Key Findings from the NASA EVA Medical Working Group

In September 2026 NASA convened a panel of experts to evaluate the latest data on extravehicular activity (EVA) prebreathe testing, decompression sickness (DCS), venous thromboembolism (VTE), and patent foramen ovale (PFO) relevance for Artemis missions beyond low‑Earth orbit. The resulting recommendations integrate three recent NASA documents: the September 2024 Assessment of Patent Foramen Ovale (PFO) as Related to Decompression Sickness (DCS) in the Spaceflight Environment, the April 2026 NASA Risk of Venous Thromboembolism in Spaceflight Working Group, and the updated DCS prevention standard in NASA‑STD‑3001 Volume 2 Rev F.

PFO and Venous Thromboembolism

The consensus was that the presence of a PFO is not considered a major risk factor for VTE formation, nor for complications from an embolism traveling from an initial formation site in the left internal jugular or cerebrum at normoxic or proposed hypoxic space habitats. Quote: “No changes to astronaut selection criteria regarding PFOs are recommended with respect to VTE.”

Bubble Grades and DCS Risk

The group concluded there is no definitive link between bubble grades and the risk of DCS at altitude for prebreathe protocols involving partial gravity and ambulation. While minimizing bubbles is desirable, the predictive value of bubble scores for DCS remains uncertain, especially for lunar surface operations. Quote: “The consensus of the group is that there is no definitive link between bubble grades and the risk of DCS at altitude for prebreathe protocols involving partial gravity and ambulation.”

Small versus Large PFO

It was determined that a “small” PFO (Grade 1 or 2) does not pose a significant risk. Opinions were mixed on whether closing or screening out crew members with a “large” PFO (Grade 3 or above) would substantially reduce the risk of a venous gas embolism (VGE) passing to the arterial side and causing a mission‑critical event. Quote: “It was determined that a “small” PFO (Grade 1 or 2) does not pose a significant risk.”

Medication Guidance for EVAs

Clear clinical guidance is required regarding medication use for all crewmembers prior to EVAs. Protocols must address the use of aspirin for DCS prevention and pain relief, and guidance is needed for the pre‑ and post‑EVA use of analgesics such as acetaminophen, ibuprofen, naproxen, and celecoxib, as these drugs have the potential to mask DCS symptoms.

Implications for Future Missions and Student Projects

These recommendations shift focus from excluding astronauts with PFOs to designing EVA protocols that mitigate risk through prebreathe adjustments, monitoring, and informed decision‑making. For educators and students, the working group’s output offers a real‑world case study in how space agencies balance scientific evidence, crew safety, and operational constraints. Potential project ideas include modeling bubble dynamics in reduced gravity, evaluating medication side‑effects on symptom recognition, or designing low‑cost prebreathe protocols for high‑altitude balloon experiments. It is important to note that these are exploratory ideas; they are not tested implementations endorsed by NASA.

Source

NASA Science