title: The accuracy of autotitrating CPAP-determined residual apnea-hypopnea index.
abstract: OBJECTIVE
  Autotitrating continuous positive airway pressure (auto-CPAP) devices not only titrate CPAP pressures but also measure residual respiratory events. The aim of the present study was to determine the accuracy of auto-CPAP-derived residual apnea-hypopnea index (AHI).
  
  
  METHODS
  We studied 137 consecutive patients (72.3% men) with obstructive sleep apnea from January 2008 to December 2010 who underwent in-laboratory overnight polysomnography (PSG) using auto-CPAP. We excluded patients with comorbidities like congestive heart disease, chronic obstructive pulmonary disease, or hypoventilation syndromes and patients with central sleep apnea. Residual AHI obtained from the auto-CPAP device by smart card (CPAP-AHI) was compared simultaneously with AHI from an overnight PSG on auto-CPAP (PSG-AHI) using Bland-Altman analysis and Wilcoxon signed-rank test.
  
  
  RESULTS
  The mean AHI on the diagnostic study was 45.08 ± 1.8. During the titration, auto-CPAP markedly suppressed the respiratory events (PSG-AHI, 3.40 ± 0.20). On the other hand, CPAP-AHI was 3.35 ± 0.17. Bland-Altman analysis showed good agreement between auto-CPAP-AHI and PSG-AHI (AHI mean difference of 0.05, and the limits of agreement for the AHI were from +4.9 to -4.8). Two methods have also been compared with paired samples t test and no statistically significant difference was found (p > 0.05).
  
  
  CONCLUSIONS
  Auto-CPAP can identify residual respiratory events equivalent to the use of PSG in a selected population.
authors.affiliation: Department of Biostatistics and Medical Informatics, Akdeniz University, Antalya, Turkey. acilli@akdeniz.edu.tr
authors.forename: Aykut
authors.initials: A
authors.lastname: Cilli
authors.forename: Rusen
authors.initials: R
authors.lastname: Uzun
authors.forename: Ugur
authors.initials: U
authors.lastname: Bilge
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure / Q000379:methods* / Q000706:statistics & numerical data; D003936:Diagnosis, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography / Q000379:methods* / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D013813:Therapy, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D010100:Oxygen