Several studies have demonstrated that for patients with intravenous access that is difficult, ultrasound guidance leads to improved success rates with a decreased number of percutaneous punctures, decreased time to intravenous access, and fewer complications than standard techniques for PIV cannulation.^1-4 Ultrasound guidance also has been shown to aid nursing personnel in difficult-access patients.⁴

Clinical Indications

Emergency physicians should consider placement of an ultrasound-guided peripheral intravenous line (UGPIV) when attempts to obtain peripheral intravenous access by standard methods have failed, and in patients with known difficult PIV access without palpable peripheral vessels. (See peripheral intravenous access algorithm on page 22.)

How to Place a Peripheral Intravenous Line Using Ultrasound Guidance

• Patient positioning: The most common area for UGPIV placement will be the antecubital fossa region. The patient’s forearm should be extended to maximize accessibility for the ultrasound probe. In a supine patient, the easiest area to attempt UGPIV placement will most likely be on the volar aspect of the patient’s forearm. (See image 1 and image 2.)
• Probe selection: The high-frequency linear array probe should be used, as it provides higher resolution of the superficial areas of soft tissue. The flat footprint of the linear array probe is less cumbersome and less prone to slip off of the vessel of interest than the curved footprint of the high-frequency endocavitary probe.
• Supplies: A longer intravenous catheter, usually more than 1.5 inches, may be necessary, as the veins used for attempted UGPIV access may be deeper than those veins that are palpable. Sterile ultrasound gel should be used, as infection may be a complication with any type of intravenous access. Also remember that a tourniquet should be placed both for standard PIV and UGPIV attempts to make the vessel easier to cannulate.
• Vessel selection: After cleaning the skin with an alcohol swab, apply an adequate amount of sterile ultrasound gel to the area where the attempt will be made. Consider the use of local anesthetic when attempting cannulation of deeper veins.

Probe Orientation

Two techniques, short axis and long axis, have been described for placing a UGPIV.5 This article will address the short-axis technique, because novice sonographers may have improved cannulation times with this method, compared with the long-axis technique.⁵

• Short-axis, dual-operator technique: Attempts at UGPIVs can be performed with a single operator or with dual operators. Using the dual-operator technique, the ultrasound operator places the probe transversely across the area of interest. (See image 2.) With the ultrasound display marker to the left side of the screen, the probe marker should also be to the operator’s left side. This will make left or right movements on the ultrasound display correspond to left or right movements of the catheter, respectively, and make catheter redirections more intuitive.

  Once a vessel is identified and centered on the screen, the ultrasound operator can compress with the probe to distinguish artery from vein. A vein should collapse more readily than an artery. The artery may also be found to be pulsatile. Color flow can also help, as the artery is pulsatile, whereas there will be continuous flow within the lumen of the vein. Augmentation is another technique that also uses color flow to differentiate artery from vein. The forearm is squeezed distal to the ultrasound probe; and with each squeeze, there should be enhanced color flow within the venous system.

  After the desired vein is identified and centered on the ultrasound display, the depth of the image should be decreased until the vessel takes up as much of the screen as possible while still allowing identification of its anterior and posterior wall, as well as any surrounding neurovascular structures. (See image 3.) The ultrasound operator will then measure the distance from the skin to the vessel of interest. This distance will aid the operator who is placing the PIV, as the distance the catheter has to travel through the soft tissue to the vessel of interest can be calculated or estimated with some simple geometry. (See Pythagorean Theorem chart on page 22.)

  As the vessel of interest should be centered on ultrasound display, the operator placing the PIV will aim the needle at the middle of the probe. While the catheter is being advanced, two sonographic findings may be visualized. In short axis, the actual catheter may not be visualized; however, reverberations caused by the ultrasound waves within the catheter may be seen as a phenomenon called the “ring down” artifact, which serves as a proxy for the catheter and helps determine the direction the catheter should be advanced or redirected. As the catheter approaches the vessel, it may push the vessel wall inwards toward the lumen, causing “tenting” of the vessel. (See image 4.) Once the needle punctures the vessel wall, resolution of “tenting” may be noted, and blood return should be seen.

  After blood return has been identified, the catheter will be advanced as usual, labs can be drawn as needed, and the line should be secured using standard techniques.

• Short-axis, single-operator technique: The single-operator technique is identical to the dual-operator technique, except only one operator is needed. This one operator will perform both the sonography and the catheter advancement. The ultrasound probe will be held with the nondominant hand, while the catheter is placed with the dominant hand. (See image 1.)

Complications

Whether placed by standard techniques or with ultrasound guidance, peripheral intravenous access can be associated with common complications, including local infiltration, cellulitis, and thrombo-phlebitis.6 Arterial puncture is another potential complication, and has been documented to occur approximately 2% of the time when attempting to cannulate the deeper veins of the arm via ultrasound guidance.¹ Hematoma formation is also possible; it may be avoided with the application of firm pressure after an unsuccessful cannulation attempt.

Pitfalls

Ultrasound-guided venous access can be a more time-consuming process, including time to set up the machine and locating a second health care provider if using the dual-operator technique. The process also may be more time consuming until operators become more familiar with the ultrasound-guided technique.

When viewing the vein in short axis, the needle may be seen only as a small hyperechoic ovoid structure, making it difficult to determine which part of the needle is being visualized. Making small adjustments in the transducer angle can bring the needle tip into view. Visualizing the needle tip will reduce the chance of overinsertion and penetrating the deep wall of the vessel. It is also possible to misidentify an artery for a vein, because they often travel together.

Deeper veins (e.g., the deep brachial) may be located 1-2 cm beneath the skin, and standard intravenous catheters may not be long enough. This is also a concern for the superficial veins of very obese patients.

If too short a catheter is used, it may come out of the vein and infiltrate when the patient moves the extremity. Longer catheters should be used to avoid this complication, or a steeper angle can be used to minimize catheter travel through the skin and soft tissues before vessel puncture.

References

1. Keyes L, Frazee B, Snoey E, Simon B, Christy D. Ultrasound-guided brachial and basilic vein cannulation in the emergency department patients with difficult intravenous access. Annals of Emergency Medicine. 1999;34:711-4.
2. Sandhu N, Sidhu D. Mid-arm approach to basilica and cephalic vein cannulation using ultrasound guidance. British Journal of Anaesthesiology. 2004;93:292-4.
3. Stein J, Cole W, Kramer N, Quinn J. Ultrasound-guided peripheral intravenous cannulation in emergency department patients with difficult IV access. Academic Emergency Medicine. 2004;11:581-2.
4. Brannam L, Blaivas M, Lyon M, Flake M. Emergency nurses’ utilization of ultrasound guidance for placement of peripheral intravenous lines in difficult-access patients. Academic Emergency Medicine. 2004;11:1361-3.
5. Blaivas M, Brennam L, Fernandez E. Short-axis versus long-axis approaches for teaching ultrasound-guided vascular access on a new inanimate model. Academic Emergency Medicine. 2003;10:1307-11.
6. Kagel EM, Rayan GM. Intravenous catheter complications in the hand and forearm. Journal of Trauma. 2004;56(1):123-7.