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Clinical trial No longer in our active list Phase 1 Interventional Ages 18 to 50

Testing methods to prevent decompression sickness during spacewalks

Official title: NASA Prebreathe Study

Run by Duke University · NCT06740305 · Data updated 2026-05-14

This study is no longer in our active list. It may have stopped recruiting or finished. The details below are as of 2026-05-14 and are kept for reference. Check ClinicalTrials.gov for its current status, or see similar studies below.

This study is testing new ways to prevent decompression sickness during spacewalks by having volunteers breathe pure oxygen and then spend time in a special chamber while doing tasks.

Quick facts

PhasePhase 1
Study typeInterventional
Ages18 Years to 50 Years
SexAll
Enrollment12 (estimated)
SponsorDuke University
Academic / other
Locations1 site (Durham, North Carolina)
Trial IDNCT06740305 on ClinicalTrials.gov

Is this trial a fit for you?

Likely a good fit

Ideal candidates for this study are healthy non-smoking individuals aged 18-50 with a VO2pk above 35 ml/kg/min for males and 30 ml/kg/min for females.

Probably not a fit

Patients with lung and heart diseases, hypertension, diabetes, or those requiring regular medications may not benefit from this study.

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This study aims to validate experimental methods and facilities at the Duke Center for Hyperbaric Medicine & Environmental Physiology to support NASA's efforts in minimizing decompression sickness (DCS) risks during extravehicular activities (spacewalks). It involves four test days where volunteer subjects aged 18-50 will breathe 100% oxygen for six hours, followed by six hours in a hypobaric chamber at 1/3 atmosphere while performing various tasks. Data will be collected on bubble scores and DCS symptoms, with immediate treatment provided if symptoms develop. The study will also include a familiarization session for participants to ensure understanding of the protocol and safety procedures.

Why it matters

Potential benefit: If successful, this study could enhance astronaut safety during space missions by reducing the risk of decompression sickness.

How similar studies have gone: Other studies have explored decompression sickness in various contexts, but this specific approach in a space-related setting is novel.

Who can join: the full rules

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Non-smokers
* VO2pk \>35 ml/kg/min (males)
* VO2pk \>30 ml/kg/min (females)

Exclusion Criteria:

* Pregnancy
* Lung and heart disease
* Hypertension
* Diabetes
* Musculoskeletal pain conditions
* Need for regular medications such as analgesics

Where it's running

  • Duke University Medical Center
    Durham, North Carolina, United States     Recruiting

Study contacts

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

How to take part

  1. Review the eligibility criteria above with your treating physician.
  2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
  3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.
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Last reviewed 2026-11-14 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.