http://www.sciam.com/article.cfm?id=genera...leep&sc=rss

'Researchers studying the effects of general anesthesia recently made a startling discovery: the drugs used to knock out patients during surgery may lead to increased pain when they wake up.

Doctors have known for decades that most general anesthetics may cause a temporary burning sensation when administered or swelling around the injection site. Similarly, inhaled agents can cause momentary coughing bouts, according to Gerard Ahern, a pharmacologist at Georgetown University Hospital in Washington, D.C.

Now Ahern has discovered that some drugs used to put patients to sleep may also increase postoperative pain from the procedure itself by boosting the activity of a protein called TRPA1 on the surface of pain-sensing nerve cells.

Ahern and his colleagues write in the journal Proceedings of the National Academy of Sciences USA that anesthesiologists may be able to limit post-op pain by sticking to meds that do not have this effect. "By understanding the mechanisms for these noxious effects," says Hugh Hemmings, a professor of anesthesiology at Weill Cornell Medical College in New York City, "it gives you a way to screen for new drugs that don't have these effects, but do produce anesthesia."'