Abstract
We examined the cause of errors in pulsed Doppler ultrasound blood flow volume measurements, and measurement of vessel diameter.[Experiment 1] We measured the blood flow volume by pulsed Doppler ultrasound at a Doppler angle of 0º after angle correction and at 10º using a polyurethane-tubing circuit with tube diameters of 5 mm and 6 mm. The range of blood flow volume was 250~2,000 mL/min. [Result 1] Blood flow volume measurement at a Doppler angle of 0º showed an error of 8.9±12.9% that was independent of the tube diameter. However, at a Doppler angle of 10º , the error in the measured flow volume was 16.3±9.8%, and the blood flow in the 6 mm tube showed 15% greater underestimation than that in the 5 mm tube. [Experiment 2] We compared angiography and B-Mode ultrasound for the measurement of radial artery diameters in 30 patients on hemodialysis. We measured 2 diameters:one was the distance between the two opposing intimal surfaces on near side and far side of the vascular wall(surface-to-surface method), and the other was the distance between the intima edge of the near side vascular wall and intima surface of far side one(edge-to-surface method) . [Result 2] The measurement of diameters using B-Mode ultrasound showed errors of 0±0.2 mm and -0.3±0.2 mm in the surface-to-surface method and edge-to-surface method, respectively. [Conclusion] Errors in blood flow volume measurements obtained using pulsed Doppler ultrasound can be reduced by controlling the corrected Doppler angle to 0º and by measuring the vessel diameter using the surface-to-surface method.
