Li-Da Chen

The relationship between excessive daytime sleepiness and metabolic syndrome in severe obstructive sleep apnea syndrome

Excessive daytime sleepiness (EDS), which is commonly considered a cardinal sign of obstructive sleep apnea (OSA), may lead to an increased rate of metabolic syndrome (MetS), and be an independent risk factor for cardiovascular morbidity and mortality. The aim of this cross‐sectional study was to examine the role of EDS in MetS and its components by researching severe OSA patients.

Effect of continuous positive airway pressure on liver enzymes in obstructive sleep apnea: A meta-analysis

Previous studies have suggested that obstructive sleep apnea (OSA) was associated with nonalcoholic fatty liver disease (NAFLD). However, the impact of OSA treatment using continuous positive airway pressure (CPAP) on liver enzymes remained controversial. This meta‐analysis was conducted to determine whether CPAP therapy could reduce liver enzyme levels.

Relationship between obstructive sleep apnea and nonalcoholic fatty liver disease in nonobese adults

PurposeObstructive sleep apnea (OSA) is closely related to nonalcoholic fatty liver disease (NAFLD), though the mechanism is not conclusive as obesity is a confounder. The objective of this observational study was to investigate the correlation between these disorders in nonobese subjects.MethodsWe consecutively enrolled nonobese individuals undergoing polysomnography and abdominal ultrasonography and analyzed differences in NAFLD patients grouped by the apnea–hypopnea index (AHI) and in OSA patients according to the presence or absence of NAFLD. Multivariate regression analysis was used to evaluate the independent risks of NAFLD in OSA patients.ResultsA total of 175 participants were included. The 106 ultrasound-diagnosed NAFLD patients were classified into four groups by AHI. There were no significant differences in triglycerides (TG), serum aminotransferase levels of alanine aminotransferase and aspartate aminotransferase, high-sensitivity C-reactive protein, and homeostasis model assessment of insulin resistance (HOMA-IR) with worsening OSA. In both OSA patients with NAFLD and those without NAFLD, body mass index (BMI), the lowest oxygen saturation (LaSO2), HOMA-IR, and TG were significantly associated. Additionally, BMI, LaSO2, and TG independently predicted the development of NAFLD after adjustments (odds ratio [OR] = 1.562, p = 0.003; OR = 0.960, p = 0.03; OR = 3.410, p < 0.001, respectively).ConclusionsIn nonobese subjects, OSA itself does not appear to induce significant changes in liver enzymes. With reference to lipid metabolism, weight control and OSA-related hypoxemia are key factors in reducing the risk of NAFLD in OSA patients. Additional large-scale, prospective studies are warranted to investigate the impact of OSA on liver injury in nonobese adults.

Obstructive sleep apnea is associated with fatty liver index, the index of nonalcoholic fatty liver disease.

Background and objectives The relationship between obstructive sleep apnea (OSA) and nonalcoholic fatty liver disease (NAFLD) is gaining increased attention. The aim of the present study was to examine the relationship of OSA with NAFLD defined by an elevated fatty liver index (FLI). Materials and methods A total of 319 consecutive patients who underwent standard polysomnography were enrolled. Fasting blood samples were obtained from all patients for biological profile measurements, and demographic data were collected. Values of FLI were determined and assessed as predictors of the presence of NAFLD, as measured by ultrasound. The discriminative ability of FLI was estimated on the basis of the area under the receiver operator characteristic curve. Results An FLI of 60 achieved the highest diagnostic accuracy and yielded an area under the receiver operator characteristic curve of 0.822 (95% confidence interval: 0.729–0.916) in the detection of NAFLD. Patients with an FLI of 60 or higher had a significantly lower lowest O2 saturation (73 vs. 83%, P<0.001), a lower mean nocturnal oxygen saturation (93 vs. 95%, P<0.001), a higher apnea–hypopnea index (39.7 vs. 18.4, P<0.001), a higher oxygen desaturation index (39 vs. 10.6, P<0.001), and a higher percentage of sleep time spent with SpO2 less than 90% (4.63 vs. 0.92%, P<0.001) compared with those with FLI less than 60. In multivariate analysis, the presence of OSA was independently associated with elevated FLI after adjusting for confounding factors (odds ratio: 5.141, 95% confidence interval: 1.414–18.696, P=0.013). Conclusion Our results suggest a positive association between the severity of OSA and NAFLD defined by an elevated FLI, which may serve as a good biomarker for detecting NAFLD in OSA patients.

Effect of continuous positive airway pressure on insulin growth factor-1 in patients with obstructive sleep apnea: A meta-analysis

OBJECTIVE Obstructive sleep apnea (OSA) has been recognized as being associated with low level of insulin growth factor-1 (IGF-1). However, the impact of OSA treatment using continuous positive airway pressure (CPAP) on IGF-1 remains controversial. We performed a meta-analysis to determine whether effective CPAP therapy could increase IGF-1 levels. DESIGN Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before September 2014. Information on characteristics of subjects, study design and pre- and post-CPAP treatment of serum IGF-1 was extracted for analysis. Standardized mean difference (SMD) was used to analyze the summary estimates for CPAP therapy. RESULTS Six articles with 168 patients were included in this meta-analysis, including five observational studies and one randomized controlled study. The meta-analysis showed that CPAP was associated with a statistically significant increase in IGF-1 in OSA patients (SMD=-0.436, 95% confidence interval=-0.653 to -0.218, P=0.000). CONCLUSIONS This meta-analysis suggested that CPAP therapy was associated with an increase in IGF-1 in patients with OSA. Further large-scale, well-designed interventional investigations are needed to clarify this issue.

Assessment of Upper-Airway Configuration in Obstructive Sleep Apnea Syndrome With Computed Tomography Imaging During Müller Maneuver.

BACKGROUND: The purpose of this observational study was to investigate the relationship between upper-airway configuration assessed by CT imaging during the Müller maneuver state and the severity of obstructive sleep apnea syndrome (OSAS). METHODS: A total of 358 snoring subjects who underwent standard polysomnography and upper-airway configuration by using CT imaging were enrolled. According to the apnea-hypopnea index (AHI), subjects were classified into 4 groups: snoring group (simple snoring), AHI < 5; mild OSAS, 5 ≤ AHI < 15; moderate OSAS, 15 ≤ AHI < 30; and severe OSAS, AHI ≥ 30. We also divided the upper airway into 3 parts, named the nasopharynx, oropharynx, and hypopharynx, from the CT scan and evaluated the minimal cross-sectional area (mCSA) and the shape of each airway level and calculated upper-airway length and distance from mandibular plane to hyoid bone (MPH). RESULTS: Multivariate logistic stepwise regression analysis identified body mass index (BMI), mCSA of nasopharynx, upper-airway length, and MPH as risk factors for the severity of OSAS. When subdivided for BMI and sex, upper-airway length was a risk factor for OSAS in non-obese (BMI < 27 kg/m2) and male subjects, and MPH was a risk factor only in obese (BMI ≥ 27 kg/m2) subjects. Meanwhile, mCSA of nasopharynx was significantly associated with the severity of OSAS independent of BMI. CONCLUSIONS: Subjects with severe OSAS have more significant abnormalities of the upper airway. Obesity, mCSA of nasopharynx, upper-airway length, and MPH may contribute to the severity of OSAS. Obesity and sex should be taken into account when evaluating the abnormalities of upper-airway anatomy in snorers and patients with OSAS.

Impact of continuous positive airway pressure on vascular endothelial growth factor in patients with obstructive sleep apnea: a meta-analysis

PurposeCumulative evidence supports the clear relationship of obstructive sleep apnea (OSA) with cardiovascular disease (CVD). And, adherence to continuous positive airway pressure (CPAP) treatment alleviates the risk of CVD in subjects with OSA. Vascular endothelial growth factor (VEGF), a potent angiogenic cytokine regulated by hypoxia-inducible factor, stimulates the progression of CVD. Thus, whether treatment with CPAP can actually decrease VEGF in patients with OSA remains inconclusive. The purpose of the present study was to quantitatively evaluate the impact of CPAP therapy on VEGF levels in OSA patients.MethodsWe systematically searched Web of Science, Cochrane Library, PubMed, and Embase databases that examined the impact of CPAP on VEGF levels in OSA patients prior to May 1, 2017. Related searching terms were “sleep apnea, obstructive,” “sleep disordered breathing,” “continuous positive airway pressure,” “positive airway pressure,” and “vascular endothelial growth factor.” We used standardized mean difference (SMD) to analyze the summary estimates for CPAP therapy.ResultsSix studies involving 392 patients were eligible for the meta-analysis. Meta-analysis of the pooled effect showed that levels of VEGF were significantly decreased in patients with OSA before and after CPAP treatment (SMD = − 0.440, 95% confidence interval (CI) = − 0.684 to − 0.196, z = 3.53, p = 0.000). Further, results demonstrated that differences in age, body mass index, apnea–hypopnea index, CPAP therapy duration, sample size, and racial differences also affected CPAP efficacy.ConclusionsImproved endothelial function measured by VEGF may be associated with CPAP therapy in OSA patients. The use of VEGF levels may be clinically important in evaluating CVD for OSA patients. Further large-scale, well-designed long-term interventional investigations are needed to clarify this issue.