Mesenteric fat thickness is associated with metabolic syndrome independently of Apnoea-Hypopnoea Index in subjects with obstructive sleep apnoea

Sonographic Measurement of Mesenteric Fat Thickness Is a Better Predictor of Aortic Stiffness Compared With Conventional Obesity Indexes

Increased aortic stiffness is closely associated with central obesity whereas mesenteric fat is the key adipose tissue in central obesity. We investigated the associations of mesenteric fat thickness with aortic stiffness, with comparison to conventional obesity measures. We used ultrasound to measure mesenteric, pre-peritoneal and subcutaneous fat thickness, carotid intima-media thickness (CIMT) and carotid-femoral pulse wave velocity (c-f PWV), an index of central aortic stiffness. Anthropometric indexes, blood pressure, fasting plasma glucose and lipid profile were measured. One hundred forty-seven healthy volunteers (age [mean ± standard deviation]: 43.2 ± 13.3 y; 41.5% men) were assessed. On univariate analysis, mesenteric, preperitoneal and subcutaneous fat thickness, body mass index (BMI), waist circumference (WC), waist/hip ratio (WHR) and waist/height ratio (WHtR) were associated with c-f PWV with or without adjustment for age. The mesenteric fat thickness had the highest correlation coefficient (r = 0.48, p < 0.001) with c-f PWV among all the investigated obesity indexes. Using multiple linear regression analysis, only mesenteric fat thickness remained to be an independent determinant of c-f PWV after adjustments for other abdominal fat thickness, anthropometric and metabolic indexes and CIMT. In conclusion, mesenteric fat thickness is an independent risk factor for aortic stiffness and has a stronger association with aortic stiffness compared with conventional obesity indexes.

Effects of CPAP therapy on subcutaneous adipose tissue in patients with obstructive sleep apnea: a meta-analysis

PURPOSE

Continuous positive airway pressure (CPAP) is an effective treatment for obstructive sleep apnea (OSA). However, studies provide conflicting results on the effects of CPAP on subcutaneous adipose tissue (SAT) in patients with OSA. We therefore performed a meta-analysis to evaluate whether or not CPAP has an effect on SAT in patients with OSA.

METHODS

Studies were retrieved by searching the Cochrane Library, Web of Science, Embase, and Pubmed. Information on study and patient characteristics, study design, and SAT pre- and post-CPAP treatment was extracted for analysis. Different methods for measurement of SAT were also notated. Standardized mean difference (SMD) and 95% confidence interval (CI) were measured to estimate the change in SAT before and after CPAP treatment. Meta-analysis was performed using the RevMan v.5.3 and Stata 14.0.

RESULTS

A total of 10 studies met inclusion criteria encompassing 309 patients in the final analysis. The pooled estimate showed that CPAP treatment resulted in no significant change in SAT (SMD = - 0.014, 95% CI = - 0.161 to 0.133, p = 0.896). Meta-regression analyses revealed no predictor, including methods of measuring SAT, that influenced the CPAP effect on SAT.

CONCLUSION

Our meta-analysis demonstrated that after CPAP therapy, there was no significant change in SAT in patients with OSA.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-analysis

BACKGROUND

Perioperative diagnosis of obstructive sleep apnea (OSA) has important resource implications as screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. Ultrasound (US) is a portable, noninvasive tool potentially useful for airway evaluation and OSA screening in the perioperative period. The objective of this systematic review was to evaluate the correlation of surface US with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help with improved screening in perioperative period.

METHODS

A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface US assessment. Article screening, data extraction, and summarization were conducted by 2 independent reviewers with ability to resolve conflict with supervising authors. Diagnostic properties and association between US parameters (index test) and OSA diagnosis using sleep study (reference standard) were evaluated. The US parameters were divided into airway and nonairway parameters. A random-effects meta-analysis was planned, wherever applicable.

RESULTS

Of the initial 3865 screened articles, 21 studies (7 airway and 14 nonairway) evaluating 3339 patients were included. Majority of studies were conducted in the general population (49%), respirology (23%), and sleep clinics (12%). No study evaluated the use of US for OSA in perioperative setting. Majority of included studies had low risk of bias for reference standard and flow and timing. Airway US parameters having moderate-good correlation with moderate-severe OSA were distance between lingual arteries (DLAs > 30 mm; sensitivity, 0.67; specificity, 0.59; 1 study/66 patients); mean resting tongue thickness (>60 mm; sensitivity, 0.85; specificity, 0.59; 1 study/66 patients); tongue base thickness during Muller maneuver (MM; sensitivity, 0.59; specificity, 0.78; 1 study/66 patients); and a combination of neck circumference and retropalatal (RP) diameter shortening during MM (sensitivity, 1.0; specificity, 0.65; 1 study/104 patients). Nonairway US parameters having a low-moderate correlation with moderate-severe OSA were carotid intimal thickness (pooled correlation coefficient, 0.444; 95% confidence interval [CI], 0.320-0.553; P value = .000, 8 studies/727 patients) and plaque presence (sensitivity, 0.24-0.75; specificity, 0.13-1.0; 4 studies/1183 patients).

CONCLUSIONS

We found that a number of airway and nonairway parameters were identified with moderate to good correlation with OSA diagnosis in the general population. In future studies, it remains to be seen whether PoCUS screening for a combination of these parameters can address the pitfalls of OSA screening questionnaires.

Preperitoneal fat as a non-invasive marker of increased risk of severe non-alcoholic fatty liver disease in patients with type 2 diabetes

BACKGROUND AND AIM

Fat distribution may have prognostic value in the evaluation of non-alcoholic fatty liver disease. This study was conducted to evaluate associations of magnetic resonance imaging-measured abdominal fat areas with steatosis, steatohepatitis, and fibrosis, assessed histopathologically, in patients with type 2 diabetes.

METHODS

This prospective study included 66 patients with type 2 diabetes (12 males, 54 females, age 26-68 years), without chronic liver disease of other causes. Axial dual-echo magnetic resonance images were acquired. Visceral, subcutaneous, and preperitoneal fat areas were measured using Osirix software. Liver biopsy specimens were obtained from all patients and examined histopathologically to evaluate steatosis, steatohepatitis, and fibrosis. Linear (for steatosis) and logistic (for steatohepatitis and fibrosis) regression models were fitted for the outcomes. R2 was used as a measure of how much model variance the predictors explained and to compare different predictors of the same outcome.

RESULTS

Visceral and preperitoneal fat areas correlated well with histopathologically determined liver steatosis grade (both P = 0.004) and liver fibrosis (P = 0.008 and P = 0.037, respectively). All fat areas correlated well with steatohepatitis (P ≤ 0.002). Preperitoneal and visceral fat areas were the best predictors of steatohepatitis (R2 = 0.379) and fibrosis (R2 = 0.181), respectively.

CONCLUSIONS

Visceral fat area was the best predictor of fibrosis in patients with type 2 diabetes. Preperitoneal fat area was the best predictor of steatohepatitis and is a potential new non-invasive marker for use in the screening of these patients to detect more aggressive forms of non-alcoholic fatty liver disease.

Association between sonographically measured mesenteric fat thickness and brachial artery flow-mediated dilation in Chinese young male adults

Objective To investigate the potential correlation between sonographically measured mesenteric fat thickness (MFT) and brachial artery flow-mediated dilation (FMD) in a sample of healthy Chinese male young adults. Methods Healthy male participants were recruited from Hong Kong Polytechnic University for this prospective observational study. The physical activity readiness questionnaire and ultrasound measurements of carotid intima media thickness were used to screen for clinically healthy subjects. MFT and brachial artery FMD were measured by ultrasound, and body mass index (BMI) was recorded. Results A total of 34 healthy male subjects, aged 19-26 years (mean ± SD BMI, 21.7 ± 3.2 kg/m²) were included. Pearson's correlation coefficient test showed that brachial artery FMD had a statistically significant inverse relationship with BMI and with Log (MFT). Further stepwise multiple linear regression analysis showed that Log (MFT), and not BMI, was an independent predictor of impaired brachial artery FMD. Conclusions Sonographic measurements of MFT were an independent predictor of brachial artery FMD in Chinese male young adults.