Objective: The purpose of this study was to compare pulsed wave (PW) Doppler velocity measurements obtained from duplex ultrasound of the carotid arteries with subjects in the seated and supine positions in an attempt to determine if this would influence the velocity criteria used in the classification of the severity of internal carotid artery disease. Methods: Carotid duplex ultrasound examinations were performed on 42 volunteers with measurement of peak systolic velocities (PSV) and end diastolic velocities (EDV) using a Doppler angle of 60u. The measurements were obtained from both the right and left extracranial carotid vessels in both the seated and supine positions. t-tests were used to compare the mean velocities obtained in the seated versus supine positions. Results: PSV and EDV measurements obtained in the seated position were lower than those in the supine position. Statistical analysis comparing the means in the seated versus the supine position showed statistical significance at the p50.05 level for all measurements except the PSV of the internal carotid artery (ICA). Conclusions: Duplex ultrasound PW Doppler derived velocity criteria are used to classify the severity of stenosis, which in turn impacts on patient treatment options. The carotid duplex scan can be adequately performed on patients in the seated position but velocities measured will be reduced and modification to the existing velocity criteria may be needed.
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