Flow-volume curves in obstructive sleep apnea and snoring

The diagnostic value of flow-volume curves for sleep apnea was studied in 32 patients with obstructive sleep apnea, 40 simple snorers, and 30 healthy nonsnorers. A sawtooth appearance of the flow-volume curve was seen in 22 of the sleep apnea patients (69%), 14 of the simple snorers (35%), and 10 of the nonsnorers (33%). The ratio of midexpiratory flow (FEF 50) to midinspiratory flow (FIF 50) was greater than 1 in 6 of the sleep apnea patients (19%), 3 of the simple snorers (8%), and 2 of the nonsnorers (7%). Thus, only the sawtooth sign was more frequently found in sleep apnea patients than in controls (p less than 0.01). Sleep apnea patients with a sawtooth appearance of the flow-volume curve had a higher apnea index (38.7 +/- 22 vs. 21.5 +/- 12.1; p less than 0.01) and lower nocturnal minimum oxygen saturation (68.1% +/- 16.8 vs. 81.3% +/- 9.97; p less than 0.01) than those without. In symptomatic snorers, sensitivity of the sawtooth sign for sleep apnea was 72% and specificity 61%, for a FEF50/FIF50 ratio above 1 sensitivity was 17% and specificity 83%. In asymptomatic patients, sensitivity of either sign was extremely poor (33%) and specificity was 67% for the sawtooth sign and 85% for FEF50/FIF50 greater than 1. We conclude that abnormal flow-volume curves are of limited value for predicting sleep apnea.     

Flow-volume curve abnormalities and obstructive sleep apnea syndrome

Recent reports have suggested that flow volume curve abnormalities may be of interest in the diagnosis of obstructive sleep apnea syndromes by showing either extrathoracic airway obstruction (ratio of expiratory flow to inspiratory flow at 50 percent of forced vital capacity [FEF50/FIF50] exceeding 1) or upper airway fluttering (indicated by a sawtooth aspect on the mid-half of the inspiratory part of the curve) or both. In our study, 57 patients referred for a suspected sleep apnea syndrome (SAS) underwent conventional spirometry, assessment of flow-volume curves, ENT examination, and polysomnography. Thirty patients had an obstructive SAS, four patients a central SAS, and 23 patients no SAS. Signs of upper airway fluttering (the sawtooth sign) were present in 61 percent of the patients with obstructive SAS and in 46 percent of the patients without obstructive SAS (central SAS or no SAS). Signs of extrathoracic upper airway obstruction (FEF50/FIF50 greater than 1) were present in 67 percent of the patients with obstructive SAS and in 71 percent of the patients without obstructive SAS. These results suggest that upper airway abnormalities, as reflected by abnormal flow volume curves, are not always associated with obstructive SAS; they favor the hypothesis of a central component in the mechanism of upper airway occlusion during sleep.     

Pulmonary function in obstructive sleep apnea. Relationships to pharyngeal resistance and cross-sectional area

Reduction in the size of the pharynx and increased pharyngeal airflow resistance have been demonstrated in patients with obstructive sleep apnea (OSA). We evaluated 15 men with severe OSA and 10 nonapneic control subjects matched for age and weight in order to determine if PCSA, inspiratory pharyngeal airflow resistance, and abnormal breathing events during sleep were associated with alterations in the flow-volume relationship and other awake PFTs. Pharyngeal cross-sectional area was determined by CT, and pharyngeal resistance between choanae and epiglottis was measured during quiet awake breathing. In patients with OSA, there was an inverse relationship between the mean cross-sectional area of the oropharynx and the ratio of FEF50%/FIF50% (rs = -0.54; p = 0.03). In all subjects, pharyngeal resistance was inversely related to percentage of predicted values for FEF25-75% (rs = -0.56; p = 0.01). The frequency of apneas during sleep was significantly (p less than 0.05) related to the percentage of predicted values for MVV, TLC, FVC, and PIF. Obesity appears to account for the strength of these relationships. Flow-volume loops and other PFTs did not distinguish patients with OSA from controls.     

Analysis of obstructive sleep apnea patients with “sawtooth sign” on the flow-volume curve

Purpose  

The aims of the present study are to determine whether there is an obstructive sleep apnea (OSA) subgroup presenting with sawtooth sign on the spirometric flow-volume curve, and to identify the clinical importance of the sawtooth sign in these patients.     

老年人鼾症对心脑血管的影响

目的　探讨老年人鼾症尤其是睡眠呼吸暂停对心脑血管的影响。方法　 1 1 8例老年鼾症 (观察组 )及74例中青年鼾症 (对照组 )按呼吸暂停低通气指数 ( AHI)分单纯性打鼾 ( SS)组 ( AHI<5 )与睡眠呼吸暂停综合征( SAS)组 ( AHI≥ 5 ) ,比较各组临床症状及合并疾病情况。结果　 1 1 8例老年鼾症中符合 SAS83例 ,检出率达 70 .3% ,但重度 SAS较中青年人少。老年人 SS同样存在缺氧 ,其氧减指数明显高于中青年组 ,最低氧饱和度明显低于中青年组。老年人鼾症合并高血压、冠心病、脑血管疾病比率明显增高。结论　老年人鼾症对心脑血管系统有损害。     

Flow-volume curves in snoring patients with and without obstructive sleep apnea

To examine the usefulness of flow-volume curves as a screening test for the diagnosis of obstructive sleep apnea (OSA), we studied 405 consecutive patients referred for evaluation of possible OSA. All patients had full pulmonary function studies, which included measurements of maximal inspiratory and expiratory flow-volume curves, and nocturnal polysomnography, including continuous monitoring of snoring sounds. When the results were analyzed, of the 405 patients studied, 207 had OSA (apnea/hypopnea index [AHI] greater than 10) and 198 did not. Flow-volume curves were examined for the presence of upper airway obstruction defined as midvital capacity flow ratio (MVCFR = ratio of the maximal expiratory flow at 50% of vital capacity to maximal inspiratory flow at 50% of vital capacity) greater than 1.0. We found no significant difference in the values of MVCFR between the two groups: MVCFR was equal to 0.69 +/- 0.31 for nonapneic snorers, and 0.68 +/- 0.29 for the apneic snorers. Furthermore, we redefined the apneic and nonapneic groups using different cutoff values of AHI: 20, 30, 40, and 50. Independently of the AHI cutoff used, we found no significant difference in the MVCFR between the two groups. Linear regression analysis for the entire group of 405 patients revealed no significant correlation between MVCFR and the AHI or the snoring indices. We calculated the sensitivity, specificity, and predictive values of MVCFR for the diagnosis of OSA. We found that this test had 12% sensitivity, 86% specificity, 47% positive predictive value, and 46% negative predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduced neurocognition in children who snore

Obstructive sleep apnea syndrome (OSAS) has been associated with reduced neurocognitive performance in children, but the underlying etiology is unclear. The aim of this study was to evaluate the relationship between hypoxemia, respiratory arousals, and neurocognitive performance in snoring children referred for adenotonsillectomy. Thirteen snoring children who were referred for evaluation regarding the need for adenotonsillectomy to a children's hospital otolaryngology/respiratory department underwent detailed neurocognitive and polysomnographic (PSG) evaluation. PSGs were evaluated for respiratory abnormalities and compared with 13 nonsnoring control children of similar age who were studied in the same manner. The snoring children had an obstructive respiratory disturbance index within normal range (mean obstructive apnea/hypopnea index, 0.6/hr). Despite this, several domains of neurocognitive function were reduced in the snoring group. These included mean verbal IQ scores (snorers 92.6 vs. nonsnorers 110.2, P < 0.001), mean global IQ scores (snorers 96.7 vs. nonsnorers 110.2, P < 0.005), mean selective attention scores (snorers 46.4 vs. nonsnorers 11.8, P < 0.001), mean sustained attention scores (snorers 8.0 vs. nonsnorers 2.2, P = 0.001), and mean memory index (snorers 95.2 vs. nonsnorers 112.1, P = 0.001). There was a direct relationship between number of mild oxygen desaturations of > or = 3%, obstructive hypopneas with > or = 3% oxygen desaturations, and respiratory arousals and severity of neurocognitive deficits, with the greatest effect being on memory scores. The disruption of sleep in snoring children produced by relatively mild changes in oxygen saturation or by increases in respiratory arousals may have a greater effect on neurocognitive function than hitherto appreciated. A possible explanation for these neurocognitive deficits may be the combination of the chronicity of sleep disruption secondary to snoring which is occurring at a time of rapid neurological development in the first decade of life. Future studies need to confirm the reversal of these relatively mild neurocognitive decrements post adenotonsillectomy.     

Contribution of flow-volume curves to the detection of central airway obstruction

OBJECTIVE:

To assess the sensitivity and specificity of flow-volume curves in detecting central airway obstruction (CAO), and to determine whether their quantitative and qualitative criteria are associated with the location, type and degree of obstruction.

METHODS:

Over a four-month period, we consecutively evaluated patients with bronchoscopy indicated. Over a one-week period, all patients underwent clinical evaluation, flow-volume curve, bronchoscopy, and completed a dyspnea scale. Four reviewers, blinded to quantitative and clinical data, and bronchoscopy results, classified the morphology of the curves. A fifth reviewer determined the morphological criteria, as well as the quantitative criteria.

RESULTS:

We studied 82 patients, 36 (44%) of whom had CAO. The sensitivity and specificity of the flow-volume curves in detecting CAO were, respectively, 88.9% and 91.3% (quantitative criteria) and 30.6% and 93.5% (qualitative criteria). The most prevalent quantitative criteria in our sample were FEF50%/FIF50% ≥ 1, in 83% of patients, and FEV1/PEF ≥ 8 mL . L^–1 . min^–1, in 36%, both being associated with the type, location, and degree of obstruction (p < 0.05). There was concordance among the reviewers as to the presence of CAO. There is a relationship between the degree of obstruction and dyspnea.

CONCLUSIONS:

The quantitative criteria should always be calculated for flow-volume curves in order to detect CAO, because of the low sensitivity of the qualitative criteria. Both FEF50%/FIF50% ≥ 1 and FEV1/PEF ≥ 8 mL . L^–1 . min^–1 were associated with the location, type and degree of obstruction.     

An evaluation of flow-volume curves as a screening test for obstructive sleep apnea

We examined flow-volume curves for their potential as screening tests for obstructive sleep apnea (OSA) in 401 patients referred for investigation of snoring. In all patients, we performed nocturnal polysomnography, maximum inspiratory and maximum expiratory flow-volume curves. The curves were examined for two features: 1) presence of flow oscillations (the "saw-tooth" sign), and 2) changes in their configuration that might suggest upper airway obstruction as documented by the expiratory/inspiratory flow ratios calculated at 50 and 75 percent of exhaled vital capacity (FR50 and FR25, respectively). Based on the results of nocturnal polysomnography, the patients were stratified according to severity into apnea groups, and the flow ratios and flow oscillations were compared among these groups. We found that neither the FR50 nor FR25 were significantly different among the groups. Inspiratory and expiratory flow oscillations were seen infrequently (32 patients) and tended to occur in patients with more severe sleep apnea. Neither the flow ratios nor the flow oscillations had good predictive values for snoring or sleep apnea. The sensitivity of the flow volume curve abnormalities ranged between 0 and 14 percent, but the specificity was high, ranging between 93 and 95 percent. We conclude that because of low sensitivity, flow-volume loops are not a useful screening test for the diagnosis of OSA in snoring patients.     

Postnasal drip causes cough and is associated with reversible upper airway obstruction

We prospectively evaluated nine patients with cough from postnasal drip for evidence of extrathoracic upper airway obstruction. Patients compared before treatment to normal control subjects had physiologic evidence of extrathoracic upper airway obstruction; their mean FIF50%/FEF50% and FIF25-75%/FEF25-75% ratios of 0.88 and 0.98 were significantly less than the values in control subjects of 1.28 and 1.37 (p less than 0.001). With specific therapy, postnasal drip decreased, cough disappeared and upper airway obstruction physiologically and physically resolved in all patients. We conclude that: 1) when postnatal drip is causally associated with cough, flow-volume loops can provide objective documentation of this clinical association; 2) flow-volume loops can be used as an objective method in comparing the efficacy of different therapeutic agents for cough due to postnasal drip; and 3) normal predicted values of extrathoracic airway function should not include measurements from patients who have recently recovered from cough associated with postnasal drip.     

Personality profiles in patients with obstructive sleep apnea

Objective

The Minnesota Multiphasic Personality Inventory (MMPI) responses between snorers and obstructive sleep apnea (OSA) may be different. Thus, we compared the MMPI responses between snorers and OSA.

Design

A clinical-based cross-sectional survey.

Participants

This is a survey of 94 treatment-naive sleep-disordered breathing (SDB) subjects.

Method

Clinical information, body mass index (BMI), 36-item Short Form Health Survey, the Turkish version of the MMPI, Epworth sleepiness scale (ESS), fatigue scale, attention-deficit scale, and polysomnography were collected. All patients with OSA and snorers was accepted as individuals with SDB (AHI?>?0 events/h). The threshold of five apnea and hypopnea per hour of sleep was chosen to define both OSA and snorers. Disability profile is consisting of four or more MMPI clinical scale elevations.

Results

OSA patients compared to snorers have significantly higher absolute scores on hypochondriasis (Hs) (65.0?±?12.0 vs 58.4?±?7.9, p?=?0.01, respectively). OSA patients compared to snorers have significantly higher rate of clinical elevation on both psychopathic deviance (13.0 vs 0?%, p?=?0.03, respectively) and Hs (26.1 vs 3.3?%, p?=?0.01, respectively). People with disability profile has lower the quality of life, a higher score for inattention, a higher fatigue scores, and higher sleepiness scores. The quality of life and attention deficit and daytime sleepiness scores were associated with total MMPI absolute score in individuals with SDB in bivariate analyses.

Conclusion

Present study indicated that patients with OSAS compared to snorers displayed significantly more hyopchondriasis and psychopathic deviance personality characteristics. The daytime functions in individuals with sleep-disordered breathing may be influenced by the severity of psychopathology.     

A screening study of snorers with or without sleep apnea

There are 76 cases of snorers with or without sleep apnea by screening study using ZD2Apnea Monitor or/and Ohmeda 3700 Pulse Oximeter. It is compared with polysomonographic recording. The sensitivity and specificity of screening study are 96.4% and 95.2% respectively. The advantage and disadvantage of these two methods are evaluated. It is suggested that ZD2Apnea Monitor is a simple, useful and cheap screening test for snorers with or without sleep apnea. It is suitable to clinical use.     

Diuretics in obstructive sleep apnea with diastolic heart failure

BACKGROUND: Upper airway edema might contribute to pharyngeal collapsibility and account for the high prevalence of obstructive sleep apnea (OSA) in patients with heart disease. The aim of this study was to evaluate if intensive unloading with diuretics improves sleep-disordered breathing and increases pharyngeal caliber in patients with severe OSA and diastolic heart failure. METHODS: Fifteen patients with severe OSA, hypertension, and diastolic heart failure were hospitalized to receive IV furosemide, 20 mg, and spironolactone, 100 mg, bid for 3 days. Polysomnography was performed for assessment of apnea-hypopnea index (AHI), acoustic pharyngometry was performed for assessment of the oropharyngeal junction (OPJ) area, and forced midinspiratory flow (FIF(50)), forced midexpiratory flow (FEF(50))/FIF(50) percentage, and exhaled nitric oxide (FeNO) were measured before and after diuretic treatment. RESULTS: Diuretic treatment produced a significant decrease in body weight, BP, and AHI (from 74.89 +/- 6.95 to 57.17 +/- 5.40/h, p < 0.001), associated with an improvement in OPJ area (from 1.33 +/- 0.10 to 1.78 +/- 0.16 cm(2), p = 0.007), FIF(50) (from 3.16 +/- 0.4 to 3.94 +/- 0.4 L/s, p = 0.006), and FEF(50)/FIF(50) percentage (from 117.9 +/- 11.8 to 93.15 +/- 10.1%, p = 0.002). Weight loss was significantly related to the decrease of AHI (R = 0.602; p = 0.018), to the increase of FIF(50) (R = 0.68; p = 0.005), and to the decrease of FEF(50)/FIF(50) (R = 0.635; p = 0.011). CONCLUSIONS: These findings suggest that pharyngeal edema contributes to sleep-disordered breathing in obese patients with severe OSA, hypertension, and diastolic heart failure. Upper airway edema may contribute to the frequent occurrence of OSA in patients with heart disease.     

Effect of Bedtime Alcohol on Inspiratory Resistance and Respiratory Drive in Snoring and Nonsnoring Men

We measured inspiratory resistance (R₁), inspiratory occlusion pressure (P_0–1), and the ventilatory responses to hypercapnia and isocapnic hypoxia during waking and during stage 2 non-rapid eye movement sleep in nine young men who were habitual snorers. They were studied on 2 nights during the 3 hours after receiving a bedtime drink containing either a placebo or 100-proof vodka (1.5 ml/kg) in orange juice. We compared the results with those we reported previously in 10 nonsnoring but otherwise similar men. Waking R₁ was the same in nonsnorers and snorers, and it was not affected by ethanol. During sleep on the control night, R₁ increased by 70% in nonsnorers and by 280% in snorers. On the ethanol night, the increase from waking to sleeping was more than doubled in both nonsnorers and snorers. P_0–1 and the responses to hypercapnia and hypoxia showed no differences between nonsnorers and snorers, therefore the results from the two groups were pooled. Minute ventilation and the hypercapnic response decreased from waking to sleeping and P_0–1 was more negative during sleep, but there was no significant effect of ethanol. There was a significant correlation between the changes from waking to sleeping in R₁ and P_0–1 on the ethanol night suggesting that inspiratory effort increased in response to the increased resistance. The response to isocapnic hypoxia showed no effect of either sleep state or drink. lnspiratory time did not change but mean inspiratory flow (V_T/t₁) was significantly reduced during sleep on both control and ethanol nights. The duty cycle ratio (T₁/T_tot) was significantly increased during sleep on the ethanol night. Despite its great effect on inspiratory resistance, especially in snorers, ethanol, in the dose used in our study, does not augment the depression of minute ventilation or of the hypercapnic response that occur normally in stage 2 non-rapid eye movement sleep. After ethanol, our subjects showed the decreased Vt/T_i and the increased T_i/T_tot that occur normally during sleep in response to an inspiratory resistive load. However, they also showed increased inspiratory effort. The combination of increased inspiratory resistance and greater inspiratory effort would increase the tendency of an unstable upper airway to collapse and could account for the aggravation of obstructive sleep apnea by ethanol.     

Effect of three alcohol doses on breathing during sleep in 30-49 year old nonobese snorers and nonsnorers

To test the effect of alcohol ingestion and snoring on sleep-disordered breathing (SDB), the sleep and respiration of 31 nonobese healthy males ages 30-49 (15 snorers, 16 nonsnorers) were studied overnight after alcohol ingestion. Subjects received placebo, 0.32, 0.65, and 0.81 g alcohol/kg body weight prior to their evening bedtime, with each dose given on one of four nonconsecutive nights in a repeated-measures counterbalanced design. On each night, respiration was assessed by recording respiratory effort from intercostal surface electromyography (EMG), ventilation from oral and nasal thermistors, and arterial oxygen saturation (SaO2) from an ear oximeter (BIOX III). Snorers had significantly: (a) more total SDB, (b) more obstructive sleep apnea (OSA), and (c) lower minimum SaO2 than nonsnorers after the placebo and each alcohol dose. Snorers had more hypoxic events than nonsnorers after each alcohol dose but not after placebo. Increasing alcohol dose caused a statistically significant (p = 0.0004) decrease in minimum SaO2 in snorers only, but this decrease was small and probably not clinically important. Alcohol did not cause significant increases in SDB and hypoxic events, and did not have different effects on SDB and hypoxic events for snorers versus nonsnorers. Because this experiment included only nonobese 30-49-year-old males, these results do not imply that alcohol has no significant effects on obese subjects or those older than 50.     

Prevalence of obstructive sleep apnea syndrome and associated symptoms in 3--11-year-old Turkish children

Our objective was to investigate the prevalence of sleep-disordered breathing (SDB) and obstructive sleep apnea syndrome (OSAS) in 3-11-year-old Turkish children. A cross-sectional study was conducted in Zonguldak, northwestern Turkey. Symptomatic children were identified by using a self-administered questionnaire and were classified into three groups: nonsnorers, occasional snorers, and habitual snorers. All habitual snoring children were invited to undergo polysomnography (PSG). Nine hundred fifty-four children (79.5%) were nonsnorers, 205 (17.2%) were occasional snorers, and 39 (3.3%) were habitual snorers. There was no significant relationship between gender and habitual snoring (male, 3.4%; female, 3.1%; P > 0.05; odds ratio (OR), 1.13; 95% confidence interval (CI), 0.59-2.14). There was a statistically significant relationship between habitual snoring and allergic rhinitis (OR, 4.23; 95% CI, 2.14-8.35). Four children who snored every night, and who had apnea spells and/or troubled sleep, underwent adenoidectomy and/or tonsillectomy before polysomnographic evaluation because of clinical detoriation. Twenty-eight of 39 children with habitual snoring participated in PSG evaluation. PSG revealed that 11 children (0.9% of the total population) had OSAS. When 4 operated children were added to these 28 children, we found the minimum prevalence of OSAS to be 1.3% in our study group. There was a significant correlation between OSAS and troubled sleeping (P <0.001; OR, 4.37; 95% CI, 1.33-14.3). We found the prevalence of habitual snoring to be 3.3% in Turkish children by using self-administered questionnaires. Allergic rhinitis was significantly correlated with habitual snoring. Minimum estimated prevalence of OSAS was found to be 1.3%.     

Frequency and correlates of the saw-tooth pattern of flow-volume curves in an epidemiological survey.

The object of this report was to assess the possibility of identifying saw-tooth patterns on flow-volume curves in men aged 28 to 58 years. We studied the frequency of these patterns and their relationships with two indirect signs of UAO increase in FEV1/PEF and FEF50%/FIF50% ratios--as well as with clinical and functional data. Twenty-six of the 360 subjects surveyed, ie, 7.2 percent, had flow oscillations in the inspiratory and/or expiratory part of flow-volume curves, corresponding to the definition of the saw-tooth pattern. We observed significant relationships between the saw-tooth pattern and the mean FEV1/PEF ratio. In 97 subjects, the proportion of those with saw-tooth patterns was 13.4 percent, and the mean FEF50%/FIF50% ratio was 1.53 in those with the pattern vs 1.07 in those without it. These results show that the saw-tooth pattern was not rare in these men.     

Should flow-volume loop be monitored in sleep apnea patients treated with continuous positive airway pressure?

Nasal continuous positive airway pressure (nCPAP) has been widely established in the treatment of obstructive sleep apnea syndrome (OSAS). However, only few studies have evaluated long-term effects of this treatment on lung function. This study assesses the effect of nCPAP on lung function parameters and response to bronchodilators in 50 OSAS patients. Spirometry and arterial blood gas measurements were performed before starting nCPAP and after 16.8 +/- 8 months of treatment. Of the 50 study patients (55 +/- 12 years, with an apnea/hypopnea index of 47 +/- 34h(-1)), 15 had asthma, 13 had chronic obstructive pulmonary disease (COPD) and 22 had no obstructive airway disease (NOAD). In the entire population, significant decreases in FEF50 (from 69 +/- 38% to 61 +/- 30%, P < 0.005), FEF25 (from 53 +/- 34% to 46 +/- 28%, P < 0.05) and FEF25-75 (from 65 +/- 33% to 57 +/- 27%, P < 0.005) were observed after treatment. No impairment of lung function was found in COPD and asthmatic patients. In contrast, lung function was changed in the NOAD group where FEF50, FEF25 and FEF25-75 as well as FEV1 and FEV1/VC ratio were significantly reduced. Moreover, bronchial hyperresponsiveness occurred in five of 22 patients of this group. These results suggest that tolerance of nCPAP should be handled by long-term follow-up of flow-volume loops.     

Effect of Three Alcohol Doses on Breathing during Sleep in 30–49 Year Old Nonobese Snorers and Nonsnorers

To test the effect of alcohol ingestion and snoring on deep-disordered breathing (SDB), the sleep and respiration of 31 nonobese healthy males ages 30-49 (15 snorers, 16 nonsnorers) were studied overnight after alcohol ingestion. Subjects received placebo, 0.32, 0.65, and 0.81 g alcohol/kg body weight prior to their evening bedtime, with each dose given on one of four nonconsecutive nights in a repeated-measures counterbalanced design. On each night, respiration was assessed by recording respiratory effort from inter-costal surface electromyography (EMG), ventilation from oral and MMI thermistors, and arterial oxygen saturation (SaO₂) from an ear oximeter (BIOX III). Snorers had significantly: (a) more total SDB, ( b ) more obstructive deep apnea (OSA), and (c) lower minimum SaO₂ than nonsnorers after the placebo and each alcohol dose. Snorers had more hypoxic events than nonsnorers after each alcohol dose but not after placebo. Increasing alcohol dose caused a statistically significant ( p = 0.0004) decrease in minimum SaO₂ in snorers only, but this decrease was small and probably not clinically important. Alcohol did not cause significant increases in SDB and hypoxic events, and did not have different effects on SDB and hypoxic events for snorers versus nonsnorers. Because this experiment included only nonobese 30–49-year-old males, these results do not imply that alcohol has no significant effects on obese subjects or those older than 50.     

Prevalence of obstructive sleep apnea syndrome in a cohort of 1,207 children of southern Italy

STUDY OBJECTIVE: To determine the prevalence of sleep-related breathing disturbances in a large cohort of school-aged and preschool-aged children of Southern Italy. DESIGN AND SETTING: This cross-sectional prevalence study was designed in two phases: a screening phase aimed to identify symptomatic children from a cohort of 1,207 by a self-administered questionnaire, and an instrumental phase for the definition of sleep-related disorders. PATIENTS AND METHODS: One thousand two hundred seven children were screened by a self-administered questionnaire. There were 612 female children (51%) and 595 male children (mean age, 7.3 years; range, 3 to 11 years). According to answers, children were classified in three groups: nonsnorers, occasional snorers, and habitual snorers. All habitual snoring children underwent a polysomnographic home evaluation, and those with an oxygen desaturation index > 2 were considered for nocturnal polygraphic monitoring (NPM). Children with an apnea/hypopnea index > 3 received a diagnosis of obstructive sleep apnea syndrome (OSAS). RESULTS: A total of 895 questionnaires (74.2%) were returned and scored; 710 children (79.3%) were identified as nonsnorers, 141 children (15.8%) were identified as occasional snorers, and 44 children (4.9%) were identified as habitual snorers. The percentage of male children who were habitual snorers was higher than the percentage of female children who were habitual snorers (6.1% vs 3.7%, respectively; p < 0.09). OSAS was diagnosed in nine children by NPM. CONCLUSION: The lower limit of prevalence of OSAS in childhood is 1% (95% confidence interval [CI], 0.8 to 1.2). If we add the five children who underwent adenoidectomy and/or tonsillectomy because of worsening clinical condition and the two children who were shown to have evidence of OSAS on domiciliary oximetry, then the prevalence is 1.8% (higher limit of prevalence; 95% CI, 1.6 to 2.0).