FDA Rejects ACG Petition: Propofol Remains in Realm of Anesthesia
by, 11-25-2010 at 11:42 AM (1570 Views)
[QUOTE=narkose;110622]“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science.” (William Thompson, knighted Lord Kelvin. Popular lectures and addresses [1891-1894])
Like the pulse oximeter, until a reusable sensor for BIS is brought to market & users know to trend EMG as a secondary trace, outliers for propofol response will continue to exist & needless danger will lurk for patients for whom anyone may be attempting to administer propofol.
Titrating propofol with BIS & EMG as a secondary trace is like taking an open book test instead of continuing to guesstimate propofol requirements for individuals. It's like the difference between looking through the front windshield of your car (BIS/EMG) versus trying to navigate with only the rear view mirror (BIS alone).
In 13 years of titrating propofol using BIS/EMG when patients received 0.2 mg po clonidine 30-60 min. preop, my average propofol rate ran between 25-50 mcg/kg/min.
Never until last year had I ever needed to turn the pump below 10 mcg/kg/min.
Over a 6 week span in 2009, I had 2 patients with a 60-fold variation in their propofol requirements, both had 6 hour procedures.
Court MH, Duan SX, Hesse LM, et al.: Cytochrome P-450 2B6 is responsible for interindividual variability of propofol hydroxylation by human liver microsomes. [I]Anesthesiol[/I] 94:110, 2001.
Only accounts for a 19-fold variation. FWIW, recently learned that hydroxylation is not the primary propofol metabolic pathway.
The first was a 62 yo otherwise fit 70.5 kg Caucasian female, who preoperatively stated she slept for [B]2 days[/B] after her last propofol experience.
I could barely keep her [I]above[/I] 55 @ 2.5 mcg/kg/min! Unbelievable at 25% of my previously lowest rate, but consistent with her story.
I welcome those (skeptics) who want documentation to view this 1 min, 14 second clip from this case: [video=youtube;EkMqMhXiEXY]http://www.youtube.com/watch?v=EkMqMhXiEXY[/video]
At the end of the 6 hour case, she awakened immediately, stated it was her best anesthetic experience, heard, felt & remembered nothing!
The second was a 58 yo Caucasian male, 100 kg, otherwise fit Greenlander whom I could barely keep [I]down[/I] to 75 @ 150 mcg/kg/min for 6 hours!
His emergence was identical to the first patient! (Sorry, no clip, but my hands fatigued trying to keep up reloading propofol syringes!)
Moral: you don't need to own stock in a brain monitor company (which I do not) to appreciate the utility of the device when used in an off-label configuration.
☛ Used monochrome BIS ~$500 @ [url]www.dotmed.com/listing/631327[/url]
Will also need to order from Covidien (formerly Aspect Medical Systems, Inc.) Software upgrade
& a BIS X (the part between the monitor and the sensor) to enable use of the 4 lead sensor.
If this is too much for you to personally invest in your patients' care, then I have a hard time believing you are really sincere about the effort.
My life (& bank account) will not change one iota but your patients', yours' & your surgeons' will & the change [I]will[/I] be dramatic. Don't be cheap. Get your own if wherever you work won't do it for you.
Although the EMG is displayed in the factory configuration, it is done on a vertical scale.
We dedicated anesthesia providers tend to process our information on a left to right screen sweep; i.e. EKG, SpO2, EtCO2, art & PA pressures.
If one responds to EMG spikes as if they were HR & BP changes, the utility of BIS is dramatically improved & 'outliers' are no longer.
Measuring is better than guessing but you have to know [I]what[/I] to measure, too!
For those who missed the recent Kuala Lumpur & Singapore venues ([url]http://www.asiaone.com/Health/Health%2BMatters/Story/A1Story20101025-244133.html[/url]),
the next learning opportunity will be much closer in San Diego, Saturday Feb. 26 ([url]http://www.expertclick.com/Newsreleasewire/34279[/url]).
Best holiday wishes to all![/QUOTE]