The “Ski Lift”: A Technique to Maximize Needle Visualization with the Long-axis Approach for Ultrasound-guided Vascular Access

Ultrasound (US)-guided vascular access can be performed with the target vascular structure and the needle imaged in the short or long axis. There have been a number of reports investigating or proposing the long-axis approach.^1–4 The most difficult but essential task when using the long-axis approach is keeping the needle in the same plane as the very narrow US beam. If the needle is not in the plane of the US beam, the needle cannot be visualized, and the benefits of the long-axis approach are lost. Needle guides can facilitate in-plane needle localization and visualization; however, the flexibility afforded by freehand needle manipulation is lost.

At our training institution, we have adopted a technique to maximize success when attempting to place the needle in plane with the US beam without the use of a needle guide. This technique requires the use of a linear transducer. After preparing the patient and transducer in the usual fashion (Video Clip S1):

• 1
   Obtain an image of the target vascular structure in long axis. The vessel should be visible along the full length of the transducer. If it is not, the transducer needs to be adjusted. (If this does not enable visualization of the vessel along the full length of the transducer, the visualized portion of the vessel likely is not straight and is not an optimal site for access.)
• 2
   After stabilizing the transducer with the nondominant hand by wedging the third or fourth digits at the distal edge of the transducer, lift the end of the transducer that is closest to the operator by rocking the transducer on its distal edge.
• 3
   Place the tip of the needle that will be used to access the vessel below the undersurface of the transducer, directly in the middle of the footprint, in line with any midline marks or seams present on the transducer with the needle directed parallel to the long axis of the transducer.
• 4
   After inserting the needle with the bevel under the skin, replace the transducer on the skin with the needle tip in the same position but underneath the transducer. Apply mild pressure with the transducer to keep the transducer from sliding and to remove the air space between the needle, transducer, and skin. The needle tip should now be visualized.
• 5
   Without withdrawing the needle, advance the needle into the skin toward the target vascular structure. If you withdraw the needle, the tip exits the skin and you are at risk of puncturing the sleeve and contaminating the needle.
• 6
   Advance the needle until you see the needle tip in the target vascular structure. Note that the long-axis approach allows you to see the depth of the needle tip and thus avoid puncturing the posterior wall.

Another variation on this technique is possible for those who prefer to approach the target vessel in short axis:

• 1
   Obtain an image of the target vascular structure and needle in short axis, advancing the needle tip until it is just superficial to the vessel’s anterior wall.
• 2
   After rotating the transducer from the short-axis view to the long-axis view, lift the end of the transducer that is closest to the operator by rocking the transducer on its distal edge and place the undersurface of the transducer on the needle shaft, directly in the middle of the footprint with the transducer directed parallel to the long axis of the needle shaft. Apply mild pressure with the transducer to keep the transducer from sliding and to remove the air space between the needle, transducer, and skin.
• 3
   The needle shaft is now in plane with the long axis of the US beam and can be followed down to the needle. The needle tip was previously placed over the target vessel in short access, confirming that the correct target vessel is visualized in long axis.
• 4
   Advance the needle, entering the target vascular structure in the long axis.

Using these techniques has made the long-axis approach to vascular access the preferred approach at our institution. When using the long-axis approach, a novice may have difficulty with continuous visualization of the needle or have too short a needle if the skin is punctured at a site too far from the undersurface of the probe. Using this technique ensures visualization of the full needle length within the imaging field.

We have named this technique the “ski lift” in honor of our Emergency Ultrasound Fellowship Director and originator of the technique, Paul Sierzenski, MD, RDMS. By using the “ski lift” technique, needle visualization can be facilitated during attempts at vascular access using the long-axis approach, likely leading to improved success rates.