Can doctors wake a patient from anesthesia without restarting their memory, too?
We commonly think of being under anesthesia as being put “to sleep.” But there are several components to this state: patients benefit from anesthesia by being sedated but also because they can’t form memories. For example, anesthesia means patients won’t remember having a breathing tube removed after an operation.
But suppose those two components could be isolated and a patient could be roused from the sleep part of anesthesia while their brain still is prevented from forming memories. Sedation carries risks, such as breathing problems, so it could be useful to quickly bring patients out of sedation after surgery but delay their ability to start forming memories until after all the potentially unpleasant steps, like breathing tube removal, are complete.
New research by Dr. Michael Fettiplace, who recently joined the University of Illinois Chicago, and colleagues has demonstrated in rats that it might be possible to separate waking from anesthesia and the resumption of memories. The discovery helps researchers better understand how anesthesia works, and it could lead to improved patient care.
“Many people thought the loss of memory was due to the fact that you were asleep, or de-aroused,” said Fettiplace, assistant professor in the College of Medicine and lead author on the study. “But this is not the case.”
The researchers began by having the animals perform a task that required them to use their short-term memory to get food. Then they sedated the animals. Next, they gave each rat a stimulant — a drug commonly prescribed for ADHD.
The researchers wanted to see if the animals, now awake, would be able to complete the memory task correctly and discovered they could not. The research is published in the British Journal of Anaesthesia.
The finding implies that “there are different areas of the brain that are activated by the anesthetic agent and you can separate out the effects,” Fettiplace said. “You may be able to reverse the de-arousing effect so the patient starts waking up and breathing but not reverse the therapeutic effect of amnesia.”
The study’s findings also point to a way to accelerate a patient’s emergence from anesthesia. Currently, there is no reversal drug for anesthesia; doctors wait for the patient to metabolize the drug, and it slowly wears off. But there are cases where it would be helpful for a patient to be revived more quickly, Fettiplace said, such as long neurosurgical surgeries where doctors want to make sure the patient’s brain can still tell the patient’s legs to move but don’t want the patient to remember being in the operating room.
“We have drugs that put people to sleep,” he said, “but we don’t have drugs that wake people up.”
Fettiplace conducted the research while he was at Harvard University. The other authors on the study are from Harvard, Touro College of Osteopathic Medicine, Brigham Young University and the University of California Irvine.
