TWENTY-SEVEN: Ultrasonography of Vascular Structures
Ultrasonography of Vascular Structures
Fairfield T. Bain
College of Veterinary Medicine, Washington State University, Pullman, WA, USA
Jugular Vein
Ultrasound imaging of the vascular system most often includes evaluation of the jugular vein (Figures 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 27.10). It is most often performed when thrombophlebitis is suspected, especially in sick horses with intravenous catheters in place. The jugular vein can be imaged from its entry into the thoracic inlet distally on the neck and throughout its course in the neck to its bifurcation into the internal and external jugular vein branches just caudal to the ramus of the mandible. As with most structures, the jugular vein should be imaged in two planes: longitudinal and transverse. The vein is best imaged when distended, which can be accomplished by occlusion of the vein distally near the thoracic inlet with the thumb of the opposite hand from the hand performing the sonography. The ultrasound probe can then be placed over the vein and the course of the vein traced with the probe. The author likes to scan from distal to proximal on the vein and then focus on the particular region of concern (e.g. site of intravenous catheter insertion or palpable thickening of the vein or perivenous tissues).
Figure 27.1 Normal jugular vein. The normal jugular vein and its relation to the underlying carotid artery and esophagus vary along its course in the neck. This image shows the close approximation of the jugular vein (J) and carotid artery (C) in the distal third of the neck. The jugular vein is distended with some increasing echogenicity of the blood from stasis. The walls of this normal vein are thin and crisply echogenic. The normal musculature of the neck can be seen surrounding the vein and artery. This sonogram was obtained from the jugular groove with a linear probe operating at 7.5 MHz at a depth of 5 cm.Figure 27.2 Occluded jugular vein. This image shows the jugular vein (J) occluded distally. Occlusion of the jugular vein will obstruct normal blood flow and swirling echogenicity of the normal blood will be observed during the first several seconds after occlusion. This sonogram was obtained from the jugular groove with a linear probe operating at 7.5 MHz at a depth of 5 cm.Figure 27.3 Myositis near jugular vein. The main indication for imaging the jugular vein is concern for possible thrombosis. Clinical evaluation of the vein would include palpation of the vein along its course, both before and after distal occlusion. Some patients may have significant perivenous swelling or swelling along the jugular groove of the neck, and ultrasonography can be useful to differentiate perivenous inflammation from actual jugular thrombosis or thrombophlebitis. This sonogram shows a central region of echogenicity (arrow) within the cervical muscles consistent with inflammation from intramuscular injection from attempted venous injection in a fractious horse. In this patient, the swelling in the neck was from the focal myositis rather than the jugular vein. This sonogram was obtained from the jugular groove with a linear probe operating at 7.5 MHz at a depth of 4 cm.Figure 27.4 Intravenous catheter. Swelling, firmness, or thickening of the jugular vein associated with the presence of an intravenous catheter is one of the more common indications for ultrasound evaluation of the jugular vein. This patient with an intravenous catheter in place (arrow) has sonographic evidence of early phlebitis with thickening of the jugular vein wall (arrowheads). A venous valve (small arrow) is also seen in this image. This sonogram was obtained from the jugular groove with a linear probe operating at 7.5 MHz at a depth of 5 cm.Figure 27.5
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