Longer-term outcomes also may be improved
Tailored doses of anesthesia can improve the safety and quality of patient care dramatically during and immediately after surgery, and may even reduce postoperative mortality rates in the longer term, report physicians from the Medical College of Georgia and MCG Health System in Augusta. They reported some of their latest findings Oct. 26, 2004, at a meeting of the American Society of Anesthesiologists (ASA).1
"Ensuring patients receive just the right amount of anesthesia may have a more dramatic impact on the safety and quality of patient care than previously thought," observes James B. Mayfield, MD, director of perioperative services and vice chairman in the department of anesthesia at MCG, and lead author of the study.
"Tailored anesthesia" refers to dosing based on medical condition, the drugs the patient is taking, and so forth, he adds. The study, based on a yearlong quality improvement initiative in MCG’s ORs, included adoption of an advanced brain-monitoring device called BIS technology.
BIS stands for bispectral analysis, Mayfield explains. "The device essentially monitors brain waves acquired from the patient’s forehead, runs the data through a sophisticated analysis in a computer box near the patient, and creates a reading of 0-100." A reading of 100 indicates the patient is completely awake, and 0, completely asleep. "Between those are varying degrees of sedation," he declares.
Not first use of BIS
Mayfield has been using the BIS for many years, notably, at Massachusetts General in Boston, where he was director of ambulatory surgery. "We showed some wonderful effects of being able use less medication, wake the patient up quicker, do better overall — but that was in an ambulatory setting," he explains.
"Here, we wanted to see if it would work in an entire operating room, and this study also helped us figure out the effects of titration on short-term outcome in the recovery room. We found if the doses were tailor-made, all those parameters greatly improved," Mayfield adds.
The patients were kept at a depth of consciousness of somewhere between 45 and 60. "Research has shown if you do that, you have maximal benefit for post-op outcomes," he notes. "If the patient is too light, there is awareness and perturbations in vital signs. If they are too deep, it takes longer to wake up, you use more sedation, there is post-op nausea and vomiting, cognitive deficits, and so forth."
The measures the researchers looked at were pain therapy, nausea and vomiting, temperature, alertness and orientation, cardiovascular status and care, and respiratory status and care. Improved outcomes were shown for all measures, and only the improvement for respiratory status and care was not statistically significant.
In short, the BIS-guided anesthesia care enabled patients to wake sooner; respond quicker; experience less nausea, vomiting, and pain; go home sooner; and have fewer postoperative cardiovascular problems.
"It was kind of shocking to us to think that just managing patients [in this manner] could have such a profound effect in the operating room," Mayfield comments.
More traditional methods of determining the proper amount of anesthesia involve taking vital signs. "Research has shown that vital signs are fairly nonspecific for deciding what dosage to give patients," he asserts.
"With BIS, you track the amount of anesthesia given at a given time; if the patient has a number higher than 60 or 65, you give them more anesthesia, and if they are too deep, you let off. It enables you to titrate to the specific needs of the patient," Mayfield notes.
The dosages stayed within a tighter range, and thus, less medicine was used than previously was used without the BIS, he points out. "When you use vital signs, you tend to overdose the patient a bit. With the BIS, using brain signs you know exactly how much to give; you use less, and the patient is safer."
The BIS, which is manufactured by Aspect Medical Systems Inc., of Newton, MA, is "fairly inexpensive compared with many medical devices," Mayfield explains. "Many hospitals could use it."
Co-author urges caution
While the study also indicated the BIS may even improve post-op mortality rates in the long run, Steffen E. Meiler, MD, associate professor, vice chairman of research and director for the program of molecular perioperative medicine and genomics in the department of anesthesiology and perioperative medicine at MCG and one of the paper’s co-authors, warns, "We have to be very careful of this. This is a very early finding that came about as a surprise from Terry Monk’s data at Duke.2 It opened up the very intriguing question about whether perioperative patient management does have impact long-term."
One of the challenges, he notes, is that other factors, such as inflammatory response, may have significance in post-op mortality rates. Drugs such as statins, for example, have been shown to be effective in controlling inflammatory responses. Some beta-blockers also have been shown to have a long-term effect on the inflammatory response.
"The BIS is a different story; all we can say in that there appears to be a correlation between long-term death and the depth of anesthesia. The research shows the more time you spent as a patient with a lower BIS value, the higher seems the likelihood for a bad event or even death in the long term."
While other factors may be playing a role in long-term survival, "The data are tantalizing enough to go after 40,000 to 50,000 deaths in the U.S. each year we could avoid by reducing mortality by just 5%," he concludes.
1. Mayfield JB, Meiler SE, Head CA. Routine cerebral monitoring improves postoperative acuity and recovery from general anesthesia. Anesthesiology 2004; 101:A291.
2. Monk T, Sigl J, Weldon BC. Intraoperative BIS utilization is associated with reduced one-year postoperative mortality. Anesthesiology 2003; 99(suppl):A1361.
Need More Information?
For more information, contact:
• James B. Mayfield, MD, Director of Perioperative Services, Vice Chairman, Department of Anesthesia, Medical College of Georgia, Augusta, GA 30912-2700. Phone: (706) 721-7773.
• Steffen E. Meiler, MD, Associate Professor, Vice Chairman of Research, Director, Program of Molecular Perioperative Medicine and Genomics, Department of Anesthesiology and Perioperative Medicine, Medical College of Georgia, 1120 15th St., BIW 2144, Augusta, GA 30912-2700. Phone: (706) 721-3287. Fax: (706) 721-4150. E-mail: firstname.lastname@example.org.
• Aspect Medical Systems Inc. (World Headquarters), 141 Needham St., Newton, MA 02464. Phone: (617) 559-7000. Fax: (617) 559-7400. E-mail: email@example.com.