Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32451
Physiological Effects on Scientist Astronaut Candidates: Hypobaric Training Assessment

Authors: Pedro Llanos, Diego García


This paper is addressed to expanding our understanding of the effects of hypoxia training on our bodies to better model its dynamics and leverage some of its implications and effects on human health. Hypoxia training is a recommended practice for military and civilian pilots that allow them to recognize their early hypoxia signs and symptoms, and Scientist Astronaut Candidates (SACs) who underwent hypobaric hypoxia (HH) exposure as part of a training activity for prospective suborbital flight applications. This observational-analytical study describes physiologic responses and symptoms experienced by a SAC group before, during and after HH exposure and proposes a model for assessing predicted versus observed physiological responses. A group of individuals with diverse Science Technology Engineering Mathematics (STEM) backgrounds conducted a hypobaric training session to an altitude up to 22,000 ft (FL220) or 6,705 meters, where heart rate (HR), breathing rate (BR) and core temperature (Tc) were monitored with the use of a chest strap sensor pre and post HH exposure. A pulse oximeter registered levels of saturation of oxygen (SpO2), number and duration of desaturations during the HH chamber flight. Hypoxia symptoms as described by the SACs during the HH training session were also registered. This data allowed to generate a preliminary predictive model of the oxygen desaturation and O2 pressure curve for each subject, which consists of a sixth-order polynomial fit during exposure, and a fifth or fourth-order polynomial fit during recovery. Data analysis showed that HR and BR showed no significant differences between pre and post HH exposure in most of the SACs, while Tc measures showed slight but consistent decrement changes. All subjects registered SpO2 greater than 94% for the majority of their individual HH exposures, but all of them presented at least one clinically significant desaturation (SpO2 < 85% for more than 5 seconds) and half of the individuals showed SpO2 below 87% for at least 30% of their HH exposure time. Finally, real time collection of HH symptoms presented temperature somatosensory perceptions (SP) for 65% of individuals, and task-focus issues for 52.5% of individuals as the most common HH indications. 95% of the subjects experienced HH onset symptoms below FL180; all participants achieved full recovery of HH symptoms within 1 minute of donning their O2 mask. The current HH study performed on this group of individuals suggests a rapid and fully reversible physiologic response after HH exposure as expected and obtained in previous studies. Our data showed consistent results between predicted versus observed SpO2 curves during HH suggesting a mathematical function that may be used to model HH performance deficiencies. During the HH study, real-time HH symptoms were registered providing evidenced SP and task focusing as the earliest and most common indicators. Finally, an assessment of HH signs of symptoms in a group of heterogeneous, non-pilot individuals showed similar results to previous studies in homogeneous populations of pilots.

Keywords: Altitude sickness, cabin pressure, hypobaric chamber training, symptoms and altitude, slow onset hypoxia.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 312


[1] Aerospace Medical Association. (AsMA) Aviation Safety Committee, Civil Aviation Subcommittee. Cabin cruising altitudes for regular transport aircraft. Aviat Space Environ Med 2008; 79:433 – 9.
[2] J. Barcroft, “The respiratory function of the blood,” Cambridge, 1914.
[3] J. M. A. Beer, B. S. Shender, D. Chauvin, T. S. Dart, and J. Fischer, “Cognitive deterioration in moderate and severe hypobaric hypoxia conditions,” Aerosp Med Hum Perform, 2017, 88(7):617–626.
[4] F. R. Blood, R. M. Glover, J. B. Henderson, and F. E D’Amour, “Relationship between hypoxia, oxygen consumption and body temperature,” Am. J. Physiol., 156:62–66 (1949).
[5] A. V. Bock, H. Jr. Field, and G. S. Adair, “The oxygen and carbon dioxide Dissociation curves of human blood”, J. Blol. Chem., 59 (1924), pp. 353-377. Google Scholar.
[6] J.-A. Collins, A. Rudenski, J. Gibson, L. Howard, and R. O’Driscoll, “Relating oxygen partial pressure, saturation and content: The haemoglobin-oxygen dissociation curve,” Breathe 2015; 11:194-201.
[7] T. Dart, M. Gallo, J. Beer, J. Fischer, T. Morgan, and A. Pilmanis, “Hyperoxia and hypoxic hypoxia effects on simple and choice reaction times,” Aerosp Med Hum Perform, 2017; 88(12):1073–1080.
[8] Federal Aviation Administration, U.S. Department of Transportation, Advisory Circular. Aircraft Operations at Altitudes above 25,000 Feet Mean Sea Level or Mach Number Greater than 0.75, 2015.
[9] H. Gautier, M. Bonora, S. A. Schultz, and J. E. Remmers, “Hypoxia-induced changes in shivering and body temperature,” J Appl Physiol (1985), 62: 2477-2484.
[10] H. D. Gerhart, Y. Seo, J. Vaughan, B. Followay, J. E. Barkley, T. Quinn, J. H. Kim, and E. L Glickman, “Cold-induced vasodilation responses before and after exercise in normobaric normoxia and hypoxia,” Eur J Appl Physiol (2019) 119: 1547.
[11] R. E. Gold, and LL. Kulak, “Effect of hypoxia on aircraft pilot performance,” Aerosp Med, 1972; 43(2):180–183.
[12] C. A. Hackworth, L. M. Peterson, D. G. Jack, C. A. Williams, and B. E. Hodges, (2003), DOT/FAA/AM/03-10, Final Report.
[13] F. Hall, “Interval of useful consciousness at various altitudes,” Journal Applied Phys., 1 (1949), pp. 490-495.
[14] A. V. Hill, “The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves,” J Physiol 40: iv–vii, 1910.
[15] P. D. Hodkinson, R. A. Anderton, B. N. Posselt, and K. J. Fong, “An overview of space medicine,” British Journal of Anesthesia, 119(S1): i143-i153, 2017.
[16] C. Hoffman, R. Clark, and E. Brown, “Blood oxygen saturations and duration of consciousness in anoxia at high altitudes. Am J Physiol. 1945; Dec 7: 685–692.
[17] S. Izraeli, D. Avgar, M. Glikson, I. Shochat, Y. Glovinsky, and J. Ribak, “Determination of the 'time of useful consciousness' (TUC) in repeated exposures to simulated altitude of 25,000 ft (7,620 m),” Aviation, space, and environmental medicine. 59. 1103-5, 1988.
[18] R. Kumar, V. Jain, N. Kushwah, A. Dheer, K. P. Mishra, D. Prasad, and S. B. Singh, “Role of DNA Methylation in Hypobaric Hypoxia-Induced Neurodegeneration and Spatial Memory Impairment,” Annals of neurosciences, 25(4), 191–200, 2018. doi:10.1159/000490368.
[19] P. Llanos, K. Kitmanyen, E. Seedhouse, and R. Kobrick, “Suitability Testing for PoSSUM Scientist-Astronaut Candidates using the Suborbital Space Flight Simulator with an IVA Spacesuit,” 47th International Conference on Environmental Systems. ICES-2017-100 16-20 July 2017, Charleston, South Carolina.
[20] P. J. Llanos, and Seedhouse E. Application of Bioinstrumentation in Developing a Pressure Suit for Suborbital Flight. Computing in Cardiology, Vancouver, September 2016.
[21] P. V. McDonald, J. M. Vaderploeg, K. Smart, and D. Hamilton, “AST Commercial Human Space Flight Participant Biomedical Data Collection,” Wyle Laboratories, Inc. Technical Report#LS-09-2006-001, February 1, 2007.
[22] S. F. Morrison, “Central control of body temperature,” F1000Research, 5, F1000 Faculty Rev-880, 2016. doi:10.12688/f1000research.7958.1.
[23] C. Neuhaus, and J. Hinkelbein, “Cognitive responses to hypobaric hypoxia: implications for aviation training,” Psychology research and behavior management, 7, 297–302, 2016. doi:10.2147/PRBM.S51844.
[24] S. Nishi, “Effects of altitude-related hypoxia on aircrews in aircraft with unpressurized cabins,” Mil Med, 2011; 176(1):79–83.
[25] F. A. Petrassi, P.D. Hodkinson, P. L. Walters, S. J. Gaydos, “Hypoxic hypoxia at moderate altitudes: review of the state of the science,” Aviat Space Environ Med, 2012; 83(10):975–984.
[26] J. S. Pickard, and D. P. Gradwell, “Respiratory physiology and protection against hypoxia," In: J. R. Davis, R. J. Johnson, J. Stepanek J., J. A. Fogarty, eds. Fundamentals of aerospace medicine. Philadelphia: Wolters Kluwer Lippincott Williams and Wilkins; 2008:20-45.
[27] R. C. Roach, P. Bartsch, P. H. Hackett, and O. Oelz, “The Lake Louise acute mountain sickness scoring system,” in Hypoxia and Molecular Medicine, pp. 272–274, Queens City Press, Burlington, Va, USA, 1993.
[28] K. P. Sausen, M. T. Wallick, B. Slobodnik, J. M. Chimiak, E. A. Bower, M. E. Stiney, and J. B. Clark, “The reduced oxygen breathing paradigm for hypoxia training: physiological, cognitive, and subjective effects,” Aviat Space Environ Med, 2001. 72:539-45
[29] A. M. Smith. "Hypoxia symptoms in military aircrew: long-term recall vs. acute experience in training,” Aviat Space Environ Med, 2008; 79: 54 – 7.
[30] R. B. Rayman, M. J. Antuñano, M. A. Garber, J. D. Hastings, P. A. Illig, J. L. Jordan, R. F., Landry, R. R. McMeekin, S. E. Northrup, C. Ruehle, A. Saenger, and V. S. Schneider, “Space Passenger Task Force: Position Paper: Medical guidelines for space passengers-II,” Aviat Space Environ Med 2002; 73(11):1132-4.
[31] Y. Steinman, M. H. A. H. van den Oord, M. H. W. Frings-Dresen, and J. K. Sluiter, “Flight performance during exposure to acute hypobaric hypoxia,” Aerosp Med Hum Perform, 2017; 88(8):760–767.
[32] S. Tommaso, “Guidelines for the safe regulation, design and operation of Suborbital Vehicles,” International Association for the Advancement of Space Safety, May 2014.
[33] G. Viscor, J. R. Torrella, L. Corral, A. Ricart, C. Javierre, T. Pages, J. L. Ventura, “Physiological and Biological Responses to Short-Term Intermittent Hypobaric Hypoxia Exposure: From Sports and Mountain Medicine to New Biomedical Applications,” Front. Physiol. 9:814, 2018. doi: 10.3389/fphys.2018.00814.
[34] I. Yoneda, M. Tomoda, O. Tokumaru, T. Sato, and Y. Watanabe, “Time of useful consciousness determination in aircrew members with reference to prior altitude chamber experience and age,” Aviation, space, and environmental medicine. 71. 72-6, 2000.
[35] A. D. Woodrow, J. T. Webb, G. S. Wier, “Recollection of hypoxia symptoms between training events,” Aviat Space Environ Med, 2011; 82:1143 – 7.
[36] Zephyr technology, BioHarness 3, Log Data Descriptions, 2016.