Venous Gas Emboli and Ambulation at 4.3 psia

Conkin, Johnny; Pollock, Neal W.; Natoli, Michael J.; Martina, Stefanie; Wessel, James H.; Gernhardt, Michael L.

doi:10.3357/amhp.4733.2017

Cited by 9 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Balldin et al (2002) showed that simulated weightlessness (supine position) did not provide any protection against DCS incidence over a control ambulatory group after both groups were exposed to hypobaric conditions, even though there was a significantly higher incidence of bubbles in the ambulatory subjects. Conkin et al (2017) found a higher incidence of VGE and DCS in subjects who exercised before and during hypobaric exposure than in those who did not exercise during the hypobaric exposure, despite both groups undertaking a prebreathe with exercise to denitrogenate themselves. Another study ( Conkin and Powell, 2001 ) compared lower body adynamia (LBA) that included upper body exercise while at altitude with random walking exercise and planned exercise.…”

Section: Introductionmentioning

confidence: 79%

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Gennser

Blogg²,

Eiken

et al. 2018

Front. Physiol.

View full text Add to dashboard Cite

Human extravehicular activity (EVA) is essential to space exploration and involves risk of decompression sickness (DCS). On Earth, the effect of microgravity on physiological systems is simulated in an experimental model where subjects are confined to a 6° head-down bed rest (HDBR). This model was used to investigate various resting and exercise regimen on the formation of venous gas emboli (VGE), an indicator of decompression stress, post-hyperbaric exposure. Eight healthy male subjects participating in a bed rest regimen also took part in this study, which incorporated five different hyperbaric exposure (HE) interventions made before, during and after the HDBR. Interventions i–iv were all made with the subjects lying in 6° HD position. They included (C1) resting control, (C2) knee-bend exercise immediately prior to HE, (T1) HE during the fifth week of the 35-day HDBR period, (C3) supine cycling exercise during the HE. In intervention (C4), subjects remained upright and ambulatory. The HE protocol followed the Royal Navy Table 11 with 100 min spent at 18 m (280 kPa), with decompression stops at 6 m for 5 min, and at 3 m for 15 min. Post-HE, regular precordial Doppler audio measurements were made to evaluate any VGE produced post-dive. VGE were graded according to the Kisman Masurel scale. The number of bubbles produced was low in comparison to previous studies using this profile [Kisman integrated severity score (KISS) ranging from 0–1], and may be because subjects were young, and lay supine during both the HE and the 2 h measurement period post-HE for interventions i–iv. However, the HE during the end of HDBR produced significantly higher maximum bubble grades and KISS score than the supine control conditions (p < 0.01). In contrast to the protective effect of pre-dive exercise on bubble production, a prolonged period of bed rest prior to a HE appears to promote the formation of post-decompression VGE. This is in contrast to the absence of DCS observed during EVA. Whether this is due to a difference between hypo- and hyperbaric decompression stress, or that the HDBR model is a not a good model for decompression sensitivity during microgravity conditions will have to be elucidated in future studies.

show abstract

Section: Introductionmentioning

confidence: 79%

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Gennser

Blogg²,

Eiken

et al. 2018

Front. Physiol.

View full text Add to dashboard Cite

show abstract

“…Two common exercise pre-breathe protocols are the “cycle ergometer with vibration stabilization” and “in-suit light exercise”, which have both been used extensively on ISS 35 . However, current DCS mitigation strategies used in microgravity will not be suitable for planetary surface exploration, and will need to be modified for safe and logistically feasible EVAs 38 , 39 . New EVA protocols for an exploration atmosphere (8.2 psia at 34% O 2 ) may be required to reduce DCS risk, as well as mild hypoxia, spaceflight associated neuro-ocular syndrome, and acute mountain sickness 40 , 41 .…”

Section: Spacesuit Designmentioning

confidence: 99%

Planetary extravehicular activity (EVA) risk mitigation strategies for long-duration space missions

2021

View full text Add to dashboard Cite

Extravehicular activity (EVA) is one of the most dangerous activities of human space exploration. To ensure astronaut safety and mission success, it is imperative to identify and mitigate the inherent risks and challenges associated with EVAs. As we continue to explore beyond low earth orbit and embark on missions back to the Moon and onward to Mars, it becomes critical to reassess EVA risks in the context of a planetary surface, rather than in microgravity. This review addresses the primary risks associated with EVAs and identifies strategies that could be implemented to mitigate those risks during planetary surface exploration. Recent findings within the context of spacesuit design, Concept of Operations (CONOPS), and lessons learned from analog research sites are summarized, and how their application could pave the way for future long-duration space missions is discussed. In this context, we divided EVA risk mitigation strategies into two main categories: (1) spacesuit design and (2) CONOPS. Spacesuit design considerations include hypercapnia prevention, thermal regulation and humidity control, nutrition, hydration, waste management, health and fitness, decompression sickness, radiation shielding, and dust mitigation. Operational strategies discussed include astronaut fatigue and psychological stressors, communication delays, and the use of augmented reality/virtual reality technologies. Although there have been significant advances in EVA performance, further research and development are still warranted to enable safer and more efficient surface exploration activities in the upcoming future.

show abstract

“…2 Human trials involving decompression from sea level (1 atmosphere absolute [ATA]) to ambient pressure of the U.S. space suit (0.3 ATA) has resulted in decompression sickness in up to 20% of exposures and venous gas emboli in up to 62%. 3 Furthermore, knee pain due to decompression sickness was experienced by Gemini X astronaut Michael Collins in 1966. 4…”

Section: To the Editormentioning

confidence: 99%

Anesthesia and Surgery in Space: Comment

Covington

Moon²

2021

Anesthesiology

View full text Add to dashboard Cite

W e read the recent article penned by Komorowski et al. 1 with great interest, and we congratulate the authors on a well-composed and thought-provoking article addressing space exploration and the challenges of medical care, especially anesthesia, in this austere environment.Although undersea and hyperbaric medicine is often associated with treating conditions secondary to increases in ambient pressure, such as those arising from scuba diving, it also aids in understanding and treating the pathophysiology 4. Wu X, Jiang Z, Ying J, Han Y, Chen Z: Optimal blood pressure decreases acute kidney injury after gastrointestinal surgery in elderly hypertensive patients: A randomized study: Optimal blood pressure reduces acute kidney injury.

show abstract

Venous Gas Emboli and Ambulation at 4.3 psia

Cited by 9 publications

References 0 publications

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Planetary extravehicular activity (EVA) risk mitigation strategies for long-duration space missions

Anesthesia and Surgery in Space: Comment

Contact Info

Product

Resources

About