Long-term effects of anesthesia
Q. Are there long-term effects to undergoing general anesthesia?
A. “Overall, anesthesia is considered to be very, very safe,’’ says Terri Monk, an anesthesiologist at Duke University Health System. Unlike local anesthesia, which is limited to a particular part of the body, general anesthesia is systemic and renders the patient unconscious and immobile. Although it carries risks, intensive monitoring and safety measures make it so that anesthesia rarely causes severe injury, and it leads to about 1 death per 200,000 people who undergo it.
The state of general anesthesia has been called a type of coma, and while it’s over quickly, there has been concern in recent years that it may leave lingering effects in the brain, particularly among very young or elderly patients. Monk says that it’s typical for patients to experience some confusion or difficulty with mental tasks for the first few days after surgery, during which they are often on pain medications and recovering physically from their procedure. Some patients also experience a temporary state of confusion and disorientation called postoperative delirium, which resolves after the first few days after surgery.
A small percentage of patients continue to experience problems for a longer period of time, a condition called postoperative cognitive dysfunction, in which they have difficulty with memory or performing cognitive tasks. Monk was involved in a 2009 study of more than 1,000 patients who had major surgery, and found that after three months, a small percentage of patients still had symptoms of POCD, but the incidence was highest (more than 12 percent) in patients over 60. Risk seems to go up with age, and patients who perform poorly on cognitive tests before surgery also tend to do worse; it’s unknown how long symptoms persist.
Other researchers have been investigating whether general anesthesia could contribute to long-term effects in the developing brains of infants and young children, such as learning disabilities or emotional problems. Monk says the evidence is inconclusive, with some studies finding a potential effect and others finding none.
These studies are difficult to interpret because people who undergo major surgery are often ill and may have underlying medical problems that lead to cognitive problems, so it’s difficult to disentangle the effects of anesthesia itself. Monk says that so far there’s no evidence in humans that anesthesia causes permanent harm to the brain.
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