How often do patients not come out of anethesia at all?

5 in 1 million: Anesthesia continues to become safer every passing year, so no doubt this will be one in a million by the end of this decade. The odds are roughly the same of dying in a plane crash.

Almost never. : In my personal experience, I have never had patient not come out of anesthesia, and have never heard of a case of it happening. While it may be described as a possible occurrence, it is not really a risk in the real world. If a patient doesn't wake up after anesthesia, it is usually temporary and for other reasons.

Very rare: The risk of general anesthesia (ga) is less than that of driving to the hospital to have the operation. Ga is thought to have a risk of death of one in 350, 000 cases or more. Advances in monitoring, medical training, drugs and support have greatley decreased the risk. The main concerns after ga are usually nausea and vomiting post operatively.