Simon A. Joosten

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.

Phenotypes of patients with mild to moderate obstructive sleep apnoea as confirmed by cluster analysis

Background and objective:  Patients with OSA manifest different patterns of disease. However, this heterogeneity is more evident in patients with mild‐moderate OSA than in those with severe disease and a high total AHI. We hypothesized that mild‐moderate OSA can be categorized into discreet disease phenotypes, and the aim of this study was to comprehensively describe the pattern of OSA phenotypes through the use of cluster analysis techniques.

The Effect of Body Position on Physiological Factors that Contribute to Obstructive Sleep Apnea

STUDY OBJECTIVES Obstructive sleep apnea (OSA) resolves in lateral sleep in 20% of patients. However, the effect of lateral positioning on factors contributing to OSA has not been studied. We aimed to measure the effect of lateral positioning on the key pathophysiological contributors to OSA including lung volume, passive airway anatomy/collapsibility, the ability of the airway to stiffen and dilate, ventilatory control instability (loop gain), and arousal threshold. DESIGN Non-randomized single arm observational study. SETTING Sleep laboratory. PATIENTS/PARTICIPANTS 20 (15M, 5F) continuous positive airway pressure (CPAP)-treated severe OSA patients. INTERVENTIONS Supine vs. lateral position. MEASUREMENTS CPAP dial-downs performed during sleep to measure: (i) Veupnea: asleep ventilatory requirement, (ii) passive V0: ventilation off CPAP when airway dilator muscles are quiescent, (iii) Varousal: ventilation at which respiratory arousals occur, (iv) active V0: ventilation off CPAP when airway dilator muscles are activated during sleep, (v) loop gain: the ratio of the ventilatory drive response to a disturbance in ventilation, (vi) arousal threshold: level of ventilatory drive which leads to arousal, (vii) upper airway gain (UAG): ability of airway muscles to restore ventilation in response to increases in ventilatory drive, and (viii) pharyngeal critical closing pressure (Pcrit). Awake functional residual capacity (FRC) was also recorded. RESULTS Lateral positioning significantly increased passive V0 (0.33 ± 0.76L/min vs. 3.56 ± 2.94L/min, P < 0.001), active V0 (1.10 ± 1.97L/min vs. 4.71 ± 3.08L/min, P < 0.001), and FRC (1.31 ± 0.56 L vs. 1.42 ± 0.62 L, P = 0.046), and significantly decreased Pcrit (2.02 ± 2.55 cm H2O vs. -1.92 ± 3.87 cm H2O, P < 0.001). Loop gain, arousal threshold, Varousal, and UAG were not significantly altered. CONCLUSIONS Lateral positioning significantly improves passive airway anatomy/collapsibility (passive V0, pharyngeal critical closing pressure), the ability of the airway to stiffen and dilate (active V0), and the awake functional residual capacity without improving loop gain or arousal threshold.

Excessive dynamic airway collapse co-morbid with COPD diagnosed using 320-slice dynamic CT scanning technology

Tracheomalacia is a term used to describe weakness of the trachea. Strictly speaking, tracheomalacia means weakness of cartilaginous structures of the trachea, while excessive dynamic airway collapse (EDAC) describes invagination of the posterior membrane of the trachea leading to a ≥50% reduction in airway lumen.1 Tracheomalacia and EDAC are thought to exist in a significant portion of patients suffering from chronic obstructive pulmonary disease (COPD).2 An 88-year-old man presented with a 2 day history of episodic dyspnoea, wheeze and non-productive cough, on a background of COPD. Despite treatment …

Night-to-night repeatability of supine-related obstructive sleep apnea.

RATIONALE Patients with obstructive sleep apnea (OSA) experience respiratory events with greater frequency and severity while in the supine sleeping position. Postural modification devices (PMDs) prevent supine sleep, although there is a paucity of guidance to help clinicians decide when to use PMDs for their patients. In order for PMDs to treat OSA effectively, patients must experience respiratory events in the supine sleeping position consistently from night to night and must have a low nonsupine apnea and hypopnea index (AHINS). OBJECTIVES To document the repeatability of traditionally defined supine predominant OSA on consecutive polysomnography, to determine whether the consistency of the supine-predominant phenotype can be improved by altering the definition of it, and to determine whether a low AHINS is repeatable from night to night. METHODS We recruited 75 patients for polysomnography on two separate nights. Patients were classified as having supine OSA on each night on the basis of traditional and novel definitions, and the classification systems used were compared on the basis of agreement from night to night. MEASUREMENTS AND MAIN RESULTS The definition of supine OSA with the highest level of agreement from night to night incorporates a supine AHI (AHIS) to AHINS ratio ≥4:1. In addition, agreement exists for males, but there is poor agreement for female patients, regardless of the definition applied. An AHINS <10 events/hour is highly repeatable from night to night. CONCLUSIONS Males with an AHIS:AHINS ratio ≥4:1 and an AHINS <10 events/hour represent a consistent supine-predominant OSA phenotype from night to night. This patient group is likely to benefit from treatment with PMD.

Positional modification techniques for supine obstructive sleep apnea: A systematic review and meta-analysis.

This review aimed to determine the effectiveness of positional modification techniques in preventing supine sleep, sleep-disordered breathing and other clinically important outcomes in patients with supine obstructive sleep apnea (OSA). Randomized controlled trials comparing positional modification techniques with any other therapy or placebo were included. Electronic searches of databases including CENTRAL, MEDLINE, CINAHL, Embase, and Web of Science up to April 2016 were performed. Meta-analysis was undertaken where possible. This comprehensive meta-analysis found benefit for positional modification techniques in those with supine OSA in terms of reduction in apnea-hypopnea index (AHI) and time spent supine. Whilst positional modification techniques were effective in terms of a reduction in AHI, continuous positive airway pressure (CPAP) was more effective than these techniques. A reliable diagnosis of supine OSA should be considered, and further research is required on patient-centred outcomes including comfort, barriers to adherence, cost-analysis, and long term outcomes including the effect on cardiovascular disease, the metabolic syndrome, and insulin resistance.

Evaluation of the role of lung volume and airway size and shape in supine‐predominant obstructive sleep apnoea patients

This study aimed to evaluate the involvement of airway cross‐sectional area and shape, and functional residual capacity (FRC), in the genesis of obstructive sleep apnoea (OSA) in patients with supine‐predominant OSA.

Role of endobronchial ultrasound in diagnosis and molecular assessment of metastatic melanoma

Background and objective:  Vemurafenib is a new inhibitor of the mutated BRAF oncogene. In the presence of mutated BRAF in metastatic melanoma, treatment with vemurafenib leads to a reduction in mortality and in tumour progression when compared with chemotherapy. This study describes nine cases in which endobronchial ultrasound (EBUS) guided transbronchial needle aspiration (TBNA) was used to assess mediastinal and hilar lymph nodes for the presence of metastatic melanoma and demonstrates the ability to detect mutations in BRAF on the tissue obtained.

Therapeutic CPAP Level Predicts Upper Airway Collapsibility in Patients With Obstructive Sleep Apnea

Study Objectives Upper airway collapsibility is a key determinant of obstructive sleep apnea (OSA) which can influence the efficacy of certain non-continuous positive airway pressure (CPAP) treatments for OSA. However, there is no simple way to measure this variable clinically. The present study aimed to develop a clinically implementable tool to evaluate the collapsibility of a patients upper airway. Methods Collapsibility, as characterized by the passive pharyngeal critical closing pressure (Pcrit), was measured in 46 patients with OSA. Associations were investigated between Pcrit and data extracted from patient history and routine polysomnography, including CPAP titration. Results Therapeutic CPAP level, demonstrated the strongest relationship to Pcrit (r2=0.51, p < .001) of all the variables investigated including apnea-hypopnea index, body mass index, sex, and age. Patients with a mildly collapsible upper airway (Pcrit ≤ -2 cmH2O) had a lower therapeutic CPAP level (6.2 ± 0.6 vs. 10.3 ± 0.4 cmH2O, p < .001) compared to patients with more severe collapsibility (Pcrit > -2 cmH2O). A therapeutic CPAP level ≤8.0 cmH2O was sensitive (89%) and specific (84%) for detecting a mildly collapsible upper airway. When applied to the independent validation data set (n = 74), this threshold maintained high specificity (91%) but reduced sensitivity (75%). Conclusions Our data demonstrate that a patients therapeutic CPAP requirement shares a strong predictive relationship with their Pcrit and may be used to accurately differentiate OSA patients with mild airway collapsibility from those with moderate-to-severe collapsibility. Although this relationship needs to be confirmed prospectively, our findings may provide clinicians with better understanding of an individual patients OSA phenotype, which ultimately could assist in determining which patients are most likely to respond to non-CPAP therapies.

Impact of Weight Loss Management in OSA

&NA; The interaction between obesity and OSA is complex. Although it is often assumed that obesity is the major cause of OSA, and that treatment of the OSA might mitigate further weight gain, new evidence is emerging that suggests this may not be the case. Obesity explains about 60% of the variance of the apnea‐hypopnea index (AHI) definition of OSA, mainly in those < 50 years and less so in the elderly. Moreover, long‐term treatment of OSA with CPAP is associated with a small but significant weight gain. This weight gain effect may result from abolition of the increased work of breathing associated with OSA. Unfortunately, weight loss by either medical or surgical techniques, which often cures type 2 diabetes, has a beneficial effect on sleep apnea in only a minority of patients. A short jaw length may be predictive of a better outcome. The slight fall in the overall AHI with weight loss, however, may be associated with a larger drop in the nonsupine AHI, thus converting some patients from nonpositional to positional (ie, supine only) OSA. Importantly, patients undergoing surgical weight loss need close monitoring to prevent complications. Finally, in patients with moderate to severe obesity‐related OSA, the combination of weight loss with CPAP appears more beneficial than either treatment in isolation.