Arousals and sleep stages in patients with obstructive sleep apnoea syndrome: changes under nCPAP treatment

Abstract

SummaryNocturnal arousals are the essential cause of disturbed sleep structure in patients with obstructive sleep apnoea syndrome (OSAS). The aim of this study was to analyse the relationship between sleep stages, respiratory (type-R) and movement (type-M) related EEG arousals. Furthermore, the value of these arousals as a criterion for the efficiency of nCPAP treatment was estimated. We examined 38 male patients aged between 30 and 71 (49.1±20.9 SD) y. All patients suffered from OSAS. The mean respiratory disturbance index (RDI) was 47.3±27.8 per h. Polysomnographic monitoring was carried out on 4 subsequent nights: baseline night, 2 nights of nCPAP titration and nCPAP control night. Sleep was visually scored and EEG arousals were classified into type R and M, depending on whether changes of respiration or movement caused the arousal. The RDI, the R index (type-R/h), the M index (type-M/h) and the R and M indices in different sleep stages were calculated. During the baseline night a deficit of slow wave sleep (SWS) and REM sleep was found. Furthermore there were more type-R than type-M arousals registered (17.4 h −1 [3.6-43.6] vs. 5.9 h −1 [1.6-11.8]) (P<0.01). They occurred during stages NREM 1, NREM 2 and REM (P<0.01). An SWS sleep rebound and a reduction of the SWS and REM latencies were already found during the first CPAP night. The R index was reduced during the first CPAP night in all sleep stages (P<0.01) and remained approximately the same in the following 2 nights (3. CPAP night: 1.1 h −1 [0.3-5.0]). Type M arousals occurred more in stages 1 and 2 (P<0.01), and remained unchanged under nCPAP. We concluded that differentiation of nocturnal arousals may provide more detailed information regarding the influence of breathing disturbances on sleep. Respiratory related, not movement related, arousals may be a useful additional tool in judging the efficiency of OSAS.

Nasal continuous positive airway pressure: influence on digital volume pulse in obstructive sleep apnoea patients

“…Delta sleep significantly increased with nCPAP treatment. These results are in agreement with improved delta sleep with CPAP therapy [41,42]; however, we cannot exclude an overestimation in our reports of delta sleep. Interscorer reliability has been shown to range from 65 to 78% when applying the criteria of RECHTSCHAFFEN and KALES [20] and NORMAN et al [43].…”

Mouth Breathing in Obstructive Sleep Apnea prior to and during Nasal Continuous Positive Airway Pressure

“…Fietze et al [19] analyzed the arousal frequency during the different sleep stages directly associated with respiratory events. The highest frequency of this type R arousal was observed in sleep stage NREM 1, whereas during slow-wave sleep the lowest number of type R arousals occurred.…”

EEG recurrence markers and sleep quality

“…CARR was defined as an increase in REM as a percentage of total sleep time of at least 20%. This threshold was higher than that used previously [11][12][13][14], but sufficiently low to ensure that an adequate number of patients were available for study after screening the database (>500 studies). Exclusion criteria included b30 minutes of REM sleep in any study, significant medical co-morbidities, current use of sleep-altering medications, and prior treatment for OSA.…”

“…CPAP-associated REM rebound (CARR) is generally accepted to indicate deeper and less fragmented sleep [11][12][13][14]. We therefore expected an increase in recurrence in CARR patients and a decrease in the variability of the recurrence, compared with the corresponding values determined prior to initiation of CPAP.…”

“…REM rebound (an increase in percent of overnight sleep that is staged as REM) occurs during recovery from chronic stress, including restorative sleep following sleep deprivation [10] and initiation of treatment for OSA using continuous positive airway pressure (CPAP) [11][12][13][14]. CPAP-associated REM rebound (CARR) is generally accepted to indicate deeper and less fragmented sleep [11][12][13][14].…”