Sex Differences in the Diastolic Blood Pressure Response to Orthostasis in Obstructive Sleep Apnea

Hypertension is commonly observed with obstructive sleep apnea (OSA), partly due to dysregulation of sympathetic activity. As OSA is considered male-dominant, potential sex differences in the sympathetic regulation of BP have yet to be explored. Hemodynamic responses to an orthostatic challenge have implications for cardiovascular risk and are sympathetically-modulated. Therefore, we tested the hypothesis that females with OSA have differential BP and HR responses to orthostasis relative to males with OSA. 160 individuals not taking antihypertensive medications completed an overnight polysomnography to identify OSA (apnea-hypopnea index ≥5 events/hr). Orthostatic responses were quantified as the changes (Δ) in BP and HR (assessed via brachial cuff) from rest (10min supine) to 60sec post-standing. Females with (n=17, 42±14yrs, 30.7±6.0kg/m2) and without (n=43, 39±12yrs, 27.6±5.7kg/m2) OSA were compared to males with (n=60, 45±11yrs, 31.4±3.8kg/m2) and without (n=40, 39±13yrs, 27.4±3.1kg/m2) OSA using a one-way ANOVA. There were no between-group differences in age (p>0.05 for post-hoc comparisons) and BMI was lower in both females, and males, without OSA relative to males with OSA (p<0.05 for both). ΔSBP did not differ between females with (1±8mmHg) and without (2±8mmHg) OSA nor between males with (4±8mmHg) and without OSA (5±12mmHg, ANOVA p=0.37). Females with OSA had a blunted ΔDBP relative to females without OSA (5±7 vs. 10±6mmHg, p<0.05), whereas males with and without OSA demonstrated similar responses (9±8 vs. 10±6mmHg, p=0.95). ΔHR did not differ between females with (8±8beats/min) and without OSA (9±11beats/min) nor between males with (13±10beats/min) and without OSA (12±10beats/min, ANOVA p=0.06). ΔDBP was not associated with the apnea-hypopnea index (Spearman's r=-0.19, p=0.47; Spearman’s r=0.23, p=0.08) nor nadir SpO2 (Spearman's r=0.27, p=0.29; Spearman’s r=0.06, p=0.64) in females or males with OSA. These data suggest that OSA influences the DBP response to orthostasis in females to a greater extent than males. As DBP is associated with sympathetic activation, this finding could indicate greater sympathetic dysregulation in females, relative to males, with OSA. This work was supported by the National Institutes of Health T32-HL007111 (JMB), HL134808 (NC), HL065176 (PS and VKS), and HL134885 (VKS). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.