Effect of uvulopalatopharyngoplasty on leptin and endothelial function in sleep apnea

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Risk of diabetes in patients with sleep apnea: comparison of surgery versus CPAP in a long-term follow-up study

This study aimed to obtain a comprehensive view of the risk of developing diabetes in patients with obstructive sleep apnea (OSA) and to compare this risk between patients receiving continuous positive airway pressure (CPAP) therapy versus upper airway surgery (UAS). We used local and the global-scale federated data research network TriNetX to obtain access to electronic medical records, including those for patients diagnosed with OSA, from health-care organizations (HCOs) worldwide. Using propensity score matching and the score-matched analyses of data for 5 years of follow-up, we found that patients who had undergone UAS had a lower risk of developing diabetes than those who used CPAP (risk ratio 0.415, 95% confidence interval (CI) 0.349-0.493). The risk for newly diagnosed diabetes patients showed a similar pattern (hazard ratio 0.382; 95% CI 0.317-0.459). Both therapies seem to protect against diabetes (Risk 0.081 after UAS vs. 0.195 after CPAP). Analysis of the large data sets collected from HCOs in Europe and globally lead us to conclude that, in patients with OSA, UAS can prevent the development of diabetes better than CPAP.

Obstructive sleep apnoea/hypopnoea syndrome: relationship with obesity and management in obese patients

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a disease characterised by upper airway obstruction during sleep, quite frequent in the general population, even if underestimated. Snoring, sleep apnoea and diurnal hypersomnia are common in these patients. Central obesity plays a key role: it reduces the size and changes the conformation of the upper airways, besides preventing lung expansion, with consequent reduction of lung volumes. Furthermore, obese people are also resistant to leptin, which physiologically stimulates ventilation; as a result, this causes scarce awakening during apnoea. OSAHS diagnosis is based on the combination of clinical parameters, such as apnoea/hypopnoea index (AHI), medical history, physical examination and Mallampati score. The first objective reference method to identify OSAHS is polysomnography followed by sleep endoscopy. Therapy provides in the first instance reduction of body weight, followed by continuous positive airway pressure (CPAP), which still remains the treatment of choice in most patients, mandibular advancement devices (MAD) and finally otolaryngology or maxillofacial surgery. Among surgical techniques, central is barbed reposition pharyngoplasty (BRP), used in the field of multilevel surgery.

Role of Leptin in Obstructive Sleep Apnea

Leptin is a peptide hormone produced mainly in white adipose tissue. It is known to regulate energy homeostasis, inflammation, metabolism, and sympathetic nerve activity. Increasing evidence suggests it has a role in ventilatory function and upper airway obstruction. Leptin levels correlate positively with measurements of adiposity and can potentially provide important insights into the pathophysiology of diseases associated with obesity. Obesity is a strong risk factor for obstructive sleep apnea, a disease characterized by periodic upper airway occlusion during sleep. The neuromuscular activity that maintains upper airway patency during sleep and the anatomy of upper airway are key factors involved in its pathogenesis. Experimental studies using animal models of a low leptin state such as leptin deficiency have shown that leptin regulates sleep architecture, upper airway patency, ventilatory function, and hypercapnic ventilatory response. However, findings from human studies do not consistently support the data from the animal models. The effect of leptin on the pathophysiology of obstructive sleep apnea is being investigated, but the results of studies have been confounded by leptin's diurnal variation and the short-term effects of feeding, adiposity, age, and sex. Improved study design and methods of assessing functional leptin levels, specifically their central versus peripheral effects, will improve understanding of the role of leptin in sleep apnea.

Leptin and Leptin Resistance in the Pathogenesis of Obstructive Sleep Apnea: A Possible Link to Oxidative Stress and Cardiovascular Complications

Obesity-related sleep breathing disorders such as obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS) cause intermittent hypoxia (IH) during sleep, a powerful trigger of oxidative stress. Obesity also leads to dramatic increases in circulating levels of leptin, a hormone produced in adipose tissue. Leptin acts in the hypothalamus to suppress food intake and increase metabolic rate. However, obese individuals are resistant to metabolic effects of leptin. Leptin also activates the sympathetic nervous system without any evidence of resistance, possibly because these effects occur peripherally without a need to penetrate the blood-brain barrier. IH is a potent stimulator of leptin expression and release from adipose tissue. Hyperleptinemia and leptin resistance may upregulate generation of reactive oxygen species, increasing oxidative stress and promoting inflammation. The current review summarizes recent data on a possible link between leptin and oxidative stress in the pathogenesis of sleep breathing disorders.

Surgical Treatment of OSA on Cardiovascular Outcomes: A Systematic Review

BACKGROUND

OSA is an increasingly prevalent clinical problem with significant effects on quality of life and cardiovascular risk. Surgical therapy represents an important treatment for those unable to use positive airway pressure. This systematic review examines the available cardiovascular risk reduction data for the surgical treatment of OSA.

METHODS

A comprehensive literature search was performed. Articles were included if they met the following criteria: (1) the sample population consisted of adults (age ≥ 18 years); (2) OSA was diagnosed according to a sleep study; (3) surgical intervention was performed for OSA; and (4) one or more physical or biochemical cardiovascular and/or cerebrovascular variables was measured preoperatively and at ≥ 14 days postoperatively.

RESULTS

Thirty-three articles were included. The majority of studies were case series and cohort studies (42% and 44%, respectively), with wide-ranging follow-up periods (4 weeks-9 years) and sample sizes (range, 6-10,339; median, 34). The following classes of surgical intervention were examined: pharyngeal surgery (n = 23), tracheostomy (n = 6), maxillomandibular advancement (n = 3), and hypoglossal nerve stimulation (n = 1). In total, 19 outcome measures were assessed. Tracheostomy was most consistently associated with improvement in cardiovascular end points. Pharyngeal surgeries (eg, uvulopalatopharyngoplasty) were variably associated with improvement in cardiovascular end points.

CONCLUSIONS

The published literature examining cardiovascular end points following surgical treatment of OSA is limited and generally of poor quality. However, available data from mainly small and observational studies suggest that surgical treatment of OSA may provide improvement in some cardiovascular end points. Larger, randomized, and prospective trials with more rigorous study designs are needed.

TRIAL REGISTRY

PROSPERO International Prospective Register of Systemic Reviews (PROSPERO 42016040120).