Science Under Pressure

Originally appeared on the Duke Research Blog | Guest post by Lauren Burianek, doctoral candidate in cell biology. Reposted with permission.

The basement of the Duke Clinic (called Duke South by everyone around here) seems like the last place you’d expect to dive for treasure, but researchers and physicians at the Center for Hyperbaric Medicine and Environmental Physiology are doing just that – diving for a better understanding of the human body.

The $10 million facility was built in 1968 to study the effects of diving, altitude, and compressed gasses on human physiology.  It features seven large steel chambers capable of simulating the high pressure of 1,000 feet below sea water to the low pressure of 100,000 feet above sea level. To put that into perspective, 1000 feet is the deepest the Smithsonian exploratory submersible, DROP, can dive, and 100,000 feet above sea level is considered to be “near-space” (with the peak of Mt. Everest at a measly 30,000 feet).

The deadly physiology of atmospheric pressure first came to light during construction of the Brooklyn Bridge in New York and the Eads Bridge in St. Louis in the late 1800s. High pressure tunnels were designed to keep the water out as footings were set in river beds, but the pressure also dissolved gas molecules in the blood streams of tunnel workers. When they emerged from the pressurized conditions, the gas would bubble out of solution like a freshly opened can of soda, causing life-threatening conditions, including damage to the organs and lungs, and killing about a quarter of the workers.

A news photo of workers in the Lincoln Tunnel under construction in the mid-1930s.

A news photo of workers in the Lincoln Tunnel under construction in the mid-1930s.

A couple decades later, a decompression chamber was used during the building of the Lincoln Tunnel under the Hudson River to slow the depressurization and reduce the chance of injury. This change reduced the deaths relating to decompression from 25% to almost 0%.

Similarly, SCUBA divers must carefully watch their rate of ascent; otherwise, they too might experience what is now known as decompression sickness or the “bends.”

The Hyperbaric facility at Duke is dedicated to researching exactly how the human body deals with these extreme pressures.

Richard Moon, MD, the Medical Director of the facility, has been working there since 1979. “It’s really interesting to learn how the lungs work when you have millions more molecules in there than you’re supposed to,” Moon says. “At high pressures, some macromolecules change conformation, and that can affect even simple things, like how your hemoglobin binds to oxygen.”

In addition to research, the facility is used to treat  hospital patients on a regular basis. Patients with carbon monoxide poisoning undergo hyperbaric (high pressure) oxygen treatment. Because carbon monoxide binds tightly to blood cells, an increase in pressure releases the carbon monoxide so the blood cells can bind oxygen again.

The interior of one of the hyperbaric chambers. The stickers are souvenirs of decades of research projects.

The interior of one of the hyperbaric chambers. The stickers are souvenirs of decades of research projects.

Patients with necrotic wounds benefit from hyperbaric oxygen therapy to increase blood flow to the area of the injury.

A physician is always on call at the facility to handle emergencies,  including SCUBA divers with decompression sickness who are rushed to Durham for treatment.

The research projects relate to diving and altitude and are funded largely by the U.S. Navy. One project is focused on the interaction of nitrogen with neurotransmitters during diving. At high pressures, nitrogen can dissolve into the bloodstream and act as an anesthetic, leading to what is known as nitrogen narcosis. Understanding the mechanism behind nitrogen narcosis may give insight into how to treat and prevent this from happening to divers in extreme situations.