Patient-predicted sleep position vs. HST data: a tendency to underestimate supine sleep

Purpose

The purpose of this study is to measure people’s accuracy when they estimate what proportion of their nightly sleep at home is supine vs. non-supine.

Methods

A series of patients referred for obstructive sleep apnea (OSA) evaluation were asked if they “knew with confidence” how they slept with regard to their body position. “Yes” responders were then asked to estimate what percentage of their sleep was supine vs. non-supine. This value was compared with the actual proportion of supine vs. non-supine sleep that they exhibited in a home sleep test (HST) that followed.

Results

We obtained data from 49 subjects who expressed that they “knew with confidence” how they sleep in terms of body position. Subjects in aggregate underestimated their proportion of supine sleep by 21.6% (p < .001). Thirty-nine subjects (80%) slept supine more in the HST whereas 8 (16%) slept supine less compared to their pre-test estimates. Using a common classification of OSA severity, 9 subjects (18%) demonstrated a more severe degree of OSA than would have occurred had they slept as they had predicted.

Conclusions

Subjects in this study frequently underestimated their proportion of supine sleep compared to values measured in an HST. Because of the increased supine sleep they exhibited, the severity of their OSA was often greater in the test than it would have been had the subjects slept as they predicted. Sleep physicians should take into account the tendency of people to underestimate supine sleep. If patients with positional sleep apnea assert that they “always sleep laterally” when at home, they may be underestimating their true night-by-night OSA disease burden.

     

The undervalued potential of positional therapy in position-dependent snoring and obstructive sleep apnea—a review of the literature

Purpose

Research during the past 10–20 years shows that positional therapy (PT) has a significant influence on the apnea–hypopnea index. These studies are predominantly performed as case series on a comparably small number of patients. Still, results have not found their way into the daily diagnostic and treatment routine. An average of 56?% of patients with obstructive sleep apnea (OSA) have position-dependent OSA (POSA), commonly defined as a difference of 50?% or more in apnea index between supine and non-supine positions. A great deal could be gained in treating patients with POSA with PT. The aim of this paper was to perform a thorough review of the literature on positional sleep apnea and its therapy.

Methods

A broad search strategy was run electronically in the MEDLINE and EMBASE databases using synonyms for position and sleep apnea.

Results

Sixteen studies were found which examined the effect of PT on OSA. In this literature review, we discuss the various techniques, results, and compliance rates.

Conclusion

Long-term compliance for PT remains an issue, and although remarkable results have been shown using innovative treatment concepts for PT, there is room for both technical improvement of the devices and for further research.     

Complete denture wear during sleep in elderly sleep apnea patients—a preliminary study

Objectives

There is no consensus in the literature about the impact of complete denture wear on obstructive sleep apnea (OSA). The goal of this randomized clinical study was to assess if complete denture wear during sleep interferes with the quality of sleep.

Materials and methods

Elderly edentulous OSA patients from a complete denture clinic were enrolled and received new complete dentures. An objective sleep analysis was determined with polysomnography performed at the sleep laboratory for all patients who slept either with or without their dentures.

Results

Twenty-three patients (74% females) completed the study with a mean age of 69.6?years and a mean body mass index of 26.7?kg/m². The apnea and hypopnea index (AHI) was significantly higher when patients slept with dentures compared to without (25.9?±?14.8/h vs. 19.9?±?10.2/h; p?>?0.005). In the mild OSA group, the AHI was significantly higher when patients slept with the dentures (16.6?±?6.9 vs. 8.9?±?2.4; p?p?=?0.2). The supine AHI in mild patients was related to a higher increase in AHI while wearing dentures (12.7?±?8.4/h vs. 51.9?±?28.6/h; p?Conclusions Contrary to previous studies, we found that OSA patients may experience more apneic events if they sleep with their dentures in place. Specifically, in mild OSAS patients, the use of dentures substantially increases the AHI especially when in the supine position.     

Positional obstructive sleep apnea in bariatric surgery patients: risk factor for postoperative cardiopulmonary complications?

Background

Up to 80 % of the bariatric surgery (BS) patients suffer from obstructive sleep apnea (OSA). BS patients with moderate to severe OSA (apnea-hypopnea index (AHI) ≥15) are usually treated with continuous positive airway pressure (CPAP). This is not indicated in mild OSA patients (AHI <15). However, >50 % of patients with mild OSA have positional OSA (POSA); their AHI is at least twice as high in supine sleeping position than in other positions. Since many patients sleep in supine position for surgical safety reasons after BS, evaluating the AHI in this position might be more relevant in this group. The aim of this study is to evaluate the postoperative cardiopulmonary complication rate in mild OSA patients with and without POSA. Secondary aim is to evaluate predictive factors for POSA.

Methods

A single-institute retrospective analysis was achieved with all consecutive patients who underwent primary laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy between 2006 and 2014. All patients with an AHI between 5 and 15 were included. Postoperative complications were compared between POSA and non-POSA patients. Predictive factors were evaluated through univariate and multivariable logistic regression analysis.

Results

A total of 277 patients, 153 with and 124 without POSA, were included. After BS, three patients (1.1 %) experienced severe cardiopulmonary complications. No significant difference was found between POSA and non-POSA patients. In multivariate analysis, age and BMI were found to be negative predictors for POSA.

Conclusion

In terms of 30-day postoperative cardiopulmonary outcome, CPAP therapy is not indicated in mild (P)OSA patients scheduled for BS.

     

Theoretical approach towards increasing effectiveness of palatal surgery in obstructive sleep apnea: role for concomitant positional therapy?

Purpose

The aims of this study are to evaluate the effect of palatal surgery (uvulopalatopharyngoplasty (UPPP) or Z-palatoplasty (ZPP)) with or without (+/?) concomitant radiofrequent ablation of the base of the tongue (RFTB) on body position-specific apnea–hypopnea index (AHI) values in patients with obstructive sleep apnea (OSA) and to compare this treatment outcome to the theoretical effect of (addition of) positional therapy (PT).

Methods

Retrospective analysis of pre- and posttreatment polysomnographies in 139 patients who had undergone UPPP/ZPP +/? RFTB was performed. Hypothetical evaluation of the effects of (addition of) ideal PT on AHI in positional OSA (POSA) patients was carried out.

Results

Median AHI significantly decreased from 18.0 to 11.2 (p?<?0.001). Median AHI in all separate positions decreased significantly as well. Sixty-eight patients suffered from POSA and showed a significant decrease in median AHI from 15.5 to 11.5 (p?=?0.002). In the 71 non-positional OSA (NPOSA) patients, the significant AHI decrease was more outspoken, from 23.0 to 11.0 (p?<?0.001). Our hypothetical model to treat POSA patients with an ideal PT (as monotherapy or in addition to surgery) resulted in a significant median AHI decrease from 18.0 to 4.5 (p?<?0.0001).

Conclusions

UPPP/ZPP +/? RFTB significantly reduces AHI and all body position-specific AHI values. This reduction is significantly higher in NPOSA than in POSA patients. When considering UPPP/ZPP +/? RFTB, the effect of body position needs to be taken into account. PT, either as monotherapy or in addition to surgery, theoretically has shown to improve treatment results dramatically in POSA patients. Prospective, controlled trials focusing on the effects of this combination of treatments should further evaluate this hypothetical conclusion.     

Measurement of dyspnea in patients with obstructive sleep apnea

Purpose

Patients with obstructive sleep apnea (OSA) frequently complain of exertional dyspnea. We aimed to assess its related factors and the significance of its measurement in OSA.

Methods

We evaluated 301 subjects with suspected OSA for dyspnea during activities of daily living using the Medical Research Council (MRC) scale. We analyzed the relationships between MRC grades and various subjective and objective indices. Further, the relationship of disease severity based on the apnea/hypopnea index (AHI) with these indices was examined. Results were compared between those obtained using MRC grades and the AHI.

Results

Of 301 subjects, 265 were diagnosed with OSA. Their MRC scores were worse than in non-OSA patients. Among OSA patients, 125 had MRC grade 1 (mild), 121 had MRC grade 2 (moderate), and 19 had MRC grade 3 or more (severe) dyspnea. Various measurements differed significantly between groups categorized according to the MRC scale although determinants between mild and moderate groups and between moderate and severe groups differed. AHI categorizations were not significantly related to patient-reported measurements such as the Medical Outcomes Study 36-item short form, Pittsburgh Sleep Quality Index, and Hospital Anxiety and Depression Scale scores, unlike categorization based on the MRC scale.

Conclusions

Dyspnea is an important outcome in OSA although dyspnea in OSA patients is unrelated to the sleep disorder per se. Measurement of dyspnea in patients with OSA might provide further insights into the health of these patients and clinical manifestations of this disease.     

Severity of obstructive sleep apnea is associated with elevated plasma fibrinogen in otherwise healthy patients

Purpose

Obstructive sleep apnea (OSA) has been implicated in both cardiovascular and cerebrovascular diseases. Systemic inflammation and coagulation may be related to cardiovascular pathophysiology in patients with OSA. Fibrinogen is a major coagulation protein associated with inflammation, and long-term elevated plasma fibrinogen is associated with an increased risk of major cardiovascular diseases. We assessed whether severity of OSA is associated with levels of fibrinogen in newly diagnosed, untreated, and otherwise healthy OSA patients.

Methods

We studied 36 men with OSA and 18 male control subjects (apnea–hypopnea index [AHI] <5 events/h). OSA patients were divided into mild (AHI ≥5?Results Fibrinogen levels were significantly elevated in patients with severe OSA compared to both control (P?=?0.003) and mild OSA (P?=?0.02) subjects after adjustment for covariates. However, there were no significant differences in fibrinogen levels between mild OSA and control subjects. Fibrinogen levels were directly related to AHI and arousal index and inversely related to mean and lowest oxygen saturation during sleep.

Conclusions

Severity of OSA was associated with increased fibrinogen level independent of other factors, suggesting that apneic events and oxygen desaturation during sleep are mechanisms for increased fibrinogen levels in patients with OSA.     

Evaluation of body position in upper airway stimulation for obstructive sleep apnea—is continuous voltage sufficient enough?

Purpose

The definition of positional obstructive sleep apnea (POSA) is widely accepted as a difference of 50% or more in AHI between supine and non-supine position. Upper airway stimulation (UAS) is an effective treatment for OSA but the implant delivers a single voltage over sleep period without consideration of body position. Clinical practice suggests different outcomes for OSA in supine position under UAS treatment.

Methods

Outcomes of 44 patients were analyzed 12 months after implantation in a two-center, prospective consecutive trial in a university hospital setting. Total night and supine AHI were evaluated and the ratio of time spent in supine was considered. Correlation between the classic and the modified definition of POSA and treatment response were evaluated.

Results

The time ratio spent in supine position did not differ before implantation and after 12 months. Total and supine AHI were reduced with the use of UAS therapy (p?<?0.001) but both the baseline and final supine AHI were higher than total night AHI. Considering POSA definition as a ratio of supine to non-supine AHI, there was no clear cutoff for defining responders neither with nor without the additional component of time in supine position.

Conclusions

The OSA reduction is strong for the total AHI and supine AHI. Nonetheless, here, there is no cutoff for defining POSA as critical for UAS therapy response. Therefore, there is no evidence for excluding POSA patients from UAS in general. Future technology improvement should take body position and adaptive voltage into account.

     

Severe obstructive sleep apnea increases mortality in patients with ischemic heart disease and myocardial injury

Objectives

We hypothesized that obstructive sleep apnea (OSA) has a dose-dependent impact on mortality in those with ischemic heart disease or previous myocardial injury.

Methods

We performed a retrospective cohort study of 281 consecutive OSA patients with a history of myocardial injury as determined by elevated troponin levels or with known existing ischemic heart disease. We compared survival between those with severe OSA [apnea–hypopnea index (AHI) ≥30] and those with mild to moderate OSA (AHI >5 and <30).

Results

Of the 281 patients (mean age 65 years, mean BMI 34, 98% male, 58% with diabetes), 151 patients had mild-moderate OSA and 130 had severe OSA. During a mean follow-up of 4.1 years, there were significantly greater deaths in the severe OSA group compared to the mild-moderate OSA group [53 deaths (41%) vs. 44 deaths (29%), respectively, p?=?0.04]. The adjusted hazard ratio for mortality with severe OSA was 1.72 (95% confidence interval 1.01–2.91, p?=?0.04).

Conclusions

The severity of obstructive sleep apnea is associated with increased risk of death, and risk stratification based on OSA severity is relevant even in the diseased cardiac patient.     

The sleep position trainer: a new treatment for positional obstructive sleep apnoea

Background

Positional obstructive sleep apnoea (POSA), defined as a supine apnoea–hypopnoea index (AHI) twice or more as compared to the AHI in the other positions, occurs in 56 % of obstructive sleep apnoea patients. Positional therapy (PT) is one of several available treatment options for these patients. So far, PT has been hampered by compliance problems, mainly because of the usage of bulky masses placed in the back. In this article, we present a novel device for treating POSA patients.

Methods

Patients older than 18 years with mild to moderate POSA slept with the Sleep Position Trainer (SPT), strapped to the chest, for a period of 29?±?2 nights. SPT measures the body position and vibrates when the patient lies in supine position.

Results

Thirty-six patients were included; 31 patients (mean age, 48.1?±?11.0 years; mean body mass index, 27.0?±?3.7 kg/m²) completed the study protocol. The median percentage of supine sleeping time decreased from 49.9 % [20.4–77.3 %] to 0.0 % [range, 0.0–48.7 %] (p?<?0.001). The median AHI decreased from 16.4 [6.6–29.9] to 5.2 [0.5–46.5] (p?<?0.001). Fifteen patients developed an overall AHI below five. Sleep efficiency did not change significantly. Epworth Sleepiness Scale decreased significantly. Functional Outcomes of Sleep Questionnaire increased significantly. Compliance was found to be 92.7 % [62.0–100.0 %].

Conclusions

The Sleep Position Trainer applied for 1 month is a highly successful and well-tolerated treatment for POSA patients, which diminishes subjective sleepiness and improves sleep-related quality of life without negatively affecting sleep efficiency. Further research, especially on long-term effectiveness, is ongoing.     

Clinical and polysomnographic data of positional sleep apnea and its predictors

Introduction

In Asian population, facial structure may contribute to the primary pathophysiology of obstructive sleep apnea (OSA). We hypothesized that sleep position may have more effect on OSA in Asians compared to the Western population. If this hypothesis is accurate, positional therapy will have a major impact on treatment of OSA among Asians.

Patients/methods

We reviewed 263 polysomnographic studies from our laboratory from January 1, 2010 to June 30, 2010. Criteria for positional and non-positional OSA were (1) supine respiratory disturbance index (RDI)/non-supine RDI ??2 and total RDI ??5 and (2) supine RDI/non-supine RDI <2 and total RDI ??5, respectively. We aimed to determine the difference in baseline characteristics, polysomnographic findings, and predictors for positional OSA.

Results

We found 144 patients diagnosed with OSA (RDI ??5), and 96 patients met the criteria for positional OSA (67%), in which in almost half of these patients (47%), RDI was normalized (RDI?<?5) in non-supine position. Snoring frequency were significantly lower among positional OSA and OSA was less severe indicated by lower RDI and arousal index, higher mean and nadir oxygen saturation, and higher %NREM3. We also found that low snoring frequency (less than 20% of total sleep time) was a significant predictor for positional OSA (odd ratio of 3.27; p?=?0.011), contrarily to low mean oxygen saturation (<95%) which was found to be a negative predictor (odd ratio of 0.31; p?=?0.009). Among OSA patients, low RDI (<15) was a significant predictor for normalization of RDI in non-supine position (odd ratio of 8.77; p?=?<?0.001), contrarily to low mean oxygen saturation (<95%) which was also found to be a negative predictor (odd ratio of 0.13; p?=?0.001).

Conclusion

Positional OSA is very prevalent and noted in almost 70% of our patients. Low snoring frequency was noted to be a positive predictor for positional OSA, contrarily to low mean oxygen saturation which was found to be a negative predictor. These findings are encouraging that positional therapy can be very beneficial as the treatment modality for OSA among Asians.     

Gender and age influence the effects of slow-wave sleep on respiration in patients with obstructive sleep apnea

Introduction

Obstructive sleep apnea (OSA) is influenced by sleep architecture with rapid eye movement (REM) sleep having the most adverse influence, especially in women. There is little data defining the influence of slow-wave sleep (SWS) on OSA. We wished to study the influence of SWS on OSA and identify differences attributable to gender and/or age, if any.

Methods

Retrospective study of polysomnography (PSG) records of adult patients referred for diagnostic PSG. Records were excluded if they underwent split night or positive airway pressure titration studies, had <180 min of total sleep time (TST) and/or <40% sleep efficiency, or had SWS <5 min and/or <1% of TST. The apnea–hypopnea index (AHI) recorded during SWS was compared with that measured during other non-rapid eye movement (NREM) sleep and during REM sleep. The REM–SWS difference in AHI was measured, and compared between genders.

Results

Records from 239 patients were included. The mean AHI in all subjects was 17.7?±?22.6. The SWS AHI was 6.8?±?18.9, compared to the REM AHI of 24.9?±?25.8, and NREM AHI of 15.8?±?22.8. Females had significantly higher SWS by percentage, and lower NREM AHI (P?<?0.0001) and SWS AHI (P?=?0.03). Among patients with OSA (AHI ≥5), the difference between REM AHI and SWS AHI was greater in women than in men (34.2?±?27.4 vs. 21.6?±?26.0, P?=?0.006).

Conclusions

The upper airway appears to be less susceptible to OSA during SWS than during REM and other NREM sleep. This may be related to phase-specific influences on both dynamic upper airway control as well as loop gain. Gender and age appear to modify this effect.     

Snoring in a sitting position and neck circumference are predictors of sleep apnea in Chinese patients

Background

Snoring is a common symptom among the adult population, and it is the most common complaint in patients with obstructive sleep apnea (OSA) syndrome. Patients who snore in a sitting position while taking a nap or sleeping may have a narrower upper airway. The aim of this study was to evaluate if snoring in a sitting position is a predictor of OSA in patients.

Method

We prospectively enrolled 166 SS+ (with a history of snoring in a sitting position) subjects and 139 SS? (who denied having a history of snoring in a sitting position) patients. All of the participants received questionnaires as well as a standard polysomnography thereafter.

Result

Patients with self-reported snoring in a sitting position (with a tilt position greater than 70°, SS+ group) had a higher body mass index as well as greater neck, waist, and buttock circumference and scored higher on the Epworth Sleepiness Scale. During the polysomnographic study, the SS+ group had a higher percentage of N1 sleep and lower percentage of N2 sleep. In addition, the SS+ group had a higher apnea–hypopnea index (AHI) as well as higher arousal index and oxygen desaturation index. The sensitivity and specificity of the SS+ group for OSA (defined as AHI?≥?5) were 0.59 and 0.73, respectively, with a positive predictive value of 0.93. The likelihood ratio was 2.2. On the other hand, the sensitivity and specificity of the SS+ group for moderate to severe OSA (defined as AHI?≥?15) were 0.82 and 0.48, respectively. Both SS+ and greater neck circumference have a high likelihood ratio for diagnosing OSA.

Conclusion

In the present study, the symptoms of self-reported snoring in a sitting position and greater neck circumference can be useful clinical predictors of OSA in Chinese patients.     

A pilot validation study for the NOX T3TM portable monitor for the detection of OSA

Purpose

The aim of the current pilot study is to compare the diagnostic accuracy of the NOX T3^TM (T3) portable sleep monitor (PM) to that of simultaneously recorded in-lab polysomnogram (PSG).

Methods

A total of 40 participants were recruited following face-to-face evaluation at a sleep disorders clinic. Each participant wore both PSG and PM equipment simultaneously during their in-lab PSG. PSG records were manually scored using the American Academy of Sleep Medicine (AASM) criteria, and PM records were double-scored using the device’s autoscore algorithm as well as manual scoring.

Results

The final sample consisted of 32 participants (56 % male, 50 % black) with a mean ESS, BMI, and apnea–hypopnea index (AHI) of 10.4, 32.8, and 16.3, respectively. Three participants (7.5 %) were excluded for poor PM signal quality. Mean AHI derived from the T3’s autoscore algorithm was similar to that from manual scoring (19.6 ± 18.9 vs. 18.6 ± 19.1, respectively). Autoscore-derived T3 AHI and PSG-derived AHI were strongly related (r = .93). The T3 (autoscored AHI) demonstrated a high degree of sensitivity for the presence of obstructive sleep apnea syndrome (OSA; 100 %) and acceptable specificity for the exclusion of OSA using an AHI cutoff of ≥5 events/h (70 %). The unit (autoscored) had a high degree of both sensitivity (92 %) and specificity (85 %) when the presence of OSA was defined more conservatively (AHI > 15 events/h). For OSA defined as an AHI of ≥5, the T3 (autoscored) correctly identified 88 % of positive cases and 100 % of negative cases.

Conclusions

In this small, clinic-based sample, the T3 demonstrated very good measurement agreement compared to PSG and a high degree of sensitivity for detecting even mild OSA. False positives appeared to be due to respiratory effort-related arousals (RERAs) being autoscored as obstructive apneas and may be due to inherent discrepancy in flow measurement sensitivity between PSG and portable monitors.     

Postoperative complications in obstructive sleep apnea

Study objectives

This study was conducted to determine whether postoperative complications are increased in patients with obstructive sleep apnea (OSA) and to study the impact of the severity of OSA and preoperative use of continuous positive airway pressure (CPAP) on the postoperative outcome.

Design and setting

This study is retrospective in nature and was undertaken at the VA Medical Center.

Participants and methods

Three hundred seventy patients who had undergone both a major surgical procedure and a sleep study from 2000 to 2010 were identified. Patients were divided into four groups: OSA negative (apnea–hypopnea index (AHI)?<?5/h), OSA positive; mild: AHI 5 to <15/h; moderate: AHI 15 to <30/h; and severe: AHI?≥?30/h. No intervention was made during the course of the study. Postoperative complications namely respiratory, cardiac, neurological, and unplanned intensive care unit transfers were collected.

Results

There were 284 (76.8 %) patients having OSA and 86 (23.2 %) without OSA. The overall incidence of total complications was significantly higher in the OSA patients compared with the control patients (48.9 vs. 31.4 %; odds ratio 2.09, 95 % CI 1.25–3.49). There was no significant difference in total complications between those using and not using CPAP prior to hospitalization. Patients with sleep apnea had a higher incidence of respiratory complications compared to patients without sleep apnea (40.4 vs. 23.2 %; odds ratio 2.24, 95 % CI 1.29–3.90). There was no significant difference in major cardiac complications in the OSA patients compared with the control patients (13.0 vs. 9.3 %; odds ratio 1.46, 95 % CI 0.65–3.26).

Conclusion

OSA is associated with a significantly increased rate of postoperative complications.     

Positional therapy in the management of positional obstructive sleep apnea—a review of the current literature

More than 50% of obstructive sleep apnea (OSA) patients have worsening of their OSA in the supine position (positional obstructive sleep apnea [POSA], commonly defined as supine to non-supine apnea hypopnea index (AHI) ratio of ≥ 2). Positional therapy (PT) aims to prevent patients from sleeping in the supine position. One of the major limiting factors to the routine use of PT in clinical practice is the lack of validated tools to measure compliance objectively. Furthermore, there are no universal guidelines to determine if PT will be effective as standalone or as adjunctive therapy. This paper assesses recent literature on PT demonstrating its effectiveness in management of POSA. It also outlines the proposed subclassification systems for POSA. Electronic literature review was done on EMBASE. Since the last review of PT by Ravesloot et al. (2012), ten studies were identified which demonstrate effectiveness of PT in POSA. We found three publications proposing different subclassification systems for POSA. There were three studies validating different compliance monitoring tools for PT. One study showed the cost benefits of incorporating PT into OSA management. Positional therapy is an effective treatment for POSA and progress has been made in development of tools for measuring compliance. Creating a subclassification of POSA may help develop targeted therapy for patients and determine its use as standalone or adjunct therapy. The integration of PT into POSA management may be cost-effective when compared to the use of CPAP alone.     

Usefulness of the Berlin Questionnaire to identify patients at high risk for obstructive sleep apnea: a population-based door-to-door study

Background

The Berlin Questionnaire (BQ) is a useful tool to identify the high-risk group for obstructive sleep apnea (OSA) in the primary care sites or hospital, but the usefulness of the BQ to identify the high-risk group for OSA in the general population has not been evaluated. The purpose of our study was to develop the Korean version of the BQ (KBQ) and evaluate the usefulness of the BQ in identifying patients with OSA in the general population.

Methods

A total of 1,305 subjects were included in a population-based door-to-door cross-sectional study. For validation of the KBQ, an overnight polysomnography (PSG) was performed on 101 subjects who were randomly selected considering their age, sex, and risk group classification at a controlled sleep laboratory.

Results

The KBQ showed a relatively good to excellent internal consistency (Cronbach’s α correlation 0.64–0.78) and test–retest reliability (intraclass correlation 0.92). The apnea–hypopnea index (AHI) was significantly correlated with the scores in each category and the total scores of the KBQ. In addition, high risk grouping based on the KBQ predicted an AHI?≥?5 with a sensitivity of 0.69 and a specificity of 0.83. According to the risk categorization based on the KBQ, 26.1 % subjects were in the high-risk group for OSA which was similar to the prevalence of OSA in a previous large epidemiological study using PSG in Korea.

Conclusion

This is the first study to confirm the usefulness of the BQ as a screening tool for OSA by prioritizing subjects at high risk for OSA in the general population.     

Nocturnal hypoxemia biomarker predicts sleepiness in patients with severe obstructive sleep apnea

Purpose

This study aims to assess the association between excessive daytime sleepiness (EDS) and variables extracted from the pulse-oximetry signal obtained during overnight polysomnography.

Methods

A cross-sectional design was used to study the relation between four hypoxemia variables and EDS as determined by Epworth Sleepiness Scale scores (ESSS) in 200 consecutive patients, newly diagnosed with obstructive sleep apnea (OSA), as defined by an apnea–hypopnea index (AHI)?≥?15. Hypoxemia measurements were compared between sleepy (ESSS?≥?10) and nonsleepy (ESSS?<?10) patients before and after dichotomizing the cohort for each hypoxemia variable (and for AHI) such that there were 35 (165) patients in each of the corresponding higher (lower) subcohorts. The hypoxemia variables were combined into a biomarker, and its accuracy for predicting sleepiness in individual patients was evaluated. We planned to interpret prediction accuracy above 80 % as evidence that hypoxemia predicted EDS.

Results

Hypoxemia was unassociated with sleepiness in OSA patients with AHI in the range of 15 to 50. In patients with AHI?>?50, the hypoxemia biomarker (but not individual hypoxemia variables) predicted sleepiness with 82 % accuracy.

Conclusion

Nocturnal hypoxemia as determined by a polyvariable biomarker reliably predicted EDS in patients with severe OSA (AHI?>?50), indicating that oxygen fluctuation had a direct role in the development of EDS in patients with severe OSA.     

Influence of the right- versus left-sided sleeping position on the apnea-hypopnea index in patients with sleep apnea

Purpose

Sleep and sleep position have a significant impact on physical, cardiac and mental health, and have been evaluated in numerous studies particularly in terms of lateral sleeping positions and their association with diseases. We retrospectively examined the relationship between the sleeping position and position-specific apnea-hypopnea index (AHI) in obstructive sleep apnea-hypopnea (OSA) patients.

Methods

We assessed the sleeping body position and the body position-specific AHI score in patients who were referred for suspected OSA and underwent diagnostic nocturnal polysomnography. In order to eliminate inter-individual differences, only those who had a similar percentage of time spent in the LSSP and RSSP for each patient were enrolled. To provide this validity, only subjects that had a similar percentage of left and right lateral sleep time (±10%) were included in the analysis.

Results

A total of 864 patients had nocturnal diagnostic PSG. Of them, 131 patients met the inclusion criteria. The percent rate spent in the supine sleeping position (SSP) was 31.3?±?18.7%, in the LSSP was 31.8?±?10% and in the RSSP was 32.6?±?10.8%. Whereas the SSP-specific AHI score was the highest with 60.4?±?36.2/h among all the sleeping position-specific AHI scores (p?<?0.001), the LSSP-specific AHI score was statistically higher than that for RSSP (30.2?±?32.6/h vs. 23.6?±?30.1/h; p?<?0.001). When comparing individuals sub-grouped based on OSA severity, there was a statistically significant difference between the LSSP-specific AHI score and RSSP-specific AHI score in patients with severe (p?=?0.002) and moderate (p?=?0.026), but not mild (p?=?0.130) OSA.

Conclusion

We found that the sleeping position had a significant influence on apneic events and RSSP decreased the frequency of obstructive respiratory events in patients with moderate and severe disease.