title: Repeated exercise-induced arterial hypoxemia in a healthy untrained woman.
abstract: A healthy 36-year-old untrained (maximal oxygen consumption (V(O2max)): 39 mL/kg/min) woman completed multiple graded exercise tests on a treadmill. Temperature-corrected arterial blood samples were obtained in addition to esophageal pressure. Significant hypoxemia (-13 mm Hg arterial oxygen tension decrease) and arterial oxyhemoglobin desaturation (-6% decrease) was observed relative to rest and occurred during submaximal exercise and worsened at maximal intensities. Expiratory flow limitation (28-40% intersection of tidal volume) was present at near-maximal intensities. Relieving mechanical ventilatory constraints with a helium inspirate (79% He:21% O(2)) partially reversed the hypoxemia. Conversely, increasing chemical ventilatory stimuli, with hypercapnia (3.5% CO(2)), failed to increase ventilation. Maintaining oxyhemoglobin saturation, via a mildly hyperoxic (26% O(2)) inspirate, increased exercise duration (+45 s) and V(O2max) (+5 mL/kg/min). We attribute the hypoxemia to an excessive A-a(O2) resulting from ventilation-perfusion mismatch and secondarily to mechanical ventilatory constraints. We conclude that a healthy untrained woman can develop EIAH and this remains stable over a period of 6 months.
authors: School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada. Paolo321@interchange.ubc.ca
authors: Paolo B
authors: PB
authors: Dominelli
authors: Glen E
authors: GE
authors: Foster
authors: Giulio S
authors: GS
authors: Dominelli
authors: Jordan S
authors: JS
authors: Querido
authors: William R
authors: WR
authors: Henderson
authors: Michael S
authors: MS
authors: Koehle
authors: A William
authors: AW
authors: Sheel
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006304:Health Status; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology