title: Prevalence of persistent sleep apnea in patients treated with continuous positive airway pressure.
abstract: OBJECTIVE
  There are limited data on the prevalence of persistent obstructive sleep apnea (OSA) in patients who are clinically asymptomatic with continuous positive airway pressure (CPAP). Our objectives were to estimate the prevalence of persistent OSA and to explore the parameters that may be capable of discriminating these patients.
  
  
  METHODS
  Prospective survey.
  
  
  METHODS
  A tertiary-care sleep-disorders clinic.
  
  
  METHODS
  Consecutive patients treated with single-pressure CPAP for at least 3 months were studied. All had undergone CPAP titrations and were compliant with treatment. They denied snoring or persistent excessive daytime somnolence. Of 114 who qualified, 101 were studied.
  
  
  METHODS
  Subjects underwent 16-channel polysomnography with electroencephalogram and pneumotachometer while using their CPAP.
  
  
  RESULTS
  Seventeen of 101 subjects (17%) had an apnea-hypopnea index of over 10. Fifty-one had only split-night protocols for CPAP titration. There was no significant difference between participants with persistent OSA and those with an apnea-hypopnea index < 5 with regard to age, sex, time since diagnosis, reported snoring, change in weight, or quality of life (all p > .10). Mean current CPAP level was higher, with a mean +/- SD 10.6 +/- 2.8 versus 8.6 +/- 2.3 cm H2O (p = .002). Unresolved air leak related to CPAP was more frequent in the patients with persistent OSA. Morning headaches, nonrestorative sleep, and frequent central apneas on the CPAP titration were all associated with persistent OSA.
  
  
  CONCLUSIONS
  Persistent OSA is frequent in patients treated with CPAP. This is more frequent in patients with high body mass index, higher prescribed pressures, and unresolved mask leak.
authors: Department of Medicine, Mount Sinai Hospital Center, Montreal, Quebec, Canada. marc.baltzan@clinepi.mcgill.ca
authors: Marcel A
authors: MA
authors: Baltzan
authors: Ibrahim
authors: I
authors: Kassissia
authors: Osama
authors: O
authors: Elkholi
authors: Mark
authors: M
authors: Palayew
authors: Richard
authors: R
authors: Dabrusin
authors: Norman
authors: N
authors: Wolkove