title: Direct calibration of a totally implantable pulsed Doppler ultrasonic blood flowmeter.
abstract: A totally implantable pulsed Doppler ultrasonic blood flowmeter has recently been developed to provide information on the velocity-flow profile in a vessel as well as its diameter. Volume flow can be indirectly obtained according to the formula: Q = (phi/4)(diam)2-v. In order to determine the accuracy of this estimate, in vivo direct bleedout measurements were performed on the abdominal aorta of six dogs with an overall accuracy in 77 trials of +2.0 +/- 8.7% (mean +/- 1 SD). The best-fit mean linear regression line was found to be: flowmeter output = 1.013-true flow + 5.1 ml/min. The scatter in the flowmeter's accuracy is thought to be due to small variations in the angle of the transducer. The source of the 2% overestimation in the mean accuracy could not be directly attributed to any one condition; the error is sufficiently small that in many cases it can be neglected.
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000502:physiology; D001783:Blood Flow Velocity; D004285:Dogs; D004301:Doppler Effect; D012039:Regional Blood Flow; D012212:Rheology / Q000295:instrumentation / Q000379:methods*; D014465:Ultrasonics / Q000295:instrumentation*