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hypoxia
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Sex differences in cardiorespiratory control under hypoxia - Frontiers frontiersin.org Jan 30, 2025 49 facts
referenceMairer et al. (2013) published a study in the International Journal of Sports Medicine titled 'Effects of exercise and hypoxia on heart rate variability and acute mountain sickness', which explores the interaction between physical exertion, low oxygen, and physiological markers.
claimMales achieve lower oxygen saturation levels compared to females under acute hypoxia, and even with tachycardia and higher tidal volume, males fail to maintain preserved oxygen saturation.
measurementUnder normoxia, males have a cardiac output (CO) of 6.43 ± 0.76 L.min−1 and females have 6.99 ± 0.96 L.min−1; under iso-saturation hypoxia, males have 6.85 ± 0.91 L.min−1 and females have 7.46 ± 1.16 L.min−1.
measurementUnder normoxia, males have a cardiac index (CI) of 3.45 ± 0.33 L.min−1.m2 and females have 4.26 ± 0.42 L.min−1.m2; under iso-saturation hypoxia, males have 3.64 ± 0.34 L.min−1.m2 and females have 4.54 ± 0.55 L.min−1.m2.
claimThe ventilatory response to hypoxia was higher in males than in females and was not influenced by time.
claimFemales counterbalance hypoxia mainly through systemic circulatory adjustments, whereas males utilize both circulatory and ventilatory adjustments.
claimAugmented heart rate under hypoxia is often a result of vagal withdrawal triggered by the aortic bodies.
claimSex differences are a significant factor that may considerably influence cardiorespiratory adjustments during hypoxia.
claimBoos et al. observed that females experience a greater increase in heart rate than males under hypoxia, while also tending to maintain higher oxygen saturation levels.
measurementIn the study on sex differences in cardiorespiratory control under hypoxia, male participants had a mean weight of 72.95 ± 10.31 kilograms, while female participants had a mean weight of 59.96 ± 12.56 kilograms (p = 0.02).
measurementThe hypoxic level used in the study by Botek et al. (21) was FiO2 = 0.096, which was more severe than the FiO2 = 0.115 used in the current investigation.
claimInconclusive results regarding autonomic responses to hypoxia may be caused by diverse methodological approaches, specifically the failure to account for exposure time and desaturation levels as confounding factors.
claimFemales presented with tachycardia and increased cardiac output during hypoxia, which may increase blood flow velocity in alveolar-capillary units and lead to a lower time for hematosis.
claimThe time effect of hypoxia was similar for both male and female groups, increasing heart rate, cardiac output, and total vascular conductance while decreasing mean blood pressure.
measurementAt 10 minutes of hypoxia (iso-time), males desaturated more than females (p = 0.004).
measurementIn the study on sex differences in cardiorespiratory control under hypoxia, male participants had a mean body surface area of 1.89 ± 0.1 square meters, while female participants had a mean body surface area of 1.64 ± 0.1 square meters (p < 0.001).
measurementUnder normoxia, males have a heart rate (HR) of 74 ± 10 bpm and females have 83 ± 6 bpm; under iso-saturation hypoxia, males have 77 ± 8 bpm and females have 90 ± 7 bpm.
claimIn the current investigation, females did not change ventilation in response to hypoxia in either iso-saturation or iso-time segment analyses.
procedureIn the study on sex differences in cardiorespiratory control under hypoxia, heart rate, stroke volume, and cardiac output were recorded using a noninvasive trans-thoracic bioimpedance device (PhysioFlow), R-R intervals were recorded via electrocardiogram (ECG Module), and continuous blood pressure was recorded via infrared photoplethysmography (Finometer PRO).
claimHypoxic pulmonary vasoconstriction is a physiological mechanism where pulmonary vessels exposed to hypoxia divert blood flow from hypoxic to non-hypoxic lung areas to prevent arterial deoxygenation.
measurementIn a study of 22 healthy individuals (12 females), participants were exposed to 10 minutes of normoxia (FiO2 = 0.21) followed by 10 minutes of hypoxia (FiO2 = 0.115).
measurementCardiovascular autonomic responses to hypoxia were consistent in females, but were only observed in males when they exhibited lower oxygen saturation.
procedureThe experimental protocol for the study on sex differences in cardiorespiratory control under hypoxia involved recording hemodynamic variables (heart rate, stroke volume, cardiac output, blood pressure) and respiratory variables (breathing frequency, tidal volume, minute ventilation, SpO2) after a 20-minute rest period in a sitting position.
procedureThe study on sex differences in cardiorespiratory control under hypoxia used an oxygen dilution system (Everest Summit II—Hypoxico®, NY, USA) coupled with two 200-L non-diffusing gas reservoirs to control the fraction of inspired oxygen (FiO2) for normoxic and hypoxic conditions.
procedureThe researchers calculated physiological changes induced by hypoxia using the delta formula (Δ = hypoxia—normoxia) for both male and female groups.
measurementUnder normoxia, males have a pulse oxygen saturation (SpO2) of 98 ± 1% and females have 98 ± 1%; under iso-saturation hypoxia, males have 91 ± 3% and females have 92 ± 2%.
claimThere is an inverse relationship between hypoxic ventilatory response and hypoxic pulmonary vasoconstriction in humans, meaning a lower ventilatory response leads to more pulmonary vasoconstriction under hypoxia.
procedureThe researchers evaluated hypoxia over time in both sexes using a two-factor analysis of variance (ANOVA) for time and group.
measurementDuring iso-time hypoxia, only males exhibited ventilatory responses, specifically decreasing breathing frequency (p = 0.022) and increasing tidal volume (p = 0.036).
procedureThe researchers conducted iso-saturation and iso-time analyses using a mixed two-way ANOVA (group and condition) with repeated measures for the gas condition to assess the main effects of hypoxia and sex differences.
claimBotek et al. (21) observed that males exhibited relatively higher cardiac sympathetic responses compared to females under short-term severe hypoxia with similar oxygen desaturation levels.
procedureHeart rate variability (HRV) analysis involves analyzing beat-to-beat time series of R-R intervals using a 300-beat time window, focusing on the last 5 minutes for normoxia and iso-time hypoxia conditions.
measurementThe relative tidal volume response to hypoxia, indexed by body surface area, is significantly different between sexes, with males showing a delta of 0.062 ± 0.077 L/m2 compared to 0.007 ± 0.053 L/m2 for females (p = 0.03).
referenceHalliwill and Minson studied the effect of hypoxia on arterial baroreflex control of heart rate and muscle sympathetic nerve activity in humans in a 2002 study published in the Journal of Applied Physiology.
referenceBoos and colleagues demonstrated that while hypoxia increases pulmonary vascular resistance, this effect occurs similarly in both males and females.
claimRubens Fazan Jr served as the editor for the article "Sex differences in cardiorespiratory control under hypoxia: the roles of oxygen desaturation and hypoxic exposure time," while Jui-Lin Fan and Sascha Treskatsch served as reviewers.
claimThe study findings on sex differences in cardiorespiratory control under hypoxia should not be extrapolated to clinical contexts without further investigation into factors such as age, obesity, and comorbidities.
claimPrevious human investigations suggest that biological sex influences the breathing frequency response to hypoxia.
claimThe article "Sex differences in cardiorespiratory control under hypoxia: the roles of oxygen desaturation and hypoxic exposure time" was received by the journal on July 31, 2024, and accepted for publication on January 16, 2025.
measurementUnder hypoxia, both males and females exhibit increased heart rate, vagal withdrawal, and augmented sympathetic modulation, shifting the sympatho-vagal balance towards sympathetic dominance.
procedureThe study on sex differences in cardiorespiratory control under hypoxia excluded individuals with known cardiopulmonary or metabolic diseases and required participants to be healthy, lowlander residents, and non-smokers who had not traveled to high altitudes for at least six months prior to the study.
referenceThe article titled 'Sex differences in cardiorespiratory control under hypoxia: the roles of oxygen desaturation and hypoxic exposure time' was published in the journal Frontiers in Cardiovascular Medicine on January 31, 2025.
claimSome studies indicate that under hypoxic conditions, females exhibit higher heart rates and sympathetic activity compared to males, despite similar levels of oxygen desaturation.
referenceMiller et al. (2019) investigated age and sex differences in sympathetic and hemodynamic responses to hypoxia and the cold pressor test.
claimIn the study, females were observed to counterbalance hypoxia primarily through systemic circulatory adjustments, which preserved oxygen saturation, while males relied on both circulatory and ventilatory adjustments but experienced greater oxygen desaturation.
measurementIn the study on sex differences in cardiorespiratory control under hypoxia, male participants had a mean height of 1.76 ± 0.07 meters, while female participants had a mean height of 1.64 ± 0.06 meters (p < 0.001).
measurementUnder normoxia, males have a tidal volume (Vt) of 999 ± 180 ml and females have 747 ± 125 ml; under iso-saturation hypoxia, males have 1,120 ± 206 ml and females have 753 ± 116 ml.
referenceRiveros-Rivera et al. (2022) conducted a randomized, cross-over pilot study showing that hypoxia differentially affects healthy men and women during a daytime nap with a dose-response relationship.
claimIn the study, females exhibited an absence of ventilatory responses to hypoxia, which may have resulted in a lower rate of alveolar gas turnover between the hypoxic gas from the mask and the alveoli.
Sex differences in respiratory and circulatory cost during hypoxic ... nature.com Jul 2, 2019 8 facts
claimThe estimated energy cost of circulation (HR) exceeded the energy cost of respiration (VE) in both normoxia and hypoxia conditions.
claimThere was no significant main effect for sex on oxygen saturation (SpO2) in either normoxia or hypoxia conditions.
measurementIn a study of physiological responses to hypoxia, multiple regression analysis showed that the change in heart rate (ΔHR) was a significant factor in predicting the change in oxygen saturation (ΔSpO2) for both men (t(8) = -6.54, P = 0.001) and women (t(8) = -4.04, P = 0.010).
claimResting minute ventilation (V̇E) responsiveness to hypoxia is sensitive to progesterone levels.
measurementIn the study, no sex differences in SpO2 changes were found during walking in either normoxia or hypoxia, despite significant reductions in SpO2 observed in both groups.
measurementResting blood lactate concentration is similar across sexes in both normoxia (1.2 ± 0.2 mmol L−1 in men vs. 1.2 ± 0.2 mmol L−1 in women) and hypoxia (1.2 ± 0.2 mmol L−1 in men vs. 1.2 ± 0.3 mmol L−1 in women).
measurementIn hypoxia, oxygen saturation (SpO2) decreased by approximately 10% in men and approximately 14% in women from resting baselines.
procedureThe researchers calculated changes in SpO2 with hypoxia and used multiple regression analysis to test for the independent, additive effects of energy expenditure (EE), ({\dot{{\rm{V}}}}{{\rm{E}}}), and heart rate (HR) on SpO2 after logarithmic transformation.
Wound Healing Phases - StatPearls - NCBI Bookshelf ncbi.nlm.nih.gov 2 facts
claimPrimary factors that impair wound healing include hypoxia, bacterial colonization, ischemia, reperfusion injury, altered cellular response, and collagen synthesis defects.
claimLocal factors that can impair wound healing include pressure, tissue edema, hypoxia, infection, maceration, and dehydration.
Sex differences in cardiorespiratory control under hypoxia - PMC pmc.ncbi.nlm.nih.gov Jan 31, 2025 1 fact
claimMales tend to experience greater oxygen desaturation under hypoxia compared to females.