Changes in central arterial stiffness during lower body negative pressure

Abstract

In order to examine the influence of lower body negative pressure (LBNP) on central arterial stiffness, nine participants were exposed to consecutive 15 min stages of LBNP at increasing intensities (−20, −40, −60, and −80 mm Hg) until pre‐syncope. Carotid‐femoral pulse wave velocity (cPWV), and continuous measures of heart rate (HR), and systolic (SBP) and mean arterial blood pressure (MAP) were recorded at each stage. SBP low frequency band power (SBPLF) and the HRV low to high frequency band power ratio (LF/HF HRV) served as surrogate indicators of sympathovagal tone. T‐tests were used to compare changes in cPWV, HR, SBPLF, LF/HF HRV, and MAP from baseline to the maximum tolerated LBNP stage (LBNPmax). Delta scores (baseline to LBNP max) were calculated and Pearson correlation used to examine the relationship between cPWV and HR, SBPLF, or LF/HF HRV. cPWV, HR, SBPLF, and LF/HF HRV increased from baseline to LBNPmax (cPWV +294.07 ± 220.98, p = 0.004; HR +26.00 ± 17.34 bpm, p = 0.002; SBPLF +7.89 ± 9.94, p = 0.044; LF/HF/ HRV +6.62 ± 4.45, p = 0.002), while MAP did not change. cPWV was not significantly related to HR, SBPLF, or HF/LF HRV. In conclusion, it appears that central arterial stiffness increases during LBNP but is not related to HR, MAP, or indirect indicators of sympathovagal tone. Supported by the National Sciences and Engineering Research Council of Canada.