Hypoxic Burden Correlates with Blood Pressure Rhythm in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is associated with disturbances in blood pressure (BP) patterns, which is recognized as an independent cardiovascular risk factor. However, conventional hypoxic indicators of OSA severity showed inconsistent associations with these BP disturbances. Hypoxic burden (HB), a metric integrating the frequency, depth, and duration of desaturation, may better represent the characteristics of hypoxia. We hypothesized that HB would be more closely associated with BP patterns compared to other traditional hypoxia indicators.

HB was measured from polysomnography (PSG), followed by 24-hour ambulatory blood pressure monitoring (ABPM) in 377 patients with suspected OSA. Patients were grouped based on the rhythms of systolic blood pressure (SBP) and diastolic blood pressure (DBP). Logistic regression analysis was conducted to assess the association between HB and BP rhythm impairment.

HB was significantly higher in the non-dipper groups than that in the dipper groups. After adjusting for various confounders, subjects with higher HB in the fourth quartile were more likely to exhibit SBP non-dipping pattern in Model 3. Similarly, the association between HB and nocturnal hypertension also remained statistically significant after adjusting for all the confounding factors. However, none of the conventional hypoxic metrics were consistently associated with BP rhythm abnormalities after adjusting for various confounders.

Compared to conventional PSG hypoxic parameters, HB is more closely associated with circadian SBP rhythm and nocturnal hypertension in OSA. HB may be a promising indicator for guiding early intervention in high-risk OSA patients and predicting adverse cardiovascular outcomes.