Anesthesia, while essential for surgeries, requires careful monitoring. You want the patient to be anesthetized enough that they won’t feel or remember anything. But you need to be careful to not anesthetize them so deeply that the anesthesia itself might cause later complications. For example, overuse of some important anesthetics such as propofol can sink a patient into a state known as “burst suppresion”. If a patient falls into this state during surgery, then after they wake up, they may experience confusion, delirium and memory loss – sometimes for months. We want to avoid that.

So, how much is too much propofol? How can the anesthesiologist tell if the patient is getting close to the burst suppression state, so that they can then back off a bit? In research funded by the National Institutes of Health, a team at the Massuchesetts Institute of Technology (MIT) used a mathematical tool known as state-space modeling to analyze the EEGs of patients undergoing anesthesia. They discovered that the strength of fluctuations in the amplitude of a particular type of brain waves is a very good measure of how close a patient is to the burst suppression state. This means that those fluctuations can be used to tell when to back off on the propofol.

While this result is too new to have made it into the clinic quite yet, it is very promising: using the new measure that the team discovered, anesthesiologists will be able to better protect their patients.