So. Plenty of oxygen was consumed discussing/arguing/debating the merits of the secret-recipe Aspect BIS cerebral monitor at this year's ASA. Isn't this getting old? First, my disclosures. I have no financial interest in or support from Aspect medical (in fact, given the state of the economy, I have no financial interest or support from anything, aside from my ever-shrinking clinical income.) Second, I use the BIS every day, on almost every case I do longer than 15 minutes, paralyzed or not. I even use it on most functional (awake) craniotomies. I have been known to shave the occiput in order to place a BIS array for ACOM aneurysm clippings (yup, we still do them here, now and then). I liiike it. I've used it at least a thousand times.
But it does have its limitations. Like last month, when a young lumbar patient on 2% Sevo and fent with a reading of 42 "BIStles" (that's what I call 'em-why not?) in one epoch, did his best unconscious imitation of upward facing dog the next... (yes Ira, I know-the brain is not the spinal cord.) Do a hundred BIS cases without paralysis and you'll understand in your gut what I mean. But I still like it.
As monitors go, in my practice, the BIS is worth about 1 pulse-ox units (pou). By comparison, the gold standard monitor, the pulse-ox is a perfect 10 pou's. The Pulse ox is the most perfect anesthesia monitor that ever was, or could be (anybody besides me old enough to remember that feeling in your gut upon hearing a surgeon say "the blood looks dark"?) Blood pressure, maybe 7 or 8 pou's. Gas monitor, about a 6. The ECG, 2 or 3. This score is obviously my subjective weighting of the sensitivity and specificity of each monitor for keeping my patients (and me) out of trouble, and can certainly vary based upon each individual patient's specific situation (for instance, a person with a history of SVT intuitively derives much more utility from intraop ecg monitoring than a fit 20 something, in whom the ecg almost never tells me anything I don't know from the plethysmograph.)