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Anesthesia

Weight and anesthesia

03/02/2007

Question:

I had outpatient surgery today under general anesthesia. The Dr told my husband it was enough to knock out an elephant before I finally was out. and following the surgery, the nurses gave me alot of fentanyl, phenerghan, patch for nausea and 10 times they put benadryl in the IV. I never went to sleep and the nurse was in awe that I was talking and making sense. It is almost midnite and I woke at 8:00 am for surgery at 12:00/ Left hospital at 4:00pm when the itching seemed to be at its lowest point. I have never used illegal drugs and have been taking hydrocodone for the pain and not as often as I should. Is there a reason I was not affected by the meds as "normal" people do. I weight 100 lbs, 5 ft 5 inches and I am 49 years old. thanks

Answer:

Its probably in your genes.

Oxycodone is an opioid pain-reliever. The more you take, the more tolerance you develop, so the more you need. This might explain why you could be given a lot of fentanyl, a drug which is also an opioid, and still be wide awake after your procedure. But it would not explain why you had to be given a lot of medication to go to sleep for your procedure.

The science of pharmacogenetics - the study of how genetics affect the body's handling of drugs - is still in its infancy. This is the science that is beginning to explain differences in how people respond to drugs, whether those drugs are antibiotics, anesthetics, cancer drugs, or others.

In fact anesthesiology has made significant contributions to pharmacogenetics by showing, for instance, that some individuals cannot metabolise a commonly used muscle relaxant called succinylcholine. Similarly, there may be a certain genetic makeup that is associated with either increased rate of redistribution or breakdown of certain anesthetic drugs, (that is a pharmacokinetic explanation) or are "resistant" to the effects of the drug at normal doses (a pharmacodynamic explanation). (Apologies for the technical language).

I don't know of any cases in which a person could not be anesthetised at all with any of the commonly used anesthetic drugs. It's simply a matter of being given enough. Although you may have needed a lot, its likely to be a matter simply of drawing up another syringe and adminsitering that. You won't siginficantly deplete the hospital formulary!

For you, the toughest part may be convincing another anesthesiologist or anesthesia team in the future that you need more than the average amount of anesthetic medication. Especially as you are apparently not elephant-sized! Many of us are born sceptics. You might want to consider getting a copy of your anesthetic record as proof and keeping that with the rest of your personal records. It'll be useful for you and your health care providers.

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Response by:

Gareth S Kantor, MD Gareth S Kantor, MD
Assistant Professor of Anesthesiology
School of Medicine
Case Western Reserve University