Obstructive sleep apnea syndrome and the nocturnal blood pressure profile

Abstract

Obstructive sleep apnea syndrome (OSAS) affects 2%-7% of the adult population and is the most common sleep-related breathing disorder. 1 It is the most frequent cause of secondary and difficultto-treat hypertension and represents a well-known risk factor for hypertension-associated end-stage organ damage. 2,3 The investigation of blood pressure (BP) behavior and of its determinants in OSAS patients helps to understand some pathophysiologic aspects of hypertension, stratify the cardiovascular risk profile, and support indication for therapy in affected patients. | NO C TURNAL B P PROFILE A SS E SS MENTThe assessment of nocturnal BP profile has important clinical relevance. Indeed, clinical studies have demonstrated that nocturnal BP and BP variability (BPV) are more closely associated with the risk of developing target-organ damage and future cardiovascular events in comparison to awake BP and BPV. 4,5 Ambulatory blood pressure monitoring (ABPM), which currently represents the gold standard of nocturnal BP assessment, measures the individual BP at fixed time intervals. Because of the lack of any synchronization with sleep apnea, ABPM can fail to detect apnea-related BP fluctuations and, hence, underestimate the extent of cardiovascular risk. 6 In this issue of The Journal of Clinical Hypertension, the study by Kuwabara and colleagues explored the association between polysomnography-derived sleep parameters and nocturnal BP indices as derived by an oxygen-triggered nocturnal BP monitoring system. 7 This is an information technology-based system, which indicates BP measurements when oxygen desaturation falls below a set variable threshold continuously monitored by pulse oxymetry. 8 In this way, the system allows the detection of the nocturnal BP surge triggered by hypoxic apnea episodes.The study clearly demonstrated that, in OSAS patients, the hypoxia-peak systolic BP, defined as the maximum systolic BP value measured by the oxygen-triggered function, and the nocturnal systolic BP surge, defined as the difference between the hypoxiapeak systolic BP and the average of the systolic BP values within 30 minutes before and after the hypoxia-peak systolic BP, were higher, ranged more broadly, and were more closely associated with respiratory-related polisomnographic parameters than maximum and mean nocturnal systolic BP obtained by the fixed-interval function through conventional ABPM. 7 In particular, the lowest oxygen saturation (SpO 2 ), defined as the minimum SpO 2 value during sleep, was the strongest independent determinant of either hypoxia-peak systolic BP or nocturnal systolic BP surge. 7These findings suggest that the severity and frequency of the decrease in SpO 2 have a strong impact on the nocturnal BP trajectories, and the hypoxia-triggered nocturnal BP measurement may be a promising technique to improve the cardiovascular evaluation of OSAS patients. Noteworthy, in OSAS patients cardiovascular events occur more frequently during sleep, and hypoxia-triggered nocturnal BP surge and exaggerated BP fluctuation...

Effect of hypertension status on the association between sleep duration and stroke among middle‐aged and elderly population

“…Sleep duration >8 hours was positively associated with the prevalence of stroke in hypertensive patients. However, the presence of obstructive sleep apnea syndrome in the different groups of the study was not assessed although there is a huge amount of evidence supporting the strong relationship between sleep breathing disorders, BP profile and cardiovascular risk . Furthermore, the cross‐sectional evaluations did not allow to assess additional hemodynamic variables, as for example the variability of BP, to improve the characterization of the hypertensive status of patients.…”

Obstructive sleep apnea syndrome (OSAS) related hypertension: A review of pathophysiology and potential therapeutic approaches

“…Is OSAS an independent cause of hypertension? OSAS is known as the most common cause of secondary hypertension and remittent hypertension-related organ damage [13]. Rates of hypertension among OSAS patients range from 35% to 80%, depending on severity and duration of untreated OSAS [8].…”

“…The indicator of severity of hypertension is considered as the hypoxia level attributed to apnea duration. Longer apnea durations cause deeper hypoxia and stronger sympathetic activation, and consequently, higher BP [13]. Also, a decrease in the sensitivity of baroreceptors and pulmonary receptors that affect cardiovascular reflexes was reported, probably due to activation of chemoreceptor reflexes [16].…”

Integrated care of hypertension and HIV infection

“…Additionally, the high burden of psychosocial stress, social stigma, and pain can contribute to alter BP either directly or indirectly as mediators of sleep disturbances . Insomnia, impaired sleep‐quality and sleep‐breathing disorders are common among HIV+ individuals and can negatively influence both diurnal and nocturnal BP levels …”

“…25 Insomnia, impaired sleep-quality and sleep-breathing disorders are common among HIV+ individuals and can negatively influence both diurnal and nocturnal BP levels. [26][27][28]…”