Secondhand tobacco smoke exposure and heart rate variability and inflammation among non-smoking construction workers: a repeated measures study

Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality with an estimated 80% of SHS-related deaths attributed to cardiovascular causes. Public health measures and smoking bans have been successful both in reducing SHS exposure and improving cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a promising target for mitigating SHS exposure-induced cardiovascular outcomes. Objectives: The objectives of this study were to determine 1) effects of environmentally relevant SHS exposure on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of an sEH inhibitor (TPPU) can reduce the adverse cardiovascular effects of SHS exposure. Methods: Male C57BL/6J mice (11 weeks old) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to filtered air or 3 mg/m3 of SHS (6 hr/d, 5 d/wk) for 12 weeks, followed by 4 weeks of recovery in filtered air. Some mice received TPPU in drinking water (15 mg/L) throughout SHS exposure. BP, heart rate (HR), HR variability (HRV), baroreflex sensitivity (BRS), and BP variability were determined monthly. Results: SHS exposure significantly decreased 1) short-term HRV by ∼20% (p < 0.05) within 4 weeks; 2) overall HRV with maximum effect at 12 weeks (-15%, p < 0.05); 3) pulse pressure (-8%, p < 0.05) as early as week 4; and 4) BRS with maximum effect at 12 weeks (-11%, p < 0.05). Four weeks of recovery following 12 weeks of SHS ameliorated all SHS-induced cardiovascular detriments. Importantly, mice exposed to TPPU in drinking water during SHS-related exposure were protected from SHS cardiovascular consequences. Discussion: The data suggest that 1) environmental relevant SHS exposure significantly alters cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be reversed by discontinuing SHS exposure; and 3) inhibiting sEH can prevent SHS-induced cardiovascular consequences.

Harmful Impact of Tobacco Smoking and Alcohol Consumption on the Atrial Myocardium

Tobacco smoking and alcohol consumption are widespread exposures that are legal and socially accepted in many societies. Both have been widely recognized as important risk factors for diseases in all vital organ systems including cardiovascular diseases, and with clinical manifestations that are associated with atrial dysfunction, so-called atrial cardiomyopathy, especially atrial fibrillation and stroke. The pathogenesis of atrial cardiomyopathy, atrial fibrillation, and stroke in context with smoking and alcohol consumption is complex and multifactorial, involving pathophysiological mechanisms, environmental, and societal aspects. This narrative review summarizes the current literature regarding alterations in the atrial myocardium that is associated with smoking and alcohol.

Secondhand Smoke Decreased Excitability and Altered Action Potential Characteristics of Cardiac Vagal Neurons in Mice

Background: Secondhand smoke (SHS), a major indoor pollutant, is a significant risk factor for cardiovascular morbidity and mortality including arrhythmias and sudden cardiac death. Exposure to SHS can produce autonomic imbalance, as evidenced by reduced heart rate variability (HRV)—a clinical metric of cardiac vagal regulation. Currently, the mechanisms through which SHS changes the vagal preganglionic neuronal inputs to the heart to produce this remains unknown.

Objectives: To characterize the effect of SHS on both the excitability and action potential (AP) characteristics of anatomically identified cardiac vagal neurons (CVNs) in the nucleus ambiguus and examine whether SHS alters small conductance calcium-activated potassium (SK) channel activity of these CVNs.

Methods: Adult male mice were exposed to four weeks of filtered air or SHS (3 mg/m³) 6 h/day, 5 day/week. Using patch-clamp recordings on identified CVNs in brainstem slices, we determined neuronal excitability and AP characteristics with depolarizing step- and ramp-current injections.

Results: Four weeks of SHS exposure reduced spiking responses to depolarizing current injections and increased AP voltage threshold in CVNs. Perfusion with apamin (20 nM) magnified these SHS-induced effects, suggesting reduced SK channel activity may serve to minimize the SHS-induced decreases in CVNs excitability. Medium afterhyperpolarization (a measurement of SK channel activity) was smaller in the SHS group, further supporting a lower SK channel activity. AP amplitude, rise rate, fast afterhyperpolarization amplitude (a measurement of voltage-gated channel activity), and decay rate were higher in the SHS group at membrane voltages more positive to 0 mV, suggesting altered inactivation properties of voltage-dependent channels underlying APs.

Discussion: SHS exposure reduced neuronal excitability of CVNs with compensatory attenuation of SK channel activity and altered AP characteristics. Neuroplasticity of CVNs could blunt regulatory cardiac vagal signaling and contribute to the cardiovascular consequences associated with SHS exposure, including reduced HRV.

Is exposure to indoor secondhand smoke associated with poor mental health? Results from non-conflict and post-conflict setting

The purpose of this study was to examine the association between exposure to indoor SHS and self-reported HRQoL among healthy non-smoking students at the University of Belgrade, Serbia and Kosovska Mitrovica located in the post-conflict Kosovo province. Students who presented at Student Public Health Center in Belgrade in 2009 and Kosovska Mitrovica in 2015 for mandatory health checks were invited to participate. Data were collected using socio-demographic and behavioral questionnaire, health-related quality of life questionnaire Short Form-36 (SF-36) and Beck Depression Inventory (BDI). A total of 82.3% students in Belgrade sample and 76.0% in Kosovska Mitrovica sample reported daily exposure to indoor SHS. After adjustment for socio-demographic characteristics and behavior, daily exposure to indoor SHS for more than 6 hours was associated with poorer Vitality (β = -5.55, 95% confidence interval [CI] -9.49, -1.61) and Mental Health (β = 5.00, 95% CI-8.94, -1.07) only among students at the University of Belgrade. This study showed that the association between longer daily indoor SHS exposure and poor mental health HRQoL was not consistent in non-conflict and post-conflict setting. This association was not found in a post-conflict setting. Strict no smoking policies are needed in student housing, university campuses and all public spaces.

The effect of smoking on disease activity in rheumatoid arthritis - our experience

The aim of this study was to investigate the association of smoking with disease activity, seropositivity, age and gender in patients with rheumatoid arthritis. We included 89 rheumatoid arthritis patients. All patients fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism rheumatoid arthritis classification criteria. Activity of the disease was measured by Disease Activity Score 28-joint count C-reactive protein (DAS28CRP). The subjects were stratified into smoking and non-smoking groups and cross-sectionally analyzed. There were 24 (27%) smokers and 65 (73%) nonsmokers. The mean age of patients was 57.1±8.8 years. The mean DAS28CRP was 5.81 in the smoking group and 5.57 in the non-smoking group, without statistically significant difference between the two groups (p=0.148). Similarly, smokers did not differ significantly from non-smokers according to age (p=0.443), gender (p=0.274), rheumatoid factor positivity (p=0.231), anti-citrullinated protein antibody positivity (p=0.754) or seropositivity (p=0.163). In this study, we found no association between smoking status and disease activity, seropositivity, age or gender in rheumatoid arthritis patients. Furthermore, disease activity was not related to age, gender or seropositivity. Additional studies on the effects of smoking on rheumatoid arthritis activity are needed.

Is second hand smoking associated with atrial fibrillation risk among women in Israel? A case-control study

BACKGROUND

The first complete ban on indoor smoking in all public spaces (including bars and restaurants) occurred in 1994 in Israel, because of clear scientific evidence that SHS (Second Hand Smoking) is dangerous to non-smokers. Despite the smoking-ban law warning about the dangers of smoking, SHS remains in houses. The role of cigarette smoking on cardiac arrhythmia is less clearly defined and secondhand smoke (SHS) impact on the risk of atrial fibrillation (AF) remains unknown. The aim of this study was to evaluate the relationship between SHS and AF risk in Israeli women.

METHODS

This was a population-based case-control study consisting of never-smoking women aged 30-80 from Israel: 102 cases (diagnosed) of AF and 109 population- based controls. All participants were interviewed using a socio-demographic questionnaire that also related to past and current exposure to SHS.

RESULTS

SHS was associated with AF risk with adjusted odds ratio (OR) of 3.81 (95% confidence interval, CI 2.02-7.18). Higher exposure to SHS was associated with higher risk of AF compared to never-exposed women. Those exposed to SHS during one, two, or three life-periods (childhood, adolescence or adulthood) had an OR of 1.71 (95% CI 0.76-3.86), 2.87 (95% CI 1.25-6.56), and 9.14 (95% CI 4.09-20.44), respectively. Moreover, exposure to one pack/day increased the risk of AF by 2.89 times compared to 'never exposed' (95% CI 2.05-4.09).

CONCLUSIONS

SHS exposure in women who never smoked is associated with increased risk for AF.

A unifying conceptual framework of factors associated to cardiac vagal control

Cardiac vagal control (CVC) reflects the activity of the vagus nerve regulating cardiac functioning. CVC can be inferred via heart rate variability measurement, and it has been positively associated to a broad range of cognitive, emotional, social, and health outcomes. It could then be considered as an indicator for effective self-regulation, and given this role, one should understand the factors increasing and decreasing CVC. The aim of this paper is to review the broad range of factors influencing CVC, and to provide a unifying conceptual framework to integrate comprehensively those factors. The structure of the unifying conceptual framework is based on the theory of ecological rationality, while its functional aspects are based on the neurovisceral integration model. The structure of this framework distinguishes two broad areas of associations: person and environment, as this reflects adequately the role played by CVC regarding adaptation. The added value of this framework lies at different levels: theoretically, it allows integrating findings from a variety of scientific disciplines and refining the predictions of the neurovisceral integration model; methodologically, it helps identifying factors that increase and decrease CVC; and lastly at the applied level, it can play an important role for society regarding health policies and for the individual to empower one's flourishing.

Exposure to Secondhand Smoke and Arrhythmogenic Cardiac Alternans in a Mouse Model

BACKGROUND

Epidemiological evidence suggests that a majority of deaths attributed to secondhand smoke (SHS) exposure are cardiovascular related. However, to our knowledge, the impact of SHS on cardiac electrophysiology, [Formula: see text] handling, and arrhythmia risk has not been studied.

OBJECTIVES

The purpose of this study was to investigate the impact of an environmentally relevant concentration of SHS on cardiac electrophysiology and indicators of arrhythmia.

METHODS

Male C57BL/6 mice were exposed to SHS [total suspended particles (THS): [Formula: see text], nicotine: [Formula: see text], carbon monoxide: [Formula: see text], or filtered air (FA) for 4, 8, or 12 wk ([Formula: see text]]. Hearts were excised and Langendorff perfused for dual optical mapping with voltage- and [Formula: see text]-sensitive dyes.

RESULTS

At slow pacing rates, SHS exposure did not alter baseline electrophysiological parameters. With increasing pacing frequency, action potential duration (APD), and intracellular [Formula: see text] alternans magnitude progressively increased in all groups. At 4 and 8 wk, there were no statistical differences in APD or [Formula: see text] alternans magnitude between SHS and FA groups. At 12 wk, both APD and [Formula: see text] alternans magnitude were significantly increased in the SHS compared to FA group ([Formula: see text]). SHS exposure did not impact the time constant of [Formula: see text] transient decay ([Formula: see text]) at any exposure time point. At 12 wk exposure, the recovery of [Formula: see text] transient amplitude with premature stimuli was slightly (but nonsignificantly) delayed in SHS compared to FA hearts, suggesting that [Formula: see text] release via ryanodine receptors may be impaired.

CONCLUSIONS

In male mice, chronic exposure to SHS at levels relevant to social situations in humans increased their susceptibility to cardiac alternans, a known precursor to ventricular arrhythmia. https://doi.org/10.1289/EHP3664.

Enhancing cardiac vagal activity: Factors of interest for sport psychology

Self-regulation plays a critical role in sport performance. An objective, psychophysiological marker of self-regulation is cardiac vagal activity, the activity of the vagus nerve regulating cardiac functioning. The aim of this paper is to provide an overview of factors influencing cardiac vagal activity, which can be useful for athletes. Specifically, we organize this overview in two main domains: personal factors and environmental factors. Among the personal factors, we discuss the behavioral strategies that can be used by athletes: nutrition, non-ingestive oral habits, water immersion, body temperature reduction, sleeping habits, relaxation methods, cognitive techniques, praying, music, and exercise. Among environmental factors, we discuss those linked to the social (i.e., contact with humans and animals) and physical (i.e., aromas, lights, sounds, temperature, outdoor, altitude) environment. Future research directions are given, as well as practical implications for athletes and coaches.

Welding fume exposure is associated with inflammation: a global metabolomics profiling study

BACKGROUND

Increasing evidence suggests that welding fume exposure is associated with systemic inflammation. Although celluar metabolites may be associated with inflammation, there is limited information on metabolomic changes during welding fume exposure. Such changes may play an important role in the occurrence, development, and prevention of metal-associated diseases. We aim to investigate human metabolomics changes pre- and post-welding fume exposure.

METHODS

This study included 52 boilermakers totally. We collected plasma samples pre- and post-shift welding fume exposure and prepared samples using the automated MicroLab STAR® system. Metabolite concentrations were measured using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) methods. Two-way analysis of variance was used to test the significance of metabolite changes with false discovery rate correction.

RESULTS

Analysis detected several metabolic changes after welding fume exposure, mainly involved in the lipid pathway [glucocorticoid class (cortisol, corticosterone, and cortisone), acylcarnitine class, and DiHOME species (9,10-DiHOME and 12,13-DiHOME)], amino acid utilization (isoleucine, proline and phenylalanine), and S-(3-hydroxypropyl) mercapturic acid (3-HPMA). These compounds are all associated with inflammation according to previous studies. Further, additive interaction effects linked smoking and 3-HPMA levels. In the metabolite set enrichment analysis for diseases, the top two disease-associated metabolite pathways were systemic inflammation-related diseases including rheumatoid arthritis and systemic lupus erythematosus.

CONCLUSIONS

This global metabolomics study shows evidence that metabolite changes during welding fume exposure are closely associated with systemic inflammation. The altered metabolites detected may be potential health monitoring biomarkers for boilermakers, especially for inflammation-related disease prevention.

Immune-regulating effects of exercise on cigarette smoke-induced inflammation

Long-term cigarette smoking (LTCS) represents an important risk factor for cardiac infarction and stroke and the central risk factor for the development of a bronchial carcinoma, smoking-associated interstitial lung fibrosis, and chronic obstructive pulmonary disease. The pathophysiologic development of these diseases is suggested to be promoted by chronic and progressive inflammation. Cigarette smoking induces repetitive inflammatory insults followed by a chronic and progressive activation of the immune system. In the pulmonary system of cigarette smokers, oxidative stress, cellular damage, and a chronic activation of pattern recognition receptors are described which are followed by the translocation of the NF-kB, the release of pro-inflammatory cytokines, chemokines, matrix metalloproteases, and damage-associated molecular patterns. In parallel, smoke pollutants cross directly through the alveolus-capillary interface and spread through the systemic bloodstream targeting different organs. Consequently, LTCS induces a systemic low-grade inflammation and increased oxidative stress in the vascular system. In blood, these processes promote an increased coagulation and endothelial dysfunction. In muscle tissue, inflammatory processes activate catabolic signaling pathways followed by muscle wasting and sarcopenia. In brain, several characteristics of neuroinflammation were described. Regular exercise training has been shown to be an effective nonpharmacological treatment strategy in smoke-induced pulmonary diseases. It is well established that exercise training exerts immune-regulating effects by activating anti-inflammatory signaling pathways. In this regard, the release of myokines from contracting skeletal muscle, the elevations of cortisol and adrenalin, the reduced expression of Toll-like receptors, and the increased mobilization of immune-regulating leukocyte subtypes might be of vital importance. Exercise training also increases the local and systemic antioxidative capacity and several compensatory mechanisms in tissues such as an increased anabolic signaling in muscle or an increased compliance of the vascular system. Accordingly, regular exercise training seems to protect long-term smokers against some important negative local and systemic consequences of smoking. Data suggest that it seems to be important to start exercise training as early as possible.

Are the Associations of Cardiac Acceleration and Deceleration Capacities With Fine Metal Particulate in Welders Mediated by Inflammation?

OBJECTIVE

The aim of this study was to investigate whether associations of acceleration capacity (AC) and deceleration capacity (DC) with metal-PM2.5 are mediated by inflammation.

METHODS

We obtained PM2.5, C-reactive protein, interleukin (IL)-6, 8, and 10, and electrocardiograms to compute AC and DC, from 45 male welders. Mediation analyses were performed using linear mixed models to assess associations between PM2.5 exposure, inflammatory mediator, and AC or DC, controlling for covariates.

RESULTS

The proportion of total effect of PM2.5 on AC or DC (indirect effect) mediated through IL-6 on AC was 4% at most. Controlling for IL-6 (direct effect), a 1 mg/m increase of PM2.5 was associated with a decrease of 2.16 (95% confidence interval -0.36 to 4.69) msec in AC and a decrease of 2.51 (95% confidence interval -0.90 to 5.93) msec in DC.

CONCLUSION

IL-6 may be mediating the effect of metal particulates on AC.

Secondhand Smoke Exposure and Subclinical Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Few studies have evaluated the association between secondhand smoke (SHS) and subclinical cardiovascular disease among ethnically diverse populations. This study assesses the impact of SHS on inflammation and atherosclerosis (carotid intima-media thickness, coronary artery calcification, and peripheral arterial disease).

METHODS AND RESULTS

We examined 5032 nonsmoking adults aged 45 to 84 years without prior cardiovascular disease participating in the Multi-Ethnic Study of Atherosclerosis (MESA) from 2000 to 2002. SHS exposure was determined by self-report, and urinary cotinine was measured in a representative subset (n=2893). The multi-adjusted geometric mean ratios (95% CIs) for high-sensitivity C-reactive protein and interleukin-6 comparing 407 participants with SHS ≥12 h/wk versus 3035 unexposed participants were 1.13 (1.02-1.26) and 1.04 (0.98-1.11), respectively. The multi-adjusted geometric mean ratio for carotid intima-media thickness was 1.02 (0.97-1.07). Fibrinogen and coronary artery calcification were not associated with SHS. The prevalence of peripheral arterial disease (ankle-brachial index ≤0.9 or ≥1.4) was associated with detectable urinary cotinine (odds ratio, 2.10; 95% CI, 1.09-4.04) but not with self-reported SHS. Urinary cotinine was not associated with inflammation or carotid intima-media thickness.

CONCLUSIONS

Despite limited exposure assessment, this study supports the association of SHS exposure with inflammation and peripheral arterial disease.

Environmental Tobacco Smoke and Atrial Fibrillation: The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study

OBJECTIVE

This study examines the association between environmental tobacco smoke (ETS) exposure and atrial fibrillation (AF).

METHODS

We examined the cross-sectional association between ETS exposure and AF in 12,021 participants (mean age: 65 ± 9.9 years; 60% women; 40% blacks) from the REasons for Geographic And Racial Differences in Stroke study who self-identified as never smokers between 2003 and 2007.

RESULTS

A total of 2503 (21%) participants reported ETS exposure. In a multivariate logistic regression model adjusted for sociodemographics and potential confounders, ETS exposure was significantly associated with AF (odds ratio = 1.27, 95% confidence interval = 1.08, 1.50).

CONCLUSIONS

Our findings suggest that the harmful effects of ETS exposure extend to sustained arrhythmias such as AF.

Obesity indices are predictive of elevated C-reactive protein in long-haul truck drivers

BACKGROUND

Obesity rates in long-haul truck drivers have been shown to be significantly higher than the general population. We hypothesized that commercial drivers with the highest levels of general obesity and abdominal adiposity would have higher concentrations of high sensitivity C-reactive protein (CRP), a marker of inflammation.

METHODS

Survey and anthropometric data were collected from 262 commercial drivers. Weight, circumference measures, and blood analysis for CRP (N = 115) were conducted and compared to National Health and Nutrition Examination Survey (NHANES) data. CRP values were non-normally distributed and logarithmically transformed for statistical analyses.

RESULTS

BMI, waist circumference, sagittal abdominal diameter, and CRP were significantly higher than in the general population. Anthropometric indices that included height (BMI, waist-to-height ratio, and sagittal diameter-to-height ratio), were most predictive of CRP values.

CONCLUSIONS

Abdominal obesity is prevalent in commercial vehicle drivers and is an important indicator of the presence of inflammation in this population. Am. J. Ind. Med. 59:665-675, 2016. © 2016 Wiley Periodicals, Inc.

Time Course of Heart Rate Variability Response to PM2.5 Exposure from Secondhand Smoke

Purpose: Exposure to secondhand smoke (SHS) has been associated with decreased heart rate variability (HRV). However, the time course of this association is unclear. Therefore, the objective of this study was to investigate the association between 15–240 minute SHS-related fine particulate matter (PM_2.5) moving averages and indices of HRV. Methods: With a panel study design, we used personal monitors to continuously measure PM_2.5 and HRV of 35 participants who were exposed to SHS for approximately 6 hours. Results: We observed negative, significant associations between 5-minute HRV indices and 15 minute PM_2.5 moving averages and 240 minute PM_2.5 moving averages: there was a significant (p<0.01) 7.5% decrease in the 5-minute square root of the mean squared differences of successive normal heart beats associated with (RMSSD), and a significant (p<0.01) 14.7% decrease in the 5-minute high frequency (HF) power associated with the 15 minute PM_2.5 moving averages; there was also a significant (p<0.01) 46.9% decrease in the 5-minute RMSSD, and a significant (p<0.01) 77.7% decrease in the 5-minute high frequency (HF) power associated with the 240 minute PM_2.5 moving averages. Conclusions: Our findings that exposure to SHS related PM_2.5 was associated with HRV support the hypothesis that SHS can affect the cardiovascular system. The negative associations reported between short and longer term PM_2.5 and HRV indicate adverse effects of SHS on the cardiovascular system.

Potential pathways by which maternal second-hand smoke exposure during pregnancy causes full-term low birth weight

It is well documented that maternal exposure to second-hand smoke (SHS) during pregnancy causes low birth weight (LBW), but its mechanism remains unknown. This study explored the potential pathways. We enrolled 195 pregnant women who delivered full-term LBW newborns, and 195 who delivered full-term normal birth weight newborns as the controls. After controlling for maternal age, education level, family income, pre-pregnant body mass index, newborn gender and gestational age, logistic regression analysis revealed that LBW was significantly and positively associated with maternal exposure to SHS during pregnancy, lower placental weight, TNF-α and IL-1β, and that SHS exposure was significantly associated with lower placental weight, TNF-α and IL-1β. Structural equation modelling identified two plausible pathways by which maternal exposure to SHS during pregnancy might cause LBW. First, SHS exposure induced the elevation of TNF-α, which might directly increase the risk of LBW by transmission across the placenta. Second, SHS exposure first increased maternal secretion of IL-1β and TNF-α, which then triggered the secretion of VCAM-1; both TNF-α and VCAM-1 were significantly associated with lower placental weight, thus increasing the risk of LBW. In conclusion, maternal exposure to SHS during pregnancy may lead to LBW through the potential pathways of maternal inflammation and lower placental weight.

The effect of workplace smoking bans on heart rate variability and pulse wave velocity of non-smoking hospitality workers

OBJECTIVES

To investigate the effect of a change in second-hand smoke (SHS) exposure on heart rate variability (HRV) and pulse wave velocity (PWV), this study utilized a quasi-experimental setting when a smoking ban was introduced.

METHODS

HRV, a quantitative marker of autonomic activity of the nervous system, and PWV, a marker of arterial stiffness, were measured in 55 non-smoking hospitality workers before and 3-12 months after a smoking ban and compared to a control group that did not experience an exposure change. SHS exposure was determined with a nicotine-specific badge and expressed as inhaled cigarette equivalents per day (CE/d).

RESULTS

PWV and HRV parameters significantly changed in a dose-dependent manner in the intervention group as compared to the control group. A one CE/d decrease was associated with a 2.3% (95% CI 0.2-4.4; p = 0.031) higher root mean square of successive differences (RMSSD), a 5.7% (95% CI 0.9-10.2; p = 0.02) higher high-frequency component and a 0.72% (95% CI 0.40-1.05; p < 0.001) lower PWV.

CONCLUSIONS

PWV and HRV significantly improved after introducing smoke-free workplaces indicating a decreased cardiovascular risk.

Gender-specific impacts of apnea, age, and BMI on parasympathetic nerve dysfunction during sleep in patients with obstructive sleep apnea

BACKGROUND

The gender-specific influences of various confounding factors, including apnea, age, BMI, and cigarette consumption, on the function of the parasympathetic nerve system (PNS) during sleep in OSA patients has never been investigated.

METHODS

One hundred ninety-seven males and 63 females with OSA were subjected to full PSG examinations including assessment of R-R intervals (RRIs) during an overnight ECG. The PNS-derived modulatory effect on the RRIs and the variability of this effect were quantified during REM and NREM using instantaneous time-frequency analysis with complex demodulation. The spectral domain with the maximum instantaneous amplitude in the high-frequency band between 0.15 and 0.4 Hz was defined as the main HF peak and used as a surrogate marker of PNS discharge. Based on density-spectrum-array maps of the main HF peaks (HF-DSA map), shifts in the central frequency of the main HF peak over time were continuously observed. When the main HF peaks on the HF-DSA maps maintained the same central frequency for more than 20 sec or 5 min, the PNS functions were considered to be "stable" or "very stable", respectively.

RESULTS

Apneas enhanced PNS-derived cardiac-modulation during REM in males, but more importantly, they made PNS-function unstable during both REM and NREM in males and during NREM in females. Aging blunted the PNS-derived cardiac-modulation during both REM and NREM regardless of gender, but aging had no impact on the stability of PNS-function. BMI blunted PNS-eliciting cardiac-modulation during REM in males and during NREM in both males and females. BMI made the PNS unstable during REM in females. Neither height nor cigarette consumption influenced any PNS-related parameter.

CONCLUSIONS

The PNS-derived cardiac-modulation was generally inhibited by aging and obesity, in which the effect of obesity was gender-specific. The PNS instability at nighttime was mainly induced by apneas but by obesity particularly during REM in females.