Hypertension and catecholamine levels in sleep apnoea

Emerging role of metabolomics for biomarker discovery in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by the complete or partial blockage of the upper airway passage during sleep which causes repetitive breaks in sleep and may result in excessive daytime sleepiness. OSA has been linked to various metabolic disorders and chronic health conditions, such as obesity, diabetes, hypertension, and depression. Profiling of alterations in metabolites and their regulation in OSA has been hypothesized to be an effective approach for early diagnosis and prognosis of OSA. Several studies have characterized metabolic fingerprints associated with sleep disorders. There is a lack of understanding of metabolite contents and their alterations in OSA that may help to identify specific biomarkers. The information provided in this review will help update new methodologies and interventions of high throughput advanced molecular/metabolomics tools which may clarify the metabolic aspects and mechanisms for improved management and treatment of OSA.

Decreased Peripapillary and Macular Vascular Densities in Patients with Moderate/Severe Obstructive Sleep Apnea/Hypopnea Syndrome

PURPOSE

To compare peripapillary and macular vascular densities (PVDs and MVDs) between patients with obstructive sleep apnea/hypopnea syndrome (OSA) and control subjects with symptoms of sleep-related breathing disorders only by swept-source optical coherence tomography angiography (OCTA).

PARTICIPANTS AND METHODS

In this prospective study, 192 participants underwent a full-night polysomnography to determine OSA severity and subsequently received OCTA measurements as well as AngioTool software analysis.

RESULTS

A total of 146 patients with OSA (51 mild, 43 moderate, 52 severe) and 24 control subjects (apnea/hypopnea index, AHI <5) were enrolled. PVDs and MVDs in the superficial and choroidal layers were significantly different among the four groups. When participants with simple snoring/mild OSA (AHI <15) were grouped together and compared with moderate/severe OSA (AHI ≥15), PVDs were significantly lower for the latter group in the superficial layer (p = 0.0003), deep layer (p = 0.004), and choroidal layer (p = 0.003). MVDs were also lower for the moderate/severe OSA group in the superficial (p = 0.012) and choroidal layer (p = 0.004). Negative correlations were identified between AHI and PVDs in the superficial layer (ρ = -0.257, p = 0.0007), deep layer (ρ = -0.197, p = 0.0102) and choroidal layer (ρ = -0.220, p = 0.0039) and between AHI and MVDs in the superficial layer (ρ = -0.199, p = 0.0094) and choroid layer (ρ = -0.186, p = 0.0152).

CONCLUSION

PVDs and MVDs were significantly lower in patients with moderate/severe OSA as compared to subjects with simple snoring/mild OSA. Furthermore, decreased PVDs and MVDs significantly correlated with OSA severity.

Moderating Effect of BMI on the Relationship Between Sympathetic Activation and Blood Pressure in Males with Obstructive Sleep Apnea

BACKGROUND

Sympathetic activation is a primary mechanism mediating increased blood pressure (BP) in obstructive sleep apnea (OSA). However, the relationships between overweight/obesity, sympathetic activation and BP in OSA are not well understood. We hypothesized that increased sympathetic drive is associated with increased BP in normal weight, but not in overweight/obese males with OSA. We therefore examined the effects of body mass index (BMI) on the association between sympathetic activation and BP in males with OSA.

METHODS

We studied 115 males with OSA recruited consecutively from clinic. Twenty-four-hour urinary norepinephrine was used to assess sympathetic activation. Blood pressure was measured both in the evening and in the morning. Hypertension was defined based on either BP measurements or an existing diagnosis. Linear and logistic regressions were conducted to examine the associations between sympathetic activation and both BP and risk of hypertension.

RESULTS

We found 24-hour urinary norepinephrine levels were associated with systolic and diastolic BP (SBP, β=0.157, p=0.082; DBP, β=0.212, p=0.023) and mean arterial pressure (MAP, β=0.198, p=0.032) after adjusting for confounders. Interestingly, these associations were modified by overweight/obesity. After adjusting for confounders, increased 24-hour urinary norepinephrine levels were significantly associated with elevated SBP (β=0.454, p=0.012), DBP (β=0.399, p=0.041), and MAP (β=0.432, p=0.023) in normal weight, but not in overweight/obese patients (all p>0.2). Similar findings were observed in the associations between 24-hour urinary norepinephrine levels and hypertension.

CONCLUSION

Sympathetic activation is associated with elevated BP in normal weight but not in overweight/obese males with OSA, suggesting that BMI may moderate the association between sympathetic activation and BP in males with OSA.

Retinal vascular manifestations of obstructive sleep apnea

PURPOSE OF REVIEW

The aim of this article is to summarize up-to-date research on the effects of obstructive sleep apnea (OSA) on retinal vascular conditions.

RECENT FINDINGS

OSA is associated with the development of diabetic retinopathy, retinal vein occlusion, and central serous chorioretinopathy. The severity of OSA and biomarkers such as the apnea-hypopnea index (AHI) correlate with the severity of retinal disease. Dysregulation of circadian locomotor output cycles kaput (CLOCK) genes that govern circadian rhythm is associated with development of proliferative retinal disease.

SUMMARY

OSA and retinal vascular disease have a high cost burden on the healthcare system. OSA creates systemic changes and hypoxic conditions that may incite or exacerbate retinal vascular diseases. Retinal changes may be the first clinical manifestation of otherwise undiagnosed OSA, so it is important to refer patients with new-onset retinal vascular disease for appropriate sleep testing.

CIN or not: An approach to the evaluation and management of chronic idiopathic neutrophilia

Neutrophilia refers to an increase in the number of circulating neutrophils in the peripheral blood. Some common etiologies include infection, inflammatory conditions, myeloproliferative disorders, malignancies, endocrinopathies, drugs, and anemia. Rare disorders such as leukocyte adhesion deficiency can also cause neutrophilia. In many cases, there is an elevation of neutrophil count that persists for months or even years with no clear underlying cause in an otherwise asymptomatic patient. This is referred to as chronic idiopathic neutrophilia (CIN). Despite being a condition encountered by many physicians, there is a paucity of literature addressing CIN. Certain conditions such as stress, exercise, smoking, obesity, and obstructive sleep apnea have been associated with CIN and may provide explanations for neutrophilia previously thought to be idiopathic. Herein, we present a review of the literature on CIN and propose a systematic approach to this commonly encountered clinical condition.

Does obesity affect the outcomes in takotsubo cardiomyopathy? Analysis of the Nationwide Inpatient Sample database, 2010-2014

BACKGROUND

Obesity can lead to increased oxidative stress which is one of the proposed mechanisms in the etiopathogenesis of takotsubo cardiomyopathy (TCM).

HYPOTHESIS

The presence of obesity adversely impacts clinical outcomes in TCM patients.

METHODS

We queried the Nationwide Inpatient Sample database (2010-2014) to identify adult patients admitted with a principal diagnosis of TCM with and without obesity. We compared the categorical and continuous variables by Pearson χ² and Student t test, respectively, in propensity-score matched cohorts.

RESULTS

The study cohort comprised 612 obese TCM (weighted n = 3034) and 5696 nonobese TCM (weighted n = 28 186) patients. Obese TCM patients were more often younger and private-insurance enrollees. Cardiac complications including acute myocardial infarction (9.0% vs 7.4%; P = 0.04), cardiac arrest (2.3% vs. 0.4%; P < 0.001), cardiogenic shock (4.3% vs. 3.2%; P = 0.03), congestive heart failure (5.0% vs. 3.8%; P = 0.02), respiratory failure (12.9% vs. 11.0%; P = 0.021) and use of mechanical hemodynamic support (Impella; 0.2% vs. 0.0%, P = 0.02) were significantly higher among obese TCM patients. There were no significant differences between the 2 groups in all-cause mortality (1.0% vs. 0.8%; P = 0.35), arrhythmia (24.5% vs. 22.7%, P = 0.123), length of stay (3.7 ±3.5 vs. 3.7 ±3.6 days; P = 0.68), and total hospital charges ($40 780.16 vs. $42 575.14; P = 0.08).

CONCLUSIONS

Obese TCM patients were more susceptible to developing TCM-related cardiac complications than were nonobese TCM patients, without any impact on all-cause in-hospital mortality, LOS, and hospital charges.

Increased microcirculatory heterogeneity in patients with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is the most common form of sleep disordered breathing and has been associated with major cardiovascular comorbidities. We hypothesized that the microcirculation is impaired in patients with OSA and that the magnitude of impairment correlates to OSA severity.

METHODS

Subjects were consecutive patients scheduled for routine diagnostic polysomnography (PSG). OSA was defined by paradoxical rib cage movements together with abdominal excursions and by the apnea-hypopnea index (AHI) (events/hour; no apnea AHI<5; mild apnea 5≤AHI<15; moderate apnea 15≤AHI<30; severe apnea AHI ≥30). Sidestream darkfield imaging was used to assess the sublingual microcirculation. Recordings of sublingual microcirculation (5 random sites) were performed before and after overnight PSG. Data are summarized as mean (±SD); p values <0.05 were considered statistically significant.

RESULTS

Thirty-three consecutive patients were included. OSA was diagnosed in 16 subjects (4 moderate, 12 severe). There was no significant difference in microcirculation between subjects with moderate OSA and without OSA. However, compared to subjects without OSA, subjects with severe OSA (AHI≥30) showed a significant decrease of microvascular flow index (-0.07±0.17 vs. 0.08±0.14; p = 0.02) and increase of microvascular flow index heterogeneity (0.06±0.15 vs. -0.06±0.11; p = 0.02) overnight. Multiple regression analysis (adjusted for age and gender) showed both decrease of flow and increase of flow heterogeneity associated with AHI (b = -0.41; F = 1.8; p = 0.04 and b = 0.43; F = 1.9; p = 0.03, respectively).

CONCLUSION

Acute overnight microcirculatory changes are observed in subjects with severe OSA characterized by decreased flow and increased flow heterogeneity.

Sleep Disordered Breathing: Hypertension and Cardiac Structure and Function

Obstructive sleep apnea (OSA) is a common form of sleep disordered breathing and has a relatively high prevalence in the general population. The frequency and severity of OSA is associated with age, male sex, and obesity, and OSA has been linked to cardiovascular complications and death. Importantly, OSA has a strong association with both prevalent and incidental hypertension and has a particularly high prevalence in patients with resistant hypertension. In these patients, CPAP and other OSA-directed treatments have been proposed as therapy to help control blood pressure (BP), especially in patients who have not attained optimal BP control despite maximum pharmacological therapy. OSA has also been associated with alterations in cardiac structure and function, although most studies are small and highly limited in study design. Existing data suggest an association between OSA greater left ventricle (LV) mass and hypertrophy that appears independent of confounders including hypertension and obesity. Although less clear and more controversial, OSA severity has been linked to LV systolic and diastolic function, pulmonary hypertension, and right ventricular hypertrophy. Further studies are needed to confirm the potential causal role of OSA in these observed associations with cardiac abnormalities.