Respiratory Studies in Women at High Altitude (3,600 m or 12,200 ft and 5,200 m or 17,200 ft)

Abstract

At two altitudes (3,600 and 5,200 m), resident native women (A) showed higher PAco₂ and Paco₂, lower PAO₂ and PaO₂, as well as lower arterial pH, than native males (C) of similar age. Resting minute ventilation (VE/m²), tidal volume (VT) and respiratory frequency (f) were similar. The differences in the alveolar-arterial gas tensions in A stem from larger dead space (VDS), VDS/VT and reduced alveolar ventilation (VA). Newcomer females (B) at both altitudes differed from new- comer males (D) in regard to larger resting VA, f and smaller VT. No differences were demonstrated in size of VDS, VDS/VT or VO₂/BSA; but PAco₂ and PacO₂ were lower, PAO₂ and Pa higher and VE/VO2 and VA/VO₂ (ventilatory equivalents) above those for resting newcomer males. A contrasted with resting B at 3,600 m (12,200 ft), showing higher PAco₂ and Paco₂, lower Pao₂ and arterial pH, reduction in VA and larger VDS/VT. Both C and D at 3,600 and 5,200 m during steady-state 60-W (367 kg/m/min) exercise showed lower PAco₂ and Paco₂, higher arterial pH, smaller VDS and higher VE/VO₂ than exercising A. The latter differed from C exercising at the same work load in that VE/m² and VA were reduced, PAco₂ and Paco₂ were higher, Pa-ao₂ gradients were wider, pH was lower and VDS as well as VDS/VT were larger. Contrasted with B during steady-state 60-W exercise at both altitudes, D showed consistently smaller VDS and larger VA. While both C and A had higher resting f than D, f of newcomer females at La Paz was higher than that of A. Control of ventilation by relating VE to Pao₂ and Paco₂ at rest and exercise at both altitudes showed marked attenuation of hypoxic and hypercapnic drives, particularly in the native resident female, suggesting diminished peripheral chemoreceptor function.

Determinants of blood oxygenation during pregnancy in Andean and European residents of high altitude

“…The extent of Amercan Indian genetic ancestry was associated with a respiratory pattern characterized by high respiratory frequency and low tidal volume, both absolutely and relative to maternal height, but not with any of the other ventilatory variables (V E, Sa O 2 , HVR, or HCVR). The significance of this association is unclear; such a respiratory pattern is generally considered inefficient, but, nonetheless, it has been observed repeatedly in long-resident, highaltitude populations, Tibetans and Andeans alike (5,10). Perhaps such a pattern contributed to minimizing intersubject variability in V E; of note, two of these variables-V E and tidal volume-had reduced variance in the Andean than European group.…”

Women at Altitude: Effect of Menstrual-Cycle Phase on Acute Mountain Sickness During Deployment to High Altitude Terrain

“…Results of early studies of ventilator/ parameters and other aspects of the physiology of altitude acclimatization in women (Campbell and Hoagland, 1901;Cudkowicz et al, 1972;FitzGerald, 1913;Hannön et al, 1966Hannön et al, , 1969Hannön et al, ,1975Hannön et al, ,1976 were interpreted to suggest that women acclimatize to high altitude at least as well, if not better, than men (Hannon, 1978). However, observations of AMS in women, when compared to men, have not been consistently in favor of women acclimatizing as well or better than men.…”

Regional Distribution of Pulmonary Blood Flow in Normal High-Altitude Dwellers at 3,650 m (12,200 ft)

“…Alveolar-arterial oxygen tension (pA-aOa) gradients of different magni tude have been documented in both male and female native HADs [1][2][3] as well as in newcomers of both sexes to the altitudes of 3,650 and 5,200 m (12,200 and 17,200 ft), respectively. The resting mean pulmonary artery pres sure (MPAP) increase, associated with residence at altitudes above 10,000 ft, has been thought to favor a more even distribution of pulmonary blood flow particularly to the apices of the lungs [4].…”