Studies have shown that obstructive sleep apnea (OSA) is linked to high blood pressure (HTN). There was a paper in 2012 that was a meta-analysis showing that CPAP significantly reduced both systolic and diastolic blood pressure (DBP). When the researchers looked closer at the data, they discovered that the reduction in DBP occurred more often when the baseline DBP was high, as well as when the patient was excessively sleepy at baseline. The results did not show that reduction in blood pressure was associated with the OSA severity.
In this study, the researchers went back over the original data to further explore the relationship between blood pressure improvement and CPAP therapy. The results showed that the sole predictor of reduction in blood pressure was the presence of uncontrolled HTN at baseline. Again, OSA severity was not related to the reduction in blood pressure seen with CPAP therapy. Also, excessive sleepiness was not a significant predictor in CPAP reducing blood pressure, in contrast to the prior study.
The researchers concluded that patients with OSA who have uncontrolled HTN would have the largest benefit in their blood pressure with CPAP therapy, despite how severe the OSA or how sleepy the person may or may not be.