Pharyngeal size in snorers, nonsnorers, and patients with obstructive sleep apnea

Co-existence of OSA and respiratory diseases and the influence of gender

INTRODUCTION

Sleep-disordered breathing (SDB), especially obstructive sleep apnea (OSA), is commonly associated with respiratory diseases, such as COPD, asthma and interstitial lung disease.

AREAS COVERED

This narrative review aims to comprehensively synthesize the existing information on SDB in respiratory diseases, investigate the role of gender in this association, and highlight the importance of OSA management in improving sleep, quality of life, and disease prognosis in these specific patient populations.

EXPERT OPINION

Research indicates a synergistic link between OSA and chronic respiratory diseases, which leads to greater morbidity and mortality compared to each disorder alone. Given the lack of an optimal OSA screening tool for these patients, a comprehensive patient approach and overnight diagnostic sleep study are imperative. Despite the limited evidence available, it seems that gender has an impact on the prevalence, severity, and susceptibility of this coexistence. Recognizing the role of gender in the coexistence of OSA and other respiratory diseases can enhance everyday medical practice and enable clinicians to adopt a more personalized approach toward optimal screening and diagnosis of these patients.

Prevalence and clinical impacts of obstructive sleep apnea in patients with idiopathic pulmonary fibrosis: A single-center, retrospective study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease with chronic, progressive lung fibrosis with a poor prognosis. Recent studies have reported a high prevalence of obstructive sleep apnea (OSA) in IPF patients and an association with poor prognosis. This study aimed to evaluate the prevalence, risk factors, and clinical effects on mortality of OSA in patients with IPF.

METHODS

Clinical data were retrospectively analyzed in 167 patients with IPF at Haeundae-Paik Hospital, Republic of Korea. A type 4 portable device was used to monitor OSA, and an apnea-hypopnea index of 5 events per sleep hour and above was diagnosed as OSA.

RESULTS

The mean follow-up period and age were 26.9 months and 71.4 years, respectively, with male predominance. OSA was confirmed in 108 patients (64.7%). Mild OSA was the most common (62.1%). Independent risk factors for OSA in the multivariate logistic regression analysis were age (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.02-1.13, p = 0.007), body weight (OR 1.05, 95% CI 1.02-1.09, p = 0.002), and risk based on the Berlin questionnaire (OR 2.76, 95% CI 1.12-6.80, p = 0.028). Shorter six-minute walk distance (6MWD) (hazard ratio [HR] 1.00, 95% CI: 1.00-1.00, p < 0.001), acute exacerbation (AE) (HR 13.83, 95% CI: 5.71-33.47, p < 0.001), and higher percentage of cumulative time with oxygen saturation below 90% in total sleep time (HR 1.08, 95% CI: 1.02-1.14, p = 0.007) were risk factors for mortality in IPF patients in the Cox regression analysis.

CONCLUSION

Approximately two-thirds of the IPF patients had OSA. Older age, higher body weight, and high risk based on the Berlin questionnaire were independent risk factors for OSA in IPF patients. Shorter 6MWD, experience of AE, and night hypoxemia during sleep were associated with a higher risk of mortality in patients with IPF.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Determinants of awake oropharyngeal volume reduction between sitting and supine positions in children evaluated for snoring

Pharyngeal collapsibility is a major determinant of obstructive sleep apnea (OSA) pathophysiology, but its anatomical predictors in children are largely unknown. We hypothesised that anatomical (tonsillar hypertrophy, narrow palate, nasal obstruction, dental/skeletal malocclusion, obesity) and OSA-related (apnea-hypopnea index, AHI) parameters could be related to a measure of awake pharyngeal collapsibility. We performed acoustic pharyngometry in children evaluated for suspected OSA, allowing us to measure the reduction of oropharyngeal volume in supine versus sitting position normalised for the volume in supine position (ΔV%), a measure of pharyngeal collapsibility. In addition to polysomnography and a clinical examination (anatomical parameters), acoustic rhinometry was used to assess nasal obstruction. A total of 188 snoring children were included, 118 (63%) of whom were obese and 74 (39%) of whom had moderate to severe OSA (AHI ≥5/h). The median (25th-75th percentiles) ΔV% in the whole population was 20.1% (4.7; 43.3). ΔV% was independently and positively associated with AHI (p = 0.023), z-score of BMI (p = 0.001), tonsillar hypertrophy (p = 0.007), narrow palate (p = 0.035), and African (p < 0.001) ancestry. By contrast, ΔV% was not modified by dental or skeletal malocclusion, Friedman palate position class or nasopharyngeal obstruction. Tonsillar hypertrophy, obesity, narrow palate and African ancestry are independently associated with an increase in pharyngeal collapsibility in snoring children, thus increasing the risk of OSA. Increased pharyngeal compliance in African children may explain the increased risk of residual OSA after adenotonsillectomy observed in this population.

Usefulness of Hard Palate Measurements in Predicting Airway Dimensions in Patients Referred for Cone Beam CT

Purpose:

The aim of the study was to evaluate the usefulness of hard palate measurements in predicting airway dimensions in patients referred for cone-beam CT (CBCT).

Materials and Methods:

Six hundred forty-three patients (239 males and 404 females) were examined by CBCT. Using dedicated CBCT software (Kodak CS 3D imaging version 3.8.6, Carestream, Rochester, NY, USA); different hard palate (palatal interalveolar length, palatal arch depth, maxillo-palatal arch angle, and alveolar width) and airway measurements (airway volume, minimum cross-sectional area, minimum anteroposterior distance, minimum right to left distance and airway length) were obtained and correlated using Pearson’s correlation coefficients and regression analysis.

Results:

Although the correlation between hard palate and airway measurements was weak (Pearson coefficient (r) < 0.40), there were significant (P < 0.05) additive effects for hard palate measurements in predicting airway dimensions. Maxillo-palatal arch angle was the only hard palate measurement that had no effect in predicting airway dimensions.

Conclusion:

Hard palate measurements are considered useful in predicting airway dimensions in patients referred for CBCT.

Acoustic pharyngometry - A new method to facilitate oral appliance therapy

Background

There is lack of reliable and accurate methods to predict treatment outcomes of oral appliance (OA) treatment. Acoustic pharyngometry (AP) is a non‐invasive technique to evaluate the volume and minimal cross‐sectional area of the upper airway, which may prove useful to locate the optimal position of OAs.

Objective

This retrospective study aimed to evaluate the effect of applying AP to OA treatment of patients with obstructive sleep apnoea (OSA).

Methods

All patients (n = 244) treated with OAs following an AP protocol at two dental clinics between 2013 and 2018 were invited to participate. A total of 129 patients accepted the invitation, and 120 patients (75 men, 45 women) were included in the analyses. Mean baseline age, BMI and apnoea hypopnea index (AHI) were 59.1 ± 0.9 years, 27.8 ± 0.4 and 21.9 ± 1.1, respectively. Mean follow‐up time was 318 ± 24 days.

Results

AHI at follow‐up was 6.4 ± 0.7, resulting in a treatment success rate of 86.7% (≥50% reduction of baseline AHI). The number of failures (<50% reduction of baseline AHI) did not differ significantly among patients with mild, moderate and severe OSA. 87.6% of the patients reported OA usage every night, and 95.5% reported > 5 hours usage per night, when worn.

Conclusion

The AP protocol applied seems to contribute to the excellent effect of OA treatment in this study. Further research on the application of AP in OA treatment is necessary in order to clarify its possible beneficial contribution to improving OA therapy.

Obstructive sleep apnea in patients with interstitial lung disease: Prevalence and predictive factors

Interstitial lung diseases (ILDs) are chronic, progressive, parenchymal lung diseases with high morbidity and mortality. In recent studies, the prevalence of obstructive sleep apnea (OSA) in patients with ILD has been reported to be high. However, the prevalence and predictive factors of OSA in Korean ILD patients are not well defined. Therefore, the aim of this study was to evaluate the prevalence and predictive factors of OSA in Korean patients with ILD. Clinical data from 86 patients with ILD enrolled from December 2017 to April 2019 at Haeundae-Paik Hospital, Busan, South Korea, were retrospectively analyzed. OSA was monitored with a level 4 portable device and defined as an apnea-hypopnea index of more than 5 per hour of sleep. The median follow-up period was 7 months. The mean age was 69.8 years, and 64% of participants were men. Among the ILDs, idiopathic pulmonary fibrosis (IPF) was the most common (66.3%), followed by connective tissue disease-associated ILD (16.3%) and cryptogenic organizing pneumonia (5.8%). Forty-six ILD patients (53.5%) were diagnosed with OSA, and IPF patients had OSA more frequently (64.9% vs. 31.0%, p = 0.003) than those with other ILDs. Older age (odds ratio [OR], 1.11, 95% CI 1.04-1.19, p = 0.002), higher body weight (OR 1.05, 95% CI 1.01-1.10, p = 0.012), and diabetes mellitus (OR 4.03, 95% CI 1.26-12.91, p = 0.019) were independent risk factors for OSA in the multivariable logistic regression analysis. In the multivariable Cox analysis, an IPF diagnosis was a significant risk factor for one-year mortality (hazard ratio [HR] 7.92, 95% CI: 1.01-61.83, p = 0.048) in ILD patients; however, OSA was not. In conclusion, half of Korean patients with ILD had OSA. Older age, higher body weight, and diabetes mellitus were risk factors for OSA in patients with ILD.

Self-reported Snoring Patterns Predict Stroke Events in High-Risk Patients With OSA: Post Hoc Analyses of the SAVE Study

BACKGROUND

The relation of snoring to risks of stroke and other major cardiovascular (CV) events is uncertain.

RESEARCH QUESTION

We aimed to determine associations of snoring patterns and major CV events in relation to OSA among participants of the international Sleep Apnea cardiovascular Endpoints (SAVE) trial.

STUDY DESIGN AND METHODS

Post hoc analyses of the SAVE trial, which involved 2,687 patients with coexisting moderate-to-severe OSA and established coronary or cerebral CV disease, who were randomly allocated to CPAP treatment plus usual care or usual care alone, and followed-up for a median 3.5 years. Associations of self-reported snoring patterns (frequency and loudness) and breathing pauses collected on the Berlin questionnaire at baseline and multiple times during follow-up, and adjudicated composites of CV outcomes (primary, CV death, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for unstable angina, heart failure, or transient ischemic attack; and separately of cardiac and cerebral events), were evaluated in time-dependent Cox proportional hazards models adjusted for various confounders including the apnea-hypopnea index.

RESULTS

Increase (per category) of snoring frequency (adjusted hazard ratio [HR], 1.10; 95% CI, 1.02-1.20; P = .015), loudness (HR, 1.16; 95% CI, 1.06-1.27; P = .001), and breathing pauses (HR, 1.16; 95% CI, 1.08-1.25; P < .001) at any time point during follow-up were each associated with the primary composite CV outcome. These associations were driven by significant associations for cerebral rather than cardiac events, and positive interactions between the three snoring patterns for cerebral events. There was no significant interaction between CPAP treatment and snoring variables for cerebral events.

INTERPRETATION

Snoring in patients with OSA with established CV disease is associated with greater risks of cerebral but not cardiac events, independent of CPAP treatment and frequency of apnea and hypopnea events.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00738179; URL: www.clinicaltrials.gov.

Efficacy of continuous positive airway pressure on subcutaneous adipose tissue in patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials

PURPOSE

It remains inconclusive whether continuous positive airway pressure (CPAP) therapy can significantly reduce subcutaneous adipose tissue (SAT) in patients with obstructive sleep apnea (OSA). This meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the impact of CPAP treatment on SAT in patients with OSA.

METHODS

We searched Pubmed, Cochrane, Web of Science, and Embase for RCTs, which investigated the effectiveness of CPAP treatment in reducing SAT among patients with OSA. Following the PRISMA guidelines, we extracted information on the study and patient characteristics, and pre- and post-CPAP measures of SAT. We then calculated the overall effects using the standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

A total of 5 RCTs (comprising 153 patients) met inclusion criteria for the meta-analysis. We found that the SAT did not change before and after CPAP treatment in patients with OSA (SMD = - 0.02, 95% CI - 0.25 to 0.2, z = 0.19, p = 0.85). Subgroup analyses indicated that the outcome was not affected by age, CPAP therapy duration, baseline body mass index, and measure utilized.

CONCLUSION

This meta-analysis of RCTs suggests that CPAP therapy does not significantly decrease the level of SAT among patients with OSA. Further large-scale, and high-quality randomized controlled trials are needed to better address this issue.

Obstructive sleep apnea in patients with interstitial lung disease: Prevalence and predictive factors

Interstitial lung diseases (ILDs) are chronic, progressive, parenchymal lung diseases with high morbidity and mortality. In recent studies, the prevalence of obstructive sleep apnea (OSA) in patients with ILD has been reported to be high. However, the prevalence and predictive factors of OSA in Korean ILD patients are not well defined. Therefore, the aim of this study was to evaluate the prevalence and predictive factors of OSA in Korean patients with ILD. Clinical data from 86 patients with ILD enrolled from December 2017 to April 2019 at Haeundae-Paik Hospital, Busan, South Korea, were retrospectively analyzed. OSA was monitored with a level 4 portable device and defined as an apnea-hypopnea index of more than 5 per hour of sleep. The median follow-up period was 7 months. The mean age was 69.8 years, and 64% of participants were men. Among the ILDs, idiopathic pulmonary fibrosis (IPF) was the most common (66.3%), followed by connective tissue disease-associated ILD (16.3%) and cryptogenic organizing pneumonia (5.8%). Forty-six ILD patients (53.5%) were diagnosed with OSA, and IPF patients had OSA more frequently (64.9% vs. 31.0%, p = 0.003) than those with other ILDs. Older age (odds ratio [OR], 1.11, 95% CI 1.04-1.19, p = 0.002), higher body weight (OR 1.05, 95% CI 1.01-1.10, p = 0.012), and diabetes mellitus (OR 4.03, 95% CI 1.26-12.91, p = 0.019) were independent risk factors for OSA in the multivariable logistic regression analysis. In the multivariable Cox analysis, an IPF diagnosis was a significant risk factor for one-year mortality (hazard ratio [HR] 7.92, 95% CI: 1.01-61.83, p = 0.048) in ILD patients; however, OSA was not. In conclusion, half of Korean patients with ILD had OSA. Older age, higher body weight, and diabetes mellitus were risk factors for OSA in patients with ILD.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-analysis

BACKGROUND

Perioperative diagnosis of obstructive sleep apnea (OSA) has important resource implications as screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. Ultrasound (US) is a portable, noninvasive tool potentially useful for airway evaluation and OSA screening in the perioperative period. The objective of this systematic review was to evaluate the correlation of surface US with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help with improved screening in perioperative period.

METHODS

A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface US assessment. Article screening, data extraction, and summarization were conducted by 2 independent reviewers with ability to resolve conflict with supervising authors. Diagnostic properties and association between US parameters (index test) and OSA diagnosis using sleep study (reference standard) were evaluated. The US parameters were divided into airway and nonairway parameters. A random-effects meta-analysis was planned, wherever applicable.

RESULTS

Of the initial 3865 screened articles, 21 studies (7 airway and 14 nonairway) evaluating 3339 patients were included. Majority of studies were conducted in the general population (49%), respirology (23%), and sleep clinics (12%). No study evaluated the use of US for OSA in perioperative setting. Majority of included studies had low risk of bias for reference standard and flow and timing. Airway US parameters having moderate-good correlation with moderate-severe OSA were distance between lingual arteries (DLAs > 30 mm; sensitivity, 0.67; specificity, 0.59; 1 study/66 patients); mean resting tongue thickness (>60 mm; sensitivity, 0.85; specificity, 0.59; 1 study/66 patients); tongue base thickness during Muller maneuver (MM; sensitivity, 0.59; specificity, 0.78; 1 study/66 patients); and a combination of neck circumference and retropalatal (RP) diameter shortening during MM (sensitivity, 1.0; specificity, 0.65; 1 study/104 patients). Nonairway US parameters having a low-moderate correlation with moderate-severe OSA were carotid intimal thickness (pooled correlation coefficient, 0.444; 95% confidence interval [CI], 0.320-0.553; P value = .000, 8 studies/727 patients) and plaque presence (sensitivity, 0.24-0.75; specificity, 0.13-1.0; 4 studies/1183 patients).

CONCLUSIONS

We found that a number of airway and nonairway parameters were identified with moderate to good correlation with OSA diagnosis in the general population. In future studies, it remains to be seen whether PoCUS screening for a combination of these parameters can address the pitfalls of OSA screening questionnaires.

Utility of acoustic pharyngometry for screening of obstructive sleep apnea

OBJECTIVE

To determine whether combining acoustic pharyngometric parameters with cephalometric and clinical parameters could improve the predictive power for significant obstructive sleep apnea (OSA) in a Korean population.

METHODS

A total of 229 consecutive adult patients with suspected OSA were enrolled. The predictability for significant OSA using acoustic pharyngometric or cephalometric parameters or combining these parameters and clinical factors was calculated and compared using multivariate logistic regression and receiver operating characteristic (ROC) curves.

RESULTS

In multivariate logistic regression, age, sex, minimum upper airway cross-sectional area (UA-CSA), and mandibular plane to hyoid distance (MPH) were all significant independent predictors of significant OSA. The minimum UA-CSA of 0.85 cm² provided fair discrimination for OSA [area under the curve (AUC): 0.60, 95% confidence interval (CI): 0.52-0.67]. The MPH of 18.75 mm provided fair discrimination for OSA (AUC; 0.65, 95% CI: 0.58-0.72). The discriminative ability of the final model of multivariate ROC curve analyses that included the minimum UA-CSA, age, sex, body mass index (BMI), and MPH was better than the minimum UA-CSA alone (AUCs: 0.77 vs. 0.60). Optimal cut-off values of predictors for discriminating significant OSA were as follows: male for sex, 40 years for age, 25.5 kg/m² for BMI, 1.06 cm² for minimum UA-CSA, and 18 mm for MPH.

CONCLUSION

Minimum UA-CSA measured using acoustic pharyngometry while sitting might be a useful method to predict OSA. Combining minimum UA-CSA with age, sex, BMI and MPH improved the predictive value for significant OSA.

The Presence of Snoring as Well as its Intensity Is Underreported by Women

STUDY OBJECTIVES

Women are underrepresented and thus sleep conditions are underdiagnosed at sleep clinics that evaluate sleep-disordered breathing. The most common sign of obstructive sleep apnea (OSA) is snoring; therefore, it is one of the main red flags for suspected OSA. The aim of this study is to determine whether self-reported snoring and snoring intensity by women and men correlates with snoring volume measured objectively during sleep laboratory study.

METHODS

Consecutive patients who were referred to a polysomnography (PSG) study in a university hospital over a 2-year period had their snoring volume quantified by means of a calibrated digital sound survey meter. Participants were given a questionnaire in which they were asked to rate the severity of their snoring. The correlation between objective snoring intensity as measured during PSG and the self-reported snoring intensity was evaluated.

RESULTS

A total of 1,913 patients were enrolled in the study. A positive correlation was found between objectively measured snoring intensity and the intensity listed by each participant in the questionnaire. Measurement of the volume of snoring revealed that women snored as loudly as men; however, 28% of the females (189/675) considered themselves to be nonsnorers compared to only 6.9% of men (P < .05). Furthermore, 36.5% of women (69/189) who reported themselves as nonsnorers turned out to have severe or very severe snoring intensity, whereas, in contrast, only 11.7% of men (10/85) of men had this discrepancy. These findings are in concordance with the finding that fewer women quantified their snoring as very severe or severe (38.4%), significantly less than men of whom 61.5% reported their snoring to be severe or very severe.

CONCLUSIONS

In a population of individuals referred to a PSG study, although no difference in snoring intensity was found between sexes, women tend to underreport the fact that they snore and to underestimate the loudness of their snoring. Improved awareness of this discrepancy may increase women's access to sleep laboratories, and improve diagnostic rates of sleep apnea in females.

Obstructive Sleep Apnea and Subclinical Interstitial Lung Disease in the Multi-Ethnic Study of Atherosclerosis (MESA)

RATIONALE

Obstructive sleep apnea (OSA) has been postulated to contribute to idiopathic pulmonary fibrosis by promoting alveolar epithelial injury via tractional forces and intermittent hypoxia.

OBJECTIVES

To determine whether OSA is associated with subclinical interstitial lung disease (ILD) and with biomarkers of alveolar epithelial injury and remodeling.

METHODS

We performed cross-sectional analyses of 1,690 community-dwelling adults who underwent 15-channel in-home polysomnography and thoracic computed tomographic imaging in the Multi-Ethnic Study of Atherosclerosis. We measured the obstructive apnea-hypopnea index (oAHI) by polysomnography and high-attenuation areas (HAAs) and interstitial lung abnormalities (ILAs) by computed tomography. Serum matrix metalloproteinase-7 (MMP-7) and surfactant protein-A (SP-A) were measured by ELISA in 99 participants. We used generalized linear models to adjust for potential confounders.

RESULTS

The mean age was 68 years, and the mean forced vital capacity was 97% predicted. The median oAHI was 8.4 events/h, and 32% had an oAHI greater than 15. After adjusting for demographics, smoking, and center, an oAHI greater than 15 was associated with a 4.0% HAA increment (95% confidence interval [CI], 1.4-6.8%; P = 0.003) and 35% increased odds of ILA (95% CI, 13-61%; P = 0.001). However, there was evidence that these associations varied by body mass index (BMI) (P for interaction = 0.08 and 0.04, respectively). Among those with a BMI less than 25 kg/m², an oAHI greater than 15 was associated with a 6.1% HAA increment (95% CI, 0.5-12%; P = 0.03) and 2.3-fold increased odds of ILA (95% CI, 1.3-4.1; P = 0.005). Among those with a BMI greater than 30 kg/m², an oAHI greater than 15 was associated with 1.8-fold greater odds of ILA (95% CI, 1.1-2.9; P = 0.01) but was not associated with HAA. There were no meaningful associations detected among those with a BMI of 25-30 kg/m². Greater oAHI was associated higher serum SP-A and MMP-7 levels, particularly among those with a BMI less than 25 kg/m².

CONCLUSIONS

Moderate to severe OSA is associated with subclinical ILD and with evidence of alveolar epithelial injury and extracellular matrix remodeling in community-dwelling adults, an association that is strongest among normal-weight individuals. These findings support the hypothesis that OSA might contribute to early ILD.

Volumetric Changes to the Pharynx in Healthy Aging: Consequence for Pharyngeal Swallow Mechanics and Function

Pharyngeal lumen volume is prone to increase as a consequence of pharyngeal muscle atrophy in aging. Yet, the impact of this on swallowing mechanics and function is poorly understood. We examined the relationship between pharyngeal volume and pharyngeal swallowing mechanics and function in a sample of healthy community-dwelling seniors. Data were collected from 44 healthy seniors (21 male, mean age = 76.9, SD = 7.1). Each participant swallowed 9 boluses of barium (3 × 5 ml thin, 3 × 20 ml thin, 3 × 5 ml nectar). Pharyngeal shortening, pharyngeal constriction, pyriform sinus and vallecular residue were quantified from lateral view videofluorosopic swallowing studies. Pharyngeal lumen volume was captured during an oral breathing task with acoustic pharyngometry. In addition, within-participant measures of strength and anthropometrics were collected. Four linear mixed effects regression models were run to study the relationship between pharyngeal volume and pharyngeal constriction, pharyngeal shortening, pyriform sinus residue, and vallecular residue while controlling for bolus condition, age, sex, and posterior tongue strength. Increasing pharyngeal lumen volume was significantly related to worse constriction and vallecular residue. In general, larger and thicker boluses resulted in worse pharyngeal constriction and residue. Pharyngeal shortening was only significantly related to posterior tongue strength. Our work establishes the utility of acoustic pharyngometry to monitor pharyngeal lumen volume. Increasing pharyngeal lumen volume appears to impact both pharyngeal swallowing mechanics and function in a sample of healthy, functional seniors.

Gender differences in morphological and functional outcomes after mandibular setback surgery

PURPOSE

The aim of this study was to examine and compare morphological and functional outcomes after either isolated mandibular setback or bimaxillary surgery in males and females.

MATERIALS AND METHODS

A retrospective study was done on 52 patients, in whom surgical correction for mandibular prognathism was performed either by isolated mandibular setback (30 cases) or by bimaxillary surgery (22 cases). Morphological changes were studied using cephalograms and functional changes studied using impulse oscillometry (IOS) taken before surgery (T0), 3 months (T1) and 1 year after surgery (T2). Also 3% oxygen desaturation index (ODI) was measured at T0 and T2.

RESULT

Posterior airway space decreased significantly in both groups and both sexes but more so in males after mandibular setback surgery and in females after bimaxillary surgery. Changes in supine R20 (central airway resistance at 20 Hz) and supine R5 (total airway resistance at 5 Hz) in IOS statistically significantly increased in the period T0-T1 in males compared with females after mandibular setback surgery (p < 0.05).

CONCLUSION

Gender dimorphism is present according to morphological and functional outcomes, with males at a higher risk for obstructive sleep apnea (OSA) after mandibular setback surgery and females after bimaxillary surgery; however, compensatory changes act as a barrier against this.

Sleep-disordered breathing in heart failure: facts and numbers

Sleep‐disordered breathing has a high prevalence in the general population, but is especially prominent in patients with heart failure (HF). HF and sleep‐disordered breathing share a bidirectional relationship, with sleep‐disordered breathing being both cause and effect of poor cardiac functioning. The high inter‐individual variability of symptom presentation can impede the clinical diagnostic process. Polysomnography is the gold‐standard method of diagnosing sleep‐disordered breathing. Therapy of sleep‐disordered breathing should always consist of optimizing the treatment of the underlying disorder of HF. Additional therapeutic measures include continuous positive airway pressure ventilation therapy. New therapeutic options using neurostimulation are yielding promising results; however, long‐term benefits still need to be confirmed.

Obstructive sleep apnoea and related comorbidities in incident idiopathic pulmonary fibrosis

The objectives of this prospective study were: 1) to determine the prevalence and determinants of obstructive sleep apnoea (OSA) in patients with newly diagnosed idiopathic pulmonary fibrosis (IPF); 2) to determine whether OSA was associated with cardiovascular disease (CVD) as well as increased oxidative stress and levels of IPF biomarkers in the blood.

A group of 45 patients with newly diagnosed IPF attended polysomnography. The prevalence of CVD and the severity of coronary artery calcification were investigated by high-resolution computed tomography. The levels of 8-hydroxydeoxyguanosine (8-OH-DG) and various IPF biomarkers in the blood were compared between patients with no or mild OSA (apnoea–hypopnoea index (AHI) <15 events·h−1), with moderate OSA (15 ≤AHI <30 events·h−1) and with severe OSA (AHI ≥30 events·h−1).

The prevalence of moderate-to-severe OSA and severe OSA was 62% and 40%, respectively. AHI did not correlate with demographic or physiological data. All patients with severe OSA had a medical history of CVD,versus41.2% and 40% of those with no or mild OSA, or with moderate OSA, respectively (p<0.0001). Ischaemic heart disease (IHD) and moderate-to-severe coronary artery calcifications were strongly associated with severe OSA. The 8-OH-DG and matrix metalloproteinase-7 serum levels were significantly increased in the severe OSA group.

Moderate-to-severe OSA is highly prevalent in incident IPF and severe OSA is strongly associated with the presence of CVD, particularly IHD.

Sleep Apnea and Obstructive Airway Disease in Older Men: Outcomes of Sleep Disorders in Older Men Study

STUDY OBJECTIVES

To evaluate the association between obstructive airway disease (OAD) and sleep apnea in older men.

METHODS

A community-based cross-sectional study of 853 community-dwelling older men (mean age 80.7 ± 4.1 years [range 73 to 90]) across 6 centers in the United States from the Outcomes of Sleep Disorders in Older Men Study. Sleep was objectively measured using full in-home polysomnography and lung function was objectively measured using spirometry. The association of OAD (pre-bronchodilator FEV1/FVC ratio < 0.7 and FEV1 < 80% predicted) and sleep apnea (apnea-hypopnea index [AHI] ≥ 15 events/hour) was assessed using logistic regression.

RESULTS

OAD and sleep apnea were identified in 111 (13.0%) and 247 (29.0%) men, respectively. In univariate analysis, participants with OAD had a lower AHI (mean ± SD; 8.7 ± 11.7 vs. 12.7 ± 13.8, P = 0.0009) and a lower prevalence of sleep apnea (14.4 vs. 31.1%, P = 0.0003) compared to participants without OAD. OAD remained independently associated with a lower odds of sleep apnea (odds ratio 0.30, 95% CI 0.16 to 0.55, P = 0.0001) after adjustment for demographics, body composition, smoking, and potential mediators (arousal index, time spent in rapid eye movement sleep). Individuals with OAD and sleep apnea (n = 16) had an increased arousal index and lower oxygen saturation level as compared to individuals with OAD alone (P values < 0.05).

CONCLUSIONS

Obstructive airway disease was associated with a lower prevalence of sleep apnea in a cohort of community-dwelling elderly men, and unexplained by differences in adiposity or sleep architecture. Although uncommon in this cohort, coexisting sleep apnea and OAD was associated with increased sleep fragmentation and nocturnal oxygen desaturation compared to OAD alone.

Hypervolemia and Sleep Apnea in Kidney Disease

In end-stage renal disease (ESRD) and heart failure, conditions characterized by fluid overload, both obstructive sleep apnea (OSA) and central sleep apnea (CSA) are highly prevalent. This observation suggests that fluid overload may be a unifying mechanism in the pathogenesis of both OSA and CSA in these conditions. An overnight rostral fluid shift from the legs to the neck and lungs has been shown to contribute to the pathogenesis of OSA and CSA, respectively, in various different patient populations. This article reviews the evidence that supports a role for fluid overload and overnight fluid shift in the pathogenesis of sleep apnea in ESRD. The diagnosis, epidemiology, and clinical features of sleep apnea in patients with ESRD also are considered.

Three-dimensional imaging of the upper airway anatomy in obstructive sleep apnea: a systematic review

INTRODUCTION

The pathogenesis of upper airway collapse in people with obstructive sleep apnea (OSA) is not fully understood. The aim of this study was to systematically review the literature in order to assess the most relevant anatomical characteristics of the upper airway related to the pathogenesis of OSA by analyzing the three-dimensional upper airway anatomy.

METHOD

A PICO (population/patient, intervention, comparison, outcome) search strategy, focusing on the upper airway anatomy of people with OSA, was conducted using the following databases: MEDLINE (PubMed), Excerpta Medica database (EMBASE), Web of Science, and Cochrane Library. The studies in which three-dimensional images were made from the participants who were awake and in the supine position during quiet breathing were selected in this systematic review.

RESULTS

Of the 758 unique retrieved studies, eight fulfilled the criteria for this systematic review. The minimum cross-sectional area of the upper airways of people with OSA, which is influenced by many factors such as hard and soft tissues surrounding the upper airway, was significantly smaller than that of those without OSA.

CONCLUSION

Within the limitation of the selected studies, this systematic review suggested that a small minimum cross-sectional area is the most relevant anatomical characteristic of the upper airway related to the pathogenesis of OSA.

Cephalometric norms for the upper airway in a healthy North Indian population

Objective:

The aim was to obtain normative data for cephalometric measurements of the upper airway in the North Indian population.

Design:

Observational study. Setting: University department and teaching hospital out-patient clinic.

Subjects and Methods:

A total of 180 healthy patients were included out of which 90 were males (age range, 8-16 years), and 90 were females (age range, 8-16 years), with normal skeletal facial profile, no history of snoring, sleep apnea, upper airway disease, tonsillectomy or adenoidectomy, obesity, or pathology in the pharynx. Twenty cephalometric airway measurements, including size of the tongue, soft palate, nasopharynx, oropharynx, hypopharynx, and relative position of the hyoid bone and valleculae were obtained. Landmarks on cephalometric radiographs were digitized and measurements were made using a specially designed computer program. Error analysis of measurements was performed and comparison of measurements according to sex was made.

Results:

Significant sex dimorphism was seen for the majority of measurements, with the exception of minimal depth of the airway, oropharyngeal depth of the airway, and the soft palate angle with the hard palate.

Conclusion:

A minimum sagittal dimension of the upper airway was evident despite differences in measurements between sexes. Findings from this study should be a useful reference for the assessment of sleep apnea in the North Indian population.

Evaluation of short-term use of nocturnal nasal continuous positive airway pressure for a clinical profile and exercise capacity in adult patients with obstructive sleep apnea-hypopnea syndrome

BACKGROUND AND AIM

The obstructive sleep apnea-hypopnea syndrome (OSAHS) is a common chronic respiratory disease, characterized by repetitive complete or partial collapse of the upper airway during sleep. The clinical spectrum extends between stoppage of breathing, snoring, daytime somnolence, and fatigue, to serious cardiovascular disease, stroke, metabolic syndrome, increased morbidity, and mortality. We aim to evaluate the short-term use of nasal continuous positive airway pressure (nCPAP) therapy for the clinical profile and exercise capacity of patients with OSAHS.

PATIENT SELECTION

Twenty patients diagnosed with moderate-to-severe OSAHS were enrolled in the study (study group - 15; clinically and PSG-matched control group - 5).

MATERIALS AND METHODS

Each patient was clinically evaluated for sleep-related symptoms, and also assessed with spirometry, the six-minute walk test (6MWT), and a symptom-limited incremental cardiopulmonary exercise test (CPET). The study group patients were administered nCPAP therapy for eight hours each night for four weeks, while the control group patients were just observed. They were re-assessed after four weeks and the data were statistically analyzed between the two groups.

RESULTS

The study group patients showed a significant (P- < 0.05) improvement in the OSAHS symptoms-the Epworth sleepiness score, six-minute walk distance; duration of exercise, power output, peak oxygen uptake, anaerobic threshold, diastolic blood pressure, dyspnea, and fatigue-in comparison with the control group patients. The improvement in exercise capacity following nCPAP therapy was attributed to the relief of disabling the OSAHS symptoms and improved cardiovascular, ventilator, and musculoskeletal functions.

CONCLUSION

All OSAHS patients must be treated with nCPAP.

Heart Failure and Sleep Apnea

Obstructive and central sleep apnea are far more common in heart failure patients than in the general population and their presence might contribute to the progression of heart failure by exposing the heart to intermittent hypoxia, increased preload and afterload, sympathetic nervous system activation, and vascular endothelial dysfunction. There is now substantial evidence that supports a role for fluid overload and nocturnal rostral fluid shift from the legs as unifying mechanisms in the pathogenesis of obstructive and central sleep apnea in heart failure patients, such that the predominant type of sleep apnea is related to the relative distribution of fluid from the leg to the neck and chest. Despite advances in therapies for heart failure, mortality rates remain high. Accordingly, the identification and treatment of sleep apnea in patients with heart failure might offer a novel therapeutic target to modulate this increased risk. In heart failure patients with obstructive or central sleep apnea, continuous positive airway pressure has been shown to improve cardiovascular function in short-term trials but this has not translated to improved mortality or reduced hospital admissions in long-term randomized trials. Other forms of positive airway pressure such as adaptive servoventilation have shown promising results in terms of attenuation of sleep apnea and improvement in cardiovascular function in short-term trials. Large scale, randomized trials are required to determine whether treating sleep apnea with various interventions can reduce morbidity and mortality.

Associated bone mineral density and obstructive sleep apnea in chronic obstructive pulmonary disease

BACKGROUND

Osteoporosis is an important issue for patients with chronic obstructive pulmonary disease (COPD). Worse systemic inflammation and reduced exercise capacity have been reported in COPD patients with obstructive sleep apnea (OSA), implying that OSA may be an independent factor for osteoporosis in COPD patients.

METHODS

A total of 66 patients with bone mineral density (BMD) and polysomnography results from a previous COPD cohort (January 2008 to January 2013) were retrospectively enrolled. Clinical characteristics such as medication, pulmonary function, BMD, and results of polysomnography were analyzed.

RESULTS

The BMD in those with OSA was significantly lower than in those without OSA (-1.99±1.63 versus -1.27±1.14, P=0.045). In univariate analysis, body mass index, forced expiratory volume in 1 second, percentage of predicted value, incremental shuttle walk test, apnea-hypopnea index, and oxygen desaturation index (ODI) were significantly associated with BMD. After multivariate linear regression analysis, the ODI was still an independent factor for BMD. In addition, smaller total lung capacity is significantly associated with higher ODI and lower BMD, which implies that lower BMD might cause severer OSA via decreased total lung capacity.

CONCLUSION

OSA may be an independent factor for BMD in patients with COPD, which implies a possible vicious cycle takes place in these patients.

Sleep disordered breathing in interstitial lung disease: A review

Patients with interstitial lung disease commonly exhibit abnormal sleep architecture and increased sleep fragmentation on polysomnography. Fatigue is a frequent complaint, and it is likely that poor sleep quality is a significant contributor. A number of studies have shown that sleep disordered breathing is prevalent in this population, particularly in the idiopathic pulmonary fibrosis subgroup. The factors that predispose these patients to obstructive sleep apnoea are not well understood, however it is believed that reduced caudal traction on the upper airway can enhance collapsibility. Ventilatory control system instability may also be an important factor, particularly in those with increased chemo-responsiveness, and in hypoxic conditions. Transient, repetitive nocturnal oxygen desaturation is frequently observed in interstitial lung disease, both with and without associated obstructive apnoeas. There is increasing evidence that sleep-desaturation is associated with increased mortality, and may be important in the pathogenesis of pulmonary hypertension in this population.

A randomized, double crossover study to investigate the influence of saline infusion on sleep apnea severity in men

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is commoner in patients with fluid-retaining states than in those without fluid retention, in men than in women, and worsens with aging. In men, OSA severity is related to the amount of fluid shifting out of the legs overnight, but a cause-effect relationship is not established. Our objective was to test the hypothesis that mimicking fluid overload during sleep would increase severity of OSA more in older (≥ 40 years) than in younger men (< 40 years).

DESIGN

Randomized, single-blind, double crossover study.

SETTING

Research sleep laboratory.

PATIENTS OR PARTICIPANTS

Seven older and 10 younger men with non-severe or no sleep apnea, matched for body mass index.

INTERVENTIONS

During the control arm, normal saline was infused to keep the vein open. During intervention, subjects received an intravenous bolus of normal saline (22 mL/kg body weight) after sleep onset while they were wearing compression stockings to prevent fluid accumulation in the legs.

MEASUREMENTS AND RESULTS

Compared to younger men, infusion of similar amounts of saline in older men caused a greater increase in neck circumference (P < 0.05) and in the AHI (32.2 ± 22.1 vs. 2.2 ± 7.1, P = 0.002).

CONCLUSIONS

Older men are more susceptible to the adverse effects of intravenous fluid loading on obstructive sleep apnea severity than younger men. This may be due to age-related differences in the amount of fluid accumulating in the neck or upper airway collapsibility in response to intravenous fluid loading. These possibilities remain to be tested in future studies.

The influence of obesity on different genders in patients with obstructive sleep apnea

Obesity is considered to be a major contributing factor to obstructive sleep apnea (OSA); however, there is limited evidence with regard to gender predominance. We analyzed 2345 patients (339 females) in correlation with body mass index (BMI) and OSA severity. Male AHIs were significantly higher than female AHIs in each BMI group. As the BMI increased, the AHI increased in both males and females, and this trend was more obvious in males. For BMI-matched male and female patients with OSA, the severity of OSA was higher in males. As BMI increased, the severity of OSA increased more obviously in males. Our findings suggest that increased body fat contributes to the pathogenesis of OSA more in males than in females and that obesity plays a more significant role in contributing to OSA in male patients.

Upper airway imaging in sleep-disordered breathing

Our understanding of sleep-disordered breathing has evolved considerably over the past three decades, and clinical techniques of evaluation have progressed tremendously. Myriad imaging techniques are now available for the physician to approach the dynamic features resulting in turbulent airflow, upper airway narrowing or collapse at different levels. Controversy exists in the choice of investigations, probably because the best evaluation should be a combination of different techniques. Physical, radiographic, endoscopic and acoustic evaluations could be integrated to understand the degree and the levels of airway reduction and/or obstruction in a given patient. This review focuses on cost-effective and easily implemented techniques in daily practice, allowing quality assessment of the dynamic anatomy of sleep-disordered breathing: cephalometry, (sleep-)endoscopy and acoustic reflectometry of the upper airway.

Assessing Orthotic Normalization of Pharyngeal Dynamics

Airway orthotic therapy, considered mainstream in the treatment of sleep-disordered breathing, has been demonstrated to normalize both structure and function of the pathological airway through manipulation of mandibular posture. Although effective, the literature reports a variable rate of success and no validated candidacy selection protocol. Acoustic reflection has been used to evaluate and document the upper airway and its dynamics with and without an orthotic in place. This paper will discuss the use of acoustic reflection to assess the level of airway normalization resulting from protrusive and vertical repositioning of the mandible and its utility to establish orthotic candidacy, construction, titration, and maintenance parameters. This protocol has potential for use in both medical and dental facilities that treat patients with sleep-disordered breathing.

Obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive collapse of the pharyngeal airway during sleep. Control of pharyngeal patency is a complex process relating primarily to basic anatomy and the activity of many pharyngeal dilator muscles. The control of these muscles is regulated by a number of processes including respiratory drive, negative pressure reflexes, and state (sleep) effects. In general, patients with OSA have an anatomically small airway the patency of which is maintained during wakefulness by reflex-driven augmented dilator muscle activation. At sleep onset, muscle activity falls, thereby compromising the upper airway. However, recent data suggest that the mechanism of OSA differs substantially among patients, with variable contributions from several physiologic characteristics including, among others: level of upper airway dilator muscle activation required to open the airway, increase in chemical drive required to recruit the pharyngeal muscles, chemical control loop gain, and arousal threshold. Thus, the cause of sleep apnea likely varies substantially between patients. Other physiologic mechanisms likely contributing to OSA pathogenesis include falling lung volume during sleep, shifts in blood volume from peripheral tissues to the neck, and airway edema. Apnea severity may progress over time, likely due to weight gain, muscle/nerve injury, aging effects on airway anatomy/collapsibility, and changes in ventilatory control stability.

Acoustic pharyngometry measurement of minimal cross-sectional airway area is a significant independent predictor of moderate-to-severe obstructive sleep apnea

STUDY OBJECTIVES

The current gold-standard method of diagnosing obstructive sleep apnea (OSA) is polysomnography, which can be inefficient. We therefore sought to determine a method to triage patients at risk of OSA, without using subjective data, which are prone to mis-reporting. We hypothesized that acoustic pharyngometry in combination with age, gender, and neck circumference would predict the presence of moderate-to-severe OSA.

METHODS

Untreated subjects with suspected OSA were recruited from a local sleep clinic and underwent polysomnography. We also included a control group to verify differences. While seated in an upright position and breathing through the mouth, an acoustic pharyngometer was used to measure the minimal cross-sectional area (MCA) of the upper airway at end-exhalation.

RESULTS

Sixty subjects were recruited (35 males, mean age 42 years, range 21-81 years; apnea-hypopnea index (AHI) 33 ± 30 events/h (mean ± standard deviation), Epworth Sleepiness Scale score 11 ± 6, body mass index 34 ± 8 kg/m(2)). In univariate logistic regression, MCA was a significant predictor of mild-no OSA (AHI < 15). A multivariate logistic regression model including MCA, age, gender, and neck circumference significantly predicted AHI < 15, explaining approximately one-third of the total variance (χ(2)(4) = 37, p < 0.01), with only MCA being a significant independent predictor (adjusted odds ratio 54, standard error 130; p < 0.01).

CONCLUSIONS

These data suggest that independent of age, gender, and neck size, objective anatomical assessment can significantly differentiate those with mild versus moderate-to-severe OSA in a clinical setting, and may have utility as a component in stratifying risk of OSA.

Sleep-disordered breathing in heart failure: identifying and treating an important but often unrecognized comorbidity in heart failure patients

Sleep-disordered breathing (SDB) is the most common comorbidity in patients with heart failure (HF) and has a significant impact on quality of life, morbidity, and mortality. A number of therapeutic options have become available in recent years that can improve quality of life and potentially the outcomes of HF patients with SDB. Unfortunately, SDB is not part of the routine evaluation and management of HF, so it remains untreated in most HF patients. Although recognition of the role of SDB in HF is increasing, clinical guidelines for the management of SDB in HF patients continue to be absent. This article provides an overview of SDB in HF and proposes a clinical care pathway to help clinicians to better recognize and treat SDB in their HF patients.

Vocal tract dimensional characteristics of professional male and female singers with different types of singing voices

The present study examined the possible relationship between classification of professional singing voices and their vocal tract parameters including vocal tract length and volume, and vowel formant frequencies. Acoustic reflection technology (ART) was used to measure vocal tract length and volume of 107 professional singers: 32 tenors, 25 baritones, 27 sopranos, and 23 mezzo-sopranos. The first three formant frequencies (F1-F3) of the English vowels /a, æ, i/ produced by the professional singers were also obtained. Results indicated significantly shorter oral and vocal tract length, and smaller oral and vocal tract volume associated with sopranos when compared with mezzo-sopranos. Acoustically, sopranos had higher F1, F2, and F3 values than mezzo-sopranos. The present findings suggest that, in addition to vocal tract length, vocal tract volume may also affect formant frequencies, implying the possibility that classifying professional singing voices is based on both vocal tract length and volume information.

Supine position related obstructive sleep apnea in adults: pathogenesis and treatment

The most striking feature of obstructive respiratory events is that they are at their most severe and frequent in the supine sleeping position: indeed, more than half of all obstructive sleep apnea (OSA) patients can be classified as supine related OSA. Existing evidence points to supine related OSA being attributable to unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses. The role of arousal threshold and ventilatory control instability in the supine position has however yet to be defined. Crucially, few physiological studies have examined patients in the lateral and supine positions, so there is little information to elucidate how breathing stability is affected by sleep posture. The mechanisms of supine related OSA can be overcome by the use of continuous positive airway pressure. There are conflicting data on the utility of oral appliances, while the effectiveness of weight loss and nasal expiratory resistance remains unclear. Avoidance of the supine posture is efficacious, but long term compliance data and well powered randomized controlled trials are lacking. The treatment of supine related OSA remains largely ignored in major clinical guidelines. Supine OSA is the dominant phenotype of the OSA syndrome. This review explains why the supine position so favors upper airway collapse and presents the available data on the management of patients with supine related OSA.

Obstructive sleep apnea is common in patients with interstitial lung disease

PURPOSE

The incidence of obstructive sleep apnea (OSA) in interstitial lung disease (ILD) has been reported at different frequencies in several studies. The aims of our study were to evaluate the frequency of OSA in ILD and to analyze the relationship between polysomnography (PSG) findings and pulmonary function, disease severity, parenchymal involvement, and Epworth Sleepiness Scale (ESS) scores.

METHODS

ILD patients with parenchymal involvement were evaluated. The disease severity was assessed using an index consisting of body mass index (BMI), carbon monoxide diffusion capacity, the Modified Medical Research Council dyspnea scale, and the 6-min walking distance. All of the patients had lung function, chest X-ray, PSG, ESS scoring, and an upper airway examination. Patients with a BMI ≥ 30 or significant upper airway pathologies were excluded.

RESULTS

Of 62 patients, 50 patients comprised the study group (14 male, 36 female; mean age 54 ± 12.35 years, mean BMI 25.9 ± 3.44 kg/m(2)) with diagnoses of idiopathic pulmonary fibrosis (IPF; n = 17), stage II-III sarcoidosis (n = 15), or scleroderma (n = 18). The frequency of OSA was 68 %. The mean apnea-hypopnea index (AHI) was 11.4 ± 12.5. OSA was more common in IPF patients (p = 0.009). The frequency of rapid eye movement-related sleep apnea was 52.9 %. The frequency of OSA was higher in patients with a disease severity index ≥3 (p = 0.04). The oxygen desaturation index and the AHI were higher in patients with diffuse radiological involvement (p = 0.007 and p = 0.043, respectively).

CONCLUSIONS

OSA is common in ILD. PSG or at minimum nocturnal oximetry should be performed, particularly in patients with functionally and radiologically severe disease.

[Idiopathic pulmonary fibrosis and sleep disorders]

Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung disease. Despite progress made in understanding the pathophysiological mechanisms behind the development of the disease, its prognosis is poor. For this reason, any measure to improve the quality of life for these patients should be preferred. Some authors are interested in sleep disorders, and possible impact on quality of life. Patients with IPF have lowered scores of quality of life compared to those found in general population, with some correlation with the scores of sleep quality. There is a hyperfragmentation with many arousals and desaturation events. Some authors also report an apnea-hypopnea index higher in these patients, but these data are not found in all the studies. Correcting these obstructive phenomena may have a beneficial effect on survival, which would make systematic the sleep assessment in these patients. Finally, the relationship between IPF, gastroesophageal reflux and sleep apnea syndrome remains unclear.

Influence of Lower Body Positive Pressure on Upper Airway Cross-Sectional Area in Drug-Resistant Hypertension

We previously showed that in hypertensive patients the amount of fluid displaced from the legs overnight is directly related to the severity of obstructive sleep apnea and that the rostral fluid shift was greater in drug-resistant hypertensive patients. The findings suggested that this fluid redistribution increases upper airway collapsibility, yet more direct evidence is lacking. The present study examines the effects of graded lower body positive pressure on leg fluid volume, upper airway cross-sectional area, and neck circumference in patients with drug-resistant hypertension (n=25) and controlled hypertension (n=15). In both groups, the reduction in mean upper airway cross-sectional area and oropharyngeal junction area, assessed by acoustic pharyngometry, and the increase in neck circumference, determined by mercury strain gauge plethysmography, were related to the amount of fluid displaced from the legs ( R 2 =0.41, P <0.0001; R 2 =0.42, P <0.0001; and R 2 =0.47, P <0.0001, respectively). Displacement of leg fluid volume was significantly greater in patients with drug-resistant hypertension than in controlled hypertension ( P <0.0001), and as a consequence, the former experienced greater reductions in mean upper airway cross-sectional area and oropharyngeal junction area ( P =0.001 and P <0.0001, respectively). The findings support the concept that in hypertensive subjects, rostral fluid displacement may participate in the pathogenesis of obstructive sleep apnea by narrowing the upper airway and making it more susceptible to collapse during sleep. The exaggerated fluid volume displacement from the legs and upper airway response to lower body positive pressure in patients with drug-resistant hypertension provide additional evidence of an important link between drug-resistant hypertension and obstructive sleep apnea.

Relationship of pharyngeal water content and jugular volume with severity of obstructive sleep apnea in renal failure

BACKGROUND

In patients with end-stage renal disease (ESRD), fluid overload may contribute to their high prevalence of obstructive sleep apnea (OSA) by increasing the amount of fluid displaced from the legs into the neck overnight, and possibly compressing the upper airway (UA). Indeed, in ESRD patients, the amount of overnight rostral fluid displacement from the legs is related to the frequency of apneas and hypopneas per hour of sleep (apnea-hypopnea index, AHI). We, therefore, hypothesized that in ESRD patients, the greater the UA-mucosal water content (UA-MWC) and internal jugular vein volume (IJVVol), the higher the AHI.

METHODS

We studied 20 patients with ESRD on thrice weekly hemodialysis who had undergone diagnostic polysomnography (age 41.0 ± 12.3 years, with a body mass index (BMI) of 25.8 ± 6.3 kg/m(2) and an AHI of 20.2 ± 26.8). The leg fluid volume (LFV) was measured by bioelectric impedance. The IJVVol and MWC were measured by UA magnetic resonance imaging (MRI).

RESULTS

The only significant independent correlates of the AHI were IJVVol (r = 0.801, P < 0.0001) and UA-MWC (r = 0.720, P = 0.0005) which together explained 72% of its variability.

CONCLUSIONS

These data suggest that fluid overload via increased IJVVol, and UA-MWC, contributes to the pathogenesis of OSA in patients with ESRD. These findings help us to explain the high prevalence of OSA in ESRD patients, and attenuation of OSA in association with nocturnal dialysis. They also suggest the need for randomized trials to determine whether more aggressive fluid removal in ESRD patients will alleviate OSA.

A threshold lung volume for optimal mechanical effects on upper airway airflow dynamics: studies in an anesthetized rabbit model

Increasing lung volume improves upper airway airflow dynamics via passive mechanisms such as reducing upper airway extraluminal tissue pressures (ETP) and increasing longitudinal tension via tracheal displacement. We hypothesized a threshold lung volume for optimal mechanical effects on upper airway airflow dynamics. Seven supine, anesthetized, spontaneously breathing New Zealand White rabbits were studied. Extrathoracic pressure was altered, and lung volume change, airflow, pharyngeal pressure, ETP laterally (ETPlat) and anteriorly (ETPant), tracheal displacement, and sternohyoid muscle activity (EMG%max) monitored. Airflow dynamics were quantified via peak inspiratory airflow, flow limitation upper airway resistance, and conductance. Every 10-ml lung volume increase resulted in caudal tracheal displacement of 2.1 ± 0.4 mm (mean ± SE), decreased ETPlat by 0.7 ± 0.3 cmH2O, increased peak inspiratory airflow of 22.8 ± 2.6% baseline (all P < 0.02), and no significant change in ETPant or EMG%max. Flow limitation was present in most rabbits at baseline, and abolished 15.7 ± 10.5 ml above baseline. Every 10-ml lung volume decrease resulted in cranial tracheal displacement of 2.6 ± 0.4 mm, increased ETPant by 0.9 ± 0.2 cmH2O, ETPlat was unchanged, increased EMG%max of 11.1 ± 0.3%, and a reduction in peak inspiratory airflow of 10.8 ± 1.0%baseline (all P < 0.01). Lung volume, resistance, and conductance relationships were described by exponential functions. In conclusion, increasing lung volume displaced the trachea caudally, reduced ETP, abolished flow limitation, but had little effect on resistance or conductance, whereas decreasing lung volume resulted in cranial tracheal displacement, increased ETP and increased resistance, and reduced conductance, and flow limitation persisted despite increased muscle activity. We conclude that there is a threshold for lung volume influences on upper airway airflow dynamics.

Observational study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers--protocol study

Abstract

Trial registration

Registro Brasileiro de Ensaios Clinicos (local acronym RBEC) [Internet]: Rio de Janeiro (RJ): Instituto de Informaçao Cientifica e Tecnologica em Saude (Brazil); 2010 - Identifier RBR-7dq5xx. Cross-sectional study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers; 2011 May 31 [7 pages]. Available from http://www.ensaiosclinicos.gov.br/rg/RBR-7dq5xx/.

Brown adipose tissue: is it affected by intermittent hypoxia?

Background

Intermittent hypoxia (IH), a model of sleep apnea, produces weight loss in animals. We hypothesized that changes in brown adipose tissue (BAT) function are involved in such phenomenon. We investigated the effect of IH, during 35 days, on body weight, brown adipose tissue wet weight (BATww) and total protein concentration (TPC) of BAT.

Methods

We exposed Balb/c mice to 35 days of IH (n = 12) or sham intermittent hypoxia (SIH; n = 12), alternating 30 seconds of progressive hypoxia to a nadir of 6%, followed by 30 seconds of normoxia. During 8 hours, the rodents underwent a total of 480 cycles of hypoxia/reoxygenation, equivalent to an apnea index of 60/hour. BAT was dissected and weighed while wet. Protein was measured using the Lowry protein assay.

Results

Body weight was significantly reduced in animals exposed to IH, at day 35, from 24.4 ± 3.3 to 20.2 ± 2.2 g (p = 0.0004), while in the SIH group it increased from 23.3 ± 3.81 to 24.1 ± 2.96 g (p = 0.23). BATww was also lower in IH than in SIH group (p = 0.00003). TPC of BAT, however, was similar in IH (204.4 ± 44.3 μg/100 μL) and SIH groups (213.2 ± 78.7 μg/100 μL; p = 0.74) and correlated neither with body weight nor with BATww. TPC appeared to be unaffected by exposure to IH also in multivariate analysis, adjusting for body weight and BATww. The correlation between body weight and BATww is significant (rho= 0.63) for the whole sample. When IH and SIH groups are tested separately, the correlations are no longer significant (rho= 0.48 and 0.05, respectively).

Conclusion

IH during 35 days in a mice model of sleep apnea causes weight loss, BATww reduction, and no change in TPC of BATww. The mechanisms of weight loss under IH demands further investigation.