title: AltitudeOmics: impaired pulmonary gas exchange efficiency and blunted ventilatory acclimatization in humans with patent foramen ovale after 16 days at 5,260 m.
abstract: A patent foramen ovale (PFO), present in ∼40% of the general population, is a potential source of right-to-left shunt that can impair pulmonary gas exchange efficiency [i.e., increase the alveolar-to-arterial Po2 difference (A-aDO2)]. Prior studies investigating human acclimatization to high-altitude with A-aDO2 as a key parameter have not investigated differences between subjects with (PFO+) or without a PFO (PFO-). We hypothesized that in PFO+ subjects A-aDO2 would not improve (i.e., decrease) after acclimatization to high altitude compared with PFO- subjects. Twenty-one (11 PFO+) healthy sea-level residents were studied at rest and during cycle ergometer exercise at the highest iso-workload achieved at sea level (SL), after acute transport to 5,260 m (ALT1), and again at 5,260 m after 16 days of high-altitude acclimatization (ALT16). In contrast to PFO- subjects, PFO+ subjects had 1) no improvement in A-aDO2 at rest and during exercise at ALT16 compared with ALT1, 2) no significant increase in resting alveolar ventilation, or alveolar Po2, at ALT16 compared with ALT1, and consequently had 3) an increased arterial Pco2 and decreased arterial Po2 and arterial O2 saturation at rest at ALT16. Furthermore, PFO+ subjects had an increased incidence of acute mountain sickness (AMS) at ALT1 concomitant with significantly lower peripheral O2 saturation (SpO2). These data suggest that PFO+ subjects have increased susceptibility to AMS when not taking prophylactic treatments, that right-to-left shunt through a PFO impairs pulmonary gas exchange efficiency even after acclimatization to high altitude, and that PFO+ subjects have blunted ventilatory acclimatization after 16 days at altitude compared with PFO- subjects.
authors: Department of Human Physiology, University of Oregon, Eugene, Oregon;
authors: Jonathan E
authors: JE
authors: Elliott
authors: Department of Human Physiology, University of Oregon, Eugene, Oregon;
authors: Steven S
authors: SS
authors: Laurie
authors: Department of Human Physiology, University of Oregon, Eugene, Oregon;
authors: Julia P
authors: JP
authors: Kern
authors: Department of Human Physiology, University of Oregon, Eugene, Oregon;
authors: Kara M
authors: KM
authors: Beasley
authors: Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon;
authors: Randall D
authors: RD
authors: Goodman
authors: University of Lausanne, Department of Physiology and Institute of Sports Sciences, Lausanne, Switzerland;
authors: Bengt
authors: B
authors: Kayser
authors: Altitude Research Center, University of Colorado Anschutz Medical Campus, Denver, Colorado; and Department of Biology, University of Colorado, Colorado Springs, Colorado.
authors: Andrew W
authors: AW
authors: Subudhi
authors: Altitude Research Center, University of Colorado Anschutz Medical Campus, Denver, Colorado; and.
authors: Robert C
authors: RC
authors: Roach
authors: Department of Human Physiology, University of Oregon, Eugene, Oregon; lovering@uoregon.edu.
authors: Andrew T
authors: AT
authors: Lovering
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D005260:Female; D054092:Foramen Ovale, Patent / Q000503:physiopathology*; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012146:Rest / Q000502:physiology; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: acute mountain sickness; high altitude; shunt