Differences In Blood Pressure And Pulse Wave Analysis Between Sitting And Supine In Young Adults

Measurements of blood pressure (BP) and arterial wave reflection may differ when taken while seated vs. supine. Therefore, knowing the quantification of these differences in cardiovascular indices may help identify best practices for cardiovascular assessments. PURPOSE: To quantify differences in BP, pulse wave analysis (PWA), and hemodynamics after 5 minutes of rest between seated vs. supine position in healthy young adults. METHODS: 20 young adults (20.6 ± 1.1 years old) participated in this study. Participants completed one laboratory visit that included a 5 minute resting period, three BP and PWA measurements (closest two were averaged), and 5 minutes of continuous beat-to-beat hemodynamic measurements in both seated (90 degrees) and supine modes in a counterbalanced approach. Data were analyzed using a one-way ANOVA by position (supine vs. sitting). Results are given as mean ± SD and alpha set as p ≤ 0.05. RESULTS: Measurements of brachial pulse pressure (49 ± 7 mmHg vs. 45 ± 8 mmHg; p < 0.036, F = 4.7), ejection duration (336 ± 9 ms vs. 292 ± 4 ms; p < 0.01, F = 50), stroke volume (87.4 ± 20.4 ml vs. 73.3 ± 16.5 ml; p = 0.021, F = 5.8) were greater in the supine position compared to seated. HR (73 ± 17 bpm vs. 61 ± 9 bpm; p < 0.01, F = 7.9). Total peripheral resistance (0.98 ± 0.28 mmHg vs. 0.83 ± 0.21 mmHg; p < 0.065, F = 3.6) was close to significance in the seated position. No differences in aortic and brachial systolic and diastolic BP were observed between positions. CONCLUSIONS: Body position should be considered during acute physiological assessments when interpreting hemodynamic and cardiovascular measurements.