CPAP reduces hypercoagulability, as assessed by thromboelastography, in severe obstructive sleep apnoea

The Correlation between Obstructive Sleep Apnea and Retinal Vein Obstruction: A Meta-Analysis and Systematic Review

Despite of inadequate evidence, previous studies have demonstrated a potential correlation between obstructive sleep apnea (OSA) and retinal vein occlusion (RVO). In this study, a meta-analysis is conducted to investigate the correlation between OSA and RVO. Databases are searched for relevant literatures up to July 14, 2021, including PubMed, Embase, Cochrane, Web of Science, CNKI, WanFang, VIP, and Chinese Biomedical Literature Database (CBM). The odds ratio (OR) and 95% confidence interval (CI) are estimated to evaluate the correlation between OSA and RVO. Six articles were finally enrolled, including 36,086 subjects from 5 case-controlled studies and 1 cohort study. It is clearly evident that the RVO risk is higher among OSA patients than non-OSA patients (OR = 3.24, 95% CI = 3.24). The results of sensitivity analysis indicate that the present meta-analysis is robust and reliable. Furthermore, Egger's test for publication bias is performed with P = 0.195, and the results reveal no significant publication bias. The findings demonstrate that OSA is significantly correlated with RVO, and OSA is a risk factor for RVO.

Use of Thromboelastography and Rotational Thromboelastometry in Otolaryngology: A Narrative Review

In the field of otolaryngology—head and neck surgery (ENT), coagulopathies present unique diagnostic and therapeutic challenges. In both hyper- and hypocoagulable patients, management of coagulopathies requires intricate attention to the nature of hemostatic competence. Common coagulation tests (CCTs) offer only a snapshot of hemostatic competence and do not provide a clear insight into the patient’s real-time hemostatic condition. Viscoelastic tests (VETs) offer a holistic and concurrent picture of the coagulation process. Although VETs have found prominent utilization in hepatic transplants, obstetrics, and emergent surgical settings, they have not been fully adopted in the realm of otolaryngology. The objective of this manuscript is to provide an overview of the literature evaluating the current utilization and possible future uses of VETs in the field of otolaryngology. The authors performed a comprehensive literature search of the utilization of VETs in otolaryngology and identified applicable studies that included descriptions of viscoelastic testing. Twenty-five studies were identified in this search, spanning topics from head and neck oncology, microvascular free flap reconstruction, obstructive sleep apnea, adenotonsillectomy, facial trauma, and epistaxis. The applicability of VETs has been demonstrated in head and neck oncology and microvascular free flap management, although their pervasiveness in practice is limited. Underutilization of VETs in the field of otolaryngology may be due to a lack of familiarity of the tests amongst practitioners. Instead, most otolaryngologists continue to rely on CCTs, including PT, PTT, INR, CBC, fibrinogen levels, and thrombin time. Learning to perform, interpret, and skillfully employ VETs in clinical and operative practice can greatly improve the management of coagulopathic patients who are at increased risk of bleeding or thrombosis.

Procoagulant State of Sleep Apnea Depends on Systemic Inflammation and Endothelial Damage

INTRODUCTION

Growing evidence shows a hypercoagulable state in obstructive sleep apnea (OSA) that could be a risk factor for thromboembolic disease.

OBJECTIVES

We aimed to elucidate mechanisms involved in the procoagulant profile observed in patients with OSA and to investigate the potential utility of global tests in its characterization.

METHODS

Thirty-eight patients with severe OSA without previous history of thrombosis and nineteen healthy age- and sex-matched controls were included. Kinetic of clot formation was determined using rotational thromboelastometry. Haemostatic capacity of plasma and microparticles was determined by Calibrated Automated Thrombinography. Platelet surface receptors, activation markers and formation of platelet/leukocytes aggregates were analyzed by flow cytometry.

RESULTS

Thromboelastometry showed a procoagulant state in patients with OSA that did not seem to be related to a basal activation of platelets but by the increased existence of platelet/leukocyte aggregates. Patients with OSA presented many signs of endothelial damage such as increased plasma levels of E-selectin and cfDNA and enhanced thrombin generation due to the presence of microparticles rich in tissue-factor, which is related to OSA severity.

CONCLUSIONS

OSA induces an enhancement in the dynamics of clot formation which appears to be caused by at least two pathological mechanisms. First, a greater formation of platelet-leukocyte aggregates; secondly, endothelial damage which provokes a greater procoagulant potential due to the increase in tissue factor-rich microparticles. Moreover, this study has identified thromboelastometry and thrombin generation assay as useful tools to evaluate the prothrombotic state in these patients.

Acute pulmonary embolism in patients with obstructive sleep apnea: frequency, hospital outcomes, and recurrence

STUDY OBJECTIVES

The objectives of this study were to assess the effect of obstructive sleep apnea (OSA) on the risk of acute pulmonary embolism (PE), hospital outcomes including mortality, and PE recurrence.

METHODS

We retrospectively enrolled adult patients, admitted to Mayo Clinic Hospital in Rochester, Minnesota, within a 5-year period (2009-2013). We compared frequency of PE, hospital mortality, and secondary outcomes in patients with OSA versus patients without OSA. We assessed risk of PE recurrence in relation to compliance with OSA therapy.

RESULTS

Of 25,038 patients, 3,184 (13%) had OSA and 283 (1.1%) experienced PE. Frequency of PE in patients with and without OSA was 2.4% versus 0.9% (odds ratio [OR], 2.51; 95% confidence interval [CI], 1.9-3.3; P < .001). OSA was independently associated with increased risk of PE after adjusting for demographics and comorbidities (OR, 1.44; 95% CI, 1.07-1.9; P = .017). Adjusted hospital mortality was increased in patients with PE (OR, 2.88; 95% CI, 1.7-4.9; P < .001) but not in patients with OSA (OR, 0.98; 95% CI, 0.7-1.4, P = .92). OSA was not a significant determining factor for mortality in patients who experienced a PE (OR, 0.56; 95% CI, 0.1.1-2.78; P = .47), adjusting for demographics, PE severity, and Charlson comorbidity index. Adjusted risk of PE recurrence was greater in patients with OSA compared with patients without OSA (OR, 2.21; 95% CI, 1.05-4.68; P < .04). The patients compliant with OSA therapy had a lower rate of PE recurrence (16% vs 32%; P = not significant).

CONCLUSIONS

Although OSA significantly increases risk of acute PE occurrence and recurrences, related hospital mortality was not greater in patients with OSA compared with those without OSA. OSA therapy might have a modifying effect on PE recurrence.

Obstructive sleep apnea and venous thromboembolism: Overview of an emerging relationship

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular syndromes. Venous thromboembolism (VTE) is a chronic disease, and pulmonary embolism (PE) is the major expression of VTE and the third most frequent cardiovascular disease. An increasing and emerging number of cross-sectional and longitudinal studies have linked OSA to VTE, and have postulated different putative pathways to explain how OSA might increase the risk of PE. We aim to provide a critical overview of the existing evidence about the complex relationship between these two conditions, with some factors and confounding variables still to be clarified. A global interpretation of the studies shows OSA is highly prevalent in VTE patients. This association represents a major public health burden, given the high prevalence and the mortality rates of both disorders. Although still not proven, OSA may induce a persistent hypercoagulable state that may contribute to increase VTE rate and its recurrence. Coagulant activity, platelet function and fibrinolytic system may improve after continuous positive airway pressure (CPAP) in OSA. However, there is a still a lack of randomized controlled trials to evaluate the potential of CPAP and/or extend oral anticoagulation to reduce PE incidence, recurrence and mortality by PE in patients with OSA.

Prevalence of obstructive sleep apnea in venous thromboembolism: a systematic review and meta-analysis

PURPOSE

Previous studies revealed that the concomitant prevalence of obstructive sleep apnea (OSA) and venous thromboembolism (VTE) was high, but the results were inconclusive due to various limitations. We aimed to systematically review the literature on the prevalence of OSA in patients with VTE.

METHODS

Relevant studies were identified on multiple electronic databases through July 2018. The DerSimonian-Laird random effects model was used to calculate the pooled prevalence of OSA, moderate-to-severe OSA, and severe OSA in VTE patients, respectively. Sensitivity analysis was performed based on diagnostic methods of OSA and races.

RESULTS

A total of 11 studies comprising 895 patients were available for the meta-analysis, but one study was excluded because of the between-study heterogeneity in the following analysis. The pooled prevalence of OSA, moderate-to-severe OSA, and severe OSA in VTE patients were 70% (95% CI = 65%, 75%), 41% (95% CI = 29%, 54%), and 19% (95% CI = 15%, 23%), respectively. Sensitivity analysis indicated that the prevalence was similar in different diagnostic methods, but the contributions of races to OSA were complex. Although the lower prevalence of all OSA and moderate-to-severe OSA as compared with Western countries, Asian countries have similar or even a little bit higher prevalence of severe OSA.

CONCLUSIONS

Findings from this meta-analysis supported that the prevalence of OSA in VTE patients was strikingly high. Screening for OSA in patients with VTE is necessary for developing effective treatment strategies.

Obstructive sleep apnoea and venous thromboembolism: pathophysiological links and clinical implications

Obstructive sleep apnoea (OSA) and pulmonary embolism (PE) remain major health issues worldwide. Data from pathophysiological studies suggest that both intermittent hypoxia and sleep fragmentation are associated with increased blood coagulability, endothelial dysfunction and venous stasis. There is growing evidence that OSA is potentially prevalent in and a risk factor for PE. Conversely, patients with acute PE have two to four times greater risk of moderate-to-severe OSA. The role of continuous positive airway pressure (CPAP) treatment in improving clinically meaningful outcomes in PE patients remains unclear, although some authors have suggested that CPAP could improve the hypercoagulability state and normalise circadian alterations in some of the coagulation molecules, as observed in patients with OSA. Emerging research highlights the complex interdependent relationships between OSA and PE, emphasising the need for rigorous, well-powered trials that address the impact of OSA and its treatment on the prevention and management of PE. Undoubtedly, these will require closer collaboration between the sleep medicine and clinical/venous thromboembolism communities.

Anaesthesia of brachycephalic dogs

Brachycephalic breeds of dog have grown in popularity in the UK and so form an increasing proportion of cases requiring anaesthesia. These breeds are predisposed to several conditions, notably brachycephalic obstructive airway syndrome and gastro-oesophageal reflux, that have important implications for anaesthetic management and carry high risk for complications. This review incorporates peer-reviewed veterinary literature with clinical experience in a discussion on perioperative management of brachycephalic dogs. We focus on preoperative identification of common concurrent conditions, practical strategies for reducing anaesthetic risk and improving postoperative management. Comparisons of brachycephalic obstructive airway syndrome with the human condition of obstructive sleep apnoea are included where appropriate.

Repercusiones cardiovasculares del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

En la población de sujetos con síndrome de apnea-hipopnea obstructiva del sueño se describen entidades clínicas cardiovasculares asociadas con esta entidad y que afectan su curso y pronóstico. Dentro de estas se encuentran hipertensión arterial, arritmias, enfermedad coronaria, insuficiencia cardíaca, hipertensión pulmonar y tromboembolismo venoso. Del mismo modo, se describen los mecanismos fisiopatológicos de estas asociaciones, su prevalencia e impacto. Dado que afectan el curso de la enfermedad y, por tanto, la severidad de la misma, estas entidades juegan un papel muy importante en la toma de decisiones al momento de ofrecer el mejor manejo en cada caso, el cual debe ser abordado de forma multidisciplinaria.

Thromboelastography (TEG)

Thromboelastography (TEG) has been used for decades to guide transfusion therapy during cardiac and hepatic surgeries. Renewed interest and improved technology have led to wider applications of TEG in other areas of hemostasis. To correctly interpret the data generated and to validate outcomes, it is important to improve the understanding of the differences in the currently available assay procedures, the issues related to sample activation, and the importance of the use of appropriate controls. Current TEG assays use a variety of samples and can vary slightly in the procedures. In this chapter, we very briefly review TEG applications and discuss interpretations, normal ranges, and reference controls, and we explain the method of TEG run using standard citrated native blood samples. We provide detailed technical steps and tips. We discuss precautions and issues related to the assay, which we hope can guide toward better application and data interpretation.

Midfacial and Dental Changes Associated with Nasal Positive Airway Pressure in Children with Obstructive Sleep Apnea and Craniofacial Conditions

STUDY OBJECTIVES

Nasal positive airway pressure (nPAP) for treatment of pediatric obstructive sleep apnea (OSA) is a widespread therapy that currently lacks longitudinal data describing how mask pressure impacts the developing facial skeleton. This retrospective cohort study compared midfacial growth in pediatric patients with underlying craniofacial conditions diagnosed with OSA who were compliant vs. noncompliant with nPAP therapy, and explored correlations between demographic, medical, and sleep variables with annual rate of facial change.

METHODS

Records from Seattle Children's Hospital's Craniofacial Center and Sleep Disorders Center were reviewed to identify patients prescribed nPAP for OSA with serial cephalographic images obtained during routine clinical care for concomitant craniofacial diagnosis. Lateral cephalometric analysis was used to determine mean annual change in midfacial structures from T1 (pre-nPAP) to T2 (post-nPAP) in compliant vs. noncompliant subjects. Compliance was indicated by nPAP usage of > 20 h/week for > 6 months.

RESULTS

50 subjects were compliant with nPAP therapy (mean age 10.42 years) for an average of 2.57 years, and 50 subjects were noncompliant (mean age 8.53 years). Compliant subjects experienced negative mean annual change (retrusion) of the midface compared to forward growth seen in noncompliant subjects (SNA: -0.57° vs. 0.56°), counterclockwise rotation of palatal plane (SN-PP: -1.15° vs. 0.09°), and upper incisor flaring (U1-SN: 2.41° vs. -0.51°).

CONCLUSIONS

Pressure to the midface from compliant nPAP use may alter normal facial growth. Cephalometric findings indicate a greater need for collaboration between sleep medicine physicians and orthodontists to monitor midfacial growth during nPAP treatment.

High D-dimer levels after stopping anticoagulants in pulmonary embolism with sleep apnoea

Obstructive sleep apnoea is a risk factor for pulmonary embolism. Elevated D-dimer levels and other biomarkers are associated with recurrent pulmonary embolism. The objectives were to compare the frequency of elevated D-dimer levels (>500 ng·mL−1) and further coagulation biomarkers after oral anticoagulation withdrawal in pulmonary embolism patients, with and without obstructive sleep apnoea, including two control groups without pulmonary embolism.

We performed home respiratory polygraphy. We also measured basic biochemical profile and haemogram, and coagulation biomarkers (D-dimer, prothrombin fragment 1+2, thrombin-antithrombin complex, plasminogen activator inhibitor 1, and soluble P-selectin).

64 (74.4%) of the pulmonary embolism cases and 41 (46.11%) of the controls without pulmonary embolism had obstructive sleep apnoea. Plasmatic D-dimer was higher in PE patients with OSA than in those without obstructive sleep apnoea. D-dimer levels were significantly correlated with apnoea–hypopnoea index, and nocturnal hypoxia. There were more patients with high D-dimer after stopping anticoagulants in those with pulmonary embolism and obstructive sleep apnoea compared with PE without obstructive sleep apnoea (35.4% versus 19.0%, p=0.003). Apnoea–hypopnoea index was independently associated with high D-dimer.

Pulmonary embolism patients with obstructive sleep apnoea had higher rates of elevated D-dimer levels after anticoagulation discontinuation for pulmonary embolism than in patients without obstructive sleep apnoea and, therefore, higher procoagulant state that might increase the risk of pulmonary embolism recurrence.

Obstructive sleep apnea syndrome: coagulation anomalies and treatment with continuous positive airway pressure

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder associated with severe cardiovascular events, morbidity and mortality. Recent evidence has highlighted OSAS as an independent risk factor for an excessive platelet activation and arterial thrombosis, but the underlying mechanisms have not yet been determined. Studies in cell culture and animal models have significantly increased our understanding of the mechanisms of inflammation in OSAS. Hypoxia is a critical pathophysiological element that leads to an intense sympathetic activity, in association with systemic inflammation, oxidative stress and procoagulant activity. While platelet dysfunction and/or hypercoagulability play an important role in the pathogenesis of vascular disease, there are limited studies on the potential role of blood viscosity in the development of vascular disease in OSAS.

CONCLUSION

Further studies are required to determine the precise role of hypercoagulability in the cardiovascular pathogenesis of OSAS, particularly its interaction with oxidative stress, thrombotic tendency and endothelial dysfunction. Nasal continuous positive airway pressure (nCPAP), the gold standard treatment for OSAS, not only significantly reduced apnea-hypopnoea indices but also markers of hypercoagulability, thus representing a potential mechanisms by which CPAP reduces the rate of cardiovascular morbidity and mortality in OSAS patients.

Clinical effectiveness and cost-effectiveness results from the randomised controlled Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and long-term economic analysis of oral devices and continuous positive airway pressure

BACKGROUND

Obstructive sleep apnoea-hypopnoea (OSAH) causes excessive daytime sleepiness (EDS), impairs quality of life (QoL) and increases cardiovascular disease and road traffic accident risks. Continuous positive airway pressure (CPAP) treatment is clinically effective but undermined by intolerance, and its cost-effectiveness is borderline in milder cases. Mandibular advancement devices (MADs) are another option, but evidence is lacking regarding their clinical effectiveness and cost-effectiveness in milder disease.

OBJECTIVES

(1) Conduct a randomised controlled trial (RCT) examining the clinical effectiveness and cost-effectiveness of MADs against no treatment in mild to moderate OSAH. (2) Update systematic reviews and an existing health economic decision model with data from the Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and newly published results to better inform long-term clinical effectiveness and cost-effectiveness of MADs and CPAP in mild to moderate OSAH.

TOMADO

A crossover RCT comparing clinical effectiveness and cost-effectiveness of three MADs: self-moulded [SleepPro 1™ (SP1); Meditas Ltd, Winchester, UK]; semibespoke [SleepPro 2™ (SP2); Meditas Ltd, Winchester, UK]; and fully bespoke [bespoke MAD (bMAD); NHS Oral-Maxillofacial Laboratory, Addenbrooke's Hospital, Cambridge, UK] against no treatment, in 90 adults with mild to moderate OSAH. All devices improved primary outcome [apnoea-hypopnoea index (AHI)] compared with no treatment: relative risk 0.74 [95% confidence interval (CI) 0.62 to 0.89] for SP1; relative risk 0.67 (95% CI 0.59 to 0.76) for SP2; and relative risk 0.64 (95% CI 0.55 to 0.76) for bMAD (p < 0.001). Differences between MADs were not significant. Sleepiness [as measured by the Epworth Sleepiness Scale (ESS)] was scored 1.51 [95% CI 0.73 to 2.29 (SP1)] to 2.37 [95% CI 1.53 to 3.22 (bMAD)] lower than no treatment (p < 0.001), with SP2 and bMAD significantly better than SP1. All MADs improved disease-specific QoL. Compliance was lower for SP1, which was unpopular at trial exit. At 4 weeks, all devices were cost-effective at £20,000/quality-adjusted life-year (QALY), with SP2 the best value below £39,800/QALY.

META-ANALYSIS

A MEDLINE, EMBASE and Science Citation Index search updating two existing systematic reviews (one from November 2006 and the other from June 2008) to August 2013 identified 77 RCTs in adult OSAH patients comparing MAD with conservative management (CM), MADs with CPAP or CPAP with CM. MADs and CPAP significantly improved AHI [MAD -9.3/hour (p < 0.001); CPAP -25.4/hour (p < 0.001)]. Effect difference between CPAP and MADs was 7.0/hour (p < 0.001), favouring CPAP. No trials compared CPAP with MADs in mild OSAH. MAD and CPAP reduced the ESS score similarly [MAD 1.6 (p < 0.001); CPAP 1.6 (p < 0.001)].

LONG-TERM COST-EFFECTIVENESS

An existing model assessed lifetime cost-utility of MAD and CPAP in mild to moderate OSAH, using the revised meta-analysis to update input values. The TOMADO provided utility estimates, mapping ESS score to European Quality of Life-5 Dimensions three-level version for device cost-utility. Using SP2 as the standard device, MADs produced higher mean costs and mean QALYs than CM [incremental cost-effectiveness ratio (ICER) £6687/QALY]. From a willingness to pay (WTP) of £15,367/QALY, CPAP is cost-effective, although the likelihood of MADs (p = 0.48) and CPAP (p = 0.49) being cost-effective is very similar. Both were better than CM, but there was much uncertainty in the choice between CPAP and MAD (at a WTP £20,000/QALY, the probability of being the most cost-effective was 47% for MAD and 52% for CPAP). When SP2 lifespan increased to 18 months, the ICER for CPAP compared with MAD became £44,066. The ICER for SP1 compared with CM was £1552, and for bMAD compared with CM the ICER was £13,836. The ICER for CPAP compared with SP1 was £89,182, but CPAP produced lower mean costs and higher mean QALYs than bMAD. Differential compliance rates for CPAP reduces cost-effectiveness so MADs become less costly and more clinically effective with CPAP compliance 90% of SP2.

CONCLUSIONS

Mandibular advancement devices are clinically effective and cost-effective in mild to moderate OSAH. A semi-bespoke MAD is the appropriate first choice in most patients in the short term. Future work should explore whether or not adjustable MADs give additional clinical and cost benefits. Further data on longer-term cardiovascular risk and its risk factors would reduce uncertainty in the health economic model and improve precision of effectiveness estimates.

TRIAL REGISTRATION

This trial is registered as ISRCTN02309506.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 67. See the NIHR Journals Library website for further project information.

Sleep apnea and venous thromboembolism. A systematic review

Recent evidence suggests that obstructive sleep apnea is a significant and independent risk factor for a number of cardiovascular disorders. Since the association between obstructive sleep apnea and cardiovascular disease is mediated by endothelial dysfunction, hypercoagulability and platelet abnormalities, we sought to investigate whether sleep apnea may also be considered a risk factor for venous thromboembolism (VTE). We carried out an electronic search in Medline and Scopus using the keywords "apnea" OR "apnoea" AND "venous thromboembolism" OR "deep vein thrombosis" OR "pulmonary embolism" in "Title/Abstract/Keywords", with no language or date restriction. Fifteen studies (8 case-control, 4 retrospective observational, 2 prospective case-control and 1 prospective observational) were finally selected for this systematic review. In all studies except one (14/15; 93 %), obstructive sleep apnea was found to be an independent risk factor for VTE, either deep-vein thrombosis (DVT) or pulmonary embolism (PE). In the two prospective case-control studies the risk of DVT or PE was found to be two- to three-fold higher in patients with obstructive sleep apnea than in those without. In conclusion, the current epidemiological evidence supports the hypothesis that obstructive sleep apnea may be an independent risk factor for VTE.

Obstructive sleep apnoea and cardiovascular disease

Obstructive sleep apnoea (OSA) is a common health concern caused by repeated episodes of collapse of the upper airway during sleep. The events associated with OSA lead to brain arousal, intrathoracic pressure changes, and intermittent episodes of hypoxaemia and reoxygenation. These events activate pathways such as oxidative stress, sympathetic activation, inflammation, hypercoagulability, endothelial dysfunction, and metabolic dysregulation that predispose patients with OSA to hypertension and atherosclerosis. OSA is a common cause of systemic hypertension and should be suspected in hypertensive individuals, especially those with resistant hypertension. In patients with OSA, continuous positive airway pressure (CPAP) treatment reduces blood pressure, and its effects are related to compliance and baseline blood pressure. Evidence suggests that OSA is a risk factor for stroke and heart failure. An association between coronary heart disease and OSA seems to be limited to middle-aged men (30-70 years). Cardiac rhythm disorders occur in about half of patients with OSA, but their clinical relevance is still unknown. The association of OSA with cardiovascular risk is mainly based on studies in men, and an association has yet to be established in women. Data on older patients is similarly scarce. Currently, there is not enough evidence to support treatment with CPAP for primary or secondary prevention of cardiovascular disease.