Hypoxic breathing produces more intense hypoxemia in elderly women than in elderly men

Abstract

Background: Brief hypoxic exposures are increasingly applied as interventions for aging-related conditions. To optimize the therapeutic impact of hypoxia, knowledge of the sex-related differences in physiological responses to hypoxia is essential. This study compared hypoxia-induced hypoxemic responses in elderly men and women.Methods: Seven elderly men (70.3 ± 6.0 years old) and nine women (69.4 ± 5.5 years old) breathed 10% O2 for 5 min while arterial (SaO2; transcutaneous photoplethysmography) and cerebral tissue O2 saturation (ScO2; near-infrared spectroscopy), ventilatory frequency, tidal volume, minute-ventilation, and partial pressures of end-tidal O2 (PETO2) and CO2 (mass spectrometry) were continuously monitored. Cerebral tissue oxygen extraction fraction (OEF) equaled (SaO2–ScO2)/SaO2.Results: During 5 min hypoxia SaO2 fell from 97.0 ± 0.8% to 80.6 ± 4.6% in the men and from 96.3 ± 1.4% to 72.6 ± 4.0% in the women. The slope ΔSaO2/min was steeper in the women than the men (−4.71 ± 0.96 vs. −3.24 ± 0.76%/min; p = 0.005). Although SaO2 fell twice as sharply per unit decrease in PETO2 in the women than the men (−1.13 ± 0.11 vs. −0.54 ± 0.06%/mmHg; p = 0.003), minute-ventilation per unit hypoxemia increased less appreciably in the women (−0.092 ± 0.014 vs. −0.160 ± 0.021 L/min/%; p = 0.023). OEF fell with hypoxia duration in the women, but remained stable in the men.Conclusion: During 5 min hypoxic breathing, elderly women experience more intense hypoxemia and reduced chemoreflex sensitivity vs. their male counterparts, which may lower OEF stability in women despite augmented O2 dissociation from hemoglobin during hypoxia. These sex-related differences merit attention when implementing brief hypoxic exposures for therapeutic purposes.

Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia

“…HVR hypoxic ventilatory response, SaO 2 oxygen saturation, BP blood pressure, HR heart rate. References: Lung and airway volume [ 37 , 38 , 44 ], Ventilatory constraints [ 22 , 23 , 33 ], Exercise-induced hypoxemia [ 27 , 28 , 33 ], BP and HR during exercise [ 57 – 59 ], Microvascular responses to occlusion and exercise [ 122 , 127 ], Muscle composition [ 130 ], Substrate preferences in endurance exercise [ 129 ] …”

“…Knowing that even untrained women are susceptible to developing EIH and that EIH may be more prevalent in female athletes, one may speculate that, on average, women may exhibit a greater hypoxia-related decline in V̇ O 2max than men. Moreover, women seemed to be more hypoxemic than men when exposed to the same hypoxic intensity and duration because of poor ventilatory response, right shift in the oxyhaemoglobin dissociation curve, and a lower circulating capacity and reservoir [i.e., lower body surface area and lower normalized blood volume and haemoglobin mass (Hb mass )] [ 33 – 35 ].…”

Impact of Age on Cognitive Testing Practice Effects and Cardiorespiratory Responses

“…Continuous stable segments (~30 s) of heart rate and breathing frequency data during MMSE, TMT-B, and DST assessments were selected and averaged to represent the responses to these cognitive challenges. This approach to analyze continuously monitored cardiorespiratory measurements has been reported previously ( Liu et al, 2017 , 2020 ; Wang et al, 2020 ; Zhang et al, 2010 , 2014 ; Zhao et al, 2022 ).…”

Recommendations for Women in Mountain Sports and Hypoxia Training/Conditioning

“…Recently, a more severe hypoxemia in response to 5 min of hypoxia (F I O 2 = 0.10) in older women [ 194 ] and after 7 h of F I O 2 = 0.15 in young women [ 50 ] compared with age-matched men has been reported. This observation is in agreement with previously described differences in oxygen transport [ 195 ] and in the respiratory system, including smaller conducting airways relative to lung size [ 196 ], which may impair ventilation in exercise conditions faster in women than in men.…”