Comparison of intra-arterial and manual auscultation of blood pressure during submaximal exercise in humans

Blood pressure (BP) is a key measure of cardiovascular function, and accurate measurement is important to ensure proper clinical evaluation, diagnosis, and treatment. We compared intra-arterial (direct) and cuff auscultation (manual) measurement techniques at rest and during 2 levels of submaximal constant-load exercise (9 min at 40% and 75% maximum watts). Sixty-four adults (aged 29.0 ± 0.7 years; 48% male; height, 173.7 ± 1.2 cm; mass, 73.0 ± 1.7 kg; body mass index, 24.1 ± 0.4 kg·m^-2; body surface area, 1.87 ± 0.03 m²) participated in the study. At rest, low, and moderate intensity, direct measurement demonstrated higher systolic BP (SBP) and diastolic BP (DBP) (bias for SBP: 22, 31, and 27 mm Hg and for DBP: 5, 7, and 17 mm Hg; rest, low-, and moderate-intensity, respectively; p < 0.01). At rest, the correlation and agreement between the 2 methods was modest (SBP: r = 0.56, bias = +22.1 mm Hg; DBP: r = 0.53, bias = +4.9 mm Hg; p < 0.001). There was good correlation and agreement with SBP at low and moderate intensity; however, DBP demonstrated a weaker relationship (SBP: r = 0.74 and 0.74, bias = +30.2 and +26.8mmHg; DBP: r = 0.39 and 0.28, bias = +7.1 and +13.4mmHg; for low and moderate intensity, respectively; p < 0.001). Further, manual measurement demonstrated a greater slope from rest to moderate exercise for the relationship between pulse pressure (PP) and cardiac output (13.6±0.4 vs 12.3±0.4, p = 0.03). As exercise intensity increases, manual DBP tends to bias low compared with direct DBP, which, when combined with parallel increases in SBP, leads to no differences in PP between methods at moderate exercise. Because PP is used to calculate other cardiovascular parameters (mean arterial pressure, systemic vascular resistance), measurement technique and exercise intensity should be considered when using cardiovascular variables as outcome measures.