Is Obstructive Sleep Apnea (OSA) a secondary cause of Hypertension (HTN)?

From the Guidelines

Yes, Obstructive Sleep Apnea (OSA) is a recognized secondary cause of hypertension (HTN). When patients experience repeated episodes of upper airway obstruction during sleep, this leads to intermittent hypoxia, increased sympathetic nervous system activity, and oxidative stress. These physiological changes contribute to elevated blood pressure both during sleep and while awake. The relationship is significant enough that current hypertension guidelines recommend screening for OSA in patients with resistant hypertension, nocturnal hypertension, or non-dipping blood pressure patterns.

Key Points

• Treatment of OSA, primarily with continuous positive airway pressure (CPAP) therapy, has been shown to reduce blood pressure levels, particularly in patients with resistant hypertension, as suggested by the American Academy of Sleep Medicine clinical practice guideline 1.
• The blood pressure-lowering effect is typically modest, averaging 2-3 mmHg for systolic pressure, but can be more substantial in patients with severe OSA or resistant hypertension.
• For optimal management, patients with suspected OSA should undergo sleep studies for diagnosis, and those with confirmed OSA should adhere to CPAP therapy nightly, with pressure settings individually calibrated by a sleep specialist.
• The 2024 ESC guidelines for the management of elevated blood pressure and hypertension also support the use of CPAP in moderate and severe OSA to improve BP control and help resolve resistant hypertension 1.
• Additionally, evidence from a 2017 study suggests that OSA is associated with an increased risk of cardiovascular disease, fatal and nonfatal stroke, and death from all causes, and that PAP treatment can reverse daytime hypertension, reduce mortality after stroke, and improve quality of life 1.

Recommendations

• Patients with suspected OSA should undergo sleep studies for diagnosis, and those with confirmed OSA should adhere to CPAP therapy nightly.
• Addressing this secondary cause of hypertension may reduce cardiovascular risk and improve overall blood pressure control, potentially reducing the need for antihypertensive medications in some patients.
• The management of OSA should be driven by the result of a polysomnography study, which should provide the value of the AHI and the sleep position in which apnoeic–hypopnoeic episodes occur, as recommended by the 2024 ESC guidelines 1.

From the Research

Relationship Between OSA and HTN

• Obstructive sleep apnea (OSA) is recognized as a secondary cause of hypertension (HTN) by the Seventh Joint National Committee (JNC VII) in 2003 2.
• OSA is a common underlying factor in resistant HTN (RHTN) and can lead to cardiovascular disease (CVD) and end-organ damage 3.
• The association between OSA and HTN is attributed to shared risk factors, including obesity, male gender, and advancing age 2.

Impact of OSA on HTN

• Studies have shown that OSA can increase the risk of developing HTN, with mild sleep apnea increasing the risk for HTN 4.
• Nocturnal oxygen desaturation rate is positively correlated with HTN severity, highlighting the importance of addressing OSA in HTN management 4.
• Treatment with continuous positive airway pressure (CPAP) can promote reductions in blood pressure in individuals with OSA, although the effect is generally small 5, 6.

Treatment of OSA-Associated HTN

• CPAP therapy is beneficial in treating HTN and RHTN, and should be used in combination with antihypertensive medications in hypertensive patients with OSA 3, 6.
• CPAP can restore nocturnal dipping and improve arterial stiffness, potentially influencing cardiovascular morbidity in high-risk patients 6.
• Other potential treatments for OSA-associated HTN include carbonic anhydrase inhibitors and probiotics, which show newfound promise in managing this condition 4.