Systemic hypertension in obstructive sleep apnea

Abstract

There is consistent epidemiological evidence that sleep disordered breathing and systemic arterial hypertension are deeply associated, being linked through a bidirectional complex interaction among multiple mechanisms including autonomic nervous system alterations, inflammation, hormonal and hemodynamic components, sleep alterations. However there are several unanswered questions not only from a pathophysiological perspective, but also regarding the effects of obstructive sleep apnea (OSA) treatment on arterial blood pressure values. At present, while many studies have supported the possibility to obtain at least a small blood pressure reduction with OSA treatment, in particular in hypertensive patients, large trials have not clearly confirmed a significant anti-hypertensive effect, nor a beneficial effect of this intervention on cardiovascular endpoints including cardiovascular mortality. Aim of the present review article is to address the relationship between OSA and hypertension in the light of the latest evidence in the field. Moreover we will discuss research topics which need to be investigated in the future, in order to better clarify still pending issues with the aim of obtaining an early diagnosis, a more suitable phenotyping including comorbidities, and better strategies to improve patients' compliance and adherence to treatment.

Keywords: Arterial hypertension; cardiovascular diseases; continuous positive airway pressure (CPAP); sleep apnea.

Figure 1

This figure illustrates a 24-hour ambulatory blood pressure profile and polysomnographic tracings obtained in a patient with OSA. The 24 h BP recording clearly shows an increase of nocturnal of BP values not accompanied by a clear BP elevation at the time of consultation (“office BP”, indicating a “masked hypertension condition) nor at the times of home BP self measurements, scheduled in the morning and in the evening according to the ESH home BP guidelines. ABPM, ambulatory blood pressure monitoring; PSG, polysomnography; BP, blood pressure; OSA, obstructive sleep apnea; ESH, European Society of Hypertension.

Figure 2

This figure shows a 5-minute recording of beat by beat blood pressure (BP, continuous finger BP monitoring by a Portapres device, upper panel) and blood oxygen saturation (pulse oximetry, SpO₂, lower panel) in a patients-affected by severe OSA. Over the 5 min recording, 6 episodes of obstructive sleep apnea occurred, and the graphs clearly show that OSA episodes were all characterized by the combined occurrence of blood oxygen desaturation (OSA-related intermittent hypoxemia) and blood pressure surges, the latter probably triggered by chemoreflex induced sympathetic activation accompanying each hypoxic event. BP, blood pressure; OSA, obstructive sleep apnea.