title: Ischemic preconditioning improves oxygen saturation and attenuates hypoxic pulmonary vasoconstriction at high altitude.
abstract: Exposure to hypoxic environments is associated with decreased arterial oxygen saturation and increased pulmonary artery pressures. Ischemic preconditioning of an extremity (IPC) is a procedure that stimulates vasoactive and inflammatory pathways that protect remote organ systems from ongoing or future ischemic injury. To test the effects of IPC on oxygen saturation and pulmonary artery pressures at high altitude, 12 healthy adult volunteers were evaluated in a randomized cross-over trial. IPC was administered utilizing a standardized protocol. IPC or placebo was administered daily for 5 days prior to ascent to altitude. All participants were evaluated twice at 4342 m altitude (placebo and IPC conditions separated by 4 weeks, randomized). The pulmonary artery systolic pressure (PASP) at 4342 m was significantly lower in the IPC condition than the placebo condition (36 ± 6.0 mmHg vs. 38.1 ± 7.6 mmHg, respectively, p = 0.035). Oxygen saturation at 4342 m was significantly higher with IPC compared to placebo (80.3 ± 8.7% vs. 75.3 ± 9.6%, respectively, p = 0.003). Prophylactic IPC treatment is associated with improved oxygen saturation and attenuation of the normal hypoxic increase in pulmonary artery pressures following ascent to high altitude.
authors.affiliation: 1 Cardiology and Pulmonary/Critical Care Sections, Medical Service VA Loma Linda Healthcare System , Loma Linda, California.
authors.forename: Gary P
authors.initials: GP
authors.lastname: Foster
authors.forename: Paresh C
authors.initials: PC
authors.lastname: Giri
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Rogers
authors.forename: Sophia R
authors.initials: SR
authors.lastname: Larson
authors.forename: James D
authors.initials: JD
authors.lastname: Anholm
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000150:complications; D015415:Biomarkers / Q000097:blood; D018592:Cross-Over Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000517:prevention & control*; D000860:Hypoxia / Q000150:complications*; D019194:Ischemic Preconditioning; D008168:Lung / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D016037:Single-Blind Method; D014661:Vasoconstriction
chemical_list: D015415:Biomarkers; D010100:Oxygen
keywords: arterial oxygen saturation; athletes at altitude; hypoxic pulmonary vasoconstriction