title: Respiratory function and blood gas variables in cystic fibrosis patients during reduced environmental pressure.
abstract: Patients with cystic fibrosis (CF) suffer from hypoxaemia even under normobaric conditions and the reduction of inspiratory PO2 (O2 partial pressure) during air travel corresponding to an altitude of 1,800-2,450 m might be a problem for these patients. Ten CF patients and 27 healthy control subjects were investigated in a chamber where the ambient pressure was reduced to that found at 2,000 and 3,000 m. The respiratory function was reduced in the CF patients with a vital capacity of 3.1 (0.3) l [vs 4.9 (0.2) l in controls; mean (SEM)] and a forced expiratory 1-s volume of 2.1 (0.3) l [vs 4.3 (0.20 l in controls], unrelated to the reduction in ambient pressure. Mean arterial PO2 decreased from 75 (4) mmHg [85 (1) mmHg in controls, P<0.01] at sea level to 58 (3) mmHg at 580 mmHg and to 46 (1) mmHg [58 (1) mmHg and 49 (2) mmHg in controls, n.s.] at 513 mmHg ambient pressure. These results indicate that during air travel with a cabin pressure that corresponds to an altitude of 2,500 m, the arterial PO2 of CF patients is likely to remain above the accepted critical value of 50 mmHg. However, a further reduction of the pressure to that found at 3,000 m altitude may lead to severe hypoxia in patients with moderate airway obstruction.
authors.affiliation: Institute of Physiology, University of Würzburg, Röntgenring 9, 97070 Würzburg, Germany. oliver.thews@mail.uni-wuerzburg.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Thews
authors.forename: Birthe
authors.initials: B
authors.lastname: Fleck
authors.forename: Wolfgang E S
authors.initials: WE
authors.lastname: Kamin
authors.forename: Dirk-Matthias
authors.initials: DM
authors.lastname: Rose
mesh_terms: D000293:Adolescent; D000328:Adult; D000399:Air Pressure; D000531:Altitude; D001359:Aviation; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D003550:Cystic Fibrosis / Q000097:blood* / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D012129:Respiratory Function Tests; D013147:Spirometry; D014797:Vital Capacity / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen