Task Progress:
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Experiment I with ambulation both pre-EVA and during EVA simulation had significantly higher DCS and VGE than the Phase II control group. The decision was made to perform Experiment 3 next, with the rationale that if there were not a significant difference between Experiment 3 and the PRP Phase II control, then it could be concluded that ambulation during the EVA exposure was the cause of the increased decompression stress in Experiment I, and that there would then be no need to perform Experiment 2.
Experiment 3 results then showed that there was not a significant difference with the PRP Phase II control, but there was significantly less DCS and grade IV VGE in Experiment 3 than Experiment I. These results suggest that pre-EVA ambulation with under-saturated tissues does not increase the risk of DCS, but ambulation during the EVA exposure with supersaturated tissues does increase the risk of DCS and VGE. The precise mechanism(s) for ambulation-induced DCS and VGE outcomes is still elusive, but possibly related to tribonucleation combined with micronuclei stabilized in hydrophobic crevices.
One limitation to this conclusion is that these results are contingent on the inclusion of the 10.2 psia depressurization and repressurization back to 14.7 psia during the prebreathe timeline. Therefore, controlling ambulation during the pre-EVA period may still be required if there is not a similar partial depressurization prior to the full EVA depressurization.
Several journal manuscripts are in process to document and share the results of the Nucleation Mechanism study.
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Abstracts for Journals and Proceedings
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Pollock NW, Natoli MJ, Conkin J, Wessel JH, Gernhardt ML. "Ambulation increases decompression sickness in altitude exposure." 85th Annual Scientific Meeting, Aerospace Medical Association, San Diego, CA, May 10-15, 2014. Aviation, Space, and Environmental Medicine. 2014 Mar;85(3):329. , Mar-2014
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Abstracts for Journals and Proceedings
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Pollock NW, Natoli MJ, Martina SD, Conkin J, Wessel JH 3rd, Gernhardt ML. "Ambulation increases decompression sickness in altitude exposure." 86th Annual Scientific Meeting, Aerospace Medical Association, Lake Buena Vista, FL, May 10-14, 2015. Aerosp Med Hum Peform. 2015 Mar;86(3):474. , Mar-2015
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Abstracts for Journals and Proceedings
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Conkin J, Pollock NW, Natoli MJ, Martina SD, Wessel JH 3rd, Gernhardt ML. "Venous gas emboli and ambulation at 4.3 psia." 87th Aerospace Medical Association Annual Meeting, Atlantic City, NJ, April 24-28, 2016. Aerosp Med Hum Peform. 2016;87(3):079. , Mar-2016
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Abstracts for Journals and Proceedings
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Pollock NW, Natoli MJ, Martina SD, Conkin J, Wessel JH 3rd Gernhardt ML. "Decompression sickness during simulated low pressure exposure is increased with mild ambulation exercise." 87th Aerospace Medical Association Annual Meeting, Atlantic City, NJ, April 24-28, 2016. Aerosp Med Hum Peform. 2016;87(3):080. , Mar-2016
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Articles in Peer-reviewed Journals
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Conkin J, Pollock NW, Natoli MJ, Martina SD, Wessel JH 3rd, Gernhardt ML. "Venous gas emboli and ambulation at 4.3 psia." Aerosp Med Hum Perform. 2017 Apr;88(4):370-6. https://doi.org/10.3357/AMHP.4733.2017 ; http://www.ingentaconnect.com/content/asma/amhp/2017/00000088/00000004/art00003 , Apr-2017
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