Central Sleep Apnea with Cheyne-Stokes Breathing in Heart Failure – From Research to Clinical Practice and Beyond. In: Islam MS, editor. Heart Failure: From Research to Clinical Practice. Cham: Springer International Publishing; 2018. pp. 327-51. [DOI: 10.1007/5584_2018_146]

The enigma of sleep: Implications of sleep neuroscience for the dental clinician and patient

BACKGROUND

Sleep disturbances have been shown to result in considerable morbidity and mortality. It is important for dental clinicians to understand the neuroscience behind sleep disorders.

TYPES OF STUDIES REVIEWED

The authors conducted a search of the literature published from January 1990 through March 2024 of sleep medicine-related articles, with a focus on neuroscience. The authors prioritized articles about the science of sleep as related to dental medicine.

RESULTS

The authors found a proliferation of articles related to sleep neuroscience along with its implications in dental medicine. The authors also found that the intricate neuroscientific principles of sleep medicine are being investigated robustly. The salient features of, and the differences between, central and obstructive sleep apneas have been elucidated. Sleep genes, such as CRY, PER1, PER2, and CLOCK, and their relationship to cancer and neurodegeneration are also additions to this rapidly developing science.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental clinician has the potential to be the first to screen patients for possible sleep disorders and make prompt referrals to the appropriate medical professionals. This can be lifesaving as well as minimize potential future morbidity for the patient.

Sleep-disordered breathing and lung function abnormalities in adults with congenital heart disease

PURPOSE

Advances in treatment enables most patients with congenital heart diseases (CHD) to survive into adulthood, implying the need to address comorbid conditions in this growing cohort of patients. The aim of this study was to evaluate the prevalence of sleep-disordered breathing (SDB) and lung function abnormalities in patients with adult congenital heart disease (ACHD).

METHODS

Patients with ACHD underwent level 3 sleep testing (Embletta MPR polygraphy) and pulmonary function testing. Results were stratified by the underlying haemodynamic ACHD lesion group.

RESULTS

Patients with ACHD (n = 100) were middle-aged (42.3 ± 14.6 years), 54% male and slightly overweight (BMI 25.9 ± 5.5 kg/m2). Polygraphy revealed a prevalence of sleep apnoea of 39% with 15% of patients presenting with predominantly obstructive apnoeic episodes, while 23% of patients presenting primarily with central sleep apnoea. The distribution of mild, moderate, and severe sleep apnoea in the total study population was 26%, 7% and 6%, respectively. Comparison of apnoea-hypopnoea index, presence of sleep apnoea, and apnoea severity did not offer significant differences between the four ACHD lesion groups (p = 0.29, p = 0.41 and p = 0.18, respectively). Pulmonary function testing revealed obstructive lung disease in 19 of 100 patients. Concomitant chronic obstructive pulmonary disease and obstructive sleep apnoea were diagnosed in 3% of patients and were associated with profound nocturnal desaturation.

CONCLUSION

The findings suggest a mild propensity amongst patients with ACHD to develop SDB that seems to be unaffected by the specific underlying congenital lesion.

Unveiling the sleep-cardiovascular connection: Novel perspectives and interventions-A narrative review

Introduction

Sleep is an important neurophysiological condition that is intricately linked to general health, laying the basis for both physiological and psychological well-being. A thorough examination of sleep disorders and cardiovascular health demonstrates their deep relationship, emphasizing the numerous diagnostic tools and treatment techniques available.

Aim

This study aims to examine the impact, mechanisms, diagnostic techniques, treatment strategies, implications, and healthcare interventions of the sleep-cardiovascular connection, to better understand the relationship between sleep disorders and cardiovascular health.

Methods

The paper reviews key studies conducted from 2015-till date, investigating the impact of sleep disorders on the cardiovascular system. It looked into data relating to cardiovascular outcomes based on the degree of sleep disorders, considered potential confounding factors, and addressed current research constraints.

Results

The findings highlight a strong link between sleep problems and poor cardiovascular outcomes. Emerging diagnostic tools, such as enhanced sleep-related technology and biomarkers, open up new avenues for determining the impact of sleep disturbances on cardiovascular health. In addition, the research discusses several treatment options, ranging from cognitive behavioral therapy to pharmaceutical therapies, and their potential benefits in addressing sleep-related cardiovascular risks.

Conclusion

The complex association between sleep disturbances and cardiovascular health emphasizes the need to recognize sleep as a critical component of overall well-being. Thus collaboration among medical disciplines, as well as individualized therapies, are critical to improving patient care. Moreover, Understanding and managing the consequences of sleep problems on cardiovascular health can lead to more effective interventions, better outcomes, and improved public health as research advances.

Neural bases for the genesis and CO2 therapy of periodic Cheyne-Stokes breathing in neonatal male connexin-36 knockout mice

Periodic Cheyne-Stokes breathing (CSB) oscillating between apnea and crescendo-decrescendo hyperpnea is the most common central apnea. Currently, there is no proven therapy for CSB, probably because the fundamental pathophysiological question of how the respiratory center generates this form of breathing instability is still unresolved. Therefore, we aimed to determine the respiratory motor pattern of CSB resulting from the interaction of inspiratory and expiratory oscillators and identify the neural mechanism responsible for breathing regularization induced by the supplemental CO₂ administration. Analysis of the inspiratory and expiratory motor pattern in a transgenic mouse model lacking connexin-36 electrical synapses, the neonatal (P14) Cx36 knockout male mouse, with a persistent CSB, revealed that the reconfigurations recurrent between apnea and hyperpnea and vice versa result from cyclical turn on/off of active expiration driven by the expiratory oscillator, which acts as a master pacemaker of respiration and entrains the inspiratory oscillator to restore ventilation. The results also showed that the suppression of CSB by supplemental 12% CO₂ in inhaled air is due to the stabilization of coupling between expiratory and inspiratory oscillators, which causes the regularization of respiration. CSB rebooted after washout of CO₂ excess when the inspiratory activity depressed again profoundly, indicating that the disability of the inspiratory oscillator to sustain ventilation is the triggering factor of CSB. Under these circumstances, the expiratory oscillator activated by the cyclic increase of CO₂ behaves as an "anti-apnea" center generating the crescendo-decrescendo hyperpnea and periodic breathing. The neurogenic mechanism of CSB identified highlights the plasticity of the two-oscillator system in the neural control of respiration and provides a rationale base for CO₂ therapy.

Of Mice and Men and Plethysmography Systems: Does LKB1 Determine the Set Point of Carotid Body Chemosensitivity and the Hypoxic Ventilatory Response?

Our recent studies suggest that the level of liver kinase B1 (LKB1) expression in some way determines carotid body afferent discharge during hypoxia and to a lesser extent during hypercapnia. In short, phosphorylation by LKB1 of an as yet unidentified target(s) determines a set point for carotid body chemosensitivity. LKB1 is the principal kinase that activates the AMP-activated protein kinase (AMPK) during metabolic stresses, but conditional deletion of AMPK in catecholaminergic cells, including therein carotid body type I cells, has little or no effect on carotid body responses to hypoxia or hypercapnia. With AMPK excluded, the most likely target of LKB1 is one or other of the 12 AMPK-related kinases, which are constitutively phosphorylated by LKB1 and, in general, regulate gene expression. By contrast, the hypoxic ventilatory response is attenuated by either LKB1 or AMPK deletion in catecholaminergic cells, precipitating hypoventilation and apnea during hypoxia rather than hyperventilation. Moreover, LKB1, but not AMPK, deficiency causes Cheyne-Stokes-like breathing. This chapter will explore further the possible mechanisms that determine these outcomes.

Efficacy of portable sleep monitoring device in diagnosing central sleep apnea in patients with congestive heart failure

Introduction

Central sleep apnea (CSA) is a common and serious comorbidity mainly occurring in patients with heart failure (HF), which tends to be underdiagnosed and has not been widely studied. Overnight polysomnography (PSG) is the gold standard for diagnosing CSA; however, the time and expense of the procedure limit its applicability. Portable monitoring (PM) devices are convenient and easy to use; however, they have not been widely studied as to their effectiveness in detecting CSA in patients with HF. In the current study, we examined the diagnostic value of PM as a screening tool to identify instances of CSA among patients with HF.

Methods

A total of 22 patients under stable heart failure conditions with an ejection fraction of <50% were enrolled. All patients underwent PM and overnight PSG within a narrow time frame. The measurements of the apnea-hypopnea index (AHI), hypopnea index (HI), central apnea index (CAI), and obstructive apnea index (OAI) obtained from PSG, automatic scoring, and manual scoring of PM were recorded. The results obtained from PSG and those from PM (automatic and manual scoring) were compared to assess the accuracy of PM.

Results

Among the patients, CSA in 11 patients was found by PSG. The AHI measurements performed using manual scoring of PM showed a significant correlation with those performed using PSG (r = 0.69; P = 0.01). Nonetheless, mean AHI measurements showed statistically significant differences between PSG and automatic scoring of PM (40.0 vs. 23.7 events/hour, respectively; P < 0.001), as well as between automatic and manual scoring of PM (23.7 vs. 29.5 events/hour; P < 0.001). Central sleep apnea was detected by PM; however, the results were easily misread as obstructive apnea, particularly in automatic scoring.

Conclusion

PM devices could be used to identify instances of central sleep apnea among patients with HF. The results from PM were well-correlated with standard PSG results, and manual scoring was preferable to automated scoring.

Practice recommendations for the role of physiotherapy in the management of sleep disorders: the 2022 Brazilian Sleep Association Guidelines

This clinical guideline supported by the Brazilian Sleep Association comprises a brief history of the development of Brazilian sleep physiotherapy, outlines the role of the physiotherapist as part of a sleep health team, and describes the clinical guidelines in respect of the management of some sleep disorders by the physiotherapist (including sleep breathing disorders, i.e., obstructive sleep apnea, central sleep apnea, upper airway resistance syndrome, hypoventilation syndromes and overlap syndrome, and pediatric sleep breathing disorders; sleep bruxism; circadian rhythms disturbances; insomnia; and Willis-Ekbom disease/periodic limb movement disorder. This clinical practice guideline reflects the state of the art at the time of publication and will be reviewed and updated as new information becomes available.

LKB1 is the gatekeeper of carotid body chemosensing and the hypoxic ventilatory response

The hypoxic ventilatory response (HVR) is critical to breathing and thus oxygen supply to the body and is primarily mediated by the carotid bodies. Here we reveal that carotid body afferent discharge during hypoxia and hypercapnia is determined by the expression of Liver Kinase B1 (LKB1), the principal kinase that activates the AMP-activated protein kinase (AMPK) during metabolic stresses. Conversely, conditional deletion in catecholaminergic cells of AMPK had no effect on carotid body responses to hypoxia or hypercapnia. By contrast, the HVR was attenuated by LKB1 and AMPK deletion. However, in LKB1 knockouts hypoxia evoked hypoventilation, apnoea and Cheyne-Stokes-like breathing, while only hypoventilation and apnoea were observed after AMPK deletion. We therefore identify LKB1 as an essential regulator of carotid body chemosensing and uncover a divergence in dependency on LKB1 and AMPK between the carotid body on one hand and the HVR on the other.

Cheyne-Stokes Breathing as a Predictive Indicator of Heart Failure in Patients With Obstructive Sleep Apnea; A Retrospective Case Control Study Using Continuous Positive Airway Pressure Remote Monitoring Data

Objective

We conducted a retrospective case control study to examine whether remote monitoring of Cheyne-Stokes breathing (CSB) was useful for predicting the onset of heart failure (HF) in patients with obstructive sleep apnea (OSA) on continuous positive airway pressure (CPAP).

Methods

Among patients with OSA treated at our hospital, 33 patients with HF that occurred between July 2014 and May 2021 [11 patients with acute HF (AHF); 22 patients with chronic HF (CHF) exacerbation] were included in the HF group. Of the 618 stable patients, 149 patients with a 30-days average CSB rate (CSB%) ≧1% were included in the non-HF control group. The chronologic change of CSB% were compared among the AHF, CHF and Control groups. Furthermore, of the 149 patients in the non-HF control group, 44 patients were matched for CSB%, body mass index, and sex in a ratio of 1:2 to 22 patients with CHF. The average cycle length (CL) of CSB was compared among three groups: CHF in stable period (CHF-stable group), CHF in exacerbation period (CHF-exacerbation group), and control group. In addition, according to the status of HF, receiver operating characteristic (ROC) curves were generated to determine the optimal cut-off points for variation of CSB% and CL.

Results

Chronological change in CSB% among the three groups was significantly different. Standard deviation of CSB% (SD CSB%) before onset HF was significantly higher in both the AHF and CHF groups than in the control group. The CL of CSB was significantly longer in the CHF group than in the control group and was longer during the exacerbation period than during the stable period. The optimal cut-off value of CL that could differentiate patients with and without the onset of HF was 68.9 s.

Conclusion

The HF group demonstrated greater CSB variations and longer CL than the non-HF control group. Furthermore, the CL was longer during the exacerbation period of HF even in the same patient. These results suggest that remote monitoring of CPAP device data for CSB variations and CL might allow early prediction of the onset and exacerbation of HF.

Elevated serum matrix metalloproteinase-2 levels in heart failure patients with reduced ejection fraction and Cheyne-Stokes respiration

STUDY OBJECTIVES

Cheyne-Stokes respiration (CSR), a kind of central sleep apnea (CSA), is referred to as a poor prognostic factor in heart failure patients with reduced ejection fraction (HFrEF). Matrix metalloproteinase (MMP) and B-type natriuretic peptide (BNP) play important roles in HFrEF patients and are markers of poor prognosis. However, there is no literature mentioning the changes in MMP and BNP in HFrEF patients with CSR.

METHODS

From June 2018 to June 2019, 41 adult patients with stable heart failure and left ventricular ejection fraction (LVEF) <50% were enrolled from the cardiology clinic. After history taking and medication review to exclude possible central nervous system or medication related CSA, an overnight polysomnography study was performed, and CSR was identified. The morning serum MMP-2, MMP-9 and BNP levels were determined using enzyme-linked immunosorbent assay and fluorescence immunoassay techniques. A positive airway pressure (PAP) device was applied to 7 patients for 3 months.

RESULTS

The serum MMP-2 and BNP levels were significantly higher in HFrEF patients with CSR than in patients without CSR. In addition, elevated serum MMP-2 levels correlated well with the severity of sleep apnea and intermittent hypoxia, which were represented as the apnea-hypopnea index and the oxygen-desaturation index. No positive correlation was found between those markers and LVEF. Finally, the treatment of sleep apnea with CPAP for 3 months tended to reduce the elevated serum MMP-2 levels.

CONCLUSIONS

Higher serum MMP-2 and BNP levels were found in HFrEF patients with CSR. Elevated MMP-2 levels were correlated with the severity of sleep apnea and intermittent hypoxia.

Periodic breathing in patients with stable obstructive sleep apnea on long-term continuous positive airway pressure treatment: a retrospective study using CPAP remote monitoring data

PURPOSE

The purpose of this study was to investigate the rate of periodic breathing (PB) and factors associated with the emergence or persistence of PB in patients with obstructive sleep apnea (OSA) by continuous positive airway pressure (CPAP) remote monitoring data.

METHODS

This was a retrospective cohort study on 775 patients who had used the same model CPAP machine for at least 1 year as of September 1, 2020. The data were analyzed online using the dedicated analysis system. Using exporter software, average apnea/hypopnea index (AHI), average central apnea index (CAI), and average the rate of PB time (PB%) were cited.

RESULTS

Among 618 patients analyzed (age 61.7 ± 12.2 years, male 89%, BMI 27.2 ± 4.9), the average duration of CPAP use was 7.5 ± 4.0 years. The median PB% in stable patients was low at 0.32%, and only 149 patients (24%) had a PB% above 1%. Multiple regression analysis of factors for the development of PB showed that the most important factor was atrial fibrillation (Af) with a coefficient of 0.693 (95% CI; 0.536 to 0.851), followed by QRS duration with a coefficient of 0.445 (95% CI; 0.304 to 0.586), followed by history of heart failure, male sex, comorbid hypertension, obesity, and age. The average PB% for paroxysmal Af was significantly lower than that for persistent and permanent Af.

CONCLUSIONS

The median PB% in stable patients on CPAP treatment was low at 0.32%, with only 24% of patients having PB% ≥ 1%. Persistent Af and an increase in QRS duration were found to be important predictors of increased PB%.

CLINICAL TRIAL REGISTRATION

UMIN000042555 2021/01/01.

[Objective sleep characteristics and risk factors for sleep apnea in heart failure patients with different left ventricular ejection fraction]

OBJECTIVE

To investigate the objective sleep characteristics and the independent risk factors for sleep apnea in heart failure (HF) patients with different left ventricular ejection fractions (LVEF).

METHODS

A total of 107 patients with chronic HF hospitalized in the Department of Cardiology of our hospital from April, 2019 to October, 2020 were included in this study. According to the LVEF measured by echocardiography, the patients were divided into reduced ejection fraction (HFrEF) group (n=35), mid-range ejection fraction (HFmrEF) group (n=21), and preserved ejection fraction (HFpEF) group (n=51). The baseline demographic and clinical characteristics of the patients were recorded. To assess the objective sleep characteristics, whole night polysomnography was scheduled for all the patients. Spearman correlation and multinomial logistic regression analyses were used to explore the factors affecting objective sleep characteristics.

RESULTS

The patients in HFpEF group had significantly lower proportion of non-rapid eye movement sleep stage 1, apnea hypopnea index (AHI), and central sleep apnea (CSA) than those in HFrEF group (all P < 0.05). The baseline demographic data or sleep structures in HFmrEF group did not differ significantly from those in the other two groups. Spearman correlation analysis revealed significant correlations of the male sex, diuretics use, NT-proBNP, LVEF, and total cholesterol levels with the severity of AHI (all P < 0.05). After adjusting for potential confounders, multiple logistics regression analysis showed that age, drinking, and LVEF levels were independently associated with the severity of AHI (all P < 0.05).

CONCLUSION

Abnormal objective sleep architectures occur in all HF patients, manifested mainly by sleep apnea. The incidences of sleep apnea and CSA are lower in patients with HFpEF than in those with HFrEF. Age, drinking, and LVEF levels are independent risk factors for the occurrence and severity of sleep apnea.

Baclofen destabilises breathing during sleep in healthy humans: A randomised, controlled, double-blind crossover trial

AIMS

Periodic breathing is frequent in patients with severe heart failure. Apart from being an indicator of severity, periodic breathing has its own deleterious consequences (sleep-related oxygen desaturations, sleep fragmentation), which justifies attempts to correct it irrespective of the underlying disease. Animal models and human data suggest that baclofen can reconfigure respiratory central pattern generators. We hypothesised that baclofen, a GABA_B agonist, may thus be able to correct periodic breathing in humans.

METHODS

Healthy volunteers were exposed to hypoxia during sleep. Participants who developed periodic breathing (n = 14 [53 screened]) were randomly assigned to double-blind oral baclofen (progressively increased to 60 mg/d) or placebo. The primary outcome was the coefficient of variation (CoVar) of respiratory cycle total time considered as an indicator of breathing irregularity. Secondary outcomes included the CoVar of tidal volume, apnoea-hypopnoea index, sleep fragmentation index and ventilatory complexity (noise limit).

RESULTS

The analysis was conducted in 9 subjects after exclusion of incomplete datasets. CoVar of respiratory cycle total time significantly increased with baclofen during non-rapid eye movement sleep (median with placebo 56.00% [37.63-78.95]; baclofen 85.42% [68.37-86.40], P = .020; significant difference during the N1-N2 phases of sleep but not during the N3 phase). CoVar of tidal volume significantly increased during N1-N2 sleep. The apnoea-hypopnoea index, sleep fragmentation index and ventilatory complexity were not significantly different between placebo and baclofen.

CONCLUSION

Baclofen did not stabilise breathing in our model. On the contrary, it increased respiratory variability. Baclofen should probably not be used in patients with or at risk of periodic breathing.

Acetazolamide Therapy in Patients with Heart Failure: A Meta-Analysis

Background and objectives: Fluid overload and central sleep apnea are highly prevalent in patients with heart failure (HF). We performed this meta-analysis to assess the effects of acetazolamide therapy on acid/base balance and apnea indexes. Methods: A literature search was conducted using EMBASE, MEDLINE, and Cochrane Database from inception through 18 November 2017 to identify studies evaluating the use of acetazolamide in HF. Study results were analyzed using a random effects model. The protocol for this systematic review is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017065401). Results: Nine studies (three randomized controlled trials and six cohort studies) with a total of 229 HF patients were enrolled. After acetazolamide treatment, there were significant decreases in serum pH (mean difference (MD) of −0.04 (95% CI, −0.06 to −0.02)), pCO₂ (MD of −2.06 mmHg (95% CI, −3.60 to −0.53 mmHg)), and serum bicarbonate levels (MD of −6.42 mmol/L (95% CI, −10.05 to −2.79 mmol/L)). When compared to a placebo, acetazolamide significantly increased natriuresis (standardized mean difference (SMD) of 0.67 (95% CI, 0.08 to 1.27)), and decreased the apnea-hypopnea index (AHI) (SMD of −1.06 (95% CI, −1.75 to −0.36)) and central apnea index (CAI) (SMD of −1.10 (95% CI, −1.80 to −0.40)). Egger’s regression asymmetry tests revealed no publication bias with p = 0.20, 0.75 and 0.59 for analysis of the changes in pH, pCO₂, and serum bicarbonate levels with use of acetazolamide in HF patients. Conclusion: Our study demonstrates significant reduction in serum pH, increase in natriuresis, and improvements in apnea indexes with use of acetazolamide among HF patients.

An application of pacemaker respiratory monitoring system for the prediction of heart failure

Sleep-disordered breathing (SDB) is one of the most common complications among heart failure (HF) patients. Changes of respiratory patterns during the various stages in patients with HF have not been fully investigated. In this case, the algorism using thoracic impedance sensor and minute ventilation (sleep apnea monitoring [SAM] algorithm) with implanted pacemaker (REPLY 200 SR or DR, Sorin CRM SAS, Clamart, France) was used to monitor respiration. Impedance data from the implanted pacemaker can be converted into respiratory data, which can be used to calculate the respiratory disturbance index (RDI) per unit of time. Using this algorithm, we observed a sudden appearance of abnormal breathing at the onset of HF, followed by gradual improvement of respiratory patterns during the recovery stage. The results from respiratory monitoring using the SAM algorithm were strongly correlated with those from the positive airway pressure device. This case report could imply that proper utilization of this sensor could facilitate the early detection and therapeutic control of HF.