title: Oxygen saturation in adult cystic fibrosis patients during exercise at high altitude.
abstract: The objective of this study was to determine the frequency and severity of decreased arterial oxy-hemoglobin saturation during exercise in adults with cystic fibrosis at 1,500 m above sea level. A convenience sample of 50 adults with cystic fibrosis who did not have hypoxemia (oxygen saturation, < 90%) at rest were evaluated. Spirometry was performed according to American Thoracic Society standards, and maximal exercise tests were performed on an electronically braked cycle ergometer using a ramp protocol individualized for each patient. Pulse oximetry was measured every 2 min. When exercising at high altitude, 45 of 50 patients had a decrease in arterial oxy-hemoglobin saturation from baseline to some degree. In 29 patients, oxy-hemoglobin saturation fell below 90%; in 14 patients, it fell below 85%; and in 4 patients, it fell below 80%. Oxy-hemoglobin saturation decreased to < 90% in 12 of 14 patients with severe pulmonary disease (FEV(1) < 40% predicted), in 15 of 26 patients with moderate disease (40% less than or equal to FEV(1) < 70% predicted), in 2 of 6 patients with mild disease (70% less than or equal to FEV(1) < 90% predicted), and in 0 of 4 with normal pulmonary function (FEV(1) greater than or equal to 90%). Percent predicted FEV(1) (r = 0.57; P < 0.0001) and FEV(1)/FVC ratio (r = 0.52; P < 0.0001) most highly correlated with arterial oxy-hemoglobin saturation at peak exercise. We conclude that at 1,500 m above sea level, adult CF patients with obstructive airways disease are at significant risk for decreased arterial oxy-hemoglobin saturation during exercise. A supervised exercise test should be considered prior to recommending an exercise program for such patients.
authors.affiliation: Intermountain Cystic Fibrosis Center, Utah Health Sciences Center, Salt Lake City, Utah 84132-4701, USA.
authors.forename: D T
authors.initials: DT
authors.lastname: Ryujin
authors.forename: S C
authors.initials: SC
authors.lastname: Mannebach
authors.forename: W M
authors.initials: WM
authors.lastname: Samuelson
authors.forename: B C
authors.initials: BC
authors.lastname: Marshall
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D003550:Cystic Fibrosis / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D013147:Spirometry; D014797:Vital Capacity
chemical_list: D010100:Oxygen