Sleep-induced apnea and disordered breathing refers to intermittent, cyclical cessations or reductions of airflow, with or without obstructions of the upper airway (OSA). In the presence of an anat...

Pathophysiology of Sleep Apnea

Sleep apnea and cardiovascular disease: an American Heart Association/American College of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing.

https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(19)30198-5.pdf

Estimation of the global prevalence and burden of obstructive sleep apnoea: a literature-based analysis.

Sleep-related breathing disorders are highly prevalent in patients with established cardiovascular disease. Obstructive sleep apnea (OSA) affects an estimated 15 million adult Americans and is present in a large proportion of patients with hypertension and in those with other cardiovascular disorders, including coronary artery disease, stroke, and atrial fibrillation.1–14 In contrast, central sleep apnea (CSA) occurs mainly in patients with heart failure.15–19 The purpose of this Scientific Statement is to describe the types and prevalence of sleep apnea and its relevance to individuals who either are at risk for or already have established cardiovascular disease. Special emphasis is given to recognizing the patient with cardiovascular disease who has coexisting sleep apnea, to understanding the mechanisms by which sleep apnea may contribute to the progression of the cardiovascular condition, and to identifying strategies for treatment. This document is not intended as a systematic review but rather seeks to highlight concepts and evidence important to understanding the interactions between sleep apnea and cardiovascular disease, with particular attention to more recent advances in patient-oriented research. Implicit in this first American Heart Association/American College of Cardiology Scientific Statement on Sleep Apnea and Cardiovascular Disease is the recognition that, although holding great promise, this general area is in need of a substantially expanded knowledge base. Specific questions include whether sleep apnea is important in initiating the development of cardiac and vascular disease, whether sleep apnea in patients with established cardiovascular disease accelerates disease progression, and whether treatment of sleep apnea results in clinical improvement, fewer cardiovascular events, and reduced mortality.

Experimental approaches directed at addressing these issues are limited by several considerations. First, the close association between obesity and OSA often obscures differentiation between the effects of obesity, the effects of OSA, and the effects of synergies between these conditions. Second, multiple comorbidities, …

Sleep Apnea and Cardiovascular Disease An American Heart Association/American College of Cardiology Foundation Scientific Statement From the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing In Collaboration With the National Heart, Lung, and Blood Institute National Center on Sleep Disorders Research (National Institutes of Health)

Prevalence of obstructive sleep apnea in the general population: A systematic review.

https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(15)00043-0.pdf

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study

Previous studies have demonstrated that lung volume during wakefulness influences upper airway size and resistance, particularly in patients with sleep apnea. We sought to determine the influence of lung volume on the level of continuous positive airway pressure (CPAP) required to prevent flow limitation during non-REM sleep in subjects with sleep apnea. Seventeen subjects (apnea–hypopnea index, 42.6 ± 6.2 [SEM]) were studied during stable non-REM sleep in a rigid head-out shell equipped with a positive/negative pressure attachment for manipulation of extrathoracic pressure. An epiglottic pressure catheter plus a mask/pneumotachometer were used to assess flow limitation. When lung volume was increased by 1,035 ± 22 ml, the CPAP level could be decreased from 11.9 ± 0.7 to 4.8 ± 0.7 cm H2O (p < 0.001) without flow limitation. The decreased CPAP at the same negative extrathoracic pressure yielded a final lung volume increase of 421 ± 36 ml above the initial value. Conversely, when lung volume was reduced by ...

Lung volume and continuous positive airway pressure requirements in obstructive sleep apnea

Background: Previous studies have shown that changes in lung volume influence upper airway size and resistance, particularly in patients with obstructive sleep apnoea (OSA), and that continuous positive airway pressure (CPAP) requirements decrease when the lung volume is increased. We sought to determine the effect of a constant lung volume increase on sleep disordered breathing during non-REM sleep. Methods: Twelve subjects with OSA were studied during non-REM sleep in a rigid head-out shell equipped with a positive/negative pressure attachment for manipulation of extrathoracic pressure. The increase in lung volume due to CPAP (at a therapeutic level) was determined with four magnetometer coils placed on the chest wall and abdomen. CPAP was then stopped and the subjects were studied for 1 hour in three conditions (in random order): (1) no treatment (baseline); (2) at “CPAP lung volume”, with the increased lung volume being reproduced by negative extrathoracic pressure alone (lung volume 1, LV1); and (3) 500 ml above the CPAP lung volume(lung volume 2, LV2). Results: The mean (SE) apnoea/hypopnoea index (AHI) for baseline, LV1, and LV2, respectively, was 62.3 (10.2), 37.2 (5.0), and 31.2 (6.7) events per hour (p = 0.009); the 3% oxygen desaturation index was 43.0 (10.1), 16.1 (5.4), and 12.3 (5.3) events per hour (p = 0.002); and the mean oxygen saturation was 95.4 (0.3)%, 96.0 (0.2)%, 96.3 (0.3)%, respectively (p = 0.001). Conclusion: An increase in lung volume causes a substantial decrease in sleep disordered breathing in patients with OSA during non-REM sleep.

https://thorax.bmj.com/content/thoraxjnl/61/5/435.full.pdf

Effect of increased lung volume on sleep disordered breathing in patients with sleep apnoea

Background: Most patients with obstructive sleep apnoea (OSA) can restore airflow after an obstructive respiratory event without arousal at least some of the time. The mechanisms that enable this ventilatory recovery are unclear but probably include increased upper airway dilator muscle activity and/or changes in respiratory timing. The aims of this study were to compare the ability to recover ventilation and the mechanisms of compensation following a sudden reduction of continuous positive airway pressure (CPAP) in subjects with and without OSA. Methods: Ten obese patients with OSA (mean (SD) apnoea-hypopnoea index 62.6 (12.4) events/h) and 15 healthy non-obese non-snorers were instrumented with intramuscular genioglossus electrodes and a mask/pneumotachograph which was connected to a modified CPAP device that could deliver either continuous positive or negative pressure. During stable non-rapid eye movement sleep the CPAP was repeatedly reduced 2–10 cm H 2 O below the level required to eliminate flow limitation and was held at this level for 5 min or until arousal from sleep occurred. Results: During reduced CPAP the increases in genioglossus activity (311.5 (49.4)% of baseline in subjects with OSA and 315.4 (76.2)% of baseline in non-snorers, p = 0.9) and duty cycle (123.8 (3.9)% of baseline in subjects with OSA and 118.2 (2.8)% of baseline in non-snorers, p = 0.4) were similar in both groups, yet patients with OSA could restore ventilation without cortical arousal less often than non-snorers (54.1% vs 65.7% of pressure drops, p = 0.04). When ventilatory recovery did not occur, genioglossus muscle and respiratory timing changes still occurred but these did not yield adequate pharyngeal patency/ventilation. Conclusions: Compensatory mechanisms (increased genioglossus muscle activity and/or duty cycle) often restore ventilation during sleep but may be less effective in obese patients with OSA than in non-snorers.

https://thorax.bmj.com/content/thoraxjnl/62/10/861.full.pdf

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans

OBJECTIVE: Periodic limb movements during sleep (PLMS) are sleep phenomena characterized by periodic episodes of repetitive stereotyped limb movements. The aim of this study was to describe the prevalence and determinants of PLMS in a middle to older aged general population.
METHODS: Data from 2,162 subjects (51.2% women, mean age = 58.4 ± 11.1 years) participating in a population-based study (HypnoLaus, Lausanne, Switzerland) were collected. Assessments included laboratory tests, sociodemographic data, personal and treatment history, and full polysomnography at home. PLMS index (PLMSI) was determined, and PLMSI > 15/h was considered as significant.
RESULTS: Prevalence of PLMSI > 15/h was 28.6% (31.3% in men, 26% in women). Compared to subjects with PLMSI ≤ 15/h, subjects with PLMSI > 15/h were older (p 15/h also had a higher prevalence of diabetes, hypertension, and beta-blocker or hypnotic treatments. The prevalence of antidepressant use was higher, but not statistically significant (p = 0.07). Single nucleotide polymorphisms (SNPs) within BTBD9 (rs3923809), TOX3 (rs3104788), and MEIS1 (rs2300478) genes were significantly associated with PLSMI > 15/h. Conversely, mean hemoglobin and ferritin levels were similar in both groups. In the multivariate analysis, age, male gender, antidepressant intake, RLS, and rs3923809, rs3104788, and rs2300478 SNPs were independently associated with PLMSI > 15/h.
INTERPRETATION: PLMS are highly prevalent in our middle-aged European population. Age, male gender, RLS, antidepressant treatment, and specific BTBD9, TOX3, and MEIS1 SNP distribution are independent predictors of PLMSI > 15/h. ANN NEUROL 2016;79:464-474.

/pdf/prevalence-and-determinants-of-periodic-limb-movements-in-574vid28ya.pdf

Raphael Heinzer

Papers

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study

Lung volume and continuous positive airway pressure requirements in obstructive sleep apnea

Effect of increased lung volume on sleep disordered breathing in patients with sleep apnoea

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans

Prevalence and determinants of periodic limb movements in the general population.