title: Accuracy of a novel auto-CPAP device to evaluate the residual apnea-hypopnea index in patients with obstructive sleep apnea.
abstract: BACKGROUND
  Patients under treatment with continuous positive airway pressure (CPAP) may have residual sleep apnea (RSA).
  
  
  OBJECTIVE
  The main objective of our study was to evaluate a novel auto-CPAP for the diagnosis of RSA.
  
  
  METHODS
  All patients referred to the sleep laboratory to undergo CPAP polysomnography were evaluated. Patients treated with oxygen or noninvasive ventilation and split-night polysomnography (PSG), PSG with artifacts, or total sleep time less than 180 min were excluded. The PSG was manually analyzed before generating the automatic report from auto-CPAP. PSG variables (respiratory disturbance index (RDI), obstructive apnea index, hypopnea index, and central apnea index) were compared with their counterparts from auto-CPAP through Bland-Altman plots and intraclass correlation coefficient. The diagnostic accuracy of autoscoring from auto-CPAP using different cutoff points of RDI (≥5 and 10) was evaluated by the receiver operating characteristics (ROCs) curve.
  
  
  RESULTS
  The study included 114 patients (24 women; mean age and BMI, 59 years old and 33 kg/m(2); RDI and apnea/hypopnea index (AHI)-auto median, 5 and 2, respectively). The average difference between the AHI-auto and the RDI was -3.5 ± 3.9. The intraclass correlation coefficient (ICC) between the total number of central apneas, obstructive, and hypopneas between the PSG and the auto-CPAP were 0.69, 0.16, and 0.15, respectively. An AHI-auto >2 (RDI ≥ 5) or >4 (RDI ≥ 10) had an area under the ROC curve, sensitivity, specificity, positive likelihood ratio, and negative for diagnosis of residual sleep apnea of 0.84/0.89, 84/81%, 82/91%, 4.5/9.5, and 0.22/0.2, respectively.
  
  
  CONCLUSIONS
  The automatic analysis from auto-CPAP (S9 Autoset) showed a good diagnostic accuracy to identify residual sleep apnea. The absolute agreement between PSG and auto-CPAP to classify the respiratory events correctly varied from very low (obstructive apneas, hypopneas) to moderate (central apneas).
authors.affiliation: Sleep Laboratory, Hospital Alemán, Pedro Goyena 620 3 B, CP 1424, Buenos Aires, Argentina, cnigro@intramed.net.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Nigro
authors.forename: Sergio
authors.initials: S
authors.lastname: González
authors.forename: Anabella
authors.initials: A
authors.lastname: Arce
authors.forename: María Rosario
authors.initials: MR
authors.lastname: Aragone
authors.forename: Luciana
authors.initials: L
authors.lastname: Nigro
mesh_terms: D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000295:instrumentation*; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000628:therapy*; D013813:Therapy, Computer-Assisted / Q000295:instrumentation*; D016896:Treatment Outcome