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While it continues to talk about BMI as though it were a valid medical tool, and buys into a fair number of canards, this NYT article has some important info about surgery, anaesthesia, and chemo as well as some good reporting:

“Surgery involves anesthesia, of course, giving rise to another issue.

There are no requirements for drug makers to figure out appropriate doses for obese patients. Only a few medical experts, like Dr. Hendrikus Lemmens, a professor of anesthesiology at Stanford University, have tried to provide answers.

His group looked at several drugs: propofol, which puts people to sleep before they get general anesthesia; succinylcholine, used to relax muscles in the windpipe when a breathing tube must be inserted; and anesthetic gases.

Propofol doses, Dr. Lemmens found, should be based on lean body weight — the weight of the body minus its fat. Using total body weight, as is routine for normal-weight people, would result in an overdose for obese patients, he said. But succinylcholine doses should be based on total body weight, he determined, and the dosing of anesthetic gases is not significantly affected by obesity.

As for regional anesthetics, he said, “There are very few data, but they probably should be dosed according to lean body weight.”

“Bad outcomes because of inappropriate dosing do occur,” said Dr. Lemmens, who added that 20 to 30 percent of all obese patients in intensive care after surgery were there because of anesthetic complications. Given the uncertainties about anesthetic doses for the obese, Dr. Lemmens said, he suspects that a significant number of them had inappropriate dosing.”