OBJECTIVES:
Decompression sickness (DCS) is an occupational hazard as long as extravehicular activity (EVA) is performed at suit pressure less than tissue inert gas tension. Efforts to eliminate DCS in astronauts through engineering control of the habitat atmosphere to minimize atmospheric nitrogen partial pressure will reduce the probability of DCS and severity of symptoms related to evolved gas. Prudent planning requires that DCS treatment resources be provided for Exploration Class missions where EVAs will be numerous, energetic, and a return to definitive medical care is not possible.

Effective treatment to achieve a high symptom resolution is when treatment starts shortly after a symptom is recognized. Effective treatment is through the application of pressure during repressurization to the habitat pressure, an increase in habitat pressure, additional pressurization from the suit above habitat pressure, and the use of 100% oxygen (O2) breathing to accelerate the natural process of bubble dissolution. Combinations of both treatment pressure and 100% O2 breathing through time to achieve greater than or equal to 0.75 symptom resolution at the lower 95% confidence interval is proposed as a requirement to establish treatment resources that assures a successful treatment outcome for Exploration Class EVAs. Adjunctive pharmaceutical and supportive critical care therapy are also necessary, even given a low probability of serious DCS. This study had the following specific aims:

1. Consolidate data on factors that provide for effective hypobaric DCS treatment from the NASA Hypobaric Decompression Sickness Database.
2. Assemble these data into an NASA Hypobaric DCS Treatment Database.
3. Create a statistical model on the probability of effective treatment given inputs on factors that influence effective treatment.
4. Consolidate data on interventions that provide for effective hypobaric DCS treatment from published literature and from the Wright-Patterson Air Force Research Laboratory Decompression Sickness Research Database into the NASA Hypobaric DCS Treatment Database.
5. Evaluate the initial statistical model (NASA data only) against data from literature and the Air Force database.
6. Optimize the model using all available data.
7. Evaluate the use of an available bubble growth index (BGI) model as a DCS treatment model and compare to statistical DCS treatment model.
8. Deliver to NASA a draft quantitative model(s) for astronaut DCS treatment.
9. Document the relevant data, literature reports, and treatment model(s).
10. Communicate findings to a wider audience in the event there are applications outside of NASA.

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Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at: https://humanresearchroadmap.nasa.gov/