A clinical, radiological and statistical survey has been made of decompression sickness during the construction of the Dartford Tunnel. Over a period of two years, 1,200 men were employed on eight-hour shifts at pressures up to 28 pounds per square inch (p.s.i.). There were 689 cases of decompression sickness out of 122,000 compressions, an incidence of 0-56%.The majority of cases (94-9 %) were simple "bends". The remainder (5 1 %) exhibited signs and symptoms other than pain and were more serious. All cases were successfully treated and no fatality or permanent disability occurred. In two serious cases, cysts in the lungs were discovered. It is suggested that these gave rise to air embolism when the subjects were decompressed, and pulmonary changes may contribute more than hitherto believed to the pathogenesis of bends. Some other clinical features are described, including "skin-mottling" and an association between bends and the site of an injury. The bends rate is higher for the back shift (3 p.m. to 11 p.m.) and the night shift (11 p.m. to 7 a.m.) than for the day shift. In the treatment of decompression sickness it appears to be more satisfactory to use the minimum pressure required for relief of symptoms followed by slow decompression with occasional "soaks", than to attempt to drive the causative bubbles into solution with high pressures.During the contract the decompression tables recently prescribed by the Ministry of Labour were used. Evidence was obtained that they could be made safer, and that the two main assumptions on which they are based (that sickness will not occur at pressures below 18 p.s.i., and that a man saturates in four hours) may be incorrect. It is desirable to test tables based on 15 p.s.i. and eighthour saturation. The existence of acclimatization to pressure was confirmed; it is such that the bends rate may fall in two to three weeks to 011% of the incidence on the first day of exposure. Acclimatization is lost again, with a "half-time" of about seven days, if a man is away from work.A study of bone damage in compressed air work has been started. In certain radiographs, abnormalities have been seen which may represent an early stage of caisson disease of bone.The new tunnel between Kent and Essex under the Thames at Dartford is part of a four miles road link between A2, the London-Rochester road, and A13, the Barking-Southend road. It is situated 14 piiles down river from the Blackwall Tunnel, until now the most easterly point at which it has been possible to cross the Thames by road. The river at Dartford is half a mile wide, so that the total length of the tunnel, including the sloping approaches at each end, will be approximately one mile. The tunnel lies about 20 ft. below the existing bed of the river in strata which consist of soft blue peaty clay overlying gravel which in turn overlies solid chalk. The preliminary pilot tunnel was completed in 1938, and the present contract for the full tunnel was let in 1956. It has an internal diameter of 28 ft. 2 in. and will accommodate tw...
1. A radiographic investigation of a group of 241 men who had worked in compressed air at pressures up to 35 pounds per square inch gauge on the construction of tunnels under the River Clyde showed that forty-seven men (19 per cent) had one or more lesions of aseptic necrosis of bone. 2. The radiological lesions have been classified as juxta-articular, which may lead to pain and limitation of movement, and head, neck and shaft lesions, which are usually symptomless. In 10 per cent of the men the lesions were juxta-articular and therefore potentially disabling. The treatment ofjuxta-articular lesions is described and reviewed. 3. The environmental factors associated with the occurrence of aseptic necrosis of bone, the radiological and histological appearances, and the pathogenesis of the lesions are discussed. Bone lesions were found to be related directly to the number of times a man had been decompressed, to the height of pressure at which he had worked and to attacks of bends for which treatment was given. 4. When the histological and radiographic appearances of aseptic necrosis of bone in compressed air workers are compared it is clear that a radiograph may not always reveal the full extent of the lesion, and some lesions may not show up at all. The cause of the necrosis is obscure because experimental and direct evidence of bone infarction by gas bubbles is lacking. 5. The currently accepted decompression procedures and treatment of bends used in civil engineering practice, do not prevent the occurrence of aseptic necrosis of bone in compressed air workers. 6. It is suggested that periodic radiological examination of the bones of compressed air workers should be carried out and the results correlated with other information about the men and the contracts on which they have worked in order to elucidate the causative factors in aseptic necrosis of bone. A central registry has been set up by the Medical Research Council in the University of Newcastle upon Tyne to fulfil this function.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.