Metabolic effects of the obstructive sleep apnea syndrome and cardiovascular risk

Comparing Sleep Patterns and Clinical Features between Preschool and School-Age Children with OSA

OBJECTIVE

This study aimed to evaluate sleep patterns and investigate differences in clinical features among young individuals with snoring and obstructive sleep apnea (OSA).

METHODS

Data from 213 children and adolescents who underwent polysomnography (PSG) for primary snoring or OSA were collected between July 2017 and December 2021. To analyze differences in sleep architecture, hypoxia levels, and other clinical features, the participants were divided into two age groups: a preschool group and a school-age group.

RESULTS

The school-age group had significantly higher apnea-hypopnea index, obstructive apnea index, oxygen desaturation index, and body mass index than the preschool group. Both the lowest and average oxygen saturation levels were lower in the school-age group. Adenoid hypertrophy was more prevalent in the preschool group. The rate of overweight or obesity was 35.6% in the preschool group and even 94.2% in the school-age group. There were higher percentages of N1 and N2 sleep stages, and lower percentages of N3 and REM sleep stages in the school-age group. The groups exhibiting moderate to severe OSA demonstrated significant alterations in the difference between sleeping and waking diastolic blood pressure.

CONCLUSION

There is a higher frequency of respiratory events among school-age children compared with their preschool peers. Moreover, alterations in sleep structure are more prominent in the school-age group. Adenoid hypertrophy may serve as the primary instigator of OSA in preschool children, whereas the predominant causes in school-age children may be obesity or excessive weight.

LEVEL OF EVIDENCE

Retrospective chart review, 3 Laryngoscope, 134:1472-1478, 2024.

Impact of OSA treatment success on changes in hypertension and obesity: A retrospective cohort study

OBJECTIVE

Pediatric obstructive sleep apnea (OSA) has been shown to lead to the development of chronic cardiometabolic conditions, including obesity and cardiovascular disease. We sought to describe the impact of the success of continuous positive airway pressure (CPAP) and surgery, common treatment options for pediatric OSA, on cardiometabolic conditions.

METHODS

A retrospective review of patients (≤18 years) diagnosed with OSA based on a polysomnogram at a tertiary care pediatric otolaryngology practice from 2015 to 2019 was conducted. Clinical data, including the systolic blood pressure (SBP) values, body mass index (BMI), overall apnea/hypopnea index (AHI) values, and CPAP compliance, were collected. Linear mixed-effects models were developed to observe the relationship between the clinical measurements of each comorbidity and OSA treatment modalities.

RESULTS

414 patients were included. BMI and SBP measures were collected for 230 and 184 patients respectively. The difference-in-difference estimate for the SBP z-score percentile after successful treatment was -5.5 ± 2.1 percentile units per 100 days. The difference-in-difference estimate for SBP z-score percentile after successful CPAP treatment was -13.2 ± 5.1 percentile units per 100 days while the estimate after successful surgical treatment was -4.6 ± 2.4 percentile units per 100 days. No significant differences were found between clinical measures for obese patients in any treatment cohort.

CONCLUSIONS

Successful OSA management was shown to have a positive impact on SBP in hypertensive patients and no impact on BMI in obese patients. In hypertensive patients, CPAP success tripled improvements in SBP z-score percentile compared to surgical treatment success.

Blood pressure variability in children with obesity and sleep-disordered breathing following positive airway pressure treatment

Obese youth with sleep-disordered breathing are treated with positive airway pressure to improve sleep and cardiovascular status. While improvements in sleep parameters have been confirmed, a study by Katz et al. showed no major improvement in ambulatory blood pressure. The aim of this ancillary study was to analyze short-term blood pressure variability, following positive airway pressure treatment, as a more sensitive marker of cardiovascular health. We analyzed 24-h blood pressure variability data in 17 children, taken at baseline and after 12 months of treatment. These data were derived from an already published prospective, multicenter cohort study conducted in 27 youth (8-16 years) with obesity who were prescribed 1-year of positive airway pressure for moderate-severe sleep-disordered breathing. Significant decreases were found in 24 h systolic blood pressure (p = 0.040) and nighttime diastolic blood pressure (p = 0.041) average real variability, and diastolic blood pressure (p = 0.035) weighted standard deviation. Significant decreases were noted in nighttime diastolic blood pressure time rate variability (p = 0.007). Positive airway pressure treatment resulted in a significant decrease in blood pressure variability, suggesting a clinically significant improvement of sympathetic nerve activity in youth with obesity and sleep-disordered breathing. IMPACT: Cardiovascular variability, as measured by blood pressure variability, is improved in children following positive airway pressure treatment. Our novel findings of improved blood pressure time rate variability are the first described in the pediatric literature. Future studies aimed at analyzing target organ damage in this patient population will allow for a better understanding as to whether alterations in blood pressure variability translate to decreasing target organ damage in children, as seen in adults.

Changes of aldosterone levels in patients with type 2 diabetes complicated by moderate to severe obstructive sleep apnea-hypopnea syndrome before and after treatment with continuous positive airway pressure

Objective

Both obstructive sleep apnea–hypopnea syndrome (OSAHS) and type 2 diabetes mellitus (T2DM) are closely related to the renin-angiotensin-aldosterone system. We investigated whether hyperaldosteronemia is found in patients with OSAHS complicated by T2DM and whether continuous positive airway pressure (CPAP) treatment can significantly reduce the aldosterone level.

Methods

Patients with T2DM were classified into an OSAHS group [apnea–hypopnea index (AHI) of ≥15] and a control group (without OSAHS; AHI of <5). The OSAHS group was exposed to CPAP for 7 days (7 h/day).

Results

The plasma aldosterone, plasma renin, and urinary aldosterone levels were higher in the OSAHS than control group. The plasma aldosterone and renin levels were significantly lower after than before treatment in the OSAHS group, but they were still higher than the baseline levels in the control group. The post-treatment urinary aldosterone level was significantly higher in the OSAHS than control group. No correlation was found between the AHI and plasma renin, plasma aldosterone, and 24-hour urinary aldosterone levels. The blood glucose level in the OSAHS group did not significantly change after treatment.

Conclusions

The plasma and urine aldosterone levels are increased in patients with concurrent T2DM and OSAHS and are significantly reduced by CPAP.

Trial registration: ChiCTR-ION-16009837

Oxidative Stress Markers and Severity of Obstructive Sleep Apnea

Oxidative stress underlies both obstructive sleep apnea (OSA) and atherosclerosis. The aim of the study was to assess the markers of oxidative stress in plasma at different stages of OSA in non-smoking obese Caucasian males aged 41-60, with normal oral glucose tolerance test. All patients were subjected to clinical and polysomnographic examinations. The stage of OSA severity was set according to the following criteria of the apnea-hypopnea index (AHI): AHI < 5/h - no disease (OSA-0; n = 26), AHI 5-15/h - mild disease (OSA-1; n = 26), AHI 16-30/h - moderate disease (OSA-2: n = 27), and AHI > 30/h obstructive episodes per hour - severe disease (OSA-3; n = 27). Plasma total antioxidant status (TAS) and thiobarbituric acid-reacting substances (TBARS), reflecting the level of lipid peroxides, were determined spectrophotometrically. We found that TAS decreased and TBARS increased significantly from OSA-0 to OSA-3. We conclude that the oxidative stress markers are conducive to setting the severity of OSA in normoglycemic patients.

Oxidative stress in patients with obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a disorder that leads to metabolic abnormalities and increased cardiovascular risk. The aim of this study was to identify early laboratory markers of cardiovascular disease through analysis of oxidative stress in normal subjects and patients with OSAS. A prospective study was designed to compare outcomes of oxidative stress laboratory tests in 20 adult patients with OSAS and a control group of 20 normal subjects. Laboratory techniques for detecting and quantifying free radical damage must be targeted to assess the pro-oxidant component and the antioxidant in order to obtain an overall picture of oxidative balance. No statistical differences in age, sex distribution, or BMI were found between the two groups (p>0.05). There were significant differences in the apnoea/hypopnoea index (AHI) between OSAS patients and the control group (p<0.05). Statistically significant differences in isoprostane, advanced oxidation protein products (AOPP) and non-protein bound iron (NPBI) levels were found between the study and control groups. No significant difference in the levels of thiol biomarkers was found between the two groups. The main finding of the present study was increased production of oxidative stress biomarkers in OSAS patients. The major difference between thiols and other oxidative stress biomarkers is that thiols are antioxidants, while the others are expressions of oxidative damage. The findings of the present study indicate that biomarkers of oxidative stress in OSAS may be used as a marker of upper airway obstructive episodes due to mechanical trauma, as well as a marker of hypoxaemia causing local oropharyngeal inflammation.

Biomarkers to improve diagnosis and monitoring of obstructive sleep apnea syndrome: current status and future perspectives

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse associated with oxygen desaturation and sleep disruption. It is proposed that these periodic changes lead to molecular variations that can be detected by assessing serum biomarkers. Studies have identified inflammatory, oxidative, and metabolic perturbations attributable to sleep-disordered breathing. Given that OSAS is associated with increased cardiovascular and cerebrovascular morbidity, the ideal biomarker should enable timely recognition with the possibility of intervention. There is accumulating data on the utility of serum biomarkers for the evaluation of disease severity, prognosis, and response to treatment. However, current knowledge is limited by data collection techniques, disease complexity, and potential confounding factors. The current paper reviews the literature on the use of serum biomarkers in OSAS. It is concluded that the ideal serum biomarker still needs to be discovered, while caution is needed in the interpretation of hitherto available results.

Relationship between aldosterone and the metabolic syndrome in patients with obstructive sleep apnea hypopnea syndrome: effect of continuous positive airway pressure treatment

Background

Metabolic syndrome (MS) occurs frequently in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). We hypothesized that aldosterone levels are elevated in OSAHS and associated with the presence of MS.

Methods

We studied 66 patients with OSAHS (33 with MS and 33 without MS) and 35 controls. The occurrence of the MS was analyzed according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) clinical criteria. Measurements of plasma renin activity (PRA), aldosterone, aldosterone:PRA ratio, creatinine, glucose, triglycerides, cholesterol and HDL cholesterol were obtained at baseline and after CPAP treatment.

Results

Aldosterone levels were associated with the severity of OSAHS and higher than controls (p = 0.046). Significant differences in aldosterone levels were detected between OSAHS patients with and without MS (p = 0.041). A significant reduction was observed in the aldosterone levels in patients under CPAP treatment (p = 0.012).

Conclusion

This study shows that aldosterone levels are elevated in OSAHS in comparison to controls, and that CPAP therapy reduces aldosterone levels. It also shows that aldosterone levels are associated with the presence of metabolic syndrome, suggesting that aldosterone excess might predispose or aggravate the metabolic and cardiovascular complications of OSAHS.

Trial registration

The study is not a randomized controlled trial and was not registered.

Pathophysiologic mechanisms of cardiovascular disease in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder, characterized by repeated disruptions of breathing during sleep. This disease has many potential consequences including excessive daytime sleepiness, neurocognitive deterioration, endocrinologic and metabolic effects, and decreased quality of life. Patients with OSAS experience repetitive episodes of hypoxia and reoxygenation during transient cessation of breathing that provoke systemic effects. Furthermore, there may be increased levels of biomarkers linked to endocrine-metabolic and cardiovascular alterations. Epidemiological studies have identified OSAS as an independent comorbid factor in cardiovascular and cerebrovascular diseases, and physiopathological links may exist with onset and progression of heart failure. In addition, OSAS is associated with other disorders and comorbidities which worsen cardiovascular consequences, such as obesity, diabetes, and metabolic syndrome. Metabolic syndrome is an emerging public health problem that represents a constellation of cardiovascular risk factors. Both OSAS and metabolic syndrome may exert negative synergistic effects on the cardiovascular system through multiple mechanisms (e.g., hypoxemia, sleep disruption, activation of the sympathetic nervous system, and inflammatory activation). It has been found that CPAP therapy for OSAS provides an objective improvement in symptoms and cardiac function, decreases cardiovascular risk, improves insulin sensitivity, and normalises biomarkers. OSAS contributes to the pathogenesis of cardiovascular disease independently and by interaction with comorbidities. The present review focuses on indirect and direct evidence regarding mechanisms implicated in cardiovascular disease among OSAS patients.

Association of epicardial fat thickness with the severity of obstructive sleep apnea in obese patients

BACKGROUND

The correlation between obesity and severity of obstructive sleep apnea (OSA) is controversial. Although fat excess is a predisposing factor for the development of OSA, it has not been determined whether fat distribution rather than obesity per se is associated with OSA severity. Epicardial fat thickness (EFT) is an independent index of visceral adiposity and cardiometabolic risk. We investigated the relation between fat distribution and cardiometabolic risk factors, including EFT and common carotid intima-media thickness (cIMT), with the severity of OSA in obese patients.

METHODS

One hundred and fifteen obese patients (56 males, 59 females) with polysomnographic evidence of OSA (≥ 5 apnea/hypopnea events per hour) of various degrees, without significant differences in grade of obesity as defined by body mass index (BMI), were evaluated. The following parameters were measured: BMI, body composition by dual energy X-ray absorptiometry, EFT, right ventricular end-diastolic diameter (RVEDD) and cIMT by ultrasound, and parameters of metabolic syndrome (waist circumference, arterial blood pressure, fasting glucose, HDL-cholesterol and triglycerides).

RESULTS

EFT, RVEDD, cIMT and trunk/leg fat mass ratio showed a positive correlation with OSA severity in univariate analysis (r=0.536, p<0.001; r=0.480, p<0.001; r=0.345, p<0.001; r=0.330, p<0.001, respectively). However, multiple linear regression analysis showed that EFT was the most significant independent correlate of the severity of OSA (R(2)=0.376, p=0.022).

CONCLUSIONS

The present study suggests that, in obese patients, EFT may be included among the clinical parameters associating with OSA severity. The association of EFT with OSA, both cardiovascular risk factors, is independent of obesity as defined by classical measures.

Obstructive sleep apnea and bone mineral density in obese patients

CONTEXT

Obesity and its co-morbidities may adversely affect bone mineral density (BMD). Obstructive sleep apnea (OSA) is a major complication of obesity. To date, the effects of OSA on BMD in obese patients have been poorly studied.

OBJECTIVE

To examine whether the severity of OSA independently correlates with BMD in obese patients.

METHODS

One hundred and fifteen obese subjects with OSA (Apnea/Hypopnea Index [AHI] ≥5 events per hour) were included in the study. BMD was measured at lumbar spine, total hip, and femoral neck by dual energy X-ray absorptiometry. Body mass index, lean mass, and representative measures of metabolic syndrome (waist circumference, fasting plasma glucose, blood pressure, HDL-cholesterol, triglycerides) and inflammation (ESR, CRP, fibrinogen) were also evaluated.

RESULTS

BMD did not differ among obese individuals regardless of OSA severity. Correlation coefficient analysis for all the covariates showed a lack of association between AHI and BMD that was strongly influenced by age and weight.

CONCLUSION

Our study does not support an independent association between AHI and BMD in obese patients. Controlled studies involving a greater number of patients are warranted.

Oxidative stress and quality of life in elderly patients with obstructive sleep apnea syndrome: are there differences after six months of Continuous Positive Airway Pressure treatment?

OBJECTIVES

This study evaluated the effect of Continuous Positive Airway Pressure treatment on oxidative stress parameters and the quality of life of elderly patients with obstructive sleep apnea syndrome.

METHODS

In total, 30 obstructive sleep apnea syndrome patients and 27 subjects without obstructive sleep apnea syndrome were included in this study. Both groups underwent quality of life and oxidative stress evaluations at baseline and after six months. Polysomnography was performed in both groups at baseline and a second time in the obstructive sleep apnea syndrome group after six months of Continuous Positive Airway Pressure treatment. All of the variables were compared between the control and obstructive sleep apnea syndrome groups in this prospective case-control study.

RESULTS

The baseline concentrations of the antioxidant enzyme catalase were higher in the obstructive sleep apnea syndrome group than the control group. After Continuous Positive Airway Pressure treatment, the obstructive sleep apnea syndrome group exhibited a reduction in the level of oxidative stress, as indicated by a decrease in the level of lipid peroxidation measured by the malondialdehyde (MDA) concentration [pre: 2.7 nmol malondialdehyde/mL (95% 1.6-3.7) vs. post: 1.3 nmol MDA/mL (0.7-1.9), p<0.01]. Additionally, improvements were observed in two domains covered by the SF-36 questionnaire: functional capacity [pre: 77.4 (69.2-85.5) vs. post: 83.4 (76.9-89.9), p = 0.002] and pain [pre: 65.4 (52.8-78.1) vs. post: 77.8 (67.2-88.3), p = 0.004].

CONCLUSION

Our study demonstrated that the use of Continuous Positive Airway Pressure to treat obstructive sleep apnea syndrome in elderly patients reduced oxidative stress and improved the quality of life.

Reactive oxygen species and the brain in sleep apnea

Rodents exposed to intermittent hypoxia (IH), a model of obstructive sleep apnea (OSA), manifest impaired learning and memory and somnolence. Increased levels of reactive oxygen species (ROS), oxidative tissue damage, and apoptotic neuronal cell death are associated with the presence of IH-induced CNS dysfunction. Furthermore, treatment with antioxidants or overexpression of antioxidant enzymes is neuroprotective during IH. These findings mimic clinical cases of OSA and suggest that ROS may play a key causal role in OSA-induced neuropathology. Controlled production of ROS occurs in multiple subcellular compartments of normal cells and de-regulation of such processes may result in excessive ROS production. The mitochondrial electron transport chain, especially complexes I and III, and the NADPH oxidase in the cellular membrane are the two main sources of ROS in brain cells, although other systems, including xanthine oxidase, phospholipase A2, lipoxygenase, cyclooxygenase, and cytochrome P450, may all play a role. The initial evidence for NADPH oxidase and mitochondrial involvement in IH-induced ROS production and neuronal injury unquestionably warrants future research efforts.

Increased oral nitric oxide in obstructive sleep apnoea

BACKGROUND

Hypoxia and snoring-related mechanical trauma contribute to airway inflammation in obstructive sleep apnoea (OSA). Increased exhaled nitric oxide (FENO), an airway inflammation marker, has been reported in OSA patients. We propose the measure of NO in the oral cavity (oNO) as marker of oropharyngeal inflammation in OSA.

METHODS

We compared oNO and FENO of 39 OSA patients with those of 26 mild asthmatics (ASTHMA), 15 patients with chronic rhinitis or rhinosinusitis (CRS) and 24 healthy subjects. A special device was used for oNO measurement. Apnoea/hypopnoea index (AHI), oxygen desaturation index, mean and nadir SaO2 were calculated from the polysomnography.

RESULTS

oNO was significantly increased in OSA (104.2 95%CI 80.2-135.5ppb) as compared to ASTHMA (71.9 95%CI 56.3-91.9ppb; p=0.015), CRS (54.4 95%CI 40.2-73.7ppb; p=0.009) and healthy subjects (63.6 95%CI 59-73ppb; p<0.001). oNO was directly related to AHI (r=0.466, p=0.003) and to minutes slept with SaO2 <90% (r=0.471, p=0.011) and it was inversely related to nadirSaO2 (r=-0.393, p=0.018). FENO was highest in asthmatics (40.3 95%CI 32.5-50.1ppb) and only slightly elevated in OSA (23.1 95%CI 19,8-28.3ppb) and CRS (22.8 95%CI 16.8-32.5ppb).

CONCLUSIONS

The finding that oral NO is increased in OSA and is related to upper airway obstructive episodes and to hypoxemia severity, strengthens the clinical and pathogenic role of oral inflammation in OSA.