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The magnitude, determinants and reversibility of cognitive deficits associated with the sleep apnea/hypopnea syndrome (SAHS) are of clinical and research interest. A quantitative overview of impairment effect sizes (ESs) from case-control studies of cognitive performance in SAHS suggests that deficits broadly worsen with disease severity, with large average values for attentional (ES approximately 1.0 SD units) and executive (ES approximately 0.9 SD units) cognitive scores, and moderate values for memory-related (ES approximately 0.6 SD units) performance scores. A study of determinants of cognitive outcomes conducted in 150 patients with SAHS (AHI 5+ and > or =2 symptoms) showed significant but weak associations between a cognitive 'intellectual ability' component score (CS) and both AHI (r=-0.14) and minimum oxygen saturation (r = 0.15), linking increasing disease severity with poorer performance. A somewhat stronger correlation between a cognitive 'response slowing' CS and a 'wakefulness' CS was observed (r=-0.34). That sleepiness as well as hypoxemia might contribute to cognitive deficit has also been suggested by experimental sleep fragmentation in normals, producing small to moderate impairments (average ES approximately 0.3 SD units) in attention-biased scores. The reversibility of attentional cognitive deficits has been investigated through a meta-analysis of randomized placebo-controlled crossover studies of CPAP treatment, involving 98 SAHS patients (AHI 5+ and > or =2 symptoms). While cognitive outcomes showed at least trends towards better performance on CPAP than on placebo (p< or =0.1), the ESs of cognitive enhancements following CPAP were small (average ES approximately 0.2 SD units). This may be due either to the relatively mild study population, suboptimal CPAP use or to an irreversible component in cognitive impairment in SAHS.

Patients commencing continuous positive airway pressure therapy (CPAP) undergo overnight airway pressure titration in sleep centres to optimize breathing and sleep patterns. We tested the hypothesis that data from formal scoring of the sleep and breathing patterns observed at the best achievable pressure during titration can predict CPAP use and effectiveness, as our clinical experience suggested otherwise. The relationship between CPAP titration scores (apnoea/hypopnoea frequency, arousal frequency and sleep staging) and subsequent CPAP use was examined in 150 sleep apnoea/hypopnoea syndrome patients. One hundred patients were continuing CPAP therapy and 50 were randomly selected patients who had discontinued CPAP. Within the CPAP group, titration scores were compared with CPAP machine use, subjective daytime sleepiness and requirements for airway pressure adjustment. Respiratory irregularities and arousals during titration did not relate to outcome. Sleep-stage analysis revealed a weak relationship between more wakefulness during titration and CPAP discontinuation (P=0.02). There was a correlation between more prolonged Stage 4 sleep during titration and reduced sleepiness on established therapy (P=0.002), but this explained less than 12% of the variance. The absence of rapid eye movement sleep during titration was not associated with poorer outcomes. We conclude that routine scoring of breathing and sleep patterns observed during CPAP titration is of little clinical value, as the results do not predict outcome for individual patients. Satisfactory CPAP therapy may be established even if significant numbers of apnoeas/hypopnoeas or arousals are observed at the optimal pressure during titration.

Investigation and treatment of sleep apnoea/hypopnoea syndrome (SAHS) is placing increasing demands on healthcare resources. This workload may be reduced by using split-night studies instead of the standard full-nights of diagnostic polysomnography and continuous positive airway pressure (CPAP) titration. Split-night studies involve polysomnography in the first half of the night followed, if there is an abnormal frequency of apnoeas and hypopneas, by CPAP titration for the remainder of the night. The authors' database of all patients prescribed a CPAP trial 1991-1997 was used to compare long-term outcomes in all 49 (46 accepting CPAP) patients prescribed split-night studies with those in full-night patients, matched 1:2 using an apnoea/ hypopnoea index (AHI) of +/-15% and Epworth score of +/-3 units. Classical symptoms of SAHS were the main reason for the split-night studies (n=27). There were no differences between the groups in long-term CPAP use, median nightly CPAP use (split-night 6.0 h x night-1, interquartile range (IQR) 3.8-7.4, full-night; 6.2 h x night-1, IQR 3.7-7.0, p=0.9), post-treatment Epworth scores and frequency of nursing interventions/clinic visits required. The median time from referral to treatment was less for the split-night patients (13 months, IQR 11-20 months) than for full-night patients (22 months, IQR 12-34 months; p=0.003). Split-night studies, in selected patients, result in equivalent long-term continuous positive airway pressure use to full-night studies with shorter treatment times and less healthcare utilization.

Continuous positive airway pressure (CPAP) therapy improves daytime function in the sleep apnea/ hypopnea syndrome (SAHS) but it is unclear which patients benefit and what factors predict this improvement. To test the hypothesis that brief arousals from sleep predict improvements in daytime functioning with CPAP therapy, we prospectively studied 62 patients with polysomnography-defined SAHS. Each underwent daytime function assessments at baseline and after 6 mo of CPAP therapy to measure objective sleepiness, psychological well-being, quality of life, and cognitive performance. The microarousal frequency and AHI were poor predictors of improvements in daytime function with CPAP. Measures of hypoxemia predicted improvements in the mean sleep latency on the maintenance of wakefulness test, SAHS symptoms, quality of life, and reaction time, but such correlations were weak or moderate only explaining between 7% and 22% of variance. Significant relationships were found between CPAP use and improvements in self-ratings of daytime function. Results suggest that standard polysomnographic baseline variables are poor predictors of the response to CPAP therapy.

This paper reviews some of the recent advances in the sleep apnoea/hypopnoea syndrome. Sleep apnoea has recently been shown to be familial and in some of these patients this is due to retroposition of the maxilla and mandible. There is now good evidence that individuals with sleep apnoea have an increased risk of road accidents and increasing, although not yet 100% robust, evidence that they have an increased frequency of systemic hypertension. The last few years have seen a large number of randomised controlled trials of CPAP therapy which have shown clear evidence that CPAP improves symptoms, subjective sleepiness, objective sleepiness, cognitive function, IQ, mood, quality of life and driving ability. Evidence that CPAP influences cardiovascular and cerebrovascular outcomes is awaited.

Previously, we found that regular sleep fragmentation, similar to that found in patients with sleep apnoea/hypopnoea syndrome (SAHS), impairs daytime function. Apnoeas and hypopnoeas occur in groups in patients with REM or posture related SAHS. Thus, we hypothesised that clustered sleep fragmentation would have a similar impact on daytime function as regular sleep fragmentation. We studied 16 subjects over two pairs of 2 nights and 2 days. The first night of each pair was for acclimatisation. On the second night, subjects either had their sleep fragmented regularly every 90 s, or fragmented every 30 s for 30 min every 90 min, the remaining 60 min being undisturbed. We fragmented sleep with tones to produce a minimum 3 s increase in EEG frequency. During the days following each pair of nights we tested subjects daytime function. Total sleep time (TST) and microarousal frequency were similar no both study nights. We found significantly less stage 2 (55 SD 4, 62 +/- 7%; P = 0.001) and more slow wave sleep (21 SD 3, 12 +/- 6%; P < 0.001) on the clustered night. Mean sleep onset latency was similar on MSLT (clustered 10 SD 5, regular 9 +/- 4 min; P = 0.7) and MWT (clustered 32 SD 7, regular 30 +/- 7 min; P = 0.2). There was no difference in subjects mood or cognitive function after either study night. These results suggest that although there is more slow wave sleep (SWS) on the clustered night, similar numbers of sleep fragmenting events produced similar daytime function whether the events were evenly spaced or clustered.

Limb and respiratory muscle (diaphragm) strength and fatiguability have been extensively studied in man and are known to vary with age and sex. However, in contrast to limb muscles and the diaphragm, force and fatiguability characteristics have not been studied in upper airway muscles. This study examines the hypotheses that tongue protrusion strength or fatiguability, determined by the properties of the intrinsic muscles and genioglossus, may change with age and may be reduced in males compared to females. A force transducer was used to compare maximal tongue protrusion force (Fmax) and fatiguability in 81 males and 86 females matched for age (mean+/-SD, 43+/-19 yrs, 42+/-19 yrs, respectively). Fatiguability indices were based on the time that subjects could maintain 50% of Fmax. Fmax declined with age in both males (r=-0.57, p<0.001) and females (r=-0.56, p<0.001). Fmax in males was greater than in females (males 26+/-8 N; females 20+/-7 N; p<0.001). However, after correction of Fmax for sex differences in total body muscle (fat-free mass) there was no significant difference between males and females (p=0.3). There was also no difference in fatiguability between males and females (p=0.5). In conclusion, tongue protrusion strength is greater in males compared to females, and decreases with age. If these differences also apply to patients with sleep apnoea, the reduction in maximal tongue protrusion force with age could be of relevance to the observed increase in prevalence and severity of sleep apnoea-hypopnoea syndrome in middle age, but would not explain the gender difference in prevalence.

Patients with the sleep apnea/hypopnea syndrome (SAHS) treated by nasal continuous positive airway pressure (CPAP) need to use CPAP long-term to prevent recurrence of symptoms. It is thus important to clarify the level of long-term CPAP use and the factors influencing long-term use. We examined determinants of objective CPAP use in 1, 211 consecutive patients with SAHS who were prescribed a CPAP trial between 1986 and 1997. Prospective CPAP use data were available in 1, 155 (95.4%), with a median follow-up of 22 mo (interquartile range [IQR], 12 to 36 mo). Fifty-two (4.5%) patients refused CPAP treatment (these were more often female and current smokers); 1,103 patients took CPAP home, and during follow-up 20% stopped treatment, primarily because of a lack of benefit. Methods of survival analysis showed that 68% of patients continued treatment at 5 yr. Independent predictors of long-term CPAP use were snoring history, apnea/hypopnea index (AHI), and Epworth score; 86% of patients with Epworth > 10 and an AHI >/= 30 were still using CPAP at 3 yr. Average nightly CPAP use within the first 3 mo was strongly predictive of long-term use. We conclude that long-term CPAP use is related to disease severity and subjective sleepiness and can be predicted within 3 mo.

Continuous positive airway pressure (CPAP) therapy is widely prescribed for patients with the sleep apnea/hypopnea syndrome (SAHS), but the use of CPAP for such patients is disappointingly low. We postulated that providing intensive educational programs and nursing support to SAHS patients might improve CPAP use and outcomes. We also examined the hypothesis that CPAP use would be greater among patients who had initiated their own referral than among those asked to seek help by a partner. We randomized 80 consecutive, new patients with SAHS to receive either usual support or additional nursing input including CPAP education at home and involving their partners, a 3-night trial of CPAP in our institution's sleep center, and additional home visits once they had begun CPAP. The primary outcome variable was objective CPAP use; symptoms, mood, and cognitive function were also assessed after 6 mo. CPAP use over 6 mo was greater (p = 0.003) among patients receiving intensive than among those receiving standard support (5.4 +/- 0.3 versus 3.9 +/- 0. 4 h/night [mean +/- SEM]), with greater improvements (p < 0.05) in SAHS symptoms, mood, and reaction time in the intensively supported group. CPAP use was greater (p = 0.002) among patients who initiated their own referrals. CPAP use and outcomes of therapy can be improved by provision of a nurse-led intensive CPAP education and support program. CPAP use is lower among patients whose partners ask them to seek treatment.

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 differing 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 (3) years, women 37 (3) years, p = 0.7), body mass index (both 25 (0. 6) kg/m2, p>0.9), and Epworth Sleepiness Score (both 5 (1), p = 0.9) were assessed; all denied symptoms of SAHS., Results: Total neck soft tissue volume was greater in men (1295 (62) vs 928 (45) cm3, p<0. 001), but the volume of fat did not differ between the sexes (291 (29) vs 273 (18) cm3, p = 0.6). The only regions impinging on the pharynx which showed a larger absolute volume of fat in men (3.2 (0. 7) vs 1.1 (0.3) cm3, p = 0.01) and also a greater proportion of neck fat in men (1.3 (0.3)% vs 0.4 (0.1)%, p = 0.03) were the anterior segments inside the mandible at the palatal level., Conclusions: There are differences 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.

The minimal disease severity at which patients with the sleep apnea/hypopnea syndrome (SAHS) gain benefit from treatment is not well characterized, although a pilot study of continuous positive airway pressure (CPAP) therapy showed daytime improvements in patients with 5 to 15 apneas + hypopneas per hour slept (AHI). We have thus performed a second, larger, randomized, placebo- controlled study in a prospective series of 34 patients (13 female) with mild SAHS (AHI 5 to 15) and daytime sleepiness. Patients spent 4 wk on CPAP treatment and 4 wk on an oral placebo, with randomization of treatment order, and daytime assessments on the last day of each treatment. Effective CPAP use averaged 2.8 +/- 2.1 h (mean +/- SD) per night. Compared with placebo, CPAP improved symptom score (p < 0.01), subjective (Epworth; p < 0.01) but not objective (maintenance of wakefulness test; p > 0.2) sleepiness, performances on 2 of 7 cognitive tasks (p < 0.02), depression score (p < 0.01), and five subscales of the SF-36 health/functional status questionnaire (p

The potential importance of the obstructive sleep apnoea syndrome (OSA) has been recognized only in the last few years. Epidemiological studies suggest that symptomatic OSA occurs in 1-2% of middle-aged men and in approximately half that number of women. The relation of OSA to vascular disease is uncertain and the main indication for treatment is the relief of disabling sleepiness. Two recent evidence based analyses have produced diametrically opposed conclusions on the efficacy of treatment with nasal continuous positive airway pressure (CPAP). However, recent controlled studies confirm the overwhelming clinical experience of benefit. Facilities for the investigation and treatment of patients with OSA in the UK are subject to severe financial constraints and the availability of CPAP treatment lags markedly behind that in other countries for which data are available.

Background: Patients with the sleep apnoea/hypopnoea syndrome (SAHS) report improved sleepiness, cognitive function, and psychological well being after continuous positive airway pressure (CPAP) therapy, and it is for these daytime features that CPAP is usually given. However, few randomised or controlled studies exist on the effects of CPAP on daytime function., Methods: A prospective, randomised, single blind, placebo controlled, crossover trial of daytime function after CPAP was conducted in 23 patients with SAHS, all with > or = 15 apnoeas + hypopnoeas/hour and > or = 2 symptoms of SAHS. All patients spent four weeks on CPAP therapy and four weeks on oral placebo treatment, following randomisation to treatment order. With ethics committee approval, patients were told the placebo tablet might improve upper airway function. Average effective CPAP use was monitored using hidden time clocks. Assessments of objective and subjective sleepiness, symptoms, cognitive performance, and psychological well being were performed on the last day of each treatment and compared., Results: Objective sleepiness measured by sleep onset latency on the multiple sleep latency test improved with CPAP (mean difference from placebo +2.4 min, 95% CI 0.8 to 4.0; p < 0.001) as did subjective sleepiness on the Epworth scale (mean difference -6, 95% CI -3 to -9; p = 0.001). Symptom total score also fell with CPAP (mean difference -1.6, 95% CI -2.2 to -1.0; p < 0.001). No determinants of these changes with active treatment were identified, and no significant enhancements to cognitive function or psychosocial well being were found in this small sample., Conclusions: These findings provide further evidence for clinically significant benefits to daytime function from CPAP.

Background: Many patients with sleep apnoea/hypopnoea syndrome (SAHS) find nasal continuous positive airway pressure (CPAP) treatment unsatisfactory due to side effects related to mouth air leakage. A study was performed to compare side effects with face mask and nose mask CPAP therapy in patients with SAHS, with and without uvulopalatopharyngoplasty (U3P)., Methods: Twenty newly diagnosed patients with SAHS took part in a randomised double limb trial of face or nose mask CPAP therapy (four weeks per limb) in which CPAP compliance in terms of machine run time was measured and patients answered a symptom questionnaire on side effects resulting from the mask. Ten patients with SAHS with U3P (SAHS/U3P) who were already regular users of nasal CPAP were also given a four week trial of face mask CPAP to compare compliance and symptoms. Ten patients with SAHS were matched with the 10 SAHS/U3P patients for body mass index, age, apnoea/hypopnoea index, and CPAP pressure. Long term compliance was estimated one year after the mask comparison studies., Results: For patients with SAHS nightly compliance was higher with a nose mask (mean (SE) 5.3 (0.4) hours/night CPAP) than with a face mask (4.3 (0.5) hours/night CPAP), p = 0.01 (mean difference 1.0 hour/night, 95% CI 1.8 to 0.3). Nose masks were rated more comfortable by 19 of 20 patients (p < 0.001) despite more mouth leak related symptoms. For SAHS/U3P patients compliance was marginally higher with nose masks (5.1 (0.7) hours/night CPAP) than with face masks (4.0 (0.8) hours/night CPAP), p = 0.07 (mean difference 1.1 hour/night, 95% CI 2.1 to 0.1). Nose masks were rated more comfortable by seven of 10 patients. There were no significant differences in side effect scores with face and nose masks. At one year nine of 10 SAHS patients and nine of 10 SAHS/U3P patients were still using CPAP. Compliance was 5.4 (0.6) hours/night for the SAHS patients and 3.5 (0.4) hours/night for the SAHS/U3P patients, p = 0.02 (mean difference 1.9 hour/night, 95% CI 3.6 to 0.3)., 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.

Patients with chronic obstructive pulmonary disease (COPD) become hypoxemic during sleep, particularly during rapid eye movement (REM) sleep. Those who are most hypoxemic when awake experience the most severe hypoxemia during sleep. The major cause of REM hypoxemia is hypoventilation, with additional contributions from alteration in ventilation/perfusion matching and functional residual capacity (FRC) reduction. REM hypoxemia probably contributes to the development of pulmonary hypertension and polycythemia and may predispose to cardiac arrhythmias in some patients. The most effective form of therapy is nocturnal oxygen therapy, but the indications for the use of nocturnal oxygen therapy are entirely based on daytime oxygenation levels. Routine polysomnography is not indicated in patients with COPD but should be performed in patients who have symptoms suggestive of coexisting sleep apnea/ hypopnea syndrome.

Alterations in non-adrenergic, non-cholinergic (NANC) function may contribute to nocturnal asthma. We have attempted to clarify the importance of the NANC system in the circadian variation in airway calibre in mild asthmatics and nocturnal asthmatics. NANC function in the human airway was studied at 0400 and 1600 hours in 12 nocturnal asthmatics and 12 mild asthmatics by measuring oscillatory resistance (Ros) following capsaicin inhalation. Measurements were made after combined beta- and atropinic blockade in the mild asthmatics but after atropinic blockade alone in the nocturnal asthmatics, in whom beta-blockade is contraindicated. To determine whether beta-blockade influences NANC bronchodilatation, we also studied 12 normal subjects with and without beta-blockade at 1600 hours only. The mild asthmatics showed differing (P = 0.007) resistance changes 1-3 min after capsaicin at 1600 hours (fall in Ros + 1%, CI -2% to 3%) from that at 0400 hours (-4%, CI -8% to -1%) but the nocturnal asthmatics showed no significant difference in response to capsaicin at the two times (fall in Ros: 1600 hours -9%, CI -15% to -3%; 0400 hours -3%, -7% to 1%). The normal subjects showed greater (P = 0.0001) bronchodilatation 1-3 min after capsaicin following atropine plus propranolol (-7%, -11% to -3%) than after atropine alone (-2%, -6% to 2%), supporting interaction between the beta-sympathetic and NANC systems in the human airway, NANC bronchodilatation being inhibited by beta-sympathetic activity. Our observations confirm circadian variation in NANC function in mild asthmatics and suggest interaction between the beta-adrenergic and the NANC bronchodilating system in the normal human airway.

Although referrals for narcolepsy are increasing, physicians continue to confront obstacles in diagnosing and treating this condition. Patients with narcolepsy also face challenges at work, at school, and at home. One of the more disturbing problems is the lack of public awareness of the disorder and its potential therapy. As a result, patients with narcolepsy are often viewed in the school or work setting as being "lazy." In addition, the psychological and sexual side effects of the medications currently available to treat narcolepsy can lead to marital, family, and work-related problems. Irritability, anxiety, and impotence are common. Of particular concern are the risk for a serious automobile accident when the person with narcolepsy remains untreated and the reluctance of narcoleptic patients to seek treatment for fear of losing their driver's license. This article addresses the health system factors that influence the identification and care of patients with narcolepsy and focuses on the psychosocial impact of the disease.

Around 50% of patients with the sleep apnea/hypopnea syndrome (SAHS) are not obese: body mass index (BMI) < 30 kg/m2. We hypothesized that local fat deposition around the upper airway may be different in nonobese patients with SAHS from that in normal subjects with the same body mass. We therefore examined the relationship between indices of general obesity; BMI, neck circumference (NC), and percentage total body fat with neck fat deposition measured by magnetic resonance imaging in three matched subject groups. Nine nonobese, nonsnoring control subjects (BMI, 25 SE 0.7 kg/m2; NC, 38.1 SE 0.5 cm; age, 37.5 SE 2.5 yr), nine nonobese patients with SAHS (BMI, 25.7 SE 0.4 kg/m2; NC, 39.8 SE 0.8 cm; age, 40 SE 4.2 yr), and nine obese patients with SAHS matched to the other groups for age (BMI, 34 SE 1.1 kg/m2; NC, 43.9 SE 0.6 cm; age, 40 SE 2.7 yr). Neck volume and fat content were assessed from the hard palate to the vocal cords using T1-weighted images. Percentage total body fat was 30 and 44% greater in nonobese and obese patients with SAHS, respectively, than in control subjects. Neck tissue volume was 10% greater in nonobese and 28% greater in obese patients with SAHS than in control subjects. The percentage of neck tissue volume attributed to fat was 27% greater in nonobese and 67% greater in obese patients with SAHS than in control subjects. The excess fat in both the nonobese and obese patients with SAHS compared with that in control subjects was localized to areas anterolateral to the upper airway, the differences were 52 and 88%, respectively. There were no significant differences between nonobese patients with SAHS and control subjects with respect to fat located in other areas of the neck; obese patients with SAHS had 42% more fat than control subjects (p < 0.05). We conclude that even relatively nonobese patients with SAHS have excess fat deposition, especially anterolateral to the upper airway when compared with control subjects with the same level of obesity assessed using BMI and NC. This may contribute to their predisposition to SAHS.

Under reporting of symptoms by patients with sleep apnoea/hypopnoea syndrome (SAHS) has been reported anecdotally, but investigation of the prevalence or determinants of this is limited. To assess this, repeated ratings in 99 patients with sleep apnoea/hypopnoea syndrome of pre-treatment Epworth sleepiness score, unintended napping, driving impairment and mood were obtained, first at presentation and then after treatment with continuous positive airway pressure (CPAP) therapy of median 22 (range 2-70) weeks duration. Median Epworth score for pre-treatment sleepiness rose from 12 (range 0-24) initially to 14 (range 5-24) retrospectively (P<0.0001). More patients initially under-rated Epworth score (67%) than over-rated (29%; P<0.001). 'False negative' cases with an initially 'normal' (< or = 10) and retrospectively 'sleepy' (> or = 11) Epworth score comprised 24% of all patients and 62% of initially 'normal' scorers. Unintended napping behaviour also was rated as significantly more severe on retrospective assessment (P<0.001). Driving impairment due to sleepiness was initially reported by 23% of all drivers and retrospectively by 37% (P=0.01), with 25% of initial deniers retrospectively admitting compromised driving ability before continuous positive airway pressure. No polysomnographic predictors of symptom under reporting were found (P>0.1). These results suggest a high prevalence of symptom minimization before treatment in patients with sleep apnoea/hypopnoea syndrome.

Surgical therapy of the sleep apnoea/hypopnoea syndrome is an attractive option to many patients as it avoids using therapy nightly for the remainder of one's life. This article reviews the outcomes of the surgical options available. The role of uvulopalatopharyngoplasty is not yet clear. It may be useful second line therapy for some patients but cannot at present be advocated as first-line therapy. Mandibular maxillary osteotomy and advancement is an effective therapy of value in a minority of patients. Other procedures such as partial glossectomy and genioglossal advancement may also be of value in some patients. There is an urgent need for more randomized controlled trials examining the outcomes of surgical therapy for the sleep apnoea/hypopnoea syndrome in comparison to continuous positive airway pressure therapy.

Upper airway obstructions during sleep cause recurrent brief awakenings or microarousals. Standard criteria exist for sleep and respiratory event scoring, however, there are different definitions currently used to score microarousals. We therefore compared three definitions of microarousal (ranging from 1.5-3 s in duration) and one of awakening (>15 s). We examined their occurrence at the termination of apnoeas and hypopnoeas and their correlation with daytime sleepiness in patients with sleep apnoea/hypopnoea syndrome (SAHS). Sixty-three patients (aged 49, SD 10) had overnight polysomnography, multiple sleep latency tests (MSLT) and Epworth Sleepiness Scales (ESS). There were significantly more microarousals by any definition than there were awakenings (P<0.001) and there were more 1.5 s than 3 s microarousals (P<0.001). Significantly more apnoeas and hypopnoeas were terminated by 1.5 s microarousals (83% and 81%) than by 3 s microarousals (75%) (all P<0.001). Apnoea/ hypopnoea index (AHI) correlated significantly with objective daytime sleepiness (rho=-0.30, P<0.01). There were weakly significant relationships between all three microarousal definitions (-0.24

Background: A study was undertaken to test the hypothesis that unsupervised domiciliary limited sleep studies do not impair the accuracy of diagnosis when used to investigate the sleep apnoea/hypopnoea syndrome (SAHS) and can be cheaper than laboratory polysomnography., Methods: For validation, 23 subjects with suspected SAHS underwent laboratory polysomnography and a home study (EdenTec 3711) on successive nights. All subjects with > 15 apnoeas + hypopnoeas (A + H)/hour on polysomnography showed > 30 A + H/hour on their home study. Thereafter, in a prospective trial 150 subjects had a home study as the initial investigation and studies showing > 30 events/hour were regarded as diagnostic of SAHS. Those showing fewer events were investigated with polysomnography if necessary. Time to treatment, outcome, and costs of this protocol were compared with those of 75 patients investigated initially with polysomnography., Results: Of the prospective trial subjects, 29% had > 30 A + H/hour and proceeded directly from home study to treatment; 15% without daytime sleepiness were not investigated further. Polysomnography was undertaken to establish a diagnosis in 56% of cases, including 18% whose home studies were unsuccessful. Compared with the 75 control patients, this protocol gave a diagnosis faster (median 18 (range 0-221) versus 47 (0-227) days, p < 0.001) and more cheaply (mean (SD) 164 pounds (104) versus 210 pounds (0), p < 0.001). The proportions offered CPAP (61% versus 67%) and subsequent objective CPAP usage (mean 4.7 (2.4) versus 5.0 (2.4) hours/night) were not different., Conclusions: Use of home sleep studies has benefits in time and cost. For diagnostic reliability a further sleep study was required in 56% of cases.

The sleep apnea/hypopnea syndrome (SAHS) affects 1-4% of the middle-aged population and is caused by repeated occlusion of the upper airway mainly at the retropalatal level. It is unclear why SAHS patients obstruct their upper airways during sleep while others do not. We hypothesized that upper airway dilator muscle function may be impaired in SAHS patients and that chronic CPAP therapy may enhance upper airway function. We, therefore, examined the effects of upper airway negative pressure on reflex palatal muscle activity in 16 normal nonsnoring awake male subjects and 16 awake SAHS patients using electromyography. The application of negative upper airway pressure (0 to -12.5 cm H2O) caused increases in levator palatini (LP, p < 0.001) and palatoglossus (PG, p < 0.001) activity, 100 msec after pressure stimulus in normal subjects. Application of upper airway negative pressure in SAHS patients caused an increase in LP activity (p < 0.05) but not in PG activity. Reflex electromyographic response to negative pressure was reduced in SAHS patients compared to normal subjects for both muscles (p < 0.001). When the seven thinnest SAHS patients were compared with seven normal subjects matched for BMI and age, the SAHS patients still demonstrated impaired responses to negative pressure for both muscles (p < 0.001). A further eight SAHS patients were studied either while concurrently taking nightly CPAP therapy and also off CPAP (at least 3 nights). Chronic nightly CPAP therapy improved the reflex response of both LP (p < 0.001) and PG (p = 0.003) to nasal negative pressure application. Thus, untreated SAHS patients have impaired electromyographic responses to negative upper airway pressure suggesting impaired defence of the upper airway, which is improved by nightly CPAP therapy.

Patients with sleep apnea/hypopnea syndrome (SAHS) suffer from impaired daytime function that correlates with hypoxemia and visible electroencephalographic (EEG) arousals. However, not all breathing irregularities during sleep terminate with visible EEG arousal. We hypothesized that sleep disturbance without visible EEG change may impair daytime function. Twelve normal subjects spent two pairs of 2 nights each in the laboratory. The first night of each pair was for acclimatization. On the second night, subjects either slept undisturbed or had sleep fragmented every minute to cause a transient increase in arterial blood pressure or increase in heart rate without visible EEG arousal. We tested daytime function after each study night. We presented 253 +/- 23 tones (mean +/- SD), 79 +/- 7% of which did not cause visible EEG arousals. Fragmentation did not alter total sleep time (undisturbed: 419 +/- 27 min; fragmented: 414 +/- 32 min; p = 0.5) or arousal frequency (undisturbed: 22 +/- 4/h; fragmented: 25 +/- 6/h; p = 0.4). Fragmentation reduced slow-wave sleep (undisturbed: 24 +/- 5%; fragmented: 20 +/- 4%; p < 0.01), mean sleep onset latency on the multiple sleep latency test (MSLT) (undisturbed: 8.0 +/- 3.1; fragmented: 6.2 +/- 2.1 min; p = 0.01) and the maintenance of wakefulness test (MWT) (undisturbed: 29.0 +/- 10.0 min; fragmented 25.7 +/- 9.7 min; p = 0.04). Fragmentation decreased hedonic tone at 7 A.M. (27 +/- 4, 25 +/- 6; p = 0.03). Nonvisible (autonomic) sleep fragmentation makes normal subjects sleepier and impairs their mood.

Background: Continuous positive airway pressure (CPAP) is an effective treatment in patients with moderate and severe sleep apnoea/hypopnoea syndrome (SAHS), but the minimum illness severity at which patients obtain benefit from CPAP is unclear. A study was therefore undertaken to investigate whether CPAP improves symptoms and daytime function in patients with mild SAHS., Methods: Sixteen consecutively recruited patients with mild SAHS (5.0-14.9 apnoeas + hypopnoeas per hour slept and two or more symptoms of SAHS) participated in a prospective placebo controlled randomised crossover trial to assess the effects of CPAP on symptoms and daytime function. Patients spent four weeks on placebo and four weeks on CPAP, undergoing assessments of sleepiness, symptoms, cognitive performance, and well being on the last day of each treatment. Data from the placebo and CPAP assessments were compared., Results: The mean (SE) objective effective use of CPAP was 2.8 (0.7) hours per night. Significant improvements in symptom score (-1.7 (0.5), p < 0.01), mental flexibility (-14 (5) seconds, p = 0.02), and depression rating (-1.6 (0.8), p = 0.03) on CPAP were observed. However, no significant differences in subjective or objective sleepiness were found. Ten of the 16 patients preferred CPAP and opted to continue with this treatment, although this proportion was non-significant (p > 0.4). The eight patients with best CPAP use showed an additional CPAP related improvement in quality of life (-4.4 (1.8), p = 0.03). Those who complied better with CPAP therapy also had a higher average microarousal frequency (p < 0.01) and apnoea+hypopnoea index (p = 0.02) than the poorer compliers., Conclusions: The results of this study provide evidence for improvements in symptoms and daytime function for patients with mild SAHS treated with CPAP.

Nocturnal cough and wheeze are common in asthma and often treated with beta2 agonists or theophyllines. As nocturnal asthma and these therapies may affect sleep and cognition, we compared 50 microg salmeterol inhaled every 12 h with individually dose-titrated sustained-release oral theophylline on sleep quality and cognitive performance in 15 patients with stable nocturnal asthma (overnight peak expiratory flow rate [PEFR] fall > or = 15%, > or = 1 asthmatic awakening/week) using a double-blind, double-dummy, crossover design with 14-d therapy limbs. Cognitive testing and polysomnography were performed on Nights 13 and 14. Trough plasma theophylline concentration after Night 14 on theophylline was median 11.1 (interquartile range 8.3, 15.2) microg/ml. Overnight PEFR falls were similar [salmeterol 2.3 (0, 10.6), theophylline 3.5 (-0.3, 9.6)%, p = 0.4] but on salmeterol there were more nights without awakenings [median difference 1 (0, 2), p < 0.01], fewer nocturnal arousals [difference -3 (-7, 2) h(-1), p < 0.05] and improved quality of life (p = 0.05). Sleep architecture did not otherwise differ. Visual vigilance improved on salmetrol (p < 0.05), but otherwise daytime cognition was unaffected. There was no patient preference for either therapy. Hence in patients with nocturnal asthma, we demonstrate no major clinical advantage, but a small benefit in sleep quality, quality of life, and daytime cognitive function with salmeterol.

Uvulopalatopharyngoplasty (U3P) has been advocated for treatment of snoring and sleep apnea/hypopnea syndrome (SAHS), but often it does not effect a cure, so that other therapy (CPAP) is often required. We hypothesized that patients with U3P will have increased mouth air leak during CPAP because of loss of the soft palatal seal. This may result in decreased tolerance and compliance if CPAP therapy is required after U3P. We have therefore compared CPAP tolerance in 13 awake normal male subjects, 13 male patients with SAHS and 13 male patients treated with U3P, all naive to CPAP and matched for age and body mass index. All normal subjects and patients with SAHS were able to tolerate pressures of at least 20 cm H2O without mouth air leak or appreciable discomfort. In contrast male U3P patients started to leak air via the mouth at a mean CPAP pressure of 6.8 (SD, 2.4) cm H2O and were able to tolerate a mean maximal pressure of only 14.5 (SD, 2.6) cm H2O, which was significantly less than that in the other two groups (p < 0.001). We also examined nasal CPAP compliance (machine run time) in eight patients with SAHS who had previous U3P compared with 16 patients with SAHS without U3P. Both groups were matched for age, body mass index, and apnea/hypopnea index. Patients with U3P had significantly lower compliance (mean, 3.5 h/night) compared with patients without U3P (mean, 5.7 h/night), p = 0.01. We conclude that U3P may compromise nasal CPAP therapy by increasing mouth air leak and reducing the maximal level of pressure that can be tolerated.

As daytime deficits in sleep apnea/hypopnea syndrome (SAHS) correlate poorly with earlier definitions of arousals, we investigated the relationship between microarousals and sleepiness in 63 patients with SAHS. There was a poor correlation between mean sleep latency and microarousal frequency. To determine whether arousals not detected by current definitions could account for some of the residual variance in normal subjects we used sound to induce "arousals" that were detected by rises in blood pressure but produced no visible EEG change. Such autonomic arousals produced an increase in sleepiness. We conclude that arousals not scored currently on polysomnography may contribute to the sleepiness of patients with SAHS.

Ambulatory blood pressure (BP) monitoring was performed in 13 patients with the sleep apnea/ hypopnea syndrome (SAHS) during a randomized, placebo controlled crossover trial of the effects of continuous positive airway pressure (CPAP) therapy. BP was monitored at half-hourly intervals for a 24-hour period both on CPAP and on an oral placebo, each given for a minimum of 3 weeks. Objective effective CPAP use averaged 4.3 hours per night. Weight and anti-hypertensive medications remained stable over the study period. Systolic, diastolic and mean arterial BP for 24-hour, daytime and nighttime periods were not significantly different on placebo compared to CPAP. Those patients with no significant overnight fall in BP on placebo ("non-dippers") showed a significant improvement in daytime mean arterial BP on CPAP (98 +/- 4 mm Hg) compared to placebo (102 +/- 4 mm Hg; p = 0.01). These findings, in a well-controlled trial, suggest that BP is not reduced by CPAP in a heterogeneous group of SAHS patients, but it may be selectively improved in those patients most at risk for cardiovascular morbidity and mortality.

The benefits of continuous positive airway pressure (CPAP) therapy in patients with the sleep apnea/hypopnea syndrome (SAHS) are poorly documented and patients use CPAP less than physicians recommend. To establish patients' perceptions of benefit from CPAP and to identify determinants of CPAP use, 204 CPAP users completed a questionnaire relating to use of CPAP therapy, sleepiness, and road traffic incident rate before and after CPAP, perceived change in daytime function and nocturnal symptoms with treatment, and problems with CPAP. Variables from these domains of interest were examined, reduced through principal components analysis and correlated to assess associations between these and polysomnographic measures of illness severity. Self-reported CPAP use averaged 5.8 +/- SD 2 h a night. Subjective sleepiness rated by the Epworth sleepiness scale and road traffic incident rate were significantly reduced by CPAP (p<0.0001). A broad range of function and symptom items were highly significantly improved with CPAP (p<0.0001), corroborating the cost to community and industry from SAHS and the preventive value of CPAP. Road traffic incident rate before treatment was correlated with pre-CPAP sleepiness and SAHS severity. Subjective CPAP use correlated with sleepiness before treatment but not with SAHS severity. CPAP mask problems and side effects were not associated with reduced CPAP use, but "nuisance" complaints of awakenings, noise, and sore eyes from CPAP correlated negatively with reported use. Greater reported CPAP use was associated with better resolution of sleepiness and greater improvement in daytime function and nocturnal symptoms.

We have sequenced DNA equivalent to the E5R ORF of Copenhagen vaccinia virus from an additional strain of vaccinia and from cowpox (three strains), camelpox (two strains), taterapox and ectromelia viruses. None of these showed the disruptions previously reported in the equivalent region of monkeypox virus. We also constructed a viable recombinant of vaccinia virus strain Dairen in which the E5R sequence was disrupted by a 436 bp deletion and substitution of the E. coli gpt gene. Quantitative analysis of the sequences, including available sequences from monkeypox, variola and vaccinia viruses revealed four main groupings, namely cowpox, ectromelia, monkeypox and a cluster which includes variola, camelpox, taterapox and vaccinia viruses. It was noted that, at over 75 % of the positions which differentiated species. all species but one had a common nucleotide. Although the analysis covers one single gene only, the results accord with what is known of the biology of the viruses.

Patients with the sleep apnea/hypopnea syndrome suffer from impaired daytime function. This has been attributed to both sleep fragmentation and hypoxemia. To help understand which is casual, we studied the effects of sleep fragmentation alone on daytime function. Sixteen normal subjects were studied on two pairs of two nights. The first night of each pair was for acclimatization, and on the second the subject either slept undisturbed or had sleep fragmented with sound pulses every 2 min. Sound volume and duration was titrated to cause a return to theta or alpha rhythm on the EEG for at least 3 s. Study nights were followed by daytime testing of psychometric function and mood and by a multiple sleep latency test (MSLT) and a maintenance of wakefulness test (MWT). Total sleep time did not differ between study nights (400 +/- 20 SD min undisturbed, 396 +/- 24 min fragmented; p = 0.6). Fragmentation decreased sleep latency on both the MSLT (11 +/- 3, 7 +/- 2 min; p = 0.001) and the MWT (34 +/- 8, 24 +/- 10 min; p<0.001). Energetic arousal (22 +/- 4, 19 +/- 4; p = 0.005) and hedonic tone (29 +/- 4, 27 +/- 4; p = 0.05) decreased after fragmentation. Fragmentation impaired daytime function adjudged by the Trailmaking B (p = 0.05) and PASAT 4-s tests (p<0.03). One night of sleep fragmentation makes normal subjects sleepier during the day, impairs their subjective assessment of mood, and decreases mental flexibility and sustained attention.

Background: There is evidence to suggest that chronic continuous positive airway pressure (CPAP) therapy may produce reversible changes in upper airway morphology and function in patients with sleep apnoea/hypopnoea. This study was designed to examine the effect of chronic CPAP therapy on upper airway calibre., Methods: Twenty four men with the sleep apnoea/hypopnoea syndrome (mean (SE) apnoea/hypopnoea index 37 (5)) underwent lateral cephalometry with measurement of posterior airway space performed before and at least three months after initiation of CPAP therapy., Results: There was no weight change between the two assessments and mean CPAP use was 4.8 (0.4) hours per night. Posterior airway space (PAS) was measured in erect and supine postures. PAS supine increased with CPAP therapy from a mean (SE) of 11.8 (0.8) mm to 13.4 (0.8) mm, but PAS erect did not. Correlation of the change in PAS (dPAS) before and after CPAP therapy showed an increase with increasing CPAP compliance measured as machine run time both for dPAS supine (r = 0.68) and dPAS erect (r = 0.47)., Conclusions: Patients with the sleep apnoea/hypopnoea syndrome regularly using CPAP for more than four hours per night all showed an increase in dPAS supine. The use of chronic CPAP increases PAS supine probably by a reduction in upper airway oedema, and the change in size is dependent on CPAP use.

Background: Increasing referral numbers make the development of simplified accurate methods of diagnosing the sleep apnoea/hypopnoea syndrome highly desirable. The accuracy of one such system--the ResCare Autoset--has been examined., Methods: Thirty one consecutive patients assessed by polysomnography had simultaneous monitoring of their respiratory pattern using the Autoset system. The Autoset detects episodes of flattening of the flow/time profile using nasal cannulae., Results: There was a good correlation (r = 0.85) between the number of apnoeas+hypopnoeas/hour in bed recorded using polysomnography and the Autoset system. The median difference in such events was 3.1 (95% confidence interval 8.4 to -1.6)/hour in bed. In two patients the Autoset scored 70 apnoeas+hypopnoeas/hour in bed compared with 34 apnoeas+hypopnoeas with 35 arousals/hour in bed by polysomnography; however, this did not alter the diagnostic category of either patient. Autoset gave a sensitivity of 100%, specificity of 92%, positive predictive value of 92%, and negative predictive value of 100%, which was better than oximetry alone. A sleep study using the Autoset system costs 14 pounds compared with 126 pounds for polysomnography., Conclusions: The Autoset is clinically useful for diagnosing the sleep apnoea/hypopnoea syndrome.

1. Patency of the upper airway is critical to respiration. Although about half of patients with the sleep apnoea/hypopnoea syndrome obstruct their upper airway at the retropalatal level, the respiratory actions of the palatal muscles have been little studied. We have therefore tested the hypothesis that the nasopharyngeal dilator muscle palatoglossus is activated during inspiration and by negative pressure. 2. Using intramuscular wire electrodes inserted perorally, we have compared the response of palatoglossus and genioglossus to breathing, posture change and airway negative pressure in 10 normal awake subjects before and after topical anaesthesia. The results are expressed as a percentage of maximal electromyogram. Data were analysed by repeated-measures analysis of variance. 3. Inspiratory activity was exhibited by both genioglossus [inspiratory, 10% +/- 2% (SEM); expiratory, 6% +/- 1%, P = 0.001] and palatoglossus (inspiratory, 16% +/- 5%, expiratory, 10% +/- 3%, P = 0.016), but only genioglossus exhibited increased activity on lying (supine 10% +/- 2%, erect 6% +/- 1% maximum, P = 0.01). 4. One hundred milliseconds after negative pressure application, activity increased in both genioglossus (7% +/- 2% and 13% +/- 3% respectively, P = 0.02) and palatoglossus (8% +/- 2% and 23% +/- 6% respectively, P < 0.001). After lignocaine surface anaesthesia to the nose and pharynx both genioglossus and palatoglossus still increased their activity in response to negative upper airway pressure, the extent of the increase being decreased for palatoglossus (P = 0.02) but not for genioglossus. 5. Thus, palatoglossus has respiratory activity and is activated by negative upper airway pressure.

After surgery, patients may receive little audiovisual stimulation and may sleep. Lack of audiovisual stimulation enhances the suppression of the hypoxic ventilatory response (HVR) by 0.1 minimum alveolar anesthetic concentration (MAC) isoflurane. Sleep also reduces the HVR and may thus increase the risk of hypoxia in patients at this time. We therefore measured the ventilatory response in volunteers to a sustained step hypoxic stimulus (mean arterial oxygen saturation [SaO2] 80% [SEM 0.3] for 20 min) in the presence of 0.1 MAC isoflurane, with subjects in the awake and asleep states. The behavioral states were studied in random order in nine male subjects. The combination of isoflurane and sleep significantly reduced (P < 0.05) normoxic ventilation (6.71 [0.39] vs 8.24 [0.29] L/min) and increased end-tidal PCO2 (PETCO2) (43.1 [0.5] vs 40.4 [0.8] mm Hg) compared with the awake state. However, ventilation was similar in the asleep and awake states during early (15.10 [1.35] vs 15.50 [1.61] L/min) and late (10.45 [0.97] vs 11.03 [0.99] L/min) hypoxia in the presence of isoflurane. Thus sleep did not reduce ventilation during hypoxia in the presence of isoflurane sedation. The increase in PETCO2 during sleep may have offset suppression of the HVR.

Background: Patients with the sleep apnoea/hypopnoea syndrome (SAHS) and their spouses often differ in their assessment of the patient's sleepiness. A study was therefore undertaken to investigate whether either the patient's or partner's rating on the Epworth sleepiness scale (ESS) was better related to illness severity., Methods: Nocturnal variables (apnoeas+hypopnoeas/hour (AHI) and arousals/hour) and patient and partner ESS scores were compared in 103 new patients attending the sleep clinic., Results: Mean patient and partner ESS scores were not different. In the whole population neither patient nor partner ESS variables correlated with AHI or arousal frequency. In the patients with SAHS (AHI > or = 15), partner ESS correlated weakly with AHI, but patient ESS did not., Conclusions: This study suggests that neither patient nor partner ESS ratings are strong predictors of SAHS severity.

Sleep apnea is worse in the supine posture and is associated with retropalatal airway narrowing or occlusion. We have, therefore, examined the effects of posture, negative pressure, and route of respiration on palatal muscle activity in 13 nonsnoring awake male subjects by using electromyography. Electromyographic activity of the levator palatini and palatoglossus was expressed as a percentage of maximum activity. Both the levator palatini (P = 0.002) and palatoglossus (P = 0.002) exhibited phasic inspiratory activity. Overall, posture did not affect the levator palatini (F = 1.58; P = 0.23) or palatoglossus (F = 0.98; P = 0.34) activity, but analysis by route of respiration showed the palatoglossus to be more active when the subjects were nose breathing supine (F = 6.64; P = 0.02). Levator palatini activity was lower when nose breathing was compared with mouth breathing in both the erect and supine postures (F = 6.67; P < 0.02). Nose breathing with the mouth held open caused an increase in palatoglossal activity (P = 0.04). Negative-pressure application (0 to -12.5 cmH2O) caused significant increases in levator palatini (P < 0.001) and palatoglossus (P < 0.001) activity, 100 ms after pressure stimulus, irrespective of route. However, the palatoglossus required significantly greater negative pressures to cause activation when applied via the nose compared with the mouth (P < 0.05). These observations indicate that the levator palatini and palatglossus have respiratory activity and are reflexly activated by negative pressure.

Snoring and sleep apnea are more common in the supine than seated position. We therefore studied the effect of posture on upper-airway caliber in normal subjects, snorers, and subjects with the sleep-apnea/hypopnea syndrome (SAHS). We measured upper-airway cross-sectional area by acoustic reflection in 110 SAHS patients (apnea/hypopnea index [AHI] > 15), 70 snorers without SAHS (AHI < 15), and 40 male controls matched for body-mass index (BMI) to the 40 SAHS patients. SAHS patients in the seated position had smaller upper-airway areas at the orophyngeal junction (OPJ) than either the snorers (p < 0.01) or the normal subjects (p < 0.02), but there were no differences between groups in airway cross-sectional areas in the supine or lateral recumbent positions. SAHS patients had significantly smaller decreases in OPJ area from the seated to either the supine (p < 0.001) or lateral recumbent (p < 0.001) positions than did the snorers. SAHS patients also had smaller (p < 0.05) decreases in OPJ area upon lying down than did the BMI-matched normal subjects. These data are compatible with SAHS patients defending their upper airway more upon lying down than do snorers or normal subjects.

Brief arousals are clinically important and increasingly scored during polysomnography. However, the frequency of arousals during routine polysomnography in the normal population is unknown. We performed overnight polysomnography in the 55 of 59 control subjects from a family practice list who were approached and agreed to undergo polysomnography. Awakenings were scored according to the criteria of Rechtschaffen and Kales and briefer arousals according to three different criteria, including the American Sleep Disorders Association (ASDA) definition. There was a mean of 4 [95% confidence interval (CI), 1-15) Rechtschaffen and Kales awakenings per hour, whereas the ASDA definition gave 21 (95% CI, 7-56) per hour slept. Arousal frequencies increased significantly (p < 0.001) with age in our subjects, who ranged from the late teens to early 70s. The high upper limit of the frequency of brief arousals was not altered by exclusion of patients who snored or had witnessed apneas or daytime sleepiness. It is important that those scoring arousals on routine polysomnography recognize that high arousal frequencies occur in the normal population on 1-night polysomnography.

Objective: To determine whether familial factors affect development of the sleep apnea-hypopnea syndrome and upper airway caliber., Design: A case-control study., Setting: Tertiary, referral clinical sleep laboratory., Participants: 51 first-degree relatives of patients with the sleep apnea-hypopnea syndrome and 51 controls matched for age, sex, height, and weight who were drawn at random from a family practice register. To avoid studying the familial nature of obesity, only relatives of index patients with body mass indices less than 30.0 kg/m2 were recruited., Measurements: Assessment of sleep-related symptoms; breathing, sleep, and oxygenation patterns on overnight polysomnograms; upper airway dimensions by acoustic reflection; and facial structure by lateral cephalometry., Results: More relatives of patients with the sleep apnea-hypopnea syndrome reported snoring (24 relatives compared with 7 controls; P < 0.001) and daytime sleepiness (28 relatives compared with 16 controls; P = 0.01). Relatives had more apneas and hypopneas per hour (median of 13/h [95% CI, 3 to 82/h] for relatives compared with median of 4/h [CI, 0 to 53/h] for controls; P < 0.001), more arousals from sleep (30/h [CI, 11 to 87/h] for relatives compared with 17/h [CI, 4 to 59/h] for controls; P < 0.001), poorer sleep quality, and more oxygen desaturations. Relatives also had narrower upper airways with retroposed maxillae and mandibles and longer soft palates with wider uvulae., Conclusion: The sleep apnea-hypopnea syndrome has a strong familial component. The familial tendency may be caused by differences in facial structure.