Respiratory chemoreflex and risk of incident increase in blood pressure

Carotid body over-activation increases sympathetic drive and blood pressure but also induces periodic breathing (high loop gain [HLG] sleep apnea). It is plausible that apnea with elevated loop gain has a disproportionate effect on development or worsening of hypertension.

Subjects from two cohort studies, Sleep Heart Health Study (SHHS) and Osteoporotic Fractures in Men Study (MrOS), were included in this analysis. Respiratory self-similarity (SS, and the related central respiratory event index, CREI) is a method of detecting expressed HLG sleep apnea independent of conventional scoring. The relationship between SS and the risk of blood pressure rise of more than 20 mm Hg was assessed.

A total of 5947 subjects, 3546 from SHHS and 2401 from MrOS with about 4.6 years follow-up was included in the final analysis. After adjustment for common confounders, higher SS% (OR 1.409, 95%CI = 1.050-1.890, p: 0.006) and CREI (OR 1.936, 95%CI = 1.208-3.102, p: 0.006) was related to delta SBP ≥ 20 mmHg in MrOS. In SHHS, we did not find any overall relationship between SS%/CREI and blood pressure trajectory. However, a significant gender effect was found. In males, a higher SS% (OR1.424, 95%CI = 1.008-2.013, p: 0.045) was related to increasing SBP and potentially associated with increasing DBP (OR 3.355, 95%CI = 0.979-11.495, p: 0.054); CREI was related to increasing DBP (OR 3.204, 95%CI = 1.033-9.937, p: 0.044). However, in females, no potential relationship was found.

HLG sleep apnea can increase the future risk of rising blood pressure. Statement of Significance High loop gain sleep apnea, detected using novel metrics of respiratory self-similarity and a central respiratory event index, independently predicts a clinically significant increase in systolic blood pressure (≥20 mmHg). A significant sex difference in the relationship between high loop gain sleep apnea and blood pressure progression.