Ropcke et al. [5] showed that BIS values were higher with surgical stimulation than without any stimulation. Other reports have shown that focal noxious stimuli in volunteers and patients induce transient increases in BIS [6-9]. Many of these studies show that adding analgesics suppresses the BIS response to noxious stimulation, and the level of suppression achieved was related to the dose of the added drugs [6, 8, 9].