Pulse Transit Time as Surrogate Measure of Blood Pressure in Children

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


Non-invasive monitoring, blood pressure, pulse transit time, and arterial compliance


Pulse transit time (PTT) is a non-invasive measure of arterial compliance and can be used for measurement of instantaneous blood pressure (BP) changes during respiratory-related studies. Two common postures adopted in such studies are sitting and supine. However, the relationship between PTT and these postures in children has yet been investigated. The objective of this study was to evaluate the differences in PTT between the recording postures and peripheries in normal children. Retrospective studies were conducted on 24 children mean age of 8.6 years. Sitting posture showed a mean PTT difference of 61.2 8.1ms or 23.9 3.0% (p<0.05) between peripheral sites while supine posture registered 100.4 12.2ms or 43.7 4.4% (p<0.05). The principal contributor to this discrepancy was the lower limb where PTT differed by 42.9 10.3ms or 14.3 3.3% (p<0.05) for sitting and supine posture respectively while, upper limb showed negligible difference of -3.3 3.0ms or -1.4 1.3% (p>0.05). Postural change caused a distinctive PTT differences in children at the lower limbs only due to the higher hydrostatic pressure changes experienced at these peripheries. Hence, PTT measure can be used as a simple and continuous non-invasive BP monitoring in children.

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