title: Predictors of exercise-induced oxygen desaturation in systemic sclerosis patients with interstitial lung disease.
abstract: BACKGROUND
  The diffusion capacity of the lung for carbon monoxide (DLCO) is a good marker of disease severity in patients with idiopathic interstitial pneumonia, and is associated with oxygen saturation; however, little is known about DLCO in systemic sclerosis patients with interstitial lung disease. We studied potential predictors of exercise-induced oxygen desaturation in patients with systemic sclerosis.
  
  
  METHODS
  Data were collected prospectively from 80 of 110 consecutive systemic sclerosis patients with normal oxygen saturation (> 95%) at rest, who could perform the 6-min walk test without physical discomfort, including leg pain. Pulmonary function tests and echocardiography were collected from all subjects.
  
  
  RESULTS
  Thirty subjects showed a ≥ 4% decline in oxygen saturation during the 6-min walk test (desaturation group). The other subjects were assigned to the normoxic group. The percent-of-predicted values for FVC, FEV1, total lung capacity, DLCO, and DLCO/alveolar volume were lower, and FEV1/FVC was higher, in the desaturation group. Logistic regression analysis showed the percent-of-predicted DLCO as a highly accurate predictor of exercise-induced oxygen desaturation: the area under the receiver operating characteristic curve was 0.92 (cutoff point 56.3%, sensitivity 0.83, specificity 0.86). Five subjects over the cutoff point of the percent-of-predicted DLCO in the desaturation group could not be distinguished from the normoxic subjects with the lung-volume measurements or right-ventricular systolic pressure.
  
  
  CONCLUSIONS
  The factor underlying exercise-induced oxygen desaturation appeared to be reduced percent-of-predicted DLCO, which was useful as a predictor in over 80% of the subjects.
authors.affiliation: School of Health Sciences, Kanazawa University.
authors.forename: Fujiko
authors.initials: F
authors.lastname: Someya
authors.forename: Naoki
authors.initials: N
authors.lastname: Mugii
authors.forename: Minoru
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Tetsutarou
authors.initials: T
authors.lastname: Yahata
authors.forename: Takao
authors.initials: T
authors.lastname: Nakagawa
mesh_terms: D000368:Aged; D019540:Area Under Curve; D002248:Carbon Monoxide / Q000378:metabolism; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011653:Pulmonary Diffusing Capacity; D012372:ROC Curve; D012595:Scleroderma, Systemic / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D014109:Total Lung Capacity; D014797:Vital Capacity
chemical_list: D002248:Carbon Monoxide; D010100:Oxygen
keywords: 6-min walk test; interstitial lung disease; oxygen saturation; pulmonary arterial hypertension; pulmonary function; systemic sclerosis