Presentation Title

Independent Effects of Hypoxia and Altitude on Human Physiology

Advisor Information

Dustin R Slivka

Location

MBSC Ballroom - Poster #809 - G

Presentation Type

Poster

Start Date

4-3-2022 2:00 PM

End Date

4-3-2022 3:15 PM

Abstract

PURPOSE: Decreased fraction of inspired oxygen (FiO2) is often used to simulate the atmospheric partial pressure of oxygen decreases experienced during high altitude sojourns. Therefore, we aimed to independently investigate hypoxia and altitude by isolating oxygen concentration and barometric pressure. METHODS: 18 subjects completed 3 trials (sea level, hypoxia, altitude). 90-minute duration and intensity matched hypoxic stimuli were induced via decreased FiO2 or 4,200 m ascent. Relative tissue oxygenation change and cardiovascular variables were measured during rest and a 3-minute step-test. RESULTS: Muscle oxygenated hemoglobin (O2Hb) and muscle deoxygenated hemoglobin (HHb) were not different across environments during rest or exercise (p>0.339) with alterations noted during rest to exercise transitions (p2Hb at hypoxia and altitude were lower than sea level (p2Hb was lower at altitude than sea level (p=0.007) similarly trending compared to hypoxia (p=0.066). Exercising brain O2Hb was not different between hypoxia and sea level (p=0.158). Brain HHb at hypoxia and altitude were higher than sea level (p-1) and altitude (141±3 beats·min-1) were lower than sea level (127±44 beats·min- 1, p0.208). Exercise stroke volume at altitude (109.6±4.1 mL) was higher than hypoxia (97.8±3.3 mL) and sea level (99.8±3.9 mL, pCONCLUSIONS: During acute hypoxic stimuli, skeletal muscle maintains oxygenation while the brain does not. Tissue oxygenation may be mediated by environmentally driven cardiovascular compensation. FiO2 decreases may not satisfactorily simulate all physiological outcomes experienced during altitude induced barometric pressure decreases.

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Mar 4th, 2:00 PM Mar 4th, 3:15 PM

Independent Effects of Hypoxia and Altitude on Human Physiology

MBSC Ballroom - Poster #809 - G

PURPOSE: Decreased fraction of inspired oxygen (FiO2) is often used to simulate the atmospheric partial pressure of oxygen decreases experienced during high altitude sojourns. Therefore, we aimed to independently investigate hypoxia and altitude by isolating oxygen concentration and barometric pressure. METHODS: 18 subjects completed 3 trials (sea level, hypoxia, altitude). 90-minute duration and intensity matched hypoxic stimuli were induced via decreased FiO2 or 4,200 m ascent. Relative tissue oxygenation change and cardiovascular variables were measured during rest and a 3-minute step-test. RESULTS: Muscle oxygenated hemoglobin (O2Hb) and muscle deoxygenated hemoglobin (HHb) were not different across environments during rest or exercise (p>0.339) with alterations noted during rest to exercise transitions (p2Hb at hypoxia and altitude were lower than sea level (p2Hb was lower at altitude than sea level (p=0.007) similarly trending compared to hypoxia (p=0.066). Exercising brain O2Hb was not different between hypoxia and sea level (p=0.158). Brain HHb at hypoxia and altitude were higher than sea level (p-1) and altitude (141±3 beats·min-1) were lower than sea level (127±44 beats·min- 1, p0.208). Exercise stroke volume at altitude (109.6±4.1 mL) was higher than hypoxia (97.8±3.3 mL) and sea level (99.8±3.9 mL, pCONCLUSIONS: During acute hypoxic stimuli, skeletal muscle maintains oxygenation while the brain does not. Tissue oxygenation may be mediated by environmentally driven cardiovascular compensation. FiO2 decreases may not satisfactorily simulate all physiological outcomes experienced during altitude induced barometric pressure decreases.