Residual effect of nCPAP applied for part of the night in patients with obstructive sleep apnoea

Abstract

The aim of the present study was to assess whether nasal continuous positive airway pressure (nCPAP) treatment, applied for only a few hours at the beginning of the night, has any residual effect on sleep and breathing during the ensuing hours of unassisted sleep in patients with obstructive sleep apnoea syndrome (OSAS).In 27 patients with newly-diagnosed OSAS, effective nCPAP was applied during the first part of the night and then withdrawn. Polysomnographic parameters after nCPAP withdrawal were compared with those of the corresponding part of the diagnostic polysomnography performed a few days or weeks before and with those of the first part of night on nCPAP.After 255±63 (mean±SD) min of sleep with normalization of sleep and breathing parameters under nCPAP, there was partial improvement of OSAS severity during the remaining 124±56 min of nocturnal sleep without treatment; mean oxygen saturation, desaturation index (equivalent to the apnoea/hypopnoea index) and movement arousal index all improved significantly with respect to the diagnostic night (p=0.001). This improvement was not accounted for by a change in sleep architecture.We conclude that there is an improvement in severity of obstructive sleep apnoea syndrome after only 4 h of nasal continuous positive airway pressure. This carryover effect could explain why a number of patients with obstructive sleep apnoea syndrome apply nasal continuous positive airway pressure for only part of the night or not every night. Eur Respir J 1997; 10: 973-976.

Effects of CPAP therapy on cardiovascular variability in obstructive sleep apnea: a closed-loop analysis

“…Because compliance varied widely across individuals, we divided the subjects into two groups: the six compliant subjects (group C) who used CPAP for an average of Ͼ3 h per night, and the seven noncompliant subjects (group N), whose average nightly CPAP use was Ͻ3 h. A previous study (13) has shown that use of CPAP therapy for an average of 3.4 h per night over a duration of 4 wk leads to improved daytime cognitive performance. Hers et al (15) found that application of CPAP in the first 4 h of sleep resulted in a significant reduction of the severity of OSA over the remainder of the night, during which treatment was not applied. A recent study (23) of CPAP compliance in 1,155 OSA patients reported that subjects who used CPAP Ͻ2 h per night in the first 3 mo were unlikely to continue with treatment for Ͼ1 year.…”

Compliance in sleep apnoea therapy: influence of home care support and pressure mode

“…One possible explanation for such an effect is the reduction of mucosal oedema by minimising vibrational trauma, which is known to account for upper airway collapsibility, in part [26]. Another possible explanation is a reduction in sleep fragmentation, reflected by a further decrease in the arousalindex in the present study; sleep fragmentation is known to increase upper airway collapsibility [27,28]. A decrease in daytime somnolence may also be due to a better acclimatisation to CPAP and therefore less sleep fragmentation.…”

Compliance with nasal CPAP therapy for obstructive sleep apnoea: how much is enough?

“…Nasal CPAP therapy in OSA has been shown to be associated with a variety of potentially beneficial neuromuscular and mechanical changes affecting the upper airway, including: reduced pharyngeal oedema; increased upper airway cross-sectional area; reduced upper airway collapsibility; and improved ventilatory load compensation [17][18][19][20]. Whilst the data available do not indicate that these effects might occur after only a few hours of therapy, as in the study by HERS et al [13] long-term therapy with NCPAP could well produce mechanical benefits to the upper airway that would persist for at least several hours after NCPAP withdrawal, and thus produce a persisting benefit for the latter part of the night among the majority of patients who only use their device for the early part of each night.…”

“…The paper by HERS et al [13] in this issue of the Journal provides important information on what happens to OSA in that part of the night without effective NCPAP therapy, and demonstrates a clinically important residual benefit which persists in the latter part of the night after NCPAP withdrawal. The frequency of apnoeas and hypopnoeas was almost halved, and the severity of oxygen desaturations greatly reduced, when compared with the latter part of a previous study night without NCPAP therapy.…”