Acute hypoxic hypoxia and isocapnic hypoxia effects on oculometric features

Jan Stepanek, Gaurav N. Pradhan, Daniela Cocco, Benn E. Smith, Jennifer Bartlett, Marc Studer, Fabian Kuhn, Michael J. Cevette

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Introduction: Visual performance impairment after hypoxia is well recognized in military and civilian aviation. The aims of this study were: 1) to assess oculometric features such as blink metrics, pupillary dynamics, fixations, and saccades as cognitive indicators of early signs of hypoxia; and 2) to analyze the impact of different hypoxic conditions [" hypoxic hypoxia" (HH) and "isocapnic hypoxia" (IH)] on specified oculometrics during mental workloads. Methods: Oculometric data were collected on 25 subjects under 3 conditions: normoxia, HH (8% O2 + balance N2), and IH (7% O2 + 5% CO2 + balance N2). The mental workload task consisted of reading aloud linear arrays of numbers after exposure to gas mixtures. Results: Blink rates were significantly increased under hypoxic conditions (by +100.7% in HH and by +92.8% in IH compared to normoxia). A faster recovery of blink rate was observed in transitioning from IH (23.6% vs. 76.3%) to normoxia. The percentage change in pupil size fluctuation was increased under HH more than under IH (29% vs. 4.4%). Under HH average fixation time and target area size were significantly higher than under IH. Total saccadic times under hypoxic conditions were significantly increased compared with normoxia. Conclusions: These results suggest that oculometric changes are indicators of hypoxia, which can be monitored using compact, portable, noninvasive eye-tracking devices in a cockpit analogous environment to detect hypoxia-induced physiological changes in aircrew. Comparative results between HH and IH support the potential role of carbon dioxide in augmenting cerebral perfusion and hence improved tissue oxygen delivery.

Original languageEnglish (US)
Pages (from-to)700-707
Number of pages8
JournalAviation Space and Environmental Medicine
Volume85
Issue number7
DOIs
StatePublished - 2014

Keywords

  • Acute hypoxia
  • Capnic status
  • Cognitive impairment
  • Eye tracking
  • Oculometrics

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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    Stepanek, J., Pradhan, G. N., Cocco, D., Smith, B. E., Bartlett, J., Studer, M., Kuhn, F., & Cevette, M. J. (2014). Acute hypoxic hypoxia and isocapnic hypoxia effects on oculometric features. Aviation Space and Environmental Medicine, 85(7), 700-707. https://doi.org/10.3357/ASEM.3645.2014