Continuous blood pressure measurement using the pulse transit time: Comparison to intra-arterial measurement

Continuous blood pressure (BP) measurement allows the investigation of transient changes in BP and thus may give insights into mechanisms of BP control. We validated a continuous, non-invasive BP measurement based on the pulse transit time (PTT), i.e., BP(PTT), by comparing it with the intra-arterial BP (BP(i.a.)) measurement. Twelve subjects (five females and seven males) were included. BP(i.a.) was obtained from the radial artery using a system from ReCor Medical. Systolic and diastolic BP were calculated using the PTT (BP(PTT), SOMNOscreen). (PTT) was determined from the electrocardiogram and the peripheral pulse wave. The BP was modulated by application of increasing doses of dobutamine (5, 10, 20 μg/kg body mass). Systolic BP(PTT) and systolic BP(i.a.) correlated significantly (R = 0.94). The limits of agreement in the Bland-Altman plot were ± 19 mmHg; the mean values differed by 1 mmHg. The correlation coefficient for the diastolic BP measurements was R = 0.42. The limits of agreement in the Bland-Altman plot were ± 18 mmHg, with a mean difference of 5 mmHg in favour of the BP(PTT). The study demonstrates a significant correlation between the measurement methods for systolic BP. The results encourage the application of PTT-based BP measurement for the evaluation of BP dynamics and pathological BP changes.