title: Zopiclone effects on breathing at sleep in stable chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  More than half of patients with chronic obstructive pulmonary disease (COPD) experiences sleep-related problems and about one fourth uses hypnotics regularly. We explored what the effect zopiclone, a commonly used hypnotic, had on nocturnal gas exchange and the apnea/hypopnea frequency in stable COPD.
  
  
  METHODS
  Randomized crossover study of 31 (ten males) inpatients at a pulmonary rehabilitation hospital, median age 64 years, of which 20 had a forced expiratory volume first second <50% of predicted. Subjects investigated in randomized order of either baseline sleep or intervention with 5 mg zopiclone by polysomnography including transcutaneous measurement of carbon dioxide pressure increased (ΔPtcCO₂).
  
  
  RESULTS
  Zopiclone increased the mean ΔPtcCO₂ from baseline both in rapid eye movement (REM) sleep, non-REM sleep, and even in stage N0 (awake after sleep onset) with a mean (SD) of 0.25 (0.40) kPa, 0.22 (0.32) kPa, and 0.14 (0.27) kPa, respectively. Subjects with sleep hypoventilation as defined by the American Academy of Sleep Medicine increased from 6 subjects (19%) to 13 subjects (42%) (P = 0.020). REM sleep minimum oxygen saturation (minSpO₂) did not change significantly from baseline median (interquartile range [IQR]) minSpO₂ 81.8 (12.1) % to zopiclone sleep median (IQR) minSpO₂ 80.0 (12.0) % (P = 0.766). Interestingly, zopiclone reduced the number of apneas/hypopneas per hour (AHI) in subjects with overlap (AHI ≥ 15) with a median difference (IQR) of -8.5 (7.8) (N = 11, P = 0.016).
  
  
  CONCLUSIONS
  In stable COPD, zopiclone moderately increases the mean ΔPtcCO₂ without changing minSpO₂ at night and reduces AHI in overlap (COPD and obstructive sleep apnea) subjects.
authors.affiliation: LHL-klinikkene Glittre, Glittreklinikken, postboks 104 Åneby, 1485, Hakadal, Norway, nilshenrik.holmedahl@lhl-klinikkene.no.
authors.forename: Nils Henrik
authors.initials: NH
authors.lastname: Holmedahl
authors.forename: Britt
authors.initials: B
authors.lastname: Øverland
authors.forename: Ove
authors.initials: O
authors.lastname: Fondenes
authors.forename: Ivar
authors.initials: I
authors.lastname: Ellingsen
authors.forename: Jon Andrew
authors.initials: JA
authors.lastname: Hardie
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D018592:Cross-Over Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography / Q000187:drug effects*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis / Q000534:rehabilitation*; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D012047:Rehabilitation Centers; D012119:Respiration / Q000187:drug effects*; D012890:Sleep / Q000187:drug effects*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen