Student Research at the Dittrick, part 2

Last week, we featured some of the work being done by undergraduates pertaining to the Dittrick collections. Today’s student guest post talks about an unusual artifact from the museum: the compression chamber of nobel-prize winner John James Rickard Macleod.

compression-chamberUnder Pressure: How a Metal Tube Saved Lives

Caisson disease was a mystery. It had no visible cause and no known treatment. The people who witnessed this were dumbfounded at how random it seemed. The symptoms were varied and sudden and even the healthiest of men could be stricken. How do you guard yourself against an invisible, undiscriminating affliction? Framed like this it sounds scary even know, but there is a more common name that is slightly less intimidating: the bends. Most people associate the bends with divers, but the term is synonymous with caisson disease. The term caisson disease actually originated with caisson workers in the late 1800s (Butler 446). A caisson is a hollow chamber that is lowered onto the seabed to dig up mud and install bridge bases and supports. The chamber is filled with high pressure gas to prevent water from entering (Butler 445). As the workers ascended, the pressure they experienced would drop to normal, atmospheric pressure. This sudden change in pressure is what causes caisson disease. There was little understanding of the effects of high pressure on humans at this time. They did not know that at high pressures, the blood is able to absorb more gases than usual. The oxygen could be used by the body and carbon dioxide could be exhaled, but nitrogen got stuck in the body. As the pressure rapidly dropped, the nitrogen formed gas bubbles in the blood, which impaired breathing and proper blood flow (Caisson illness and diver’s palsy: an experimental study 407). Even mild cases resulted in death due to a lack of treatment. People saw workers bending over in pain, throwing up and dying (often hours after they left the caisson) with no visible cause or way to treat it. John James Macleod’s work with the compression chamber helped shed light on the mysterious caisson disease and was ultimately adapted for use in medicine.

Macleod constructed the compression chamber for his research. It consisted of a bronze tube with thick, glass walls on both ends and valves to control the internal pressure (Dittrick Museum). He placed mice inside the chamber and subjected them to differing pressures and changes in pressure. He looked at the physiological changes experienced by the mice to hypothesize how the pressures would affect humans. Specifically, Macleod focused his attention on the caisson workers from the Eads and Brooklyn bridges (Compression Chamber, 1904)

The Eads and Brooklyn bridges were both constructed in the 1870s using a pressurized, metal chamber called a caisson (Butler 448-452). The workers would ascend from the caisson quickly, the pressure dropping just as rapidly. What made the situation worse was that the gas that was pumped into the caisson was not controlled. It was the same air that was in the surrounding area. If the workers had known the dangers of nitrogen gas, they could have limited illness by pumping in air with higher concentrations of oxygen. Andrew Smith studied the Brooklyn workers and devised a preventative plan to reduce caisson disease. He advocated for gradual introduction to high pressure for new works and staged decompression both entering and exiting the caisson (Butler 452-457). Alphonse Jaminet came up with very similar preventative measures during the construction of the Eads Bridge. Unfortunately, there was very little medical evidence and employers were hesitant to implement them for fear of losing productivity. Word of caisson disease was already out there, and the pool of potential employees had already shrunk. To implement these preventative measures would mean more shift rotations, more workers and possibly better compensation.

Macleod’s experiments were conducted after the bridge incidents, but he helped to shed light on the mystery of caisson disease and provided scientific evidence to back up the claims made by Smith and Jaminet. Macleod started at the source. He first looked at cases of illness in caisson workers to determine what kinds of symptoms were related to the disease (Caisson illness and diver’s palsy: an experimental study 404-406). He also observed autopsies to see what physical changes occurred inside the body. From this information, he tried to predict the length and intensity of pressure a person could be exposed to before suffering noticeable ill effects. Through his observational research, Macleod was able to formulate a plan for experimentation with high pressure without using human guinea pigs. What Macleod did do was use mice as the guinea pigs. His observation oh caisson workers had allowed him to guess that long exposure and high pressure were the causes of caisson disease (Caisson illness and a diver’s palsy: an experimental study 425). With the mice, he noticed that they suffered less ill effects if the pressure was increased incrementally (The influence of compressed air on the respiratory exchange 494-495). He determined that the best way to prevent caisson disease was to stage the decompression process so that the body would have time to adjust and expel gasses, eliminating the toxic buildup of nitrogen. Macleod’s discoveries helped ease the minds of everyone—they now knew the cause of caisson disease and how to prevent it. Furthermore, the evidence was enough for employers to start tentatively implementing the safer working conditions advocated for by Smith and Jaminet. Workers now knew that at higher pressures, they were to get more frequent breaks along with staged decompression. Research concerning compressed air and the human body continued on after Macleod and the compression chamber grew from an experimental tool to a medical one.

Macleod created the compression tube so he could study caisson disease without exposing people. Ironically, a larger version is now in use specifically for people, utilizing a process called hyperbolic oxygen therapy (HBOT). The high pressure in the chamber allows more oxygen to be absorbed by the body (National Institutes of Health). This absorption process aids in the healing of bones and burns as well as gas poisonings and embolisms. The addition of pure oxygen speeds up this process and limits exposure time to high pressures, and thanks to the work of Macleod, the patients are carefully and slowly returned to normal pressure. The compression chamber is also available to help people who have already succumbed to caisson disease (National Institutes of Health). It is mostly for divers since working conditions are now under stricter safety controls. The compression chamber helps to ease people back to standard pressure in a controlled setting.

The compression tube helped to shed light on the mysteries of caisson disease and has even led to some helpful medical uses. Though Macleod was just one of many scientists looking into caisson disease, he was one of the few to have a laboratory compression tube. His model compression experiments allowed him to discover symptoms and causes of caisson disease without having to expose humans to those conditions. His discoveries eventually led to safer working conditions being implemented for caisson workers and the compression tube was later adapted for medical use.


Masato Miyagi: Born in Okinawa, Masato moved to the U.S. at the age of three. He is a second year student at Case Western, studying psychology. He hopes to work as a sports psychiatrist in the future.


Works Cited

Butler, W.P. “Caisson disease during the construction of the Eads and Brooklyn Bridges: A review.” Undersea Hyperbaric Medical Journal. 31.4 (2004): 445-459. Web. 14 September 2014.

“Compression Chamber, 1904.” Dittrick Medical History Center. Case Western Reserve University, 2014. Web. 14 September 2014.

Dittrick Museum. “Compression Chamber.” Case Western Reserve University: Dittrick Museum, 2014. Placard.

Hill, Leonard; Macleod, J.J.R. “Caisson illness and diver’s palsy: an experimental study.” Journal of Hygiene 3 (1903): 401-445. Web. 14 September 2014.

Hill, Leonard; Macleod, J.J.R. “The influence of compressed air on the respiratory exchange.” Journal of Physiology 29 (1903): 492-510. Web. 14 September 2014.

National Institutes of Health. “Hyperbaric oxygen therapy.” Medline Plus. 30 August 2012. Web. 14 September 2014.

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