RESPIRATORY PATTERNS DURING SLEEP IN DOWNS-SYNDROME - IMPORTANCE OF CENTRAL APNEAS

Obstructive sleep apnoea episodes have been reported repeatedly in Dow n's syndrome (DS) patients as a consequence of the presence of predisp osing malformations or intercurrent pathology of the upper airways. Th ere are no data on respiratory patterns of uncomplicated Down's syndro me subjects, In order to evaluate the eventual effects of central nerv ous system (CNS) impairment on respiration in DS, we studied the respi ratory patterns during sleep of a group of 10 DS subjects, aged 8.6-32 .2 y, without relevant upper airway pathology, In order to control the possible effects of sleep structure and mental retardation on the res ults obtained, we compared the findings in DS with those obtained from a group formed by subjects affected by fragile X syndrome (six males and one female, aged 10.0-15.42 y), another genetically determined typ e of mental retardation. Sleep structure was similar in both groups; h owever, DS subjects showed significantly higher indices of central sle ep apnoea and of oxygen desaturation than fragile X patients (P<0.005) . As far as DS individuals were considered, a significant preponderanc e of central, as opposed to obstructive, sleep apnoeas was found (89.4 % vs. 9.4%, respectively; 1.2% were mixed) which showed a significant age-related increase. Central respiratory pauses were mostly preceded by sighs, which occurred more frequently during sleep stages 1 and REM , and were often organized in long sequences of periodic-like breathin g. During REM sleep, they were less frequently preceded by sighs and b y body movements than during NREM sleep, Obstructive sleep apnoeas occ urred more often during REM sleep and were more rarely preceded by sig hs or by body movements. Both central and obstructive apnoeas induced significant oxygen desaturation in 50-69.6%. Sleep structure was not s ignificantly modified by apnoeas and oxygen desaturation, We hypothesi ze that the increase in central sleep apnoeas is related to a dysfunct ion of the central respiratory control at a brainstem level in DS.