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Body: Rationale: Upper airway and nasal airflow resistance are significant in infancy, due to the fact that infants are nasal breathers in early life, and that obstructive nasal diseases are frequent at this age. Nasal flow resistance is closely determined by anatomy, which rapidly changes with growth. The goal of this study was to assess standardized measurements of the nasal cavity dimensions in the first 2 years of life. Methods: 34 head CT scans of infants aged 4.13±4.08 months (range: 0.07 to 19.4, 17 male, 17 female) available in the Amiens University Hospital Dept. of Radiology database were retrospectively analyzed. Infants with craniofacial deformities were excluded. Images were 3D reconstructed, axially oriented and the nasal cavity was segmented by density thresholding from nares to vocal cords. Surface areas of the piriform and choanal apertures were automatically computed in the coronal plane, in standardized positions based on bony reference points. Results:Piriform surface area measured (mean±SD): 54.3±13.8 mm2 (range: 29.1 - 83.9), and was significantly correlated to age (R=0.59, p

Continuous positive airway pressure (CPAP) remains the best treatment for sleep apnoea syndrome (SAS). In the 1990s, many authors reported on daily compliance, but all of the studies utilised relatively short periods of follow-up that did not exceed a few years. The mean annual rate of CPAP use in patients with SAS was prospectively recorded. In the current study, the results are presented along with compliance data from patients who started CPAP between 1991 and 1998 and were still using it by the end of 2003. The cohort was chosen in order to obtain >or=5 yrs of follow-up for each patient. In total, there were 204 patients. For the whole group, mean+/-sd compliance reached 321+/-90 and 393+/-84 min after 1 and 10 yrs, respectively. There was no significant change in the first 2 yrs, with a significant increase from the third year onwards. Compliance, or its evolution over time, was not correlated either to the baseline polysomnographical data (except slightly for the CPAP pressure), to the difference of these data before and under CPAP therapy, to the age of retirement or to changes in the marital status. In conclusion, very long-term compliance with continuous positive airway pressure increases by a mean of 8 min.day-1 per year of follow-up in patients with sleep apnoea syndrome.

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 α-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, pversus25.3±6.6 min, pIn 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.

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.

Obstructive sleep apnoea is a chronic condition characterized by repetitive episodes of upper airway collapse during sleep, leading to sleep fragmentation. The management of sleep apnoea consists of general and specific measures. General measures should include weight loss in overweight patients; avoidance of alcohol during the evening hours; avoidance of any hypnotic drug. Specific measures may range from simple position training in patients with positional sleep apnoea (sleep apnoea appearing only when lying on the back) of slight severity; to oral appliances with the aim of creating a prognathism during sleep, to the introduction of a nasopharyngeal tube during sleep every night. When position training, oral appliances or a nasopharyngeal tube are used, their effect should be monitored by full night polysomnography. The best specific treatment for sleep apnoea is nasal continuous positive airway pressure. The main problem with nasal continuous positive airway pressure is the long-term compliance which should be assessed regularly over the years. In cases where nasal continuous positive airway pressure is not tolerated or compliance is bad, a surgical treatment can be proposed. Uvulopalatopharyngoplasty seems to give disappointing results. By contrast, maxillomandibular surgery is credited with the best results available as far as surgery is concerned, comparable to nasal continuous positive airway pressure.

According to a recent theoretical model, snoring is related to instability of the upper airway (UA). Factors promoting UA instability include increased gas density. The aim of this study was to test the influence of gas density on simulated snoring production and supraglottic resistance. Supraglottic pressure and flow rate (V') were measured in 10 healthy seated subjects during simulated snoring. Subjects breathed three different gas mixtures: Helium-oxygen, He 79%-O2 21% (He-O2); air; and sulphur hexafluoride-oxygen, F6S 79%-O2 21% (F6S-O2) administered in a random order. Supraglottic resistance (Rsg) was measured on its linear range during quiet breathing and V' was measured at the onset and middle of snoring. Linear Rsg increased and V' conversely decreased with gas density. These data are in agreement with predictions of a mathematical model of the upper airway showing that snoring occurs at lower flow rates when gas density is increased.

Size and distensibility of large airways have important implications for flow limitation and the efficacy of coughing. From radiological and functional data, some authors have suggested an increased size and distensibility of the trachea in cystic fibrosis (CF). Using computed tomography (CT) we compared size and distensibility of the trachea in 5 cystic fibrosis patients and five age- and height-matched healthy volunteers. Tracheal cross-sectional area was measured 25 mm below the cricoid cartilage. CT recordings were made at functional residual capacity, at 0 and +20 cmH2O mouth pressure. Inductive plethysmography was used to check that during these manoeuvres lung volume did not change and that the glottis remained open. Tracheal cross-sectional area and derived indices of tracheal distensibility were similar in the two groups. This study does not support the concept of an increased size and distensibility of the trachea in cystic fibrosis.