title: Overnight features of transcutaneous carbon dioxide measurement as predictors of metabolic status.
abstract: OBJECTIVE
  To systematically investigate whether overnight features in transcutaneous carbon dioxide (P(TcCO(2)) measurements can predict metabolic variables in subject with suspected sleep-disordered breathing.
  
  
  METHODS
  The features extracted from the P(TcCO(2)) signal included the number of abrupt descents per hour and attributes that characterize the recovery after such an event. For each outcome variable, the subgroup of the 108 study subjects with the particular variable present was divided into two representative classes, and the optimal features that can predict the classes were learned. Overfitting was avoided by evaluating the classification algorithms using 10-fold cross-validation.
  
  
  RESULTS
  (P(TcCO(2)) signal has a key role in determining the classes of high-density lipoprotein cholesterol and thyroid-stimulating hormone concentrations, and it improves the classification accuracy of glycosylated hemoglobin A1c and fasting plasma glucose values.
  
  
  CONCLUSIONS
  The features learned from the (P(TcCO(2)) signal reflected the state of the selected metabolic variables in a subtle, but systematic, way. These findings provide a step towards understanding how metabolic disturbances are connected to carbon dioxide exchange during sleep.
authors.affiliation: Biomathematics Research Group, Department of Mathematics, University of Turku, Turku, Finland. arho.virkki@utu.fi
authors.forename: Arho
authors.initials: A
authors.lastname: Virkki
authors.forename: Olli
authors.initials: O
authors.lastname: Polo
authors.forename: Tarja
authors.initials: T
authors.lastname: Saaresranta
authors.forename: Anne
authors.initials: A
authors.lastname: Laapotti-Salo
authors.forename: Mats
authors.initials: M
authors.lastname: Gyllenberg
authors.forename: Tero
authors.initials: T
authors.lastname: Aittokallio
mesh_terms: D000465:Algorithms; D001785:Blood Gas Monitoring, Transcutaneous; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood
chemical_list: D002245:Carbon Dioxide; D006442:Glycated Hemoglobin; D008055:Lipids; D013972:Thyrotropin