title: Ageing does not influence the sleep-related decrease in the hypercapnic ventilatory response.
abstract: In young people, a sleep-related reduction in the gain of the ventilatory chemoreflex feedback loop occurs; in the elderly, it has been reported that no sleep-related reduction occurs. A relatively high loop gain could contribute to periodic breathing and central sleep apnoea in the elderly. This study tested the hypothesis that ageing is associated with a reduction in the magnitude of the sleep-related decrease in the hypercapnic ventilatory response (HCVR). The HCVR was measured using a steady state method, awake and asleep, in groups (n = 10) of elderly (66-81 yrs) and young (23-35 yrs) nonapnoeics. Upper airway resistance was maintained close to wakefulness levels using continuous positive airway pressure (mean sleep-related increase in resistance: elderly 1.6 +/- 1.2 cmH2O L x s(-1), young 1.2 +/- 0.8 cmH2O x L x s(-1)). The sleep-related decrease in the HCVR was similar in the elderly and young groups (elderly: wake 0.14 +/- 0.06 and sleep 0.06 +/- 0.02 L min(-1) x kPa and young, wake 0.19 +/- 0.07 and sleep 0.10 +/- 0.04 L x min(-1) x kPa). Ageing per se was shown not to change the magnitude of the sleep-related decrease in hypercapnic ventilatory response. The authors speculate that age-related changes in the hypercapnic ventilatory response are unlikely to contribute to the increased prevalence of central sleep apnoea in the elderly.
authors.affiliation: National Heart and Lung Institute, Imperial College School of Medicine, Charing Cross Campus, London, UK.
authors.forename: H A K
authors.initials: HA
authors.lastname: Browne
authors.forename: L
authors.initials: L
authors.lastname: Adams
authors.forename: A K
authors.initials: AK
authors.lastname: Simonds
authors.forename: M J
authors.initials: MJ
authors.lastname: Morrell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D002628:Chemoreceptor Cells / Q000502:physiology; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D008297:Male; D011336:Probability; D012123:Pulmonary Ventilation / Q000502:physiology; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000503:physiopathology*; D012892:Sleep Deprivation / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology
chemical_list: D002245:Carbon Dioxide