Book Review

The Bends: Compressed air in the history of science, diving, and engineering

N Engl J Med 1998; 339:1721December 3, 1998

Article

The Bends: Compressed air in the history of science, diving, and engineering
By John L. Phillips. 256 pp. New Haven, Conn., Yale University Press, 1998. $30. ISBN: 0-300-07125-6

The spanning of deep rivers and estuaries, the extraction of minerals from wet ground, and the exploration of the continental shelf were possible only when it became feasible for men to work under conditions of increased air pressure. Blacksmiths used leather bellows to generate compressed air as early as the 14th century, and natural philosophers experimented with air pumps in the 16th and 17th centuries, but these hand-powered devices could not conveniently compress the large volume of air needed to provide a practical work space. In the third decade of the 19th century, when engineers developed air pumps powered by steam engines that could force water from mines and fill caissons with compressed air, men began to work under hyperbaric conditions. Soon thereafter, physicians took note of the sicknesses produced, strangely, by a surfeit of life-sustaining air. “The bends,” as the new disease of industrial progress came to be called, is the subject of John Phillips's fascinating new book.

Today, we think it obvious that new industrial technology can threaten workers, and we demand full investigations after any occupational injury. Phillips recounts the many hundreds of injuries during the nearly 50 years that preceded the development of rational safety measures for the use of compressed-air environments in the 19th century. He focuses rightly on the early use of compressed air in caissons and in mining, for there the majority of workers were to be found. Following Triger's initial observations of new symptoms in the miners, Pol and Watelle, two physicians attending workers in a pressurized coal mine in Douchy, France, wrote the first medical report on mal de caisson, in 1854. There followed contributions from occupational physicians attending the caisson works at the Eads Bridge in St. Louis and the Brooklyn Bridge in New York. Clinical epidemiologic studies gradually associated the bends with the return to a normal atmosphere from the high pressure of the caisson. Physicians and engineers then noted that increasing the pressure in the caisson and extending the duration of the work shift increased the risk of the disorder. They instituted preventive regulations and provided comforts for the workers, making their industry, as Phillips points out, the first to institute on-site medical attendance and monitoring to prevent occupational injuries. Phillips also recounts the belated efforts of government to intervene in the management of workers' health. Miners and tunnel workers were among the first industrial workers to be covered by occupational-safety regulations. New York State introduced guidelines governing caisson work in 1909, as “sandhogs” began digging the East River and Hudson River railway tunnels. An unintended action of government rule-making has been, in Phillips's narrative, to ensure that traditional regulations remain in force when newer limits would be more effective.

Phillips discusses the pioneering physiologic work of Paul Bert and of J.S. Haldane, as well as the mid-20th-century successes of military and commercial open-water diving. Military needs for stealth and commercial needs for deep salvage and oil exploration drove the development of equipment allowing divers to swim freely, untethered to a surface air supply, and of techniques of diving to great depths while breathing helium–oxygen mixtures. Phillips notes the remarkable rapidity with which researchers influenced the operational practices at diving sites. Divers relied on the advice and expertise of the diving medical officer, who struggled with sophisticated physiology in an effort to enhance safety and extend the depth and usefulness of diving.

Phillips ranges widely and rapidly over early research into the physical properties of air and over the modern understanding of diving physiology. Writing with a general audience in mind, Phillips explains the relevant physiology at length and with perhaps less rigor than a professional medical audience would demand. The need to explain physiology frequently interrupts the flow of the historical narrative. These transitions, however, are the focus of the book, since Phillips is most concerned not with the history of engineering but with the response of the physiologist and physician to the unexpected medical challenge of working with compressed air. The Bends is highly recommended as a recreation, an educational exploration of a largely unfamiliar area of physiology, and a reminder of the responsibility of physicians to understand the working environments of their patients.

Andrew J. Dutka, M.D.
National Naval Medical Center, Bethesda, MD 20889