D G Longley

Effects of Central Venous Catheter Placement on Upper Extremity Duplex US Findings

PURPOSE The upper extremity veins of 17 patients who underwent operative central venous catheter placement were studied prospectively with color duplex sonography to determine which duplex changes, if any, could be due to the presence of the catheter alone and to determine if these waveform changes could mimic the dampened waveform seen peripheral to central nonvisualized or nonocclusive thrombosis or proximal stenosis. PATIENTS AND METHODS The subclavian, internal jugular, and brachiocephalic veins were examined with color duplex sonography immediately before and after catheter placement. Images obtained before and after catheterization were reviewed by two radiologists for (a) spectral broadening in both the vein of insertion and the brachiocephalic vein, (b) transmission of atrial pulsations, and (c) respiratory phasicity. RESULTS In all cases, atrial pulsatility and respiratory phasicity were present before and after catheter placement. There was no statistically significant change in the amount of spectral broadening after catheter placement. A mild increase in the peak blood flow velocity of 7 cm/sec (P = .04) in the ipsilateral brachiocephalic vein was demonstrated; however, no significant increase in velocity could be shown in the vein of insertion. CONCLUSION In this clinical setting, the hemodynamic changes within the vein from the catheter placement are minimal. Any damping of the venous waveform seen with sonography performed to rule out upper extremity deep venous thrombosis secondary to indwelling catheter--for example, loss of atrial pulsatility or respiratory phasicity--is presumably due to the presence of venous thrombosis or stenosis.

Portal vein reflectors : duplex sonographic appearance

Duplex sonography has established utility in the noninvasive evaluation of the portal venous system. Recently, the duplex sonographic features of suspected portal venous air have been described. We report on an experimental study in dogs undertaken to establish if the same sonographic features could be reproduced in a laboratory setting and to determine if small fragments of clot emboli could produce similar gray-scale and Doppler findings. Injections of microbubbles of air and clot fragments into the portal venous system were monitored using duplex ultrasound. The gray-scale and Doppler features of flow in the main portal vein were indistinguishable in both microbubble and clot injections. Superimposition of high-amplitude spikes on the normal portal venous waveform was seen in 19 of 24 (79%) microbubble and 13 of 23 (56%) clot fragment injections. We conclude that the appearance of rapidly moving, bright intraluminal echoes coupled with spike-like aberrations of the portal venous waveform can be associated with portal venous air bubbles or small blood clot emboli.