Correlation between hypoxia parameters and endothelial dysfunction in patients with hypertension and obstructive sleep apnea-hypopnea syndrome

Objective  To investigate the association between hypoxia parameters and vascular endothelial dysfunction in patients with hypertension combined with obstructive sleep apnea-hypopnea syndrome (OSAHS) of different severity.

Methods  A cross-sectional study was conducted. A total of 629 hypertensive patients, aged (39.21±8.87) years, who visited the Hypertension Department of TEDA International Cardiovascular Hospital from April 2020 to July 2023 or Tianjin Kanghui Hospital from December 2023 to September 2024, were included. Male patients accounted for 77.6% (488/629) and female patients accounted for 22.4% (141/629). The patients underwent portable sleep monitoring and were categorized into 4 groups based on the apnea-hypopnea index (AHI): essential hypertension without OSAHS group (AHI＜5 events/hour, n=205), hypertension with mild OSAHS group (AHI 5 to ＜15 events/hour, n=227), hypertension with moderate OSAHS group (AHI 15 to ＜30 events/hour, n=112), and hypertension with severe OSAHS group (AHI≥30 events/hour, n=85). Vascular endothelial function was assessed via brachial artery flow-mediated dilation (FMD). Multivariate linear regression analysis was used to assess the correlation between hypoxia parameters and endothelial dysfunction. Receiver operating characteristic (ROC) curve analysis was used to preliminarily evaluate the diagnostic performance of the time spent below oxygen saturation of 90% (TS90%) on severe endothelial dysfunction in hypertensive patients with severe OSAHS.

Results FMD in the hypertension with mild, moderate, and severe OSAHS group was (4.38±2.25)%, (4.20±1.96)%, and (3.95±2.04)%, respectively, which was lower than that in the essential hypertension group (5.56±2.66)% (F=15.465, P＜0.001). Multivariate linear regression analysis showed that, after adjusting for estimated glomerular filtration rate (eGFR), uric acid, and other factors, TS90% had an independent impact on FMD in the hypertension with severe OSAHS group (B=−0.008, P=0.006). In the hypertension with severe OSAHS group, the area under the ROC curve (AUC) for TS90% diagnosing severe endothelial dysfunction was 0.692 (95%CI: 0.579 to 0.806; P＜0.001). The optimal cut-off value was 30.25 minutes, with a sensitivity of 80.43% and a specificity of 56.41%.

Conclusion  In hypertensive patients with severe OSAHS, TS90% is an independent influencing factor for endothelial dysfunction.