Background: Although tonometry-based devices have been applied in several population studies and clinical trials, the agreement between them remains unclear.
Methods: Carotid systolic blood pressure (SBP) and augmentation index (AI) were randomly measured from 3 devices, SphygmoCor, PulsePen, and A-Pulse, in 66 consecutive patients from our ambulatory cardiovascular department. The study contains 2 phases: in Study 1, SphygmoCor and PulsePen were performed on each participant by 2 experienced physicians (n = 66); in Study 2, A-Pulse was added after the measurements of SphygmoCor and PulsePen and performed by another technician on the last 34 patients.
Results: Carotid SBP and AI measured by the 3 devices were strongly correlated (R ≥ 0.78; P < 0.001), but with significant discrepancies. Specifically, in 66 participants of Study 1, PulsePen estimated higher carotid SBP and AI by 5mm Hg and 5.7%, respectively, than SphygmoCor. In 34 patients of Study 2, A-Pulse estimated higher central SBP by 3.7 mm Hg than SphygmoCor, and lower central SBP by 5.7 mm Hg than PulsePen. However, no significant difference in interclass comparison was detected between the 3 devices (P ≥ 0.26). Furthermore, slopes of correlation plots of parameters between SphygmoCor and PulsePen were not significantly different from 1 (P ≥ 0.09), but were different in the case of A-Pulse (P ≤ 0.004).
Conclusions: Tonometry-based devices were not consistent in measurements of central BP and wave reflections in clinical practice, with considerable and significant differences among them. However, in contrast to A-Pulse, SphygmoCor and PulsePen can probably assess similar cardiovascular risk for individuals, with a systematical discrepancy.