title: Overnight changes of chemoreflex control in obstructive sleep apnoea patients.
abstract: We hypothesized that the numerous episodes of hypoxia, hypercapnia and arousal experienced by obstructive sleep apnoea (OSA) patients induce overnight changes in respiratory chemoreflexes. A modification of the Read rebreathing technique assessed chemoreflex characteristics in the evening and the morning of patients undergoing diagnostic assessment for OSA in a clinical sleep laboratory. Two groups were studied: those with apnoea-hypopnoea indices (AHI) greater than 30 composed the OSA group (n = 12), and those with AHI indices less than 10 composed the non-OSA group (n = 12). There was a significant (approximately 30%) overnight increase in chemoreflex sensitivities, without changes in thresholds, in the OSA group. In the non-OSA group there was a significant overnight reduction in chemoreflex thresholds (approximately 5%), without changes in sensitivities. We suggest that these changes affect the stability of the chemoreflex control system in opposite ways as the night proceeds: destabilizing breathing for patients in the OSA group, and stabilising breathing for patients in the non-OSA group.
authors.affiliation: Department of Physiology, University of Toronto, Toronto, Ont., Canada M5S 1A8.
authors.forename: Safraaz
authors.initials: S
authors.lastname: Mahamed
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hanly
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gabor
authors.forename: Jaime
authors.initials: J
authors.lastname: Beecroft
authors.forename: James
authors.initials: J
authors.lastname: Duffin
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002628:Chemoreceptor Cells / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D016857:Hypocapnia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D017286:Polysomnography / Q000379:methods; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D012119:Respiration; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D013147:Spirometry / Q000379:methods