Japanese Obstructive Sleep Apnea Syndrome Research Articles

Findings of the Maintenance of Wakefulness Test and its relationship with response to modafinil therapy for residual excessive daytime sleepiness in obstructive sleep apnea patients adequately treated with nasal continuous positive airway pressure

ObjectiveWe aimed to examine the relationship between subjective and objective sleepiness in obstructive sleep apnea syndrome (OSAS) patients with residual sleepiness, and to determine whether baseline objective sleepiness severity predicts the response to modafinil therapy. MethodsData were obtained from a randomized, placebo-controlled modafinil (200 mg/day) study in Japanese OSAS patients with residual sleepiness receiving nasal continuous positive pressure (n-CPAP) treatment. We analyzed 50 participants whose subjective (Epworth Sleepiness Scale [ESS] total score) and objective (Maintenance of Wakefulness Test [MWT] sleep latency) sleepiness were evaluated before and after treatment. Subjects were dichotomized into two subgroups according to the mean baseline MWT sleep latency. ESS total score and MWT sleep latency changes after treatment were compared between the placebo and modafinil groups in both subgroups. ResultsThe mean baseline ESS total score and MWT sleep latency were 14.1 ± 2.8 and 14.2 ± 4.9 min, respectively; there was no significant correlation between these two variables. Patient characteristics were similar between the two subgroups (MWT sleep latency: <14 min, n = 23; ≥14 min, n = 27). In the <14-min subgroup, changes in ESS total score and MWT sleep latency after treatment were significantly greater in the modafinil group than in the placebo group (p = 0.005). In the ≥14-min subgroup, changes in these parameters did not differ between the treatment groups. ConclusionIn OSAS patients with residual sleepiness, the objective sleepiness level was not as high as expected, despite increased subjective sleepiness. Improvements in subjective and objective sleepiness seemed difficult to achieve with modafinil treatment among subjects with less objective sleepiness.

Insufficient sleep rather than the apnea–hypopnea index can be associated with sleepiness-related driving problems of Japanese obstructive sleep apnea syndrome patients residing in metropolitan areas

ObjectiveObstructive sleep apnea syndrome (OSAS) and insufficient sleep might increase the risk of drowsy driving and sleepiness-related vehicular accidents. This study retrospectively investigated the factors associated with these driving problems, particularly addressing OSAS severity and sleep amounts of affected drivers. MethodsThis study examined 161 patients (146 male and 15 female) with OSAS (apnea−hypopnea index [AHI] ≥ 5) who drove on a routine basis and who completed study questionnaires. To investigate factors associated with drowsy driving during the prior year and sleepiness-related vehicular accidents or near-miss events during the prior five years, logistic regression analyses were performed with age, body mass index, monthly driving distance, habitual sleep duration on weekdays, the Japanese version of Epworth Sleepiness Scale score, AHI, and periodic limb movement index as independent variables. ResultsOf the patients, 68 (42.2%) reported drowsy driving experiences, and 86 (53.4%) reported sleepiness-related vehicular accidents or near-miss events. Analyses revealed the following: older age (46–65 years, ≥66 years) was negatively associated with drowsy driving (p < 0.05, p < 0.05), and habitually shorter sleep duration on weekdays (≤6 hours) was positively associated with drowsy driving (p < 0.01). Habitual sleep duration of ≤6 hours (p < 0.01) and Epworth Sleepiness Scale score of ≥11 (p < 0.01) were positively associated with sleepiness-related vehicular accidents and near-miss events. However, AHI was not associated with these driving problems. ConclusionInsufficient sleep, rather than severity of OSAS, was associated with sleepiness-related driving problems in these Japanese OSAS patients.

Upper airway anatomical balance contributes to optimal continuous positive airway pressure for Japanese patients with obstructive sleep apnea syndrome.

The aim of this study was to examine whether the upper airway anatomical balance, as reflected by tongue size relative to maxillomandibular size, is related to optimal nasal continuous positive airway pressure (PnCPAP). Sixty-six male Japanese obstructive sleep apnea syndrome (OSAS) patients (median apnea-hypopnea index [AHI] = 33.9 episodes/h [10th/90th percentile = 19.5/59.9], median body mass index [BMI] = 25.1 kg/m(2) [10th/90th percentile = 21.2/30.4]) were recruited. All patients underwent standard polysomnography (PSG), and PnCPAP was determined by nasal continuous positive airway pressure (nCPAP) titration. The anatomical balance was defined as the tongue area (TG) divided by the lower face cage (LFC) measured on cephalometry. A predictive equation of PnCPAP was created using demographic, polysomnographic, and cephalometric variables. Significant correlations were found between PnCPAP and descriptive variables, including BMI, AHI, lowest SpO2, distance from the anterosuperior point of the hyoid bone to the mandibular plane (MP-H), and TG/LFC. Stepwise multiple regression analysis revealed that AHI and TG/LFC were independent predictors of PnCPAP. The predictive equation was: PnCPAP = 1.000 + 0.043 × AHI + 9.699 × TG / LFC, which accounted for 28.0% of the total variance in PnCPAP (R(2) = 0.280, p < 0.01). Anatomical balance of upper airway in addition to the severity of OSAS is an important contributing factor for PnCPAP in Japanese OSAS patients.

Efficacy and safety of adjunctive modafinil treatment on residual excessive daytime sleepiness among nasal continuous positive airway pressure-treated japanese patients with obstructive sleep apnea syndrome: a double-blind placebo-controlled study.

This double-blind study evaluated the efficacy and safety of modafinil for treating excessive daytime sleepiness in Japanese patients with obstructive sleep apnea syndrome (OSAS). Patients with residual excessive sleepiness (Epworth Sleepiness Scale [ESS] ≥ 11) on optimal nasal continuous positive airway pressure (nCPAP) therapy (apnea-hypopnea index ≤ 10) were randomized to either 200 mg modafinil (n = 52) or placebo (n = 62) once daily for 4 weeks. Outcomes included baseline-week 4 changes in ESS total score, sleep latency on maintenance of wakefulness test (SL-MWT), nocturnal polysomnography, Pittsburgh Sleep Quality Index (PSQI), and safety. All 114 randomized patients completed the study. Mean change in ESS total score (-6.6 vs -2.4, p < 0.001) and SL-MWT (+2.8 vs -0.4 minutes, p = 0.009) were significantly greater with modafinil than with placebo. ESS total score decreased from > 11 to < 11 at the final assessment in 69.2% of modafinil-treated patients and 30.6% of placebo-treated patients (p < 0.001). Corresponding rates at week 1 were 57.7% and 33.9% (p = 0.014). Changes in nocturnal polysomnography, PSQI, and apnea-hypopnea index from baseline to the final assessment were similar in both groups. Adverse drug reactions occurred in 36.5% and 22.6% of patients in the modafinil and placebo groups, respectively (p = 0.146). Once-daily modafinil was effective and well tolerated for managing residual daytime sleepiness in Japanese OSAS patients with residual excessive daytime sleepiness on optimal nCPAP therapy.

Characteristics of Japanese Patients with Complex Sleep Apnea Syndrome: A Retrospective Comparison with Obstructive Sleep Apnea Syndrome

The prevalence of complex sleep apnea syndrome (CompSAS) among Asian patients with obstructive sleep apnea syndrome (OSAS) has not yet been reported. Distinguishing CompSAS from pure OSAS is difficult using only diagnostic polysomnography (PSG). We examined the prevalence of CompSAS in Japanese patients with OSAS and the possibility to distinguish CompSAS from pure OSAS by analyzing the severity of respiratory events based on either sleep body position or sleep stage using a diagnostic PSG. A retrospective chart review of 297 consecutive Japanese patients who were 15 years of age or older with a primary diagnosis of OSAS who were referred for CPAP titration (AHI> or =20 events/hr). Seventeen patients (5.7%) out of the 297 patients who had an obstructive apnea hypopnea index (AHI) of 20 or higher showed adverse increases in central apnea index (CAI) by the treatment with CPAP whereas obstructive apnea index (OAI) and mixed apnea index (MAI) were significantly decreased. In the results, the AHI on the PSG for CPAP titration reached only approximately half of the values on the diagnostic PSG. In these CompSAS patients, both the total CAI and the CAI in the supine position during NREM sleep on the diagnostic PSG were significantly higher than those in the OSAS group. The sleep body position did not so strongly affect the AHI, OAI and MAI in the CompSAS group. Multiple, stepwise, and logistic regression analyses revealed that the CAI in the supine position during NREM (p=0.026) was a significant variable to distinguish CompSAS from OSAS statistically although the variables were within the normal range. The prevalence of CompSAS in Japanese OSAS patients may be lower when compared with Caucasian patients. The increase of CAI in the supine position during NREM sleep on diagnostic PSG may be a characteristic feature in CompSAS.

Metabolic Syndrome in Japanese Patients with Obstructive Sleep Apnea Syndrome

We investigated the prevalence of metabolic syndrome in patients with obstructive sleep apnea syndrome (OSAS) referred to a tertiary university-based medical center. A cross-sectional study of patients with a definite diagnosis of OSAS was performed using new diagnostic criteria for metabolic syndrome that were designed for the Japanese population. Clinical features and comorbidities related to metabolic syndrome were compared between 819 patients with OSAS (719 men and 100 women) and 89 control subjects without OSAS. Metabolic syndrome was significantly more common in the patients with OSAS than in the controls (49.5% vs. 22.0% for men, p < 0.01; 32.0% vs. 6.7% for women, p < 0.01). Men with OSAS (apnea-hypopnea index [AHI] > or =5/h) had a higher risk of metabolic syndrome compared with controls (odds ratio [OR]: 3.47; 95% confidence interval [CI]: 1.84-6.53). There was a significantly increased risk of metabolic syndrome in men with moderate OSAS (AHI: 15-29.9/h) (OR: 2.83; 95% CI: 1.42-5.66) and men with severe OSAS (AHI > or =30/h) (OR: 5.09; 95% CI: 2.67-9.71). Women with OSAS (AHI> or =5/h) also had an increased risk of metabolic syndrome (OR: 6.59; 95% CI: 1.47-29.38), and the risk was significantly higher in women with severe OSAS (AHI > or =30/h) (OR 14.00; 95% CI: 2.93-66.82). Risk factors for metabolic syndrome differed by gender: in men, age, body mass index (BMI), and OSAS (AHI > or =15/h) were significantly associated with metabolic syndrome, whereas, in women, BMI was the only risk factor for metabolic syndrome. The increase of metabolic syndrome in Japanese OSAS patients suggests that this patient population is burdened with multiple risk factors for cardiovascular disease.

Comparison of Ricketts analysis and Downs-Northwestern analysis for the evaluation of obstructive sleep apnea cephalograms.

To determine which analysis is suitable to examine the dentofacial skeletal pattern characteristics of the obstructive sleep apnea syndrome (OSAS), we took lateral cephalograms of 44 Japanese OSAS patients and 34 Japanese non-OSAS controls. By Ricketts analysis, we found significant differences between OSAS patients and non-OSAS controls on facial axis, lower facial height and total facial height, which showed that Japanese OSAS patients have dolico facial patterns. However, by Downs-Northwestern analysis, we did not find any significant difference between OSAS patients and non-OSAS controls using the same cephalograms as the Ricketts analysis.

Differential diagnosis of obstructive sleep apnea syndrome patients and snorers using cephalograms.

Severe snoring is thought by many to be an early stage of obstructive sleep apnea syndrome (OSAS), but the anatomical relation between snoring and OSAS, if any, has remained unclear. To compare the morphology of the airway between snorers and OSAS patients for possible similarities, we conducted a cephalometric analysis of Japanese OSAS patients (n=10), habitual snorers (n=10), and non-snoring controls (n=50). There was no significant difference in SNB (the angle formed by the sella, nasion and point B) between OSAS patients and the control subjects. Obstructive sleep apnea syndrome patients tended to have an anteriorly positioned maxilla, and an anteroposterior misalignment between the maxilla and mandible. There was also a tendency toward skeletal openbite. Both OSAS patients and snorers had large tongues and large soft palates, thus causing constriction of the airway with resultant smaller airway diameter and smaller airway surface area. Significant differences between OSAS patients and snorers were found in thickness and length of soft palate surface area, and thickness, length, and position of the hyoid bone. These results suggest that cephalographic measurements may be of considerable use in determining the seriousness of a patient's condition.

Mesopharyngometric Analysis in Patients with Obstructive Sleep Apnea Syndrome

The stenosis of the mesopharynx is a type of blockage in the upper airway in patients with obstructive sleep apnea syndrome (OSAS). The purpose of Uvulopalatopharyngoplasty (UPPP) is not only to excise the soft palate but also to expand the airway by reconstructing the mesopharynx. In this study, we measured the size of the mesopharynx in patients with OSAS and in those with snoring pre-and postoperatively in order to evaluate their anatomic condition and the effect of the operation. The width of the uvula in patients with OSAS was wider compared with that of the snoring and the length of the uvula in snoring was longer than that of OSAS The size of the mesopharynx of the Japanese OSAS patients was found to be midway between those of American OSAS patients and snoring The width of the uvula was significantly wider in the UPPP-responder group compared with the UPPP non-responder group. The mesopharynx expansion which was the purpose of UPPP were achieved, both in responder and in non-responder The result would indicate that there is another area of blockage other than the mesopharynx. We concluded that the judgment of the effectiveness of UPPP was insufficient only by the respiratory disturbance index.