Real time bedside ultrasonography facilitates rapid

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Real-time bedside ultrasonography facilitates rapid and successful vascu- lar access [ 1 –6]. Indeed, there is increasing institutional and literature support for performing cannulation under direct visualization as the technology spreads throughout the hospital. This is not limited to the emergency depart- ment but is applicable to any critical care unit or patient care area in the hospital. Focused questions for vascular access The questions for vascular access are as follows: 1. Where is the target vein? 2. Is it patent? This chapter will cover techniques to make this assessment seem second nature. Anatomy The most common venous cannulations assisted by ultrasound guidance are internal jugular, femoral vein, and peripheral venous cannulations. Ultrasound-guided subclavian vein cannulation has been described but is Procedural ultrasound 273 Vascular access
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technically more challenging because the clavicle serves to obstruct ultra- sound waves and imaging can be difficult. Anatomic landmarks for internal jugular and femoral vein cannulation are well described. However, a brief review of relevant anatomy as it applies to sonographic evaluation is warranted. Internal jugular anatomy Figure 15.1 shows variations in the anatomy encountered when the ultrasound probe is placed at the apex of the sternocleidomastoid muscle triangle (where the sternal and clavicular heads of the muscle meet near the level of the larynx). This is not predictable using landmarks to guide cannulation, but is readily apparent using ultrasound. The internal jugular in most patients will be strikingly obvious, and with compression it will be easy to identify whether the vessel is patent and thus amenable to cannulation. Variations in the internal jugular–carotid relationship occur with neck position as well; this can be assessed in real time under ultrasound. Femoral triangle anatomy Just distal to the inguinal ligament is the femoral triangle. From lateral to medial, this space contains the femoral nerve, artery, and vein, then empty space and lymphatics. This arrangement is sometimes recalled using the mnemonic “NAVEL.” Typically, one would palpate for a pulse in this area and then direct a needle medially to find venous blood. Figure 15.2 shows the image obtained when the ultrasound probe is placed just distal to the inguinal ligament over the common femoral vein. Figure 15.1 Variations in the relationship between the internal jugular vein (V) and carotid artery (*) visualized using ultrasound. Note that the relative position of the vessels differs between patients and with neck position. 274 Procedural ultrasound Vascular access
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If the same ultrasound probe were then guided more distally along the vein, an image like that in Figure 15.3 would be obtained. Here, the superfi- cial femoral vein is demonstrated. At this level, the common femoral artery has bifurcated to superficial and deep femoral arteries. The common femoral vein has also bifurcated into superficial and deep, and usually the superficial is the only vessel seen at this level. It is also quite common at this level to find
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