Mixing local anesthetics to produce rapid onset, yet long duration, is a potentially hazardous practice, a University of Washington School of Medicine investigator cautioned the American Society of Anesthesiologists.
Addressing a scientific session of the ASA's annual meeting in Philadelphia, T. Jason Akamatsu, MD, suggested that such combinations "should be used with caution in the good risk patient and perhaps are to be avoided in the poor risk patient."Dr. Akamatsu, assistant professor of anesthesiology at the Seattle institution, reported that a synergistic toxicity was noted when solutions of mixed local anesthetics were injected into mice. His coauthors are Klaus H. Siebold, MD, a research fellow now enroute to Britain for further work, and John J. Bonica, MD, Anesthesiology Department chairman.Median lethal dose for 20% of the test mice was determined for individual local anesthetics, Dr. Akamatsu said. These LD20 doses then were injected in combinations