SUMMARY With the use of a new ultrasonic volume flow meter (VFM), over 8000 measurements of common carotid blood flow were made in 120 normal control subjects and 550 patients with various neurological disease. The accuracy of the flow meter in measuring blood flow on an experimental model ranged from 93 to 97%.In normal subjects, common carotid blood flow varies with age. It increased from newborn to age 20 and gradually decreased thereafter. In normal healthy subjects, the flow varies within ± 6.7% (2SD) at one sitting (intrasession) and ± 21.2% (2SD) from week to week (intersession study). Carotid blood flow varies linearly with P a C0 2 and increased markedly in response to endotracheal intubation. In healthy adults, the flow ratio between the two common carotid arteries is 1.07 ± 0.052. This ratio increases in patients with transient ischemic attacks to 1.28 ± 0.23 (p < 0.05) and in patients with intracranial space occupying lesions to 1.46 ± 0.39, (p < 0.01).In 26 consecutive cases of carotid endarterectomies, the preoperative common carotid blood volume flow was 5.1 ± 1.0 cc/sec. AH cases preoperatively had at least 30% stenosis and ranged from 30 to 100% stenosis. The carotid blood volume was significantly increased post-operatively (p < 0.001). The overall accuracy in detecting carotid and cerebral arterial disease is 89% with sensitivity of 96% and the specificity of 71%.Our clinical experience indicates that this device is not only a valuable noninvasive diagnostic tool for evaluation of carotid disease but also appears to be useful in assessing cerebral blood flow.Stroke, Vol 14, No 2, 1983 ULTRASONIC DOPPLER FLOW METERS have been used extensively in recent years in the evaluation of the hemodynamics of the vascular system. However, the currently routinely used devices have not been able to determine the actual amount of blood flow in cc/sec. In our previous paper, we have reported the accuracy of a new Doppler device, the transcutaneous Doppler Volume Flow Meter-VFM, in measuring the actual flow in cc/sec on an experimental model.' In this paper we summarize our experiences in the use of this device in assessing common carotid blood flow in various clinical states.
PrincipleThe device was developed by Furuhata and his coworkers with collaboration of Hayashi-Denki Co., Kawasaki, Japan in 1978.2 An A-mode transducer is used to measure the diameter of the pulsating artery in real time, and "an angle-independent" Doppler ultrasound technique to measure the velocity of blood flow at a cross-section of the common carotid artery.2 -3 The diameter is measured and tracked by a phase-locked echo-tracking method. 4 The operator selects a point in the A-mode echo of the artery wall and moves a tracking gate to coincide with it. The tracking gate will then lock onto and track the motion of a single cycle from the echo of the wall of the artery. The diameter of the pulsating artery is calculated every 2 msec from the distance between two tracking gates. The system is In order to measure the true diameter of th...
