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tidal volume
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Sex differences in cardiorespiratory control under hypoxia - Frontiers frontiersin.org Jan 30, 2025 20 facts
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.
claimIn the current study, tidal volume increased markedly in males in response to short-term hypoxia.
claimExposure to iso-saturation hypoxia causes increases in heart rate, cardiac output, low-frequency bands of R-R intervals, blood pressure, tidal volume, and ventilation, while causing decreases in baroreflex sensitivity, total power, and the high-frequency band of R-R intervals.
claimDuring iso-time hypoxic analysis, males desaturate more than females, and only males increase tidal volume while decreasing breathing frequency.
claimWhen analyzing sex as a factor in iso-saturation hypoxia, females exhibit a higher heart rate and cardiac output index, but lower tidal volume, ventilation, and low-frequency band of blood pressure compared to males.
claimUnder iso-time hypoxia, females exhibit higher heart rates, cardiac output, and total vascular conductance, while males exhibit higher tidal volume, ventilation, and low-frequency bands of blood pressure.
measurementDuring iso-saturation hypoxia, only males increased tidal volume (p = 0.037).
procedureTo account for body size differences between males and females, stroke volume (SV), cardiac output (CO), and tidal volume (Vt) are normalized by body surface area (BSA) to produce the indexes SVi, CI, and Vt/BSA, respectively.
claimUnder hypoxic iso-saturation, females have higher heart rates and a greater low-frequency band response of heart rate variability compared to males, while males present a higher tidal volume.
measurementFemales had a tidal volume (Vt) of 747 ± 125 ml under normoxia and 753 ± 116 ml under iso-saturation hypoxia.
measurementA power analysis for the study revealed large effect sizes (f) of 0.68 for oxygen saturation (SpO2), 0.61 for heart rate (HR), and 0.52 for tidal volume (Vt).
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.
claimVentilatory data remained unchanged in females under iso-saturation hypoxia, while only males increased tidal volume under iso-saturation, as evidenced by the sex-condition interaction.
formulaMinute ventilation (VE) is calculated as the product of breath-by-breath tidal volume (Vt) and breathing frequency (BF), where tidal volume is determined from the integral of the flow signal and breathing frequency is determined by the number of events per minute in the flow signal.
measurementDuring iso-time hypoxia, only males exhibited ventilatory responses, specifically decreasing breathing frequency (p = 0.022) and increasing tidal volume (p = 0.036).
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).
procedureThe sample size for variables including SpO2 (iso-time) and HR and Vt (iso-saturation) was calculated using G*Power 3.1.9.7 software (Heinrich-Heine-Universität, Düsseldorf, Germany) with a β of 0.80 and an α of 0.05.
claimUnder iso-time hypoxic conditions, females defend oxygen saturation over time better than males, and while there are no sex differences in cardiovascular responses, males utilize ventilatory compensation through greater tidal volume, whereas females do not.
measurementMales had a tidal volume (Vt) of 999 ± 180 ml under normoxia and 1,120 ± 206 ml under iso-saturation hypoxia.
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.
Sex differences in respiratory and circulatory cost during hypoxic ... nature.com Jul 2, 2019 3 facts
measurementIn the study, women exhibited a greater respiration frequency compared to men, while men exhibited a greater tidal volume compared to women.
claimSignificant sex differences in breathing frequency and tidal volume were observed during hypoxic walking.
procedureStatistical comparisons between men and women for physical characteristics, respiratory function, and lactate (La) are performed using an unpaired t-test, while comparisons of EE, VE, HR, SpO2, tidal volume (TV), and respiratory rate (RR) in normoxia and hypoxia are performed using a two-way repeated ANOVA (sex × walking speed).