Myriam Dury

Acceptance and long-term compliance with nCPAP in patients with obstructive sleep apnoea syndrome

Previous studies have generally shown poor effective long-term compliance with nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnoea syndrome (OSAS). We performed a retrospective study of patients treated with nCPAP for more than one year. Compliance was defined as the average number of hours of nCPAP use per day, where hours of use were obtained from the built-in time counter of the nCPAP device, after deduction of the 10% difference between effective use and time counters previously shown by others. We present data on the first 95 patients for whom results were available. The follow-up period was 784 +/- 366 (mean +/- SD) days for the whole group. Compliance was 5 +/- 1.8 h. For a subgroup of 36 patients, we had data on two consecutive follow-up periods (673 +/- 235 and 390 +/- 147 days for the first and second period, respectively). Compliance remained stable (5.2 +/- 1.5 and 5 +/- 2.3 h, respectively). For the whole group, a significant correlation was found between compliance and sleep fragmentation expressed as the movement arousal index (r = 0.226). During a similar 3 year period, 155 patients with a confirmed diagnosis of OSAS were offered a nCPAP trial. CPAP was actually delivered for home use to 117 patients (76%). During this same 3 year period, only 21 patients out of a total of 192 followed-up in our institution quit treatment, mainly due to intolerance or cure. These results indicate that in a nonselected group of obstructive sleep apnoea syndrome patients a high and stable compliance with nasal continuous positive pressure can be achieved, contradicting recent results of other series.

Effects of nasal positive-pressure hyperventilation on the glottis in normal sleeping subjects

We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.

Targeted hypoglossal neurostimulation for obstructive sleep apnoea: a 1-year pilot study

Continuous positive airway pressure (CPAP) is an effective but cumbersome treatment for obstructive sleep apnoea (OSA). Noncompliant patients need alternative therapies. We studied a tongue neurostimulation approach: targeted hypoglossal neurostimulation (THN) therapy with the aura6000™ System. A multi-contact electrode positioned around the main trunk of the twelfth nerve connected to an implanted pulse generator stimulates segments of the nerve, activating dilator muscles. The primary objective was to improve the polysomnographically determined apnoea/hypopnoea index (AHI) at 3 months, and maintain the improvement after 12 months of treatment. 13 out of 14 operated patients were successfully implanted. At 12 months, the AHI decreased from 45±18 to 21±17, a 53% reduction (p<0.001). The 4% oxygen desaturation index fell from 29±20 to 15±16 and the arousal index from 37±13 to 25±14, both p<0.001. The Epworth sleepiness scale decreased from 11±7 to 8±4 (p=0.09). THN was neither painful nor awakened patients, who all complied with therapy. There were two transient tongue paresis. The present study represents the longest study of any hypoglossal neurostimulation reported to date. We conclude that THN is safe and effective to treat OSA in patients not compliant with CPAP.

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

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.

Effects of Breathe Right™ on snoring: a polysomnographic study

The nasal vestibule is a major site of resistance to airflow in healthy subjects. A high nasal resistance may increase snoring. Activation of the alae nasi and alar retraction reduce resistance to airflow and improve ventilation. The Breathe Right (BR) device has been proposed to reduce or eliminate snoring by improving nasal breathing. We assessed the efficacy of BR on sleep quality and snoring during 2 full-night polysomnographies, the first without and the second with BR. Ten non-apnoeic snorers were studied. Snoring was present during 22-98% of total sleep time during the control night. Ear-nose-throat examination disclosed a nasal valve anomaly in five subjects, objectivated by anterior and posterior rhinomanometry. Quality of sleep and snoring were not influenced by BR, even when different sleep stages were analysed separately. No difference in snoring index was found between snorers with or without nasal valve anomaly. We conclude that BR is ineffective in relieving snoring in non-apnoeic snorers.

Sleep in ventilatory failure in restrictive thoracic disorders. Effects of treatment with non invasive ventilation

STUDY OBJECTIVES Hypercapnic ventilatory failure due to restrictive disorders may have a negative impact on sleep architecture. Non-invasive ventilation (NIV) may improve arterial blood gases but may adversely affect sleep. We assessed sleep structure and blood gases before and during NIV in patients with restrictive disorders in hypercapnic ventilatory failure. DESIGN Retrospective cohort study. SETTING Sleep laboratory of Saint-Luc University Hospital (Belgium). PATIENTS Chart review of all patients with predominantly restrictive disorders and respiratory failure seen between 1987 and 2008 and evaluated with a baseline polysomnography (PSG) and a PSG under NIV. MEASUREMENTS AND RESULTS Sixty patients aged (mean±SD) 48±20 years, with total lung capacity of 57±20% of predicted value, PaO(2) of 62±16 mm Hg and PaCO(2) 54±10 mm Hg, were included. At baseline, total sleep time, sleep efficiency, slow wave and rapid-eye movement (REM) sleep were markedly decreased. Conversely, micro-arousals and stage I sleep (N1) were increased. NIV administered with volume-cycled (53%) or pressure-cycled (47%) ventilators improved daytime PaO(2), PaCO(2), pH and HCO(3)(-). In addition, sleep efficiency, REM sleep, mean and lowest nocturnal SpO(2) increased while stage 1, sleep fragmentation, and oxygen desaturation index decreased significantly. CONCLUSION Hypercapnic ventilatory failure in restrictive disorders profoundly affects sleep quality. NIV can improve not only blood gases, but also sleep architecture.

Sleep fragmentation: comparison of two definitions of short arousals during sleep in OSAS patients

The measurement of arousals during sleep is useful to quantify sleep fragmentation. The criteria for electroencephalography (EEG) arousals defined by the American Sleep Disorders Association (ASDA) have recently been criticized because of lack of interobserver agreement. The authors have adopted a scoring method that associates the increase in chin electromyography (EMG) with the occurrence of an alpha-rhythm in all sleep stages (Université Catholique de Louvain (UCL) definition of arousals). The aim of the present study was to compare the two scoring definitions in terms of agreement and repeatability and the time taken for scoring in patients with obstructive sleep apnoea syndrome (OSAS) of varying severity. Two readers using both ASDA and UCL definitions scored twenty polysomnographies (PSGs) each on two occasions. The PSGs were chosen retrospectively to represent a wide range of arousal index (from 6-82) in OSAS patients. There was no difference in the arousal indices between readers and between scoring methods. The mean+/-SD difference between the two definitions (the bias) was 1.1+/-3.76 (95% confidence interval: -0.66-2.86). There was a strong linear relationship between the arousal index scored with the two definitions (r=0.981, p<0.001). Mean+/-SD scoring duration was significantly shorter for UCL than for ASDA definitions (18.5+/-5.4 versus 25.3+/-6.6 min, p<0.001). In conclusion, it has been found that in obstructive sleep apnoea syndrome patients, the American Sleep Disorders Association and Université Catholique de Louvain definitions were comparable in terms of agreement and repeatability.

Response of automatic continuous positive airway pressure devices in a normal subject

To the Editors: Obstructive sleep apnoea (OSA) is a prevalent disease whereby people become unable to breathe when asleep. During sleep the pharyngeal walls are sucked in and collapse completely, causing full (termed apnoea) or incomplete (termed hypopnoea) abolition of airflow. OSA can lead to daytime fatigue and sleepiness, impairment in cognitive functions, motor vehicle crashes, hypertension, cardiovascular disease, stroke and premature deaths [1]. OSA is easily treated with continuous positive pressure applied throughout sleep [2]. The right amount of pressure is determined individually during a titration night, when pressure is gradually increased to keep the airway open to allow for normal sleep and breathing [2]. In 1993 it was postulated that this process of titration could be performed with a stand alone blower equipped with a microprocessor guiding the positive pressure [3]. The idea was to use the blower as a monitoring device identifying abnormal breathing events and react by increasing pressure until disappearance of the abnormal events. The device would then slowly decrease pressure until events reappeared and the pressure would then be increased again [3]. These machines, termed automatic continuous positive airway pressure devices (autoCPAP), were proposed as monitoring or even diagnostic machines [4], as devices used for one night to determine the fixed CPAP level to be used thereafter [5] or even as therapeutic machines to be used every night and to adapt the pressure necessary to keep the pharynx open at all times [6]. When autoCPAP devices were tested in a bench study it was shown that no two devices reacted alike, that many devices did not even recognise the events they were supposed to act upon and that even when recognising the events, many were not able to …