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• We used an in vitro pulsatile flow model to examine the velocity profile distal to a variable nonaxisymmetric stenosis. Using a continuous-wave Doppler velocimeter, the peak systolic frequency was determined distal to the stenosis and in planes parallel and perpendicular to the long axis of the stenosis. In both planes, an exponential regression best describes the relationship between peak systolic frequency and reduction in cross-sectional area. Regressions at each point of insonation diverged as a direct function of reduction in cross-sectional area and as an indirect function of distance from the stenosis. At each point of insonation, regressions representing the relationship in the mutually perpendicular planes diverged in direct proportion to reduction in cross-sectional area. Slopes were greater in parallel planes of insonation. These data demonstrate that two variables, distance and geometry, may influence the results of spectral analytic studies.(Arch Surg 1987;122:358-363)

• Improved accuracy and objectivity in the evaluation of Intestinal viability has been reported by some investigators using Doppler ultrasound, and more recently laser Doppler velocimetry and perfusion fluorometry. To compare the sensitivity and clinical applicability of these techniques, intestinal viability was evaluated by each method in nine 15- to 50-cm loops of small bowel prepared by division of the mesenteric vasculature in five anesthetized dogs. The sensitivity of Doppler ultrasound was 86%, of laser Doppler flow velocity 85%, of laser Doppler index 94%, and of perfusion fluorometry 95%. Though the sensitivity of Doppler ultrasound is significantly less than that of laser Doppler and perfusion fluorometry, this is not unexpected since the latter two techniques are more quantitative than Doppler ultrasound. Clinically, Doppler ultrasound compares favorably with laser Doppler and perfusion fluorometry, and its low cost and simplicity suggest its adjunctive use in the operative setting.(Arch Surg 1988;123:483-486)

• Pulsed Doppler ultrasonic imaging (UI) of the cervical carotid artery provides flow-dependent anatomic detail of the carotid bifurcation, while oculoplethysmography (Kartchner) (OPG-K) and ocular pneumoplethysmography (Gee) (OPG-G) reflect changes in flow and pressure resulting from hemodynamically significant lesions. We examined 66 patients prospectively with UI, OPG-K, and OPG-G to compare the relative accuracy of these techniques with contrast arteriography. Both UI and OPG-G were significantly more accurate than OPG-K. While the accuracies of UI and OPG-G were not significantly different, their combined use resulted in a significant increase in sensitivity compared with that of Doppler imaging alone. In addition, UI correctly identified 22(85%) of 26 occlusions of the internal carotid artery. The use of UI and OPG-G together provided accurate anatomic and hemodynamic information useful in the evaluation of carotid occlusive disease.(Arch Surg 1983;118:1161-1163)

• Subclavian catheterization in patients with cancer is associated with up to a 38% incidence of subclavian vein thrombosis. These thrombi seldom recanalize. The persistent occlusion of the subclavian vein may hinder subsequent catheter placement. To determine the frequency of this occurrence and to determine if preoperative duplex scanning could identify these individuals, we performed preoperative duplex scanning in 22 patients who had previously had an indwelling subclavian catheter for chemotherapy. Subsequent subclavian vein catheterization was attempted without knowledge of the results of the duplex scan. Nineteen scans were normal. Of these, 18 patients underwent successful catheter placement. In one patient, catheterization was unsuccessful and an intraoperative venogram showed a focal obstruction of the proximal portion of the subclavian vein. Three scans showed noncompressibility of the vein, and catheter placement was unsuccessful in these three veins. In patients who have had previous subclavian catheters, persistent obstruction of the vein prevents subsequent catheter placement in 14%. Duplex scanning before subsequent catheter placement generally identifies these individuals.(Arch Surg. 1992;127:229-230)