Depth of Anaesthesia Associated with 2.5% Isoflurane During Cardiopulmonary Bypass

Since its inception, and to this day, measurement of the depth anaesthesia during cardiopulmonary bypass (CPB) has been challenging. Bispectral index (BIS) is commonly used but remains controversial. One pragmatic approach to anaesthesia is to administer 2.5% isoflurane into the sweep gas supply to the oxygenator and allow neuromuscular blockade to fade so that patient movement indicates an insufficient depth of anaesthesia.