Effects of aging on peripheral chemoreceptor CO2 response during sleep and wakefulness in healthy men.

Sleep-disordered breathing (SDB) prevalence multiplies with age and the mechanisms underlying this disorder are complex. Fifteen young and 13 elderly healthy male volunteers, ages ranging from 25 to 38 and from 55 to 76 years, were studied on three consecutive nights at the sleep laboratory. The peripheral chemoreceptor CO2 response was estimated by the single breath CO2 test (SBCO2T). The apnea-hypopnea index (AHI) was non-significantly higher in elderly men than in young men. During rapid eye movement (REM) sleep and non-REM sleep SBCO2T was similar in young and elderly subjects. During wakefulness, young had a tendency to higher SBCO2T than elderly (0.25+/-0.08 L/min/mmHg vs. 0.19+/-0.07 L/min/mmHg, respectively; p=0.054), but the five elderly subjects with AHI>5 had significantly higher SBCO2T than the remaining elderly subjects (0.24+/-0.07 L/min/mmHg vs. 0.16+/-0.04 L/min/mmHg, respectively; p=0.024). Aging seems to spare the SBCO2T during sleep. Investigation of SBCO2T during transition from wakefulness to sleep, as a factor in the pathogenesis of disordered breathing in elderly men, is justified.