Relationship between hypoxic burden and cardiovascular effects in OSA - a post hoc analysis of an RCT

Area of Science:

• Cardiology
• Sleep Medicine
• Respiratory Medicine

Background:

• Obstructive sleep apnoea (OSA) is linked to cardiovascular issues.
• Nocturnal intermittent hypoxemia is a key OSA feature.
• Hypoxic burden (HB) quantifies this hypoxemia near respiratory events.

Purpose of the Study:

• To evaluate if HB is a better cardiovascular marker for OSA than standard severity metrics.
• To compare HB's predictive capacity for CPAP treatment response against other OSA markers.

Main Methods:

• A CPAP withdrawal study involving 40 OSA patients (AHI > 10/h).
• Patients were randomized to CPAP continuation or sham CPAP for two weeks.
• Linear and multivariate fractional polynomial regression analyzed the relationship between ΔHB and cardiovascular outcomes (blood pressure, HR, FMD, urinary catecholamines).

Main Results:

• CPAP withdrawal increased AHI and HB significantly.
• ΔHB correlated with changes in urinary catecholamines and morning HR, but not FMD or blood pressure.
• Multivariate fractional polynomial regression showed ΔHB predicted CPAP effects on catecholamines and morning HR better than AHI, ODI, time<90% SpO2, and arousal index.

Conclusions:

• In untreated OSA, HB is associated with increased urinary catecholamines and morning HR.
• HB demonstrates superior predictive value for CPAP response in these cardiovascular markers compared to other OSA severity indices.