In January of 1928, George J. Brett, D.D.S. (1896 to 1969), received a copyright for his “Brettometer Index” from the U.S. Copyright Office. Mounted on his namesake Brettometer anesthesia machine, the index was designed to assist dentists and physicians in delivering nitrous oxide and oxygen through “Stages I–IV” of anesthetic depth. According to Dr. Brett’s index, increasing the ratio of nitrous oxide to oxygen generally led to breathing changes: respirations increased slightly (stage I), quickened (II), regularized progressively toward a mechanical rhythm (III) and, if carried too far, became dangerously “spasmatic” (IV). On his unpremedicated patients, the Brettometer Index suggested that patient’s pupils dilated in stages I and II, constricted (III) and, if carried too far, finally dilated again (IV). Notice that Brett’s index presumed that men would need to be carried under greater inspired nitrous oxide concentration (hence lower oxygen) than would women and children! (Copyright © the American Society of Anesthesiologists’ Wood Library-Museum of Anesthesiology.)
In January of 1928, George J. Brett, D.D.S. (1896 to 1969), received a copyright for his “Brettometer Index” from the U.S. Copyright Office. Mounted on his namesake Brettometer anesthesia machine, the index was designed to assist dentists and physicians in delivering nitrous oxide and oxygen through “Stages I–IV” of anesthetic depth. According to Dr. Brett’s index, increasing the ratio of nitrous oxide to oxygen generally led to breathing changes: respirations increased slightly (stage I), quickened (II), regularized progressively toward a mechanical rhythm (III) and, if carried too far, became dangerously “spasmatic” (IV). On his unpremedicated patients, the Brettometer Index suggested that patient’s pupils dilated in stages I and II, constricted (III) and, if carried too far, finally dilated again (IV). Notice that Brett’s index presumed that men would need to be carried under greater inspired nitrous oxide concentration (hence lower oxygen) than would women and children! (Copyright © the American Society of Anesthesiologists’ Wood Library-Museum of Anesthesiology.)
George S. Bause, M.D., M.P.H., Honorary Curator and Laureate of the History of Anesthesia, Wood Library-Museum of Anesthesiology, Schaumburg, Illinois, and Clinical Associate Professor, Case Western Reserve University, Cleveland, Ohio. UJYC@aol.com.
