Prevalence of obstructive sleep apnoea syndrome in oncological patients: A systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) has garnered increasing attention in recent years due to its potential association with cancer. This systematic review and meta-analysis aimed to assess the prevalence of OSAS in cancer patients through a comprehensive analysis of existing literature.

METHODS

This systematic review and meta-analysis, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, aimed to evaluate the prevalence of OSAS in cancer patients. A comprehensive search of electronic databases was performed to identify relevant studies published up to September 2021. Eligible studies reporting on the prevalence of OSAS in cancer patients, encompassing various study designs, were included in the analysis. Pooled estimates of the odds ratios (OR) with 95% confidence intervals (CIs) were calculated using a random effects model. Heterogeneity among the studies was assessed using the I2 statistic.

RESULTS

Seventeen studies fulfilled the inclusion criteria and were subsequently included in the review. The prevalence of OSAS in cancer patients was estimated to have an overall OR of 0.80 (95% CI: 0.75-0.85). In comparison with non-cancer patients, cancer patients had a statistically significant greater risk of OSAS, as indicated by the total estimated RR for the prevalence of OSAS in cancer patients, which was 0.89 (95% CI: 0.86-0.92). Nonetheless, there was a significant amount of heterogeneity (I2 = 96%) among the studies.

CONCLUSION

The overall data analysed in this review indicates that patients with cancer had far reduced likelihood of developing OSAS than individuals without cancer. However, the significant variation across the included studies highlights the need for additional investigation to fully clarify the complex association between OSAS and cancer incidence. These results emphasise how critical it is to identify OSAS as a possible comorbidity in cancer patients, one that should be taken into account for clinical management and ongoing research.

A Systematic Review and Meta-Analysis of Mean Platelet Volume and Platelet Distribution Width in Patients with Obstructive Sleep Apnoea Syndrome

Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent yet underestimated disorder caused by the complete or partial obstruction of the upper airways. Although polysomnography is the gold standard for OSAS diagnosis, there is an active search for easily accessible biomarkers of disease presence and severity, particularly those reflecting morphological changes in specific blood cells. We investigated the associations between the presence and severity of OSAS, continuous positive airway pressure (CPAP) treatment, mean platelet volume (MPV), and platelet distribution width (PDW), routinely assessed as part of the complete blood count. From 262 retrieved records from PubMed, the Web of Science, Scopus, and Google Scholar, 31 manuscripts were selected for a final analysis, 30 investigating MPV and 15 investigating PDW. MPV was not statistically different between OSAS patients and healthy controls; however, it progressively increased with disease severity. By contrast, OSAS patients had significantly higher PDW values than controls (SMD = 0.40, 95% CI: 0.25 to 0.56; p ˂ 0.001), and the difference increased with disease severity. In a univariate meta-regression, there were significant associations between the MPV and publication year, the apnoea-hypopnea index, and diabetes mellitus, while no associations were observed with the PDW. No significant between-group differences were observed in the subgroup analyses. These data suggest that PDW, and to a lesser extent, MPV, are potential biomarkers of OSAS and require further research to ascertain their pathophysiological significance (PROSPERO, CRD42023459413).

Occurrence of Temporomandibular Disorders among patients undergoing treatment for Obstructive Sleep Apnoea Syndrome (OSAS) using Mandibular Advancement Device (MAD): A Systematic Review conducted according to PRISMA guidelines and the Cochrane handbook for systematic reviews of interventions

BACKGROUND

Patients undergoing mandibular advancement device (MAD) therapy for obstructive sleep apnea (OSA) may experience changes in jaw position and altered occlusion. This could potentially contribute to the development or exacerbation of TMD symptoms. The literature on the long-term impact of MAD treated for OSA on TMD is scarce. Hence, this review was undertaken to ascertain the occurrence of TMD in MAD users.

METHODS

A comprehensive search protocol was implemented across several online databases using MeSH keywords and Boolean operators. A standardised data extraction form was developed specifically for this review. Two reviewers independently extracted the data. RoB-2 was used to evaluate the methodological quality of the included studies.

RESULTS

A total of 13 clinical studies were selected for this review. Some studies reported a significant reduction in the severity and frequency of TMD symptoms following MAD treatment. However, other studies did not observe significant changes in TMD symptoms or TMJ-related parameters from baseline to follow-up intervals. Temporary increases in TMJ-related pain or symptoms at the beginning of the follow-up period, which later subsided, were reported in some studies. Overall, MAD was not discontinued in any OSA patient due to TMDs.

CONCLUSION

The findings reveal that different outcomes associated with TMD are affected differently by MAD treatment for OSAS. According to a few studies, MAD therapy significantly reduced the severity and frequency of TMD symptoms. Other research, however, found no appreciable modifications in TMD symptoms or TMJ-related indicators. Although the overall results point to no significant effect of MAD treatment on TMD symptoms, the disparity in results between studies highlights the need for additional studies using standardised approaches.

[Prevalence of childhood obstructive sleep apnoea syndrome in a referral sleep unit]

INTRODUCTION

Obstructive sleep apnoea syndrome (OSAS) affects between 1% and 6% of children. Its diagnosis includes: a) snoring and/or apnoea; and b) an apnoea and hypopnoea index >3/hour obtained by polysomnography (PSG). The main aim of this work is to determine the prevalence of OSAS in our study population.

PATIENTS AND METHODS

We conducted a descriptive study with a sample of 151 children aged between 1 and 12 years, who had been referred to the sleep unit of the Hospital General Universitario Gregorio Maranon for a PSG. We analysed the demographic variables sex and age; the clinical variables snoring, apnoeas and tonsillar hypertrophy; and the presence of OSAS based on the polysomnographic diagnostic criterion of an apnoea and hypopnoea index >3/hour.

RESULTS

The mean age of the sample was 5.37 years (standard deviation: 3.05) and 64.9% were males. In 90.1% of cases, the reason for the visit was suspected OSAS. Snoring, apnoeas and tonsillar hypertrophy were observed in 73.5, 48.7 and 60% of cases, respectively. OSAS was diagnosed en 19 children (12.6%); in 13.5% of snorers; in 15.1% of those with apnoeas; and in 15.6% of the children with tonsillar hypertrophy.

CONCLUSIONS

In our study, the prevalence of OSAS in children was 12.6%, which is higher than that reported in most epidemiological studies that include PSG for the diagnosis of OSAS.

Intermittent hypoxia treatments cause cellular priming in human microglia

Obstructive sleep apnoea syndrome (OSAS) is a sleep-disordered breathing characterized by nocturnal collapses of the upper airway resulting in cycles of blood oxygen partial pressure oscillations, which lead to tissue and cell damage due to intermittent hypoxia (IH) episodes. Since OSAS-derived IH may lead to cognitive impairment through not fully cleared mechanisms, herein we developed a new in vitro model mimicking IH conditions to shed light on its molecular effects on microglial cells, with particular attention to the inflammatory response. The in vitro model was set-up and validated by measuring the hypoxic state, HIF-1α levels, oxidative stress by ROS production and mitochondrial activity by MTS assay. Then, the mRNA and protein levels of certain inflammatory markers (NF-κB and interleukin 6 (IL-6)) after different IH treatment protocols were investigated. The IH treatments followed by a normoxic period were not able to produce a high inflammatory state in human microglial cells. Nevertheless, microglia appeared to be in a state characterized by increased expression of NF-κB and markers related to a primed phenotype. The microglia exposed to IH cycles and stimulated with exogenous IL-1β resulted in an exaggerated inflammatory response with increased NF-κB and IL-6 expression, suggesting a role for primed microglia in OSAS-driven neuroinflammation.

Factors determining the therapeutic level of positive airway pressure in patients with obstructive sleep apnea syndrome

Objectives

In daily practice, we encounter with obstructive sleep apnoea syndrome (OSAS) patients who require different levels of positive airway pressure (PAP) despite having a similar apnoea-hypopnea index (AHI). We aimed to determine the parameters contributing to the determination of the therapeutic level of PAP.

Methods

Data on 548 patients who underwent polysomnography and PAP titration were analysed retrospectively. Patients were divided into groups according to OSAS severity (mild, moderate, and severe) and the mean pressure in each group was determined, after which patients were further divided into those who required a PAP below the mean and those who required a PAP above the mean.

Results

The mean optimal PAP level in the mild, moderate, and severe OSAS groups was 7.4 ± 2.3, 8.6 ± 2.4, and 9.8 ± 2.9 cm H2O, respectively. In the moderate and severe OSAS group, the subgroup that needed high pressure had a higher supine AHI, a longer apnoea time, and a longer SaO2 <90% time as compared with the subgroup that needed low pressure.

Conclusion

A longer apnoea duration and a higher supine AHI are associated with a higher PAP level in patients with moderate and severe OSAS.

Does Obstructive Sleep Apnoea Syndrome Influence the Development and Treatment of Diabetic Foot? A Brief Narrative Review

Both obstructive sleep apnoea syndrome (OSAS) and diabetes mellitus (DM) are common conditions that often coexist and share many similar risk factors. Diabetic foot is a common complication of DM, which may lead to lower-limb amputation. OSAS is considered a risk factor for type 2 DM (T2DM). There is also evidence that OSAS may be linked with the development, as well as the healing of diabetic foot. Multiple mechanisms triggered by sleep fragmentation and intermittent hypoxaemia in OSAS could contribute to the development of diabetic foot ulcers (DFUs). More interestingly, emerging evidence implies a favourable impact of continuous positive airway pressure (CPAP) treatment on DFU healing. Healing DFUs and minimising recurrence rates remains a challenge for health care professionals. In this context, management of OSAS might prove a useful therapeutic adjunct for DFUS. However, data is still limited and randomised controlled trials are needed to further explore this interesting potential.

Risk of Cardiovascular Disease in Apnoeic Individuals: Role of Comorbid Insomnia Disorder

Given the limited data available, the aim of this study was to examine the 10-year cardiovascular disease (CVD) risk associated with comorbid insomnia disorder and its specific subtypes in apnoeic individuals. Data from 1104 apnoeic individuals recruited from the database of the Erasme Hospital Sleep Laboratory were analysed. Only apnoeic individuals with a Framingham Risk Score ≥10% were included in the group at moderate-to-high 10-year CVD risk. Logistic regression analyses were conducted to examine the risk of 10-year CVD risk associated with comorbid insomnia disorder and its specific subtypes in apnoeic individuals. Moderate-to-high 10-year CVD risk was present in 59.6% of the apnoeic individuals in our sample. After adjustment for the main confounding factors, multivariate logistic regression analyses revealed that comorbid insomnia disorder and, more particularly, its subtype with short sleep duration were significantly associated with moderate-to-high 10-year CVD risk in apnoeic individuals. In this study, we demonstrate that comorbid insomnia disorder and, more specifically, its subtype with short sleep duration appear to have a negative cumulative effect on 10-year CVD risk in apnoeic individuals, which justifies more systematic research and adequate therapeutic management of this disorder to allow for better cardiovascular disease prevention in this particular subpopulation.

Obstructive Sleep Apnoea Syndrome Screening Through Wrist-Worn Smartbands: A Machine-Learning Approach

Purpose

A large portion of the adult population is thought to suffer from obstructive sleep apnoea syndrome (OSAS), a sleep-related breathing disorder associated with increased morbidity and mortality. International guidelines include the polysomnography and the cardiorespiratory monitoring (CRM) as diagnostic tools for OSAS, but they are unfit for a large-scale screening, given their invasiveness, high cost and lengthy process of scoring. Current screening methods are based on self-reported questionnaires that suffer from lack of objectivity. On the contrary, commercial smartbands are wearable devices capable of collecting accelerometric and photoplethysmographic data in a user-friendly and objective way. We questioned whether machine-learning (ML) classifiers trained on data collected through these wearable devices would help predict OSAS severity.

Patients and Methods

Each of the patients (n = 78, mean age ± SD: 57.2 ± 12.9 years; 30 females) underwent CRM and concurrently wore a commercial wrist smartband. CRM's traces were scored, and OSAS severity was reported as apnoea hypopnoea index (AHI). We trained three pairs of classifiers to make the following prediction: AHI <5 vs AHI ≥5, AHI <15 vs AHI ≥15, and AHI <30 vs AHI ≥30.

Results

According to the Matthews correlation coefficient (MCC), the proposed algorithms reached an overall good correlation with the ground truth (CRM) for AHI <5 vs AHI ≥5 (MCC: 0.4) and AHI <30 vs AHI ≥30 (MCC: 0.3) classifications. AHI <5 vs AHI ≥5 and AHI <30 vs AHI ≥30 classifiers' sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and diagnostic odds ratio (DOR) are comparable with the STOP-Bang questionnaire, an established OSAS screening tool.

Conclusion

Machine learning algorithms showed an overall good performance. Unlike questionnaires, these are based on objectively collected data. Furthermore, these commercial devices are widely distributed in the general population. The aforementioned advantages of machine-learning algorithms applied to smartbands' data over questionnaires lead to the conclusion that they could serve a population-scale screening for OSAS.

Comparison of invasive intubation and noninvasive mechanical ventilation in patients with chronic obstructive pulmonary disease and obstructive sleep apnoea syndrome

Objective

The concurrence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea syndrome (OSAS) is defined as overlap syndrome (OS), but investigations into predictors of OS in patients with COPD remain limited. Here, potential markers of OS in patients with COPD were investigated, and results of intubation were compared between patients with COPD only or OS.

Methods

This retrospective study included patients with COPD who were divided according to OS diagnosis: COPD only (COPD group) or OS (OS group).

Results

Among 206 patients with COPD, 120 were diagnosed with OS. Mean body mass index (BMI) was significantly higher in the OS versus COPD group (28.95 ± 2.96 versus 23.84 ± 4.06, respectively). Receiver operating characteristic curve analyses revealed that BMI was associated with OS (area under the curve, 0.835). The rate of invasive intubation within 48 h was lower in the OS versus COPD group (9.2% versus 20.9%, respectively), and the duration of noninvasive ventilation was longer in the OS versus COPD group.

Conclusions

BMI may be a predictor of OS in patients with COPD. The duration of noninvasive ventilation was longer in patients with OS than in patients with COPD alone.

Cone beam computed tomography analysis results in patients with obstructive sleep apnoea syndrome

INTRODUCTION

The present study aimed to investigate the contribution of cone-beam computed tomography (CBCT) to the diagnosis of obstructive sleep apnoea syndrome (OSAS).

METHODS

The present study investigate the relationships among body mass index (BMI), upper airway, septum deviation, nasal cavity width, airway, and the hard and soft palate width using CBCT images of 64 patients obtained in Uşak University Faculty of Dentistry. The study included 31 (8 female and 23 male; mean age: 52.52 ± 10.01 years) and 33 patients (12 female and 21 male; mean age: 47.39 ± 10.27 years) with and without OSAS, respectively. Between-group comparisons of non-normally and normally distributed variables were performed using the Mann-Whitney U test and Student's t-test, respectively. Spearman's correlation analysis was used to determine the relationship between quantitative data. Statistical significance was evaluated at P < .01 and P < .05.

RESULTS

There were significant differences between groups in the BMI, nasal septum position, hard and soft palate width, maxillary skeletal width, and palatal alveolar angle (P < .01). In addition it was also found that BMI was higher, the nasopharyngeal airway was longer, and the soft palate was longer and wider in males. (P = .001; P < .01).

CONCLUSION

This study concluded that patients with OSAS had marked narrowing of the upper airway, nasal cavity and maxillary width, shortening and enlargement of the soft palate, and marked increase in BMI. However, to gather sufficiently reliable data for routine use in orthodontic analyses, there is a need for greater number of samples to improve the database.

Continuous positive airway pressure adherence and blood pressure lowering in patients with obstructive sleep apnoea syndrome and nocturnal hypertension

PURPOSE

We investigated continuous positive airway pressure (CPAP) adherence and its association with the blood pressure (BP) and pulse rate changes in patients with obstructive sleep apnoea syndrome (OSAS) and hypertension.

MATERIALS AND METHODS

In a single-blind trial, patients were randomly assigned to CPAP or sham CPAP treatment for 3 months. We performed clinic, ambulatory and home BP measurements at baseline and during follow-up. CPAP adherence was assessed as the CPAP frequency per week and time per night. Non-adherence was defined as a CPAP use for <5 days/week or <4 h/night.

RESULTS

In the CPAP (n = 26) and sham CPAP groups (n = 21), the CPAP frequency was 5.5 and 4.8 days/week (p = 0.17), respectively, and the CPAP time was 5.0 and 4.1 h/night (p = 0.03), respectively. The corresponding prevalence of non-adherence was 46.2% and 66.7% (p = 0.16), respectively. The CPAP frequency but not time tended to be associated with the changes in BP and pulse rate at 3 months of follow-up, especially home systolic/diastolic BP in the CPAP group (3.2/1.3 mmHg greater reductions per 1 day increment, p ≤ 0.01). Adherent, compared with non-adherent patients, had greater reductions in BP or pulse rate at 3 months of follow-up. In the CPAP and sham CPAP groups combined, statistical significance was achieved for the adjusted between adherence and non-adherence differences in home systolic/diastolic BP (-5.0/-3.8 mmHg) and 24-h, daytime and night-time ambulatory pulse rate (-6.2, -7.8 and -4.4 beats/min, respectively, p ≤ 0.04).

CONCLUSION

CPAP adherence was associated with the BP lowering and pulse rate slowing effects, especially the CPAP frequency.

Evaluation of facial soft tissues by stereophotogrammetry method in patients with obstructive sleep apnoea: a morphological study

BACKGROUND

We aimed to use the "SomnoMed MAS" device, which brings the mandible forward in obstructive sleep apnoea syndrome patients due to mandibular retrognathia, and to examine its effects on facial soft tissues by stereophotogrammetry (3dMD) method.

MATERIALS AND METHODS

Thirty-one patients with a mean age of 44 years and 6 months were included in the study. SomnoMed MAS, one of the splint appliances that position the mandible in front, was applied to all patients and the changes in facial soft tissues were examined by overlapping the images taken at different times with the 3dMD face system. The obtained data were analysed statistically and the level of statistical significance was determined as p ≤ 0.05.

RESULTS

Mouth width decreased statistically during T0-T1 period. In T0-T2 period, while crista philtri and labiale inferius points moved backwards, Mouth width, nose width decreased and nasal base width increased. In the T0-T3 period, nasal base width increased statistically, the philtrum width and the mouth width decreased, and the soft tissue nasion point came to the fore.

CONCLUSIONS

Splint treatment, which positions the mandible in front in adult obstructive sleep apnoea syndrome patients, affected the middle and lower facial soft tissues with the forward and downward translational movement of the lower jaw.

Correlation of serum myonectin concentrations with the presence and severity of obstructive sleep apnoea syndrome

OBJECTIVE

Myonectin, a newly discovered myokine, enhances fatty acid uptake in cultured adipocytes and hepatocytes and suppresses circulating concentrations of free fatty acids in mice. This study is performed to evaluate the association between serum myonectin concentrations with the presence and severity of OSAS.

METHODS

This study was performed in a population of 191 patients with OSAS and 105 control subjects. Serum myonectin concentrations were measured using enzyme-linked immunosorbent assay method.

RESULTS

Lower serum myonectin concentrations were found in OSAS patients than in the controls. Serum myonectin concentrations were associated with a reduced risk of OSAS (OR: 0.988, 95% CI: 0.984-0.993, P < 0.001). Severe OSAS patients had significantly lower myonectin concentrations compared with mild and moderate OSAS patients (P < 0.001 and P  =  0.001, respectively). There are lower serum myonectin concentrations in moderate patients compared with mild patients (P  =  0.024). Pearson correlation analysis revealed that serum myonectin concentrations were negatively correlated with the severity of OSAS (r = -0.344, P < 0.001). Simple linear regression analysis showed that serum myonectin concentrations in OSAS patients were negatively correlated with body mass index, fasting plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol, low-density lipoprotein cholesterol (LDL-C) and apnoea hypopnea index. Multiple stepwise regression analysis shows that body mass index (β = -0.289, P  =  0.03), HOMA-IR (β = -0.19, P  =  0.003), total cholesterol (β = -0.155, P  =  0.016), LDL-C (β = -0.176, P  =  0.006) and apnoea hypopnea index (β = -0.263, P < 0.001) remained to be associated with serum myonectin.

CONCLUSION

Serum myonectin concentrations are inversely correlated with the presence and severity of OSAS.

Prospective Trial of CPAP in Community-Dwelling Adults with Down Syndrome and Obstructive Sleep Apnea Syndrome

Adults with Down syndrome (DS) are predisposed to obstructive sleep apnoea (OSA), but the effectiveness and acceptability of continuous positive airway pressure treatment (CPAP) in this group has rarely been formally assessed. This study was designed as a pilot randomised, parallel controlled trial for one month, continuing as an uncontrolled cohort study whereby the control group also received the intervention. Symptomatic, community-dwelling DS individuals exhibiting ≥10 apnoeas/hypopneas per hour in bed on a Type 3 home sleep study were invited to participate in this study, with follow-up at 1, 3, 6, and 12 months from baseline. Measurements of sleepiness, behaviour, cognitive function and general health were undertaken; the primary outcome was a change in the pictorial Epworth Sleepiness Scale (pESS) score. Twenty-eight participants (19 male) were enrolled: age 28 ± 9 year; body mass index 31.5 ± 7.9 kg/m2; 39.6 ± 32.2 apnoeas/hypopneas per hour in bed; pESS 11 ± 6/24. The pilot randomised controlled trial at one month demonstrated no change between the groups. At 12 months, participant (p = 0.001) pESS and Disruptive (p < 0.0001), Anxiety/Antisocial (p = 0.024), and Depressive (p = 0.008) behaviour scores were reduced compared to baseline. Improvement was noted in verbal (p = 0.001) and nonverbal intelligence scores (p = 0.011). General health scores also improved (p = 0.02). At the end of the trial, 19 participants continued on treatment. Use of CPAP in adults with DS and OSA led to a number of significant, sustained improvements in sleepiness and behavioural/emotional outcomes at 12 months.

Continuous positive airway pressure can improve depression in patients with obstructive sleep apnoea syndrome: a meta-analysis based on randomized controlled trials

Objective

Substantial research indicates a clear relationship between obstructive sleep apnoea syndrome (OSAS) and depression. The study aim was to quantitatively evaluate whether continuous positive airway pressure (CPAP) therapy improves mood symptoms in OSAS patients.

Methods

PubMed and Embase databases were systematically searched up to 2017 for publications on the impact of CPAP on mood symptoms in OSAS patients.

Results

For the final analysis, nine randomized controlled trials comprising 1,052 patients were selected. The pooled standard mean difference (SMD) of the effect of CPAP on depression was 0.31 (95% confidence interval 0.18, 0.43). A subgroup analysis showed that when CPAP use was greater than 4 hours per night, it tended to be effective in improving patients’ mood symptoms (SMD = 0.38; confidence interval 0.23, 0.54). Analysis of publication bias using Egger’s test found no evidence of publication bias.

Conclusion

CPAP treatment can improve depression in OSAS patients.

Increased risk for cardiovascular disease in patients with obstructive sleep apnoea syndrome-chronic obstructive pulmonary disease (overlap syndrome)

INTRODUCTION

Accumulating evidence suggests that cardiovascular disease (CVD) is highly prevalent among patients with concurrent obstructive sleep apnoea syndrome (OSAS) and chronic obstructive pulmonary disease, otherwise known as overlap syndrome (OS).

OBJECTIVES

The aim of this study was to investigate the 10-year risk for CVD in OS patients compared with OSAS patients and controls.

METHODS

Consecutive patients, referred for symptoms suggestive of OSAS, were evaluated with polysomnography and pulmonary function testing. Cardiovascular risk was assessed using the Framingham risk score (FRS) and systematic coronary risk evaluation (SCORE).

RESULTS

Overall, 244 participants (184 males) without CVD and diabetes were divided into 3 groups: controls (n = 63), OSAS (n = 139) and OS (n = 42). Both FRS and SCORE were found to be elevated in the OS group compared with the OSAS and control groups (P < .001 for all). In multivariate analysis, age (β = .461, P < .001), forced expiratory volume in first second (β = -.285, P = .036) and oxygen desaturation index (ODI) (β = .234, P = .007) were major determinants for the SCORE, whereas age (β = .308, P < .001) and apnoea-hypopnoea index (β = .252, P = .010) for the FRS.

CONCLUSION

In our study, an increased risk for CVD was observed in a group of patients with OS at the time of their initial evaluation. Further studies are needed in the field of OS in order to investigate, prevent and manage early CVD in this population.

Correlation of serum meteorin-like concentration with the presence and severity of obstructive sleep apnoea syndrome

Objective

Inflammatory processes that occur in subjects with obstructive sleep apnoea syndrome may contribute to progressive atherosclerosis and increased cardiovascular and cerebrovascular morbidity. Meteorin-like protein, which is also known as subfatin, is transcribed similarly to meteorin protein. Meteorin-like alleviates skeletal muscle inflammation. We aimed to investigate the serum meteorin-like status of obstructive sleep apnoea syndrome subjects and determine the potential link between serum meteorin-like concentration with the presence and severity of obstructive sleep apnoea syndrome.

Methods

The obstructive sleep apnoea syndrome group was composed of 207 obstructive sleep apnoea syndrome subjects diagnosed via polysomnography. A total of 106 healthy volunteers without clinical symptoms of obstructive sleep apnoea syndrome were recruited as the control group. Blood samples were obtained from all subjects to evaluate the serum meteorin-like concentrations via enzyme-linked immunosorbent assay method.

Results

Decreased serum meteorin-like concentration was found in obstructive sleep apnoea syndrome subjects compared with the controls. Serum meteorin-like concentration was associated with a reduced OR for having obstructive sleep apnoea syndrome (OR 0.97, 95% CI 0.961 to 0.98; P < 0.001). Severe obstructive sleep apnoea syndrome subjects showed significantly lower meteorin-like concentration compared with mild and moderate cases. Moderate subjects exhibited decreased serum meteorin-like concentration compared with mild cases. Pearson correlation analysis revealed that serum meteorin-like concentration was negatively correlated with obstructive sleep apnoea syndrome severity. Serum meteorin-like concentration negatively correlated with body mass index, low-density lipoprotein cholesterol, apnoea–hypopnea index, number of arousals, hypopnoea and apnoea in subjects with obstructive sleep apnoea syndrome.

Conclusion

Serum meteorin-like concentration is inversely correlated with the presence and severity of obstructive sleep apnoea syndrome.

Non-invasive ventilation for obese patients with chronic respiratory failure: Are two pressures always better than one?

Obesity-related respiratory failure is increasingly common but remains under-diagnosed and under-treated. There are several clinical phenotypes reported, including severe obstructive sleep apnoea (OSA), isolated nocturnal hypoventilation with or without severe OSA and OSA complicating chronic obstructive pulmonary disease (COPD). The presence of hypercapnic respiratory failure is associated with poor clinical outcomes in each of these groups. While weight loss is a core aim of management, this is often unachievable, and treatment of sleep-disordered breathing with positive airway pressure (PAP) therapy is the mainstay of clinical practice. Although there are few long-term clinical efficacy trials, the lack of equipoise would prevent the utilization of an untreated control group. The current data support the use of PAP therapy to improve respiratory failure and is associated with improvements in health-related quality of life, reduced healthcare utilization and reduced mortality. Both continuous PAP (CPAP) and non-invasive ventilation (NIV) appear safe and effective in patients with obesity-related respiratory failure and OSA, with or without COPD, and the current evidence would not support a single therapy choice in all patients. There are no studies of CPAP in patients with isolated nocturnal hypoventilation, and NIV would be the current recommendation in this patient group. Whichever starting therapy is used, titration should be performed to correct sleep-disordered breathing and reverse chronic respiratory failure, with consideration of step-down of the treatment based on a clinical re-evaluation. In contrast, failure to reach physiological and clinical treatment targets should lead to the consideration of treatment escalation.

Is Aberrant Reno-Renal Reflex Control of Blood Pressure a Contributor to Chronic Intermittent Hypoxia-Induced Hypertension?

Renal sensory nerves are important in the regulation of body fluid and electrolyte homeostasis, and blood pressure. Activation of renal mechanoreceptor afferents triggers a negative feedback reno-renal reflex that leads to the inhibition of sympathetic nervous outflow. Conversely, activation of renal chemoreceptor afferents elicits reflex sympathoexcitation. Dysregulation of reno-renal reflexes by suppression of the inhibitory reflex and/or activation of the excitatory reflex impairs blood pressure control, predisposing to hypertension. Obstructive sleep apnoea syndrome (OSAS) is causally related to hypertension. Renal denervation in patients with OSAS or in experimental models of chronic intermittent hypoxia (CIH), a cardinal feature of OSAS due to recurrent apnoeas (pauses in breathing), results in a decrease in circulating norepinephrine levels and attenuation of hypertension. The mechanism of the beneficial effect of renal denervation on blood pressure control in models of CIH and OSAS is not fully understood, since renal denervation interrupts renal afferent signaling to the brain and sympathetic efferent signals to the kidneys. Herein, we consider the currently proposed mechanisms involved in the development of hypertension in CIH disease models with a focus on oxidative and inflammatory mediators in the kidneys and their potential influence on renal afferent control of blood pressure, with wider consideration of the evidence available from a variety of hypertension models. We draw focus to the potential contribution of aberrant renal afferent signaling in the development, maintenance and progression of high blood pressure, which may have relevance to CIH-induced hypertension.

Influence of Chronic Obstructive Pulmonary Disease and Moderate-To-Severe Sleep Apnoea in Overnight Cardiac Autonomic Modulation: Time, Frequency and Non-Linear Analyses

Chronic obstructive pulmonary disease (COPD) is one of the most prevalent lung diseases worldwide. COPD patients show major dysfunction in cardiac autonomic modulation due to sustained hypoxaemia, which has been significantly related to higher risk of cardiovascular disease. Obstructive sleep apnoea syndrome (OSAS) is a frequent comorbidity in COPD patients. It has been found that patients suffering from both COPD and OSAS simultaneously, the so-called overlap syndrome, have notably higher morbidity and mortality. Heart rate variability (HRV) has demonstrated to be useful to assess changes in autonomic functioning in different clinical conditions. However, there is still little scientific evidence on the magnitude of changes in cardiovascular dynamics elicited by the combined effect of both respiratory diseases, particularly during sleep, when apnoeic events occur. In this regard, we hypothesised that a non-linear analysis is able to provide further insight into long-term dynamics of overnight cardiovascular modulation. Accordingly, this study is aimed at assessing the usefulness of sample entropy (SampEn) to distinguish changes in overnight pulse rate variability (PRV) recordings among three patient groups while sleeping: COPD, moderate-to-severe OSAS, and overlap syndrome. In order to achieve this goal, a population composed of 297 patients were studied: 22 with COPD alone, 213 showing moderate-to-severe OSAS, and 62 with COPD and moderate-to-severe OSAS simultaneously (COPD+OSAS). Cardiovascular dynamics were analysed using pulse rate (PR) recordings from unattended pulse oximetry carried out at patients’ home. Conventional time- and frequency- domain analyses were performed to characterise sympathetic and parasympathetic activation of the nervous system, while SampEn was applied to quantify long-term changes in irregularity. Our analyses revealed that overnight PRV recordings from COPD+OSAS patients were significantly more irregular (higher SampEn) than those from patients with COPD alone (0.267 [0.210–0.407] vs. 0.212 [0.151–0.267]; p < 0.05) due to recurrent apnoeic events during the night. Similarly, COPD + OSAS patients also showed significantly higher irregularity in PRV during the night than subjects with OSAS alone (0.267 [0.210–0.407] vs. 0.241 [0.189–0.325]; p = 0.05), which suggests that the cumulative effect of both diseases increases disorganization of pulse rate while sleeping. On the other hand, no statistical significant differences were found between COPD and COPD + OSAS patients when traditional frequency bands (LF and HF) were analysed. We conclude that SampEn is able to properly quantify changes in overnight cardiovascular dynamics of patients with overlap syndrome, which could be useful to assess cardiovascular impairment in COPD patients due to the presence of concomitant OSAS.

Vitamin D Levels in Middle-Aged Patients with Obstructive Sleep Apnoea Syndrome

BACKGROUND

Vitamin D (Vit D) insufficiency has been implicated in the pathophysiology of numerous diseases. Obstructive sleep apnoea syndrome (OSAS), a disorder associated with increased cardiovascular and cerebrovascular morbidity, has been associated with decreased Vit D levels, but reports are inconclusive.

AIM

To evaluate the association between serum 25-hydroxyvitamin D [25(OH)D], a marker of Vit D status, with anthropometric and sleep characteristics of OSAS patients and to compare those levels between OSAS patients and non-apnoeic controls.

METHOD

Consecutive subjects who had undergone polysomnography and pulmonary function testing were divided into controls (apnoea-hypopnea index, AHI <5/h) and OSAS group (AHI ≥5/h).

RESULTS

A total of 169 subjects (135 men) were included. OSAS patients (n=139) significantly differed from non-apnoeic controls in terms of age (53.9±12.8 vs. 44.9±12.8 years, p=0.002) and body mass index (BMI) (35.9±6.9 vs. 29.9±6.8 kg/m2, p<0.001). Serum 25(OH)D levels were lower in OSAS patients (17.8±7.8 vs. 23.9±12.4 ng/ml, p=0.019). In OSAS patients, levels of serum 25(OH)D were negatively correlated with sleep stage transitions (r=-0.205, p=0.028), AHI (r=-0.187, p=0.045), oxygen desaturation index (r=-0.234, p=0.011) and percentage of time with oxyhaemoglobin saturation <90% (r=-0.172, p=0.041). In contrast, they were positively correlated with average oxyhaemoglobin saturation during sleep (r=0.179, p=0.033), forced expiratory volume in 1 sec (r=0.207, p=0.037) and oxygen partial pressure (r=0.197, p=0.029).

CONCLUSION

Vit D levels were lower in OSAS patients compared with non-apnoeic controls. Several indices of OSAS severity also correlated with Vit D levels.

Pharyngeal distensibility during expiration is an independent predictor of the severity of obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Pharyngeal distensibility and collapsibility reflect the passive properties of tissue in the airway, are an indicator of the ease with which an airway can be deformed and are related to the severity of obstructive sleep apnoea (OSA). During normal tidal respiration, the collapsibility of the pharynx during expiration is passive without confounding by neuromuscular activation that occurs during inspiration. We evaluated the distensibility and collapsibility of the upper airway in subjects with OSA during wakefulness using sophisticated dynamic computed tomography (CT) imaging. We hypothesized that the dynamic changes of the upper airway during expiration would be related to the severity of OSA.

METHODS

Twenty-three patients with OSA and eight normal subjects underwent simultaneous measurement of respiratory flow and airway calibre using ultrafast CT. The change in pharyngeal cross-sectional area divided by the change in concomitant flow (as distensibility or collapsibility) was measured and compared across different severities of OSA.

RESULTS

The slope of this relationship between delta area and delta flow during expiration was significantly higher in severe OSA when compared with normal controls and mild-moderate OSA. Differences in airway distensibility or collapsibility between severity groups were significant in expiration but not in inspiration. Distensibility or collapsibility contributed most to the apnoea-hypopnoea index in regression modelling. Age, gender, and body mass index (BMI) were not significant independent predictors.

CONCLUSION

Our study demonstrates that airway distensibility during the expiratory phase of awake respiration is correlated with the severity of OSA.

Effect of mandibular advancement therapy on inflammatory and metabolic biomarkers in patients with severe obstructive sleep apnoea: a randomised controlled trial

Systemic inflammation and metabolic disorders are among the mechanisms linking obstructive sleep apnoea (OSA) and cardiovascular disease (CVD). In 109 patients with severe OSA and no overt CVD, biomarkers of inflammation (C reactive protein, interleukin-6, tumour necrosis factor-α and its receptors, adiponectin, leptin and P-selectin), glucose and lipid metabolism, and N-terminal pro-brain natriuretic peptide, were measured before and after 2 months of treatment with a mandibular advancement device (MAD) (n=55) or a sham device (n=54). MAD reduced the Apnoea-Hypopnoea Index (p<0.001) but had no effect on circulating biomarkers compared with the sham device, despite high treatment adherence (6.6 hour/night). TRIAL REGISTRATION NUMBER: NCT01426607.

Severity of OSAS, CPAP and cardiovascular events: A follow-up study

BACKGROUND

Previous studies suggested obstructive sleep apnoea syndrome (OSAS) as a major risk factor for incident cardiovascular events. However, the relationship between OSAS severity, the use of continuous positive airway pressure (CPAP) treatment and the development of cardiovascular disease is still matter of debate.

STUDY OBJECTIVES

The aim was to test the association between OSAS and cardiovascular events in patients with concomitant cardio-metabolic diseases and the potential impact of CPAP therapy on cardiovascular outcomes.

METHODS

Prospective observational cohort study of consecutive outpatients with suspected metabolic disorders who had complete clinical and biochemical workup including polysomnography because of heavy snoring and possible OSAS. The primary endpoint was a composite of major adverse cardiovascular and cerebrovascular events (MACCE).

RESULTS

Median follow-up was 81.3 months, including 434 patients (2701.2 person/years); 83 had a primary snoring, 84 had mild, 93 moderate and 174 severe OSAS, respectively. The incidence of MACCE was 0.8% per year (95% confidence interval [CI] 0.2-2.1) in primary snorers and 2.1% per year (95% CI 1.5-2.8) for those with OSAS. A positive association was observed between event-free survival and OSAS severity (log-rank test; P = .041). A multivariable Cox regression analysis showed obesity (HR = 8.011, 95% CI 1.071-59.922, P = .043), moderate OSAS (vs non-OSAS HR = 3.853, 95% CI 1.069-13.879, P = .039) and severe OSAS (vs non-OSAS HR = 3.540, 95% CI 1.026-12.217, P = .045) as predictors of MACCE. No significant association was observed between CPAP treatment and MACCE (log-rank test; P = .227).

CONCLUSIONS

Our findings support the role of moderate/severe OSAS as a risk factor for incident MACCE. CPAP treatment was not associated with a lower rate of MACCE.

Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity.

METHODS

Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed.

RESULTS

Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry.

CONCLUSION

3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.

Galectin-3 is associated with coronary plaque burden and obstructive sleep apnoea syndrome severity

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is reported to be associated with hypertension, coronary artery disease, atrial fibrillation, and heart failure. Galectin-3 plays an important role in the regulation of inflammation, development of cardiac fibrosis, and remodelling. A significant relationship between galectin-3 and the total number of coronary plaques and the macrocalcified plaque structures of patients with type 2 diabetes mellitus has been reported.

AIM

The aim of this study was to investigate the association between galectin-3 level and coronary plaque burden as well as OSAS severity in patients with OSAS.

METHODS

A total of 87 consecutive patients with a diagnosis of OSAS and 21 age- and gender-matched control subjects were recruited for the present study. The patients with OSAS were also categorised according to their apnoea hypopnoea index (AHI) as follows: mild (AHI = 5-15), moderate (AHI = 15-30), and severe (AHI > 30). All study subjects underwent coronary computed tomography angiography to detect coronary atherosclerosis. Also, all participants of serum galectin-3 concentrations were measured.

RESULTS

Mean galectin-3 level was significantly higher in patients with OSAS compared to control subjects (p < 0.001) and in the severe OSAS group, compared to the moderate and mild OSAS groups (p < 0.001). Correlation analysis indicated significant positive relationships between galectin-3 concentrations and the total number of coronary plaques (p < 0.001), high-sensitivity C-reactive protein (p = 0.001), and severity of OSAS (p < 0.001). In multivariate analysis, galectin-3 (p = 0.01) and age (p = 0.025) were significant independent predictors of coronary atherosclerosis, after adjusting for other risk factors. Also, it has been found that galectin-3 concentration is a predictor of OSAS severity (p = 0.001).

CONCLUSIONS

Galectin-3 is associated with coronary atherosclerosis and OSAS severity in OSAS patients.

Managing obstructive sleep apnoea in children: the role of craniofacial morphology

Obstructive sleep apnoea syndrome is a type of sleep-disordered breathing that affects 1 to 5% of all children. Pharyngeal and palatine tonsil hypertrophy is the main predisposing factor. Various abnormalities are predisposing factors for obstructive sleep apnoea, such as decreased mandibular and maxillary lengths, skeletal retrusion, increased lower facial height and, consequently, increased total anterior facial height, a larger cranio-cervical angle, small posterior airway space and an inferiorly positioned hyoid bone. The diagnosis is based on the clinical history, a physical examination and tests confirming the presence and severity of upper airway obstruction. The gold standard test for diagnosis is overnight polysomnography. Attention must be paid to identify the craniofacial characteristics. When necessary, children should be referred to orthodontists and/or sleep medicine specialists for adequate treatment in addition to undergoing an adenotonsillectomy.

Variability of breathing during wakefulness while using CPAP predicts adherence

BACKGROUND AND OBJECTIVE

The standard therapy for obstructive sleep apnoea (OSA) is continuous positive airway pressure (CPAP) therapy. However, long-term adherence remains at ~50% despite improvements in behavioural and educational interventions. Based on prior work, we explored whether regularity of breathing during wakefulness might be a physiologic predictor of CPAP adherence.

METHODS

Of the 117 consecutive patients who were diagnosed with OSA and prescribed CPAP, 79 CPAP naïve patients were enrolled in this prospective study. During CPAP initiation, respiratory signals were collected using respiratory inductance plethysmography while wearing CPAP during wakefulness in a seated position. Breathing regularity was assessed by the coefficient of variation (CV) for breath-by-breath estimated tidal volume (V_T ) and total duration of respiratory cycle (Ttot). In a derivation group (n = 36), we determined the cut-off CV value which predicted poor CPAP adherence at the first month of therapy, and verified the validity of this predetermined cut-off value in the remaining participants (validation group; n = 43).

RESULTS

In the derivation group, the CV for estimated V_T was significantly higher in patients with poor adherence than with good adherence (median (interquartile range): 44.2 (33.4-57.4) vs 26.0 (20.4-33.2), P < 0.001). The CV cut-off value for estimated V_T for poor CPAP adherence was 34.0, according to a receiver-operating characteristic (ROC) curve. In the validation group, the CV value for estimated V_T >34.0 confirmed to be predicting poor CPAP adherence (sensitivity, 0.78; specificity, 0.83).

CONCLUSION

At the initiation of therapy, breathing regularity during wakefulness while wearing CPAP is an objective predictor of short-term CPAP adherence.

Arterial stiffness in obstructive sleep apnoea: Is there a difference between daytime and night-time?

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea syndrome (OSAS) is a common chronic systemic disease in the general population, with known associated cardiovascular outcomes. We aimed to investigate arterial stiffness in OSAS patients and compare daytime and night-time values with control subjects.

METHODS

A total of 104 patients undergoing investigation for OSAS with polysomnography also underwent pulse wave velocity (PWV) and augmentation index (AIx) measurements with Mobil-O-Graph for 24 h. Eighty-two patients were found to have OSAS and 22 did not have OSAS and acted as controls.

RESULTS

PWV values of the 82 OSAS patients during the 24-h period, both daytime and night-time, were significantly higher than that of the control subjects. Moreover, night-time levels of AIx were significantly higher in OSAS patients than control subjects (P = 0.025). PWV during night-time was higher than daytime measurements in OSAS patients (P = 0.012). Apnoea hypopnoea index (AHI) was significantly correlated with PWV and AIx over 24 h (P = 0.0001, r = 0.412; P = 0.002, r = 0.333, respectively). Positive correlations were also found between oxygen desaturation index (ODI) with PWV and AIx during the night (P = 0.0001, r = 0.480; P = 0.002, r = 0.325, respectively). However, daytime AIx was not significantly correlated with ODI (P = 0.052, r = 0.205).

CONCLUSION

OSAS patients, without known cardiovascular disease, have increased PWV, indicating an increased arterial stiffness, compared with control subjects and correlations between AHI and arterial stiffness indices suggest increased arterial stiffness with increased disease severity. Therefore, arterial stiffness should be considered as a possible cause for cardiovascular complications in OSAS patients.

Continuous positive airway pressure in clinically stable patients with mild-to-moderate obesity hypoventilation syndrome and obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

The use of continuous positive airway pressure (CPAP) treatment in patients with obesity hypoventilation syndrome (OHS) and obstructive sleep apnoea (OSA) was evaluated, and factors that might predict CPAP treatment failure were determined.

METHODS

A sleep study was performed in 29 newly diagnosed, clinically stable OHS patients. CPAP treatment was commenced if the apnoea-hypopnoea index was >15. Lung function, night-time oximetry, blood adipokine and C-reactive protein levels were assessed prospectively on enrollment and after 3 months. Treatment failure at 3 months was defined as daytime arterial partial pressure of carbon dioxide (PaCO(2)) >45 mm Hg and/or oxygen saturation (SpO(2)) <90% for >30% of the night-time oximetry study.

RESULTS

All patients had severe OSA (median apnoea-hypopnoea index = 74.7 (62-100) with a nocturnal mean SpO(2) of 81.4 ± 7), and all patients were treated with CPAP. The percentage of time spent below 90% saturation improved from 8.4% (0.0-39.0%) to 0.3% (0.4-4.0%). Awake PaCO(2) decreased from 50 (47-53) mm Hg to 43 (40-45) mm Hg. Seven patients failed CPAP treatment after 3 months. PaCO(2) at 1 month and mean night-time SpO(2) during the first night of optimal CPAP were associated with treatment failure at 3 months (odds ratio 1.4 (1.03-1.98); P = 0.034 and 0.6 (0.34-0.93); P = 0.027).

CONCLUSIONS

CPAP treatment improves night-time oxygenation and daytime hypoventilation in selected clinically stable OHS patients who also have OSA. Patients with worse night-time saturation while on CPAP and higher daytime PaCO(2) at 1 month were more likely to fail CPAP treatment.

Evaluation of the macular choroidal thickness using spectral optical coherence tomography in patients with obstructive sleep apnoea syndrome

BACKGROUND

To assess the choroidal thickness (CT) in patients with obstructive sleep apnoea syndrome (OSAS) and healthy controls.

DESIGN

Prospective, cross-sectional study

PARTICIPANTS

Ninety-two eyes of 92 patients with OSAS and 32 eyes of 32 aged and body mass index-matched healthy subjects were enrolled.

METHODS

OSAS patients were further divided into mild, moderate and severe OSAS groups according to their apnoea hypopnea index (AHI) values. The macular CT and peripapillary retinal nerve fibre layer (RNFL) thickness measurements of the subjects were obtained using spectral domain optical coherence tomography (RTVue-100, Optovue). The CT and RNFL thickness measurements of the groups were compared, and correlations among the AHI values and these measurements were calculated.

MAIN OUTCOME MEASURES

Choroidal thickness.

RESULTS

There were no significant differences in subfoveal and temporal CT measurements of the groups. A pairwise comparison between the groups revealed that severe OSAS group has significantly thinner CT than mild OSAS group at 3.0 mm nasal to the fovea. Also, compared with severe OSAS group, the CT measurements at 1.5 mm and 3.0 mm nasal to the fovea were significantly thicker in control eyes (both, P < 0.05). There were weak negative correlations between the nasal CT measurements and AHI in the OSAS group (nasal 1.5 mm, P = 0.002, r = -0.358; nasal 3.0 mm, P = 0.004, r = -0.336). Compared with controls, severe OSAS group had significantly thinner nasal and superior RNFL thickness measurement.

CONCLUSIONS

Sleep apnoea patients had choroidal structural alterations that may have significance on the pathophysiology of the ophthalmic disorders associated with OSAS.

The β2 -adrenoceptor agonist terbutaline recovers rat pharyngeal dilator muscle force decline during severe hypoxia

RATIONALE

Obstructive sleep apnoea syndrome (OSAS) is a debilitating condition characterized by recurrent occlusions of the pharyngeal airway during sleep accompanied by arterial hypoxaemia. Upper airway muscle dysfunction is implicated in the pathophysiology of OSAS. Pharmacological agents that improve muscle contractile and endurance properties may have therapeutic value.

AIM

We tested the hypothesis that the β(2) -adrenoceptor agonist terbutaline improves rat sternohyoid muscle performance especially during hypoxic stress.

METHODS

Isometric contractile and endurance properties were examined ex vivo in Krebs solution at 35°C. Muscles were incubated in tissue baths under hyperoxic (95% O(2) /5% CO(2)) conditions in the absence (control) or presence of the β(2) -adrenoceptor agonist terbutaline (1 μM). In additional experiments under hypoxic (95% N(2) /5% CO(2)) conditions, the effects of terbutaline were examined in the presence of the β-adrenoceptor antagonist propranolol (1 μM).

RESULTS

Hypoxia significantly impaired sternohyoid force production. Terbutaline completely recovered hypoxic depression of force, an effect that was blocked by co-application with propranolol.

CONCLUSION

The β(2) -adrenoceptor agonist terbutaline completely recovers hypoxic depression of upper airway muscle force. β(2) -adrenoceptor agonists warrant investigation in animal models of OSAS reporting upper airway and diaphragm muscle dysfunction.

Sleep disordered breathing and airway disease in primary ciliary dyskinesia

BACKGROUND AND OBJECTIVE

Sleep-disordered breathing (SDB) may develop in primary ciliary dyskinesia (PCD), leading to these diseases worsening one another.

METHODS

Sixteen stable PCD patients (4.9-17.2 years) and 42 controls underwent overnight respiratory polysomnography (rPSG) and Sleep Disturbances Scale for Children (SDSC). In PCD we assessed nasal endoscopy, pulmonary function tests and chest high-resolution computed tomography (HRCT).

RESULTS

Compared with controls, PCD had higher obstructive apnoea (4.7 vs 0.2, P < 0.001), central apnoea (0.8 vs 0.2, P < 0.001), hypopnoea (1.8 vs 0.2, P < 0.001), apnoea-hypopnoea (7.8 vs 0.6, P < 0.001), oxygen desaturation indexes (ODI; 0.7 vs 0.2, P = 0.002), and mean oxygen desaturation (4% vs 1%, P < 0.001), while mean and nadir oxygen saturation (97.1% vs 98.1, P < 0.001) (93% vs 97.2%, P < 0.001) were lower, respectively. In PCD, SDSC was unrelated to rPSG (P > 0.05), with total score and subscores of disorders in initiating and maintaining sleep, and sleep-wake transition lower than controls. PCD patients had chronic rhinosinusitis (100%) and adenoidal hypertrophy (50%). Total HRCT score was 7 (range 0-14). ODI correlated with functional residual capacity (r = 0.8, P = 0.02), total HRCT (r = 0.6, P = 0.03) and peribronchial thickening scores (r = 0.7, P = 0.02). Oxygen saturation was associated with bronchiectasis severity score (r = -0.6, P = 0.02).

CONCLUSIONS

PCD's parents may underestimate SDB. As nocturnal desaturation is associated with lung function and structure abnormalities, SDB may significantly contribute to pulmonary morbidity.

Investigation and management of childhood sleep apnoea

Sleep-disordered breathing includes disorders of breathing that affect airway patency, e.g. obstructive sleep apnoea syndrome, and also conditions that affect respiratory drive (central sleep disorders) or cause hypoventilation, either as a direct central effect or due to peripheral muscle weakness. Obstructive sleep apnoea syndrome (OSAS) is an increasingly-recognised clinical entity affecting up to 5.7% of children, which, if left untreated, is associated with adverse effects on growth and development including deleterious cognitive and behavioural outcomes. Evidence exists also that untreated OSAS impacts on cardiovascular risk. Close attention should be paid to assessment and investigation of this relatively common condition, instigating early and appropriate treatment to children with OSAS. First-line treatment in younger children is adenotonsillectomy, although other treatment options available include continuous positive airways pressure (CPAP), anti-inflammatory therapies (nasal corticosteroids and anti-leukotrienes), airway adjuncts and orthodontic appliances. Central sleep-disordered breathing may be related to immaturity of respiratory control and can be associated with prematurity as well as disorders such as Prader-Willi syndrome. In some cases, central apnoeas occur as part of a central hypoventilation disorder, which may be inherited, e.g. Congenital Central hypoventilation Syndrome, or acquired, e.g. Arnold-Chiari malformation, brain tumour, or spinal injury. The treatments of central breathing problems depend upon the underlying aetiology.

Circulating levels of vascular endothelial markers in obstructive sleep apnoea syndrome. Effects of nasal continuous positive airway pressure

INTRODUCTION

Obstructive sleep apnoea syndrome (OSAS) is an important risk factor in cardiovascular disorders. Although the exact mechanism remains to be elucidated, the endothelial dysfunction process seems to be implicated.

MATERIAL AND METHODS

In order to test this hypothesis, blood circulating levels of endothelial markers were measured at baseline and 1 year after treatment with continuous positive airway pressure (CPAP). We studied 37 males using polysomnography: 20 subjects with OSAS and a 17-subject control group. An OSAS-validated sleep questionnaire covering the most important cardiovascular risk factors was applied to all subjects. Furthermore, patients received a complete general physical examination and biochemistry test with lipid profile. The specific markers measured were intercellular cell adhesion molecule-1 (ICAM-1), E-selectin, endothelin-1, von Willebrand factor (vWF) and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

Obstructive sleep apnoea syndrome patients presented higher circulating levels of ICAM-1, endothelin-1 and PAI-1 than the control group. On the other hand, no differences were found in E-selectin and vWF. After 1 year of CPAP treatment, there was a significant decrease in circulating levels of ICAM-1 and PAI-1. On the other hand, no differences were found in endothelin-1, E-selectin and vWF.

CONCLUSIONS

Obstructive sleep apnoea syndrome is associated with elevated levels of ICAM-1 and PAI-1 and these levels normalize after treatment with CPAP.