Relationship between obstructive sleep apnea and pulmonary hypertension: past, present and future

ABSTRACT

Introduction

Obstructive sleep apnea (OSA) is a widely prevalent condition with consequent multiple organ systems complications. There is consensus that OSA is associated with negative effects on pulmonary hemodynamics but whether it contributes to development of clinical pulmonary hypertension (PH) is unclear.

Areas covered

In this review, we (1) highlight previous studies looking into the possible bidirectional association of OSA and PH, focusing on those that explore clinical prognostic implications, (2) explore potential pathophysiology, (3) discuss the new metrics in OSA, (4) describe endo-phenotyping of OSA, (5) recommend possible risk assessment and screening pathways.

Expert opinion

Relying only on symptoms to consider a sleep study in PH patients is a missed opportunity to detect OSA, which, if present and not treated, can worsen outcomes. The potential prognostic role of sleep study metrics such as oxygen desaturation index (ODI), hypoxic burden (HB) and ventilatory burden (VB) in OSA should be studied in prospective trials to identify patients at risk for PH. AHI alone has not provided clarity. In those with PH, we should consider replacing ambulatory overnight pulse oximetry (OPO) with home sleep studies (HST). In PH patients, mild OSA should be sufficient to consider PAP therapy.

KEYWORDS:

• Obstructive sleep apnea
• pulmonary hypertension
• sleep study
• oxygen desaturation index
• hypoxic burden

Article highlights

• OSA and PH have high epidemiological burden and high healthcare expenditure.

• Nocturnal hypoxemia seems to be the main pathophysiological driver in development of pre-capillary PH in OSA.

• One should look beyond the AHI on sleep studies, to include metrics of nocturnal hypoxemia like T90, ODI, HB.

• In PH patients, mild OSA should be sufficient to consider PAP therapy.

• Those who need supplemental O2 despite adequate CPAP optimization, may need additional evaluation for other causes including PH.

• In patients with OSA, the presence of dyspnea, fatigue, edema and murmurs, should trigger further investigation for PH.

• In patients with PH, an ambulatory overnight pulse oximetry (OPO) can miss underlying OSA. Future guidelines should consider implementation of HST instead.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.