Confounding Physiologic Parameters in Pulse Transit Time Monitoring of Children

J.Y.A. Foo, S.J. Wilson, G.R. Williams, M.-A. Harris, and D.M. Cooper (Australia)

Keywords

Measurement and Instrumentation, pulse transit time, blood pressure, and arterial compliance

Abstract

Pulse Transit Time (PTT) measurement has showed potential in non-invasive monitoring of changes in blood pressure. In children, the common peripheral sites used for these studies are a finger or toe. Presently, there are no known studies conducted to investigate any possible physiologic parameters affecting PTT measurement at these sites for children. In this study, PTT values of both peripheral sites were recorded from 64 children in their sitting posture. Their mean age with standard deviation (SD) was 8.2 2.6years (ranged 3 to 12years). Subjects' peripheries path length, heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP) were measured to investigate any contributions to PTT measurement. The peripheral pulse timing characteristic measured by photoplethysmography (PPG) shows a 59.5 8.5ms (or 24.8 0.4%) difference between the two peripheries (p<0.05). The results also revealed PTT is directly proportional to age (p<0.05). HR, SBP, peripheral path length and peripheral site also contributed significantly (p<0.05) to PTT variations, except for DBP. Results also suggest an upward trend in PTT with age. Hence, changes in any of these physiologic parameters can affect the nominal PTT value of a child.

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