ABSTRACT
Evidence accumulated over many years indicates that all the current caisson decompression schedules in use are inadequate. The reported incidence of decompression illness (DCI) is considerably lower than the actual. Most previous decompression schemes for tunnel workers have been extrapolated from naval schedules, albeit navies have had very little experience with long-duration dives at shallow depths. Oxygen decompression tables developed in Milwaukee are based on commercial data and eliminate nitrogen several times more effectively than existing schedules. Oxygen decompression appears to be the only viable method of decompressing tunnel workers on a daily basis. These tables appear to be a great deal safer than existing tables, but regulating bodies in the United States, Great Britain and Japan have failed to keep pace with recent developments in decompression physiology. In the past, dysbaric osteonecrosis has been the most feared complication of tunnel decompression. New evidence from Milwaukee, Wisconsin, indicates that there may be the possibility of central nervous system damage secondary to improper decompression. Tables from Japan, the United States, Great Britain, Germany and France are compared with the new oxygen decompression tables. Data regarding central nervous system changes in the brain of compressed air tunnel workers as seen with magnetic resonance imaging are reported.
