases. Infarction occurred in all 3 eases when re trobulbar now was severely impaired for 40 minutes or longer, while none of the remaining 21 cases had infarction (p = 0.0005). Among the latter cases , perfusion pressure was below BPt for longer than 100 minutes in all 5 cas es with events, and in 5 of 16 cases without events (p = 0.0124). No signif icant difference was found in age, duration of cardiopulmonary bypass, SCP, and circulatory arrest, and duration of blood pressure below 50 mm Hg. Conclusions. Sustained hypoperfusion detected with OUS monitoring is relate d to an occurrence of neurological events. (C) 2001 by The Society of Thora cic Surgeons.