NSMRL’s Hyperbaric Chamber Complex Ready for a New Genesis

GROTON, CT, UNITED STATES

03.19.2021

Courtesy Story

Naval Medical Research Command

The Naval Submarine Medical Research Laboratory’s (NSMRL) “Genesis” hyper/hypobaric chamber complex is getting new life. Initiated in 2019, a total overhaul of the complex, which houses three different chambers, is expected to be complete in early 2022. The massive renovation will result in a fully modernized facility that will allow cutting-edge scientific research on the effects of pressure on human health and performance. Although renovation and repairs to the chambers have occurred periodically throughout its more than 60-year history, this will be the largest and most comprehensive update to the complex since its installation at NSMRL in the early 1960s.

NSMRL’s three chambers in the complex are distinct and serve different purposes. Chamber 1 is the larger of two multi-person chambers, with an internal diameter of 9 feet and a length of 25 feet (approximately the length of a mini school bus). It is capable of pressurization to a depth of 337 feet of seawater, and can also simulate low pressure, such as what you would experience at high altitude (for example, at the top of Mount Everest). Chamber 2 is a smaller multi-person hyperbaric chamber, with an internal diameter of 6.5 feet and a length of 15 feet. It is primarily designed for short duration dives and is kept ready as a decompression sickness or embolism treatment back-up to Chamber 1. A third, small hyperbaric chamber is used for testing instruments and equipment.
Much of what we know today about human health and performance under different pressures and gas mixtures can be traced back to early experiments conducted in NSMRL’s chambers. The first, and perhaps best known of these were the Genesis Project experiments, conducted by Captain George S. Bond (Medical Corps) in the late 1950s and early 1960s to explore the feasibility of saturation diving. The project’s name reportedly came from the first book of the Old Testament and the idea that building an underwater habitat would fulfill the biblical prophecy of human “dominion over the seas.”

The Genesis Project was designed to test Bond’s theories about saturation diving. Saturation diving is a phenomenon by which at a fixed depth, body tissues become saturated with available breathing gases. Once saturated, the time required for safe decompression does not increase—the amount of time required to decompress relies only on the depth and gases breathed. In the 1950s, Bond believed that saturation diving was possible, but no one had formally tested this idea or provided evidence that it was safe.

To test his theory, Bond commissioned The Bethlehem Corporation to build a “man rated vacuum-pressure-climatized facility with hyperbaric oxygenation operating room capabilities,” what became known as the Genesis Chamber. This chamber was the world’s first to be built specifically for saturation dive research purposes (and not primarily as a treatment facility). Findings from Bond’s six-year (1957-1963) Genesis Project provided the documentation needed to prove that saturation diving was both feasible and safe for humans. These experiments paved the way for the SeaLab habitat studies, where humans lived in a pressurized, underwater habitat, SeaLab, for days and even weeks at a time. Bond’s results also laid the foundation for the use of saturation diving in commercial and military institutions today.

While NSMRL’s chamber complex is best known for the Genesis Project experiments, a number of other ground-braking studies were carried out in the facility.

Later studies in the 1960s, for example, explored the use of gas mixtures other than the relatively expensive combination of helium/oxygen (heliox) used in Bond’s Genesis experiments. Among these studies were a series of nitrogen/oxygen (nitrox) dives, which resulted in a recalculation of decompression values after determining that the existing values were “grossly inadequate.” Other work focused on human ability to tolerate and perform in an atmosphere of elevated carbon dioxide and lowered oxygen levels, and still other research studied nitrogen narcosis.
In the 1970s, NSMRL initiated Project SHAD (Shallow Habitat Air Diving) using only compressed air as breathing gas. Divers in the SHAD experiments spent up to thirty days at simulated depths of 50 feet, demonstrating that at shallow depths, compressed air could be a feasible alternative to more expensive helium/oxygen mixtures. The SHAD experiments also simulated excursions from the habitat, including those that would be both deeper and shallower than the saturation habitat and covered a variety of distances and times.

Following the SHAD experiments, the Nisat project focused on rescue of a submarine crew exposed to increased air pressure. The Nisat dives were designed to emulate a possible rescue scenario in which a crew trapped in a compressed air environment (and saturated with nitrogen) might be required to switch to a heliox atmosphere during rescue. Over three dives, the Nisat project assessed the effects of several days of exposure to high nitrogen pressures and the physiological effects of switching the inert gas in saturated divers from nitrogen to helium. Results from this research are still included in decompression tables used today and inform the Navy’s diving and submarine rescue missions.
The chambers have also been used for non-pressurization research, such as studies to test how humans function in confined spaces to draw conclusions about how submariners adjust to the confined nature of the submarine. For example, a 2019 study in the chamber had volunteers living in the chamber under conditions of caffeine deprivation to determine how abrupt caffeine withdrawal might affect submariner cognitive abilities during a disabled submarine scenario. Other pressurized and non-pressurized studies in the chambers tested the underwater hearing abilities of humans, the sound attenuation provided by wetsuit hoods at different depths, and defined the natural frequency response of a diver’s lung as a function of depth.

To date, research in the chamber complex has led to breakthroughs in what we know about how humans can survive and function under both high (hyper) and low (hypo) pressure when supplied with different mixtures of breathing gases and how they function in a confined space analogous to a submarine. The current renovation of the chambers will reopen the door to new studies on hyper/hypo baric pressure changes and how humans can safely and effectively work in extreme environments such as those in space and undersea, all with the goal of maintaining the readiness and health of our nation’s warfighters and ensuring mission success, regardless of, or in spite of, harsh environmental conditions.

• Date Taken: 03.19.2021
• Date Posted: 03.19.2021 10:26
• Story ID: 391832
• Location: GROTON, CT, US