Physiologic parameters that affect pulse transit time difference between the upper and lower limbs in children.
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Biomedical subjects
J Y A Foo
Publications and source records attributed to J Y A Foo.
Age-related factors that confound peripheral pulse timing characteristics in Caucasian children.
Characteristics obtained from peripheral pulses can be used to assess the status of cardiovascular system of subjects. However, nonintrusive techniques are preferred when prolonged monitoring is required for their comfort. Pulse transit time (PTT) measurement has showed its potentials to monitor timing changes in peripheral pulse in cardiovascular and respiratory studies. In children, the common peripheries used for these studies are fingers or toes. Presently, there is no known study conducted on children to investigate the possible physiologic parameters that can confound PTT measure at these sites. In this study, PTT values from both peripheral sites were recorded from 55 healthy Caucasian children (39 male) with mean age of 8.4+/-2.3 years (range 5-12 years). Peripheries' path length, heart rate, systolic blood pressure, diastolic blood pressure (DBP) and mean arterial pressure (MAP) were measured to investigate their contributions to PTT measurement. The results reveal that PTT is significantly related to all parameters (P<0.05), except for DBP and MAP. Age is observed to be the dominant factor that affects PTT at both peripheries in a child. Regression equations for PTT were derived for measuring from a finger and toe, (6.09 age+189.2) ms and (6.70 age+243.0) ms, respectively.
Aging↗
Pulse transit time as a derived noninvasive mean to monitor arterial distensibility changes in children.
Changes in arterial distensibility have been widely used to identify the presence of cardiovascular abnormalities like hypertension. Pulse wave velocity (PWV) has shown to be related to arterial distensibility. However, the lack of suitable techniques to measure PWV nonintrusively has impeded its clinical usefulness. Pulse transit time (PTT) is a noninvasive technique derived from the principle of PWV. PTT has shown its capabilities in cardiovascular and cardiorespiratory studies in adults. However, no known study has been conducted to understand the suitability and utility of PTT to estimate PWV in children. Two computational methods to derive PWV from PTT values obtained from 23 normotensive Caucasian children (19 males, aged 5-12 years old) from their finger and toe were conducted. Furthermore, the effects of adopting different postures on the PWV derivations were investigated. Statistical analyses were performed in comparison with two previous PWV studies conducted on children. Results revealed that PWV derived from the upper limb correlated significantly (P<0.05) regardless of computing methods or postures adopted. The findings here suggest that PTT measurement can be used as a convenient and noninvasive surrogate measure of derived PWV in prolonged clinical studies, especially on younger or less cooperative children. Furthermore, the simple set-up and noninvasive nature of PTT can promote its usefulness in ambulatory monitoring.
Arteries↗
Motion artefact reduction of the photoplethysmographic signal in pulse transit time measurement.
Motion artefact is a common occurrence that contaminates photoplethysmographic (PPG) measurements. To extract timing information from signals during artefact is challenging. PPG signal is very sensitive to artefacts and can be used in applications like, pulse transit time (PTT) as part of the polysomnographic studies. A correlation cancellation or signal processing approach is implemented with the adaptive cancelling filter concept and a triaxial accelerometry. PPG signals obtained from a Masimo (Reference) pulse oximeter is used as reference to compare with the reconstructed PPG signals. Different hands are used for each PPG source, one stationary while the other involves typical movements during sleep. A second Masimo pulse oximeter is used to register intensity of timing errors on commercial PPG signals. 108 PTT measurements are recorded in three different movements with PTT estimates from unprocessed PPG signals showing 35.51+/-27.42%, Masimo 50.02+/-29.40% and reconstructed 4.32+/-3.59% difference against those from the Reference PPG. The triaxial accelerometry can be used to detect the presence of artefact on PPG signals. This is useful in PTT measurements when signal contaminated with artefacts are required for further analysis, especially after and during arousals in sleep. The suggested filtering model can then reconstruct these corrupted PPG signals.
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Detection method to minimize variability in photoplethysmographic signals for timing-related measurement.
Photoplethysmography (PPG) is a common optical technique used to monitor peripheral pulsation. Studies have shown that minimal variability in phase characteristics is critical to attain accurate estimation of timing-related measurements, such as heart rate and pulse transit time. Observed abrupt changes from baseline of these measurements have shown to identify abnormalities in clinical studies. This study investigates nominal fluctuations when different detection settings were used on the PPG signals. The results indicate that there can be differences in variations observed, and an appropriate detection setting can minimize phase-induced errors in clinical interpretation of timing-related physiologic measurements.
Adult↗