Intermittent Hypoxemia and OSA

Abstract

OSA is a common chronic disorder that is associated with signifi cant morbidity and mortality including cardiovascular, metabolic, and neurocognitive disease and increased cancer-related deaths. OSA is characterized by recurrent episodes of apneas and hypopneas associated with repetitive episodes of intermittent hypoxemia, intrathoracic pressure changes, and arousals.Intermittent hypoxemia (IH) is now being recognized as a potential major factor contributing to the pathogenesis of OSA-related comorbidities. OSA-related high-frequency IH is characterized by cycles of hypoxemia with reoxygenation that is distinctly diff erent than sustained low-frequency hypoxia and contributes to ischemia-reperfusion injury. Data from both animal and human studies support mechanistic links between IH and its adverse impact at the tissue level. IH promotes oxidative stress by increased production of reactive oxygen species and angiogenesis, increased sympathetic activation with BP elevation, and systemic and vascular infl ammation with endothelial dysfunction that contributes to diverse multiorgan chronic morbidity and mortality aff ecting cardiovascular disease, metabolic dysfunction, cognitive decline, and progression of cancer. Data from observational studies in large population groups also support the role for hypoxia in the pathogenesis of OSA comorbidity. Treatment with CPAP to reverse OSA-related symptoms and comorbidities has been shown to provide variable benefi t in some but not all patient groups. Early treatment with CPAP makes intuitive sense to promote maximal functional recovery and minimize residual injury. More studies are needed to determine the interacting eff ects of IH and obesity, diff erential eff ects of both short-term and longterm hypoxemia, and the eff ect of CPAP treatment.CHEST 2015; 147 ( 1 ): 266 -274 ABBREVIATIONS : AF 5 atrial fi brillation ; AHI 5 apnea-hypopnea index ; HIF 5 hypoxia-inducible factor ; IH 5 intermittent hypoxemia ; NADPH 5 reduced nicotinamide adenine dinucleotide phosphate ; NO 5 nitric oxide ; ROS 5 reactive oxygen species ; Sp o 2 5 pulse oximetry blood oxygen saturation ; VEGF 5 vascular endothelial growth factor[ Contemporary Reviews in Sleep Medicine ]

Nocturnal Hypoxemia Due to Obstructive Sleep Apnea Is an Independent Predictor of Poor Prognosis After Myocardial Infarction

“…As the conventionally accepted standard to diagnose OSA, AHI is commonly used to predict outcomes related to the diagnosis 4, 18, 19, 26. Because hypoxemia may be the physiological consequence triggering most of the adverse effects caused by breathing events,6 indices of hypoxemia, such as minSaO 2 and T90SaO 2 , could provide a better prognostic marker in this cohort.…”

“…Among these, hypoxemia is thought to be the primary factor in mediating cardiovascular damage 6. The unique oxygen desaturation pattern seen in OSA produces tissue hypoxemia and re‐oxygenation similar to ischemia–reperfusion injury.…”

Subclinical sleep apnoea and plasma levels of endothelin-1 among young and healthy adults

“…However, it is very unlikely that increased ET-1 levels induce night-time hypoxaemia, such that the latter seems to be the driving force for elevated ET-1 levels. 40 Second, the generalisability of our results to other populations is uncertain. Third, we did not use polysomnography as the gold standard diagnostic tool for sleep apnoea.…”

Obstructieve slaapapneu: pathofysiologie en gevolgen

“…Deze chemoreflex wordt normaal gesproken gedempt door rekreceptoren in de thoraxwand: naarmate de thoraxwand meer uitzet tijdens een inademing, verzwakt de chemoreflexrespons. Deze demping blijft uit wanneer er geen effectieve inademing optreedt tijdens de apneu, waardoor er een veel sterkere sympathicusactivatie optreedt, die niet alleen 's nachts maar ook overdag in verhoogde mate aanwezig is [1]. De beëindiging van de apneu gaat vaak samen met een arousal, een verdere stimulans voor sympathicusactiviteit.…”