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Upper airway stimulation less effective in lowering BP than positive airway pressure in OSA

Positive airway pressure as a treatment for obstructive sleep apnea showed greater improvement in blood pressure than upper airway stimulation, but sleepiness symptoms were improved most using upper airway stimulation, according to a study published in CHEST.

However, these findings may be in error and should be interpreted with caution due to nonstandard approaches to BP measurement in the upper airway stimulation (UAS) group.

“[Positive airway pressure] therapy appears to exert a more pronounced impact on BP than UAS, and UAS had greater improvement in daytime sleep propensity,” Harneet K. Walia, MD, of the Sleep Disorders Center at Cleveland Clinic, and colleagues wrote. “This has potential important implications for sleep clinicians by providing guidance in terms of anticipated BP and daytime sleepiness responsiveness with these treatment strategies.”

Researchers studied clinic-based BP and Epworth Sleepiness Scale (ESS) measurements in patients with OSA. Measurements from 517 patients receiving positive airway pressure (PAP) for OSA at the Cleveland Clinic were compared with 278 patients who received UAS implantation via an international registry.

Researchers stated that in each arm of the study, outcomes for 201 patients were compared after propensity matching.

“It is important to note that nonstandard approaches to BP measures in the clinic-based UAS registry may have contributed to measurement error and, therefore, represent a threat to internal validity, potentially accounting for the null study findings of the impact of UAS on BP,” researchers wrote. “Therefore, these study findings should not be viewed as definitive and should be interpreted with caution.”

Investigators found that PAP therapy for OSA showed greater improvement in mean arterial pressure and BP than UAS, and was even more pronounced in patients with higher baseline BP.

UAS, however, showed improved ESS measurements compared with PAP.

“Although the current study was not designed to elucidate underlying mechanisms, it is conceivable that PAP, via direct mechanical influences mediated by positive pressure, may be more effective than UAS in addressing the OSA-related intrathoracic pressure swings,” researchers wrote.

Investigators reported a 3.7-point decrease in ESS among patients receiving UAS treatment and a 2.7-point reduction in PAP, regardless of baseline ESS.

“One should also emphasize that the patients with UAS were PAP intolerant and may have had exposure to untreated OSA pathophysiology for a longer period of time (despite the matching) with possible irreversibility of vascular dysfunction, thereby mitigating appreciation of BP benefit potentially due to vascular remodeling,” investigators wrote. – by Scott Buzby

Disclosures: Walia reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.