Technology Profile: Studies Awakening New Understanding of Anesthesia

Emery Brown, MD, PhD, and Patrick Purdon, PhD give insight into their research and use of a new neuroscience-based approach to researching anesthesia.

A few years ago, Emery Brown, MD, PhD, realized that something seemingly obvious was missing from the way anesthesiologists historically had approached their research since drugs were first used to induce general anesthesia at MGH in the mid-1800s. Even after 167 years, little is known about how the drugs lead to the deep loss of consciousness necessary to undergo surgery. Thus, he began thinking about his field from a different perspective. “We give drugs that affect the brain and the central nervous system,” says the MGH anesthesiologist and MIT Professor. “But anesthesiologists don't know neuroscience, and as a consequence, neuroscience paradigms are not used in the way we take care of patients or the way we design our drugs.” Dr. Brown believed that applying the neuroscience paradigm would create infinite possibilities for improving understanding of anesthesia, and more effective drugs and techniques for monitoring patients in the operating room. Working with Patrick Purdon, PhD, an instructor of anesthesia at MGH and Harvard Medical School, and their colleagues, Dr. Brown tracked brain activity in human volunteers over a two-hour period as they lost and regained consciousness. The study identified distinctive brain patterns associated with different stages of general anesthesia. The patterns provide important mechanistic insight as they relate directly to the way in which the drugs act in the brain to produce unconsciousness. Anesthesiologists can now use these readings for more accurate monitoring of patients' brain-wave signatures during surgery. Using this clearer picture of the brain activity provided by neuroscience, Dr. Brown and his colleagues have created a program at MGH to train anesthesiologists how to read electroencephalograms (EEGs) so that they have a better understanding of the state of the patient while anesthetized. “The main thing is for anesthesiologists to understand how to read the different patterns of the drugs in the EEG,” he says. “That's important because each drug has a different signature, and we also have to know how that changes with the different clinical scenarios of the patients.” Dr. Brown and Dr. Purdon have taken full advantage of all of the state-of-the-art diagnostic technology available to them, from electrodes implanted in the brains of patients with epilepsy – which led to the first study that recorded neuron activity of patients under anesthesia – to functional Magnetic Resonance Imaging. Moreover, all of MGH's approximately 50 operating rooms are equipped with EEG recording equipment, so they can evaluate the patient data from the 200 to 250 daily operations. One of the next steps in their research is studying new ways to wake patients from anesthesia. Right now, once the surgery is over, the anesthesiologists stop administering the gas, and the patient wakes up slowly – and groggily – as the effects dissipate. But Dr. Brown's lab and his colleague Ken Solt, MD, an MGH anesthesiologist and Harvard Assistant Professor, are examining more proactive measures, such as using drugs that would wake the person up and eliminate the fuzziness or cognitive problems patients initially experience. The FDA recently gave approval for clinical trials with humans to test the effectiveness of using Ritalin to awaken patients from anesthesia. Using the new neuroscience-based approach to research will open new opportunities to learn about the brain for applications across medicine, Dr. Brown says. “We're going to gain insights into other problems like how to treat pain better,” he states. “And maybe better ways to help people sleep, better ways to treat depression,” he states. “So, there are a lot of potential discoveries in this research beyond just the benefits that we are reasonably certain will accrue to anesthesiology.”