Background-Obesity and increased neck circumference are risk factors for the obstructive sleep apnoea/hypopnoea syndrome (SAHS). SAHS is more common in men than in women, despite the fact that women have higher rates of obesity and greater overall body fat. One factor in this apparently paradoxical sex distribution may be the diVering patterns of fat deposition adjacent to the upper airway in men and women. A study was therefore undertaken to compare neck fat deposition in normal men and women. Methods-Using T1 weighted magnetic resonance imaging, the fat and tissue volumes in the necks of 10 non-obese men and 10 women matched for age (men mean (SE) 36 ( Conclusions-There are diVerences in neck fat deposition between the sexes which, together with the greater overall soft tissue loading on the airway in men, may be factors in the sex distribution of SAHS. (Thorax 1999;54:323-328) Keywords: sleep apnoea; neck fat; sex diVerences; magnetic resonance imaging Sleep disordered breathing, snoring, and the sleep apnoea/hypopnoea syndrome (SAHS) are 2-8 times more common in men than in women in all adult age groups.1 2 In men these conditions are associated with obesity, increased neck circumference, and reduced cross sectional area of the upper airway, 3-6 all factors which predispose to the partial or complete obstruction of the upper airway.The male predominance in SAHS has not been fully explained and is in some respects paradoxical. Compared with men, a greater proportion of total body soft tissue in normal women is fat and obesity is more frequent in women.7 8 A condition strongly associated with obesity might therefore be predicted to show a higher frequency in women. Similarly, pharyngeal airway cross sectional area has been reported to be less in women when matched for body mass index (BMI), 9 which would be expected to predispose to airway obstruction. However, women do have a smaller neck circumference when matched for BMI and so overall mass loading on the upper airway may be less.10 Dynamic factors are also relevant; the upper airway when seated is smaller in women, but there is no diVerence between supine men and women. 10 This suggests that women have a greater ability to defend the airway against posture related changes, and a higher waking upper airway dilating muscle tone in women may provide a physiological basis for this. 11Magnetic resonance imaging (MRI) has become an established method for the in vivo quantification of fat tissue.12 13 Fat has a relatively short T1 relaxation time, so fatty tissue has a higher intensity than other soft tissues in T1 weighted spin echo MRI images. The availability of this technique has prompted a number of studies which have attempted to clarify the relationship between obesity and upper airway obstruction at a detailed anatomical level. Although there is a clear relationship between overall neck size and airway obstruction in men, 3 there is still controversy about the significance of the precise anatomical distribution of fat deposition in the neck. Ho...

3).Conclusions-Compliance is greater with nose mask CPAP than with face mask CPAP because the overall comfort is better and compensates for increased symptoms associated with mouth leakage. Improved face mask design is needed. (Thorax 1998;53:290-292) Keywords: continuous positive airway pressure; sleep apnoea/hypopnoea syndrome; face masks Continuous positive airway pressure (CPAP) therapy for sleep apnoea/hypopnoea syndrome (SAHS) is traditionally given via a nose mask. However, many patients with SAHS find this method of treatment unsatisfactory, often due to symptoms related to mouth air leakage. 1Patients who have had unsuccessful uvulopalatopharyngoplasties (U3P) for treatment of SAHS are particularly likely to experience increased mouth leakage on nasal CPAP which is associated with reduced nightly compliance. 2The CPAP pressure required is essentially the same for nose masks and face masks, 3 so face masks which cover both nose and mouth may be advantageous if they reduce the symptoms associated with mouth leakage.We have compared nose and face mask CPAP therapy with respect to side eVects from the mask and compliance in newly diagnosed patients with SAHS in a randomised double limb trial. We also compared nose and face mask CPAP in patients with unsuccessful uvulopalatopharyngoplasties for treatment of SAHS (SAHS/U3P patients). MethodsAll subjects gave informed consent to take part in the study. RANDOMISED TRIALTwenty consecutive newly diagnosed patients with SAHS (mean (SE) apnoea/hypopnoea index 34 (5.2)/hour, age 52 (3) years, body mass index 32 (1) kg/m 2 , CPAP pressure 9 (1) cm H 2 O) were enrolled into the study after their CPAP titration night. Initial CPAP titration was performed using a nose mask. Patients were randomised to face mask or nose mask CPAP for four weeks each. At the end of

Abstractpatients referred for investigation is rising rapidly. New referrals to the Edinburgh sleep clinic Background -A study was undertaken to test the hypothesis that unsupervised dom-increased 10-fold between 1990 and 1996.Most require some form of sleep study for iciliary limited sleep studies do not impair the accuracy of diagnosis when used to diagnosis, and this puts increasing strain on a service based on overnight studies in the investigate the sleep apnoea/hypopnoea syndrome (SAHS) and can be cheaper laboratory. We have therefore investigated the validity and practicality of performing limited than laboratory polysomnography. Methods -For validation, 23 subjects with sleep studies unsupervised in the patients' homes. suspected SAHS underwent laboratory polysomnography and a home study A number of portable sleep study systems have been validated by recording simul-(EdenTec 3711) on successive nights. All subjects with >15 apnoeas+hypopnoeas taneously with polysomnography in a sleep laboratory. 5-11 Portable systems have been used (A+H)/hour on polysomnography showed >30 A+H/hour on their home study. for epidemiological studies [12][13][14] and are increasingly used routinely for diagnosis or exThereafter, in a prospective trial 150 subjects had a home study as the initial clusion of SAHS by sleep services.15 16 However, sleep quality is not recorded in a limited home investigation and studies showing >30 events/hour were regarded as diagnostic study; subjects may sleep better at home than in a laboratory study 17 but, equally, patients of SAHS. Those showing fewer events were investigated with polysomnography if with severe SAHS may sleep very little. It is therefore important that the use of portable necessary. Time to treatment, outcome, and costs of this protocol were compared systems in the home is validated by comparing studies performed at home with polywith those of 75 patients investigated initially with polysomnography.somnography. Few of the groups using home studies have reported this; one group found Results -Of the prospective trial subjects, 29% had >30 A+H/hour and proceeded that the portable system underestimated the severity of SAHS. 18directly from home study to treatment; 15% without daytime sleepiness were not Our study had two aims. The first was to validate the use of limited sleep studies in investigated further. Polysomnography was undertaken to establish a diagnosis in the home, and to determine a criterion for a confident diagnosis of SAHS from a home 56% of cases, including 18% whose home studies were unsuccessful. Compared with study. The second was to test in a prospective trial whether home studies in clinical practice the 75 control patients, this protocol gave a diagnosis faster (median 18 (range 0-221) can maintain diagnostic accuracy and have benefits in time and cost without affecting outversus 47 (0-227) days, p<0.001) and more cheaply (mean (SD) £164 (104) versus £210 come when compared with an investigative protocol based on laboratory polysomno-(0), p<0.001). The ...