Emergency physicians are procedural experts in central venous access. The subclavian vein is the best site for such access, because it has been shown to have the lowest rate of iatrogenic infections and deep venous clots.
Bedside ultrasonography has really revolutionized how we obtain vascular access over the past 10 years. Identifying the subclavian vein using ultrasonography, however, is still technically challenging. The vein is located just posterior to the clavicle, which often gets in the way of the linear transducer.
Trick of the trade:
Ultrasound-guided supraclavicular central line
Did you know that there are two approaches to access the subclavian vein -- infraclavicular and supraclavicular? The traditional approach is the infraclavicular approach, however, more studies are showing that the supraclavicular approach is just as safe and as procedurally easy as the infraclavicular approach.
The subclavian vein courses posterior to the clavicle but reaches its most superior point just lateral to the clavicular belly of the sternocleidomastoid muscle. In the above photo, the needles are pointing to insertion site for both the supra- and infraclavicular approaches.
Use the ultrasound to guide your supraclavicular line placement.
Instead of using a flat linear transducer, use the endocavitary transducer, which emits a similar high frequency signal. Its footprint is much smaller and more curved, allowing you to better visualize the subclavian vein. Position the transducer so that you get a long axis view of the vein. Often you can also see IJ vein in view, merging with the subclavian vein.
I unfortunately don't have an ultrasound image of this. If you have one, could you send and I'll post it? I'd be happy to credit you.
There is a good, copyrighted image in the article by Mallin et al. This survey study showed that 15 residents felt more comfortable with identifying the subclavian vein using this technique after a brief training period.
Reference
Mallin M, Louis H, Madsen T. A novel technique for ultrasound-guided supraclavicular subclavian cannulation. Amer J Emerg Med, 2000, 28 (8), 966-9.
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