Effects of normobaric hypoxia on oxygen saturation variability

Joseph Costello, Amar S. Bhogal, Thomas Benjamin Williams, Richard Bekoe, Amin Sabir, Mike Tipton, Jo Corbett, Ali R. Mani

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Background: The study is the first to evaluate the effects of graded normobaric hypoxia on SpO2 variability in healthy individuals.

Materials and Methods: Twelve healthy males (mean [standard deviation] age 22 [4] years) were exposed to four simulated environments (fraction of inspired oxygen [FIO2]: 0.12, 0.145, 0.17, and 0.21) for 45 minutes, in a balanced crossover design.

Results: Sample entropy, a tool that quantifies the irregularity of pulse oximetry fluctuations, was used as a measure of SpO2 variability. SpO2 entropy increased as the FIO2 decreased, and there was a strong significant negative correlation between mean SpO2 and its entropy during hypoxic exposure (r = −0.841 to −0.896, p < 0.001). In addition, SpO2 sample entropy, but not mean SpO2, was correlated (r = 0.630–0.760, p < 0.05) with dyspnea in FIO2 0.17, 0.145, and 0.12 and importantly, SpO2 sample entropy at FIO2 0.17 was correlated with dyspnea at FIO2 0.145 (r = 0.811, p < 0.01).

Conclusions: These findings suggest that SpO2 variability analysis may have the potential to be used in a clinical setting as a noninvasive measure to identify the negative sequelae of hypoxemia.
Original languageEnglish
Journal High Altitude Medicine and Biology
Early online date18 Feb 2020
Publication statusEarly online - 18 Feb 2020


  • dyspnea
  • oxygen saturation
  • pulse oximetry
  • sample entropy
  • Sp02 variability


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