Recently released outcomes from a randomized, controlled clinical trial in Japan involving over 170 children aged 1 to 6 who underwent surgery indicate that by utilizing electroencephalogram (EEG) readings to observe brain waves during unconsciousness, an anesthesiologist can notably minimize the amount of anesthesia given, thereby safely inducing and maintaining each patient’s anesthetized condition. On average, the young patients demonstrated considerable enhancements in various post-operative results, which included faster recovery and fewer cases of delirium.
“The primary conclusion is that for children, employing the EEG allows us to lessen the dosage of anesthesia while still keeping the same level of unconsciousness,” states study co-author Emery N. Brown, the Edward Hood Taplin Professor of Medical Engineering and Computational Neuroscience at MIT, an anesthesiologist affiliated with Massachusetts General Hospital, and a professor at Harvard Medical School. The study was published on April 21 in JAMA Pediatrics.
Yasuko Nagasaka, head of anesthesiology at Tokyo Women’s Medical University and a former associate of Brown in the United States, conceptualized the study. She requested Brown to mentor and guide lead author Kiyoyuki Miyasaka from St. Luke’s International Hospital in Tokyo on utilizing EEG for monitoring unconsciousness and adjusting anesthesia dosages in children. Miyasaka subsequently acted as the anesthesiologist for all trial participants. Attending anesthesiologists not involved in the this research were consistently available for oversight.
Brown’s research at The Picower Institute for Learning and Memory, the Institute for Medical Engineering and Science, and the Department of Brain and Cognitive Sciences at MIT has demonstrated that an individual’s level of consciousness under any specific anesthetic agent can be distinguished through their brain wave patterns. Each child’s brain wave activity was recorded using EEG; however, in the control cohort, Miyasaka followed conventional anesthesia dosing protocols, whereas in the experimental cohort, he used EEG data to guide his dosing decisions. The findings illustrate that with the aid of EEG, he was able to achieve the desired level of unconsciousness with a concentration of 2 percent sevoflurane gas, compared to the conventional 5 percent. To maintain unconsciousness, he found that only a concentration of 0.9 percent was necessary, rather than the usual 2.5 percent.
Simultaneously, a separate investigator, unaware of whether EEG or standard protocols were utilized, evaluated the children for signs of “pediatric anesthesia emergence delirium” (PAED), where children might awaken from anesthesia exhibiting symptoms such as lack of eye contact, inconsolability, detachment from their surroundings, restlessness, and random movements. Among those receiving standard anesthesia dosages, 35 percent (30 out of 86) met the criteria for PAED, while in the EEG-guided dosing group, only 21 percent (19 out of 91) reached the threshold. This disparity of 14 percentage points was statistically significant.
Moreover, the authors noted that, on average, EEG-guided patients had their breathing tubes removed 3.3 minutes sooner, emerged from anesthesia 21.4 minutes earlier, and were discharged from post-acute care 16.5 minutes quicker than those who received anesthesia following the standard guidelines. All these differences were statistically significant as well. Additionally, no child in this study experienced awareness during surgery.
The authors pointed out that the faster recovery for patients who received EEG-guided anesthesia was not only medically advantageous but also helped lower health-care expenses. Time spent in post-acute care in the United States costs approximately $46 per minute, so the average reduction of 16.5 minutes could save around $750 per instance. Sevoflurane is also a potent greenhouse gas, Brown emphasizes, making its reduced use beneficial for the environment.
In this research, the authors also provide comparisons of EEG recordings from children in both the control and experimental groups. There are distinct differences in the “spectrograms” that illustrate the power of specific brain wave frequencies both during surgery and as children were nearing emergence from anesthesia, according to Brown.
For example, among children who received EEG-guided dosing, there were clearly defined bands of high power at around 1-3 Hertz and 10-12 Hz. In contrast, in children subjected to standard protocol dosing, the entire frequency range up to approximately 15 Hz displayed high power. Additionally, children who presented with PAED exhibited higher power across several frequencies up to 30Hz compared to those without PAED.
These results further reinforce the concept that monitoring brain waves during surgery can offer anesthesiologists practical insights to enhance patient care, asserts Brown. Training in interpreting EEGs and managing dosing can be easily incorporated into ongoing medical education at hospitals, he adds.
Alongside Miyasaka, Brown, and Nagasaka, Yasuyuki Suzuki is also a co-author of the study.
Funding sources for this research include the MIT-Massachusetts General Brigham Brain Arousal State Control Innovation Center, the Freedom Together Foundation, and the Picower Institute.