Copyright ©ERS Journals Ltd 2003 Ageing does not influence the sleep-related decrease in the hypercapnic ventilatory response1 National Heart and Lung Institute, Imperial College School of Medicine, Charing Cross Campus, and 2 Royal Brompton Hospital, London, UK. 3 School of Physiotherapy and Exercise Science, Griffith University, Gold Coast, Australia CORRESPONDENCE: M.J. Morrell, Sleep and Ventilation Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. Fax: 44 2073518911. E-mail: m.morrell@ic.ac.uk Keywords: ageing, carbon dioxide, control of breathing, sleep, sleep apnoea
Received: May 10, 2002
A Welcome Trust Research Career Development Fellowship in Basic Biomedical Science awarded to M.J. Morrell supported this work.
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 (6681 yrs) and young (2335 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·s1, young 1.2±0.8 cmH2O·L·s1).
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·min1·kPa and young, wake 0.19±0.07 and sleep 0.10±0.04 L·min1·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.
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