"Most patients tolerate their anesthetic experience despite the care they receive rather than because of it," claims Dr. Barry Friedberg, holder of the trademark "minimally invasive anesthesia (MIA)®." Anesthesiologists (and nurse anesthetists) have traditionally been taught to medicate patients on a per-kilogram of body weight to begin the patient's anesthesia. After the patient is asleep, subsequent medication doses are then adjusted primarily based upon changes in heart rate and blood pressure. However, the object of the anesthetic agents is to medicate the patient's BRAIN, not the heart rate and blood pressure. To ensure patients are actually asleep, the anesthesia provider was formerly obliged to over-medicate for fear of under-medicating. (N.B. "This common practice is informally known as the art of the controlled overdose," says Dr. Friedberg.) It is now possible to directly measure the brain's response to anesthetic agents.
Modern anesthetic agents are shorter acting, allowing patients to wake up faster. However, recent research points out the dangers of routinely giving excess anesthesia. At Duke, Monk showed higher one year postoperative death rates when patients were overmedicated as defined by bispectral index (BIS) values below 45 on a 0-100 scale. An inflammatory response to excessive anesthesia was suggested as the cause. At Emory, Sebel subsequently published a study confirming elevated levels of inflammatory markers (C-reactive protein) in patients that were overmedicated (BIS below 45) compared to those patients who were accurately medicated for general anesthesia (i.e. BIS 45-60).
It is not uncommon for relatives of elderly patients to observe that, in layman's terms, they are 'not quite the same' after their anesthesia as they were before surgery. This phenomenon is formally known as postoperative cognitive dysfunction (POCD). "Many believe POCD may also be a function of anesthetic overdose," states Dr. Friedberg.
"How can prospective patients avoid being routinely overdosed? By being sure the BIS monitor (Aspect Medical Systems, Inc., Norwood, MA) is used," asserts Dr. Friedberg.
The BIS is the first level of consciousness monitor to be FDA approved in 1996. Although several competitors exist in the marketplace, none has presented any studies demonstrating superiority to the BIS. Conversely, over 3,000 scientific papers attest to the BIS' utility.
Why have considerable numbers of anesthesia providers been reluctant to change to BIS monitoring? "Because measuring the brain's response to anesthetics challenges the deeply held belief system that heart rate and blood pressure are reliable guides to depth of anesthesia," opines Dr. Friedberg (N.B. Heart rate and blood pressure are unreliable guides.) Unfortunately, belief systems are not subject to rational discussion. Therefore, a FORCE FOR CHANGE must be created by greater PUBLIC awareness of the dangers of excessive anesthesia. "For maximum patient safety, BIS monitoring should be the standard of care," claims Dr. Friedberg.
Disclaimer: Dr. Friedberg is not employed by Aspect Medical Systems, makers of the BIS monitor. He is not a stockholder or a paid consultant. The opinions expressed herein are his professional opinion based on 10 years experience with BIS monitoring.