CPAP with algorithm-based versus titrated pressure: A randomized study.

BACKGROUND: Our goal was to evaluate whether an algorithm-prescribed pressure is effective in sleep apnea-hypopnea syndrome (SAHS) patients requiring continuous positive airway pressure (CPAP). METHODS: SAHS patients with an apnea-hypopnea index (AHI)>20/h were selected for a parallel group randomized study including an in-sleep laboratory acute phase and a domiciliary chronic phase. After baseline polysomnography, patients had a second night polysomnography either with CPAP at the algorithm-calculated pressure, followed by home treatment at this pressure without any correction or adjustment (calculation group), or with auto-CPAP titration, followed by home treatment at the pressure judged to be optimal from the auto-titration (titration group). The primary outcome was the change in Epworth sleepiness scale (ESS) at 6 months. RESULTS: The calculated pressure (mean (SD)) was 7.0 (1.4) in the calculation group (n=33), while the optimal pressure was 7.0 (2.2)cmH(2)O in the titration group (n=36). During the 6-month treatment at home, the ESS decreased from 8.3 (4.9) to 5.4 (4.0) in the calculation group (n=20) and from 8.7 (5.4) to 6.4 (5.4) in the titration group (n=20) (between-group difference not significant). CONCLUSION: In these SAHS patients with moderate sleepiness treated with CPAP, we found no difference in effectiveness between an algorithm-based pressure and an auto-titrated pressure.

Shorter REM latency associated with more sleep cycles of a shorter duration in healthy humans.

A significant association between rapid eye movement (REM) sleep latency and the number of non-REM/REM sleep cycles was found 15 years ago in a large retrospective study. The present prospective study further explored this intra-sleep relationship and analyzed the links between these two variables and the mean cycle duration. It was based on a carefully selected group of healthy control subjects whose sleep was polysomnographically recorded at home for 4 sequential nights. The latency of REM sleep was inversely correlated with the number of cycles and positively correlated with the mean cycle duration, both in individual nights and on means of 4 nights. The present study demonstrated that variations in the number of cycles or the mean cycle duration between the nights are far less important than the substantial differences observed between subjects. Present outcomes support the study of sleep cycle periods and frequencies in those psychiatric disorders where REM sleep latencies have been found to be shorter, and they suggest that these variables be included in sleep studies in which cycles are compared with each other.

The first-night effect may last more than one night.

The first-night effect in sleep polysomnographic studies is usually considered to last for one night. However, a few observations have indicated that variables associated to rapid eye movement sleep take longer to stabilize. Notwithstanding, current opinion holds that second nights of recording can be used without restriction for research and clinical purposes. The goal of this study was to describe the dynamics of habituation to polysomnography in optimal conditions. Twenty-six young, carefully screened, healthy subjects were recorded in their home for four consecutive full polysomnographies. Repeated measures ANOVA were applied. Between the two first nights, while there were no differences in sleep duration in non-rapid eye movement sleep, marked modifications in corresponding spectral power were observed. The dynamics of adaptation of rapid eye movement sleep appeared to be a process extending up to the fourth night. Similar dynamics in NREMS and REMS homeostasis have been observed in sleep deprivation studies, and it appears that the same mechanisms may be responsible for the FNE. The longer habituation process of REMS in particular has important implications for sleep research in psychiatry.