title: Obstructive sleep-disordered breathing with a dominant cyclic alternating pattern--a recognizable polysomnographic variant with practical clinical implications.
abstract: OBJECTIVE
  To define the clinical and polysomnographic features of a distinct variant of obstructive sleep-disordered breathing that is remarkably mild during rapid eye movement (REM) sleep.
  
  
  METHODS
  Observational study and evaluation of polysomnographic and clinical records.
  
  
  METHODS
  American Academy of Sleep Medicine-accredited multidisciplinary sleep disorders center and laboratory.
  
  
  METHODS
  35 medication-free subjects with clinical and polysomnographic severe obstructive sleep-disordered breathing selected for dominance of 1 of 2 disordered breathing patterns.
  
  
  METHODS
  Positive airway pressure titration.
  
  
  RESULTS
  Nasal pressure was used to score respiratory events. Sleep was scored by both the standard criteria and cyclic alternating pattern (CAP), and the distribution of respiratory events was tabulated and analyzed. A distinct clinical and polysomnographic syndrome emerged, CAP-dominant sleep-disordered breathing, characterized by severe relatively short cycle obstructive events during non-REM sleep that were mild in REM sleep. Characteristics include lower body mass index, fewer apneas, and a lower hypoxic burden as reflected by frequency and severity of nocturnal oxygen saturation. During positive pressure titration, a remarkable respiratory instability emerged selectively during CAP, in contrast to stability during REM sleep. This partial treatment failure was associated with persistent clinical symptoms.
  
  
  CONCLUSIONS
  This variant of sleep apnea may reflect a dominant component of respiratory instability and periodic breathing coupled with upper-airway obstruction. Its existence questions the conventional practice of calculating global respiratory indexes. Besides positive airway pressure, measures to treat periodic breathing may be required.
authors.affiliation: Division of Pulmonary Critical Care and Sleep Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Mass 02215, USA. rthomas1@bidmc.harvard.edu
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Thomas
authors.forename: Mario G
authors.initials: MG
authors.lastname: Terzano
authors.forename: Liborio
authors.initials: L
authors.lastname: Parrino
authors.forename: J Woodrow
authors.initials: JW
authors.lastname: Weiss
mesh_terms: D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000453:epidemiology*; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis / Q000453:epidemiology*; D012895:Sleep, REM / Q000502:physiology; D016896:Treatment Outcome