Ultrasound-Guided Intravenous Access

Anatomy and Physiology

Ultrasound guidance can facilitate the cannulation of superficial peripheral vessels that are typically used during palpation-based PIV placement. They also allow the visualization and guidance to cannulate deeper vessels. A good habit is to try to keep any attempts at the most peripheral vein available to save proximal veins for subsequent attempts. Placing PIVs in larger and superficial vessels has been associated with longer vessel functionality.[5] Vessels greater than 4 mm are associated with a higher chance of cannulation.[6]

When visualizing the arm with ultrasound, blood vessels will show up as black, or anechoic, circles when viewed in cross-section. Muscle tissue is characteristically grey with a feather appearance of lighter grey striations cutting through them. Bone shows up as a bright white line on ultrasound. Ultrasound is unable to penetrate bone, so no grey echoes typically appear deep to the bone.

Although there are multiple variations in anatomy, the forearm cephalic, antebrachial, median cubital, and basilic veins are all common targets for USGIVs. With the patient’s palm facing the ceiling, the cephalic vein will run along the lateral side of their forearm. The median antebrachial will run in the middle of the forearm, while the basilic vein will run along the medial side of the forearm.  

If no forearm veins are adequate targets, the probe can be advanced to the patient’s upper arm. In the upper arm, the cephalic vein will course along the anterior portion of the bicep. Its superficial course makes it an ideal target for ultrasound guidance. The next vessel to visualize is the basilic vein which runs along the medial edge of the upper arm. The basilic vein is an ideal target for USGIVs because it is typically deep enough that it cannot be cannulated via palpation and there is not an artery associated with it. As the basilic vein is traced proximally, it often becomes a larger caliber vessel. Ideally, try to cannulate the vessel as far distal, or close to the elbow, as is practical.

If the basilic vein is not available, the deep brachial veins are a possibility for USGIVs. The deep brachial veins are often paired vessels on either side of the brachial artery. They are also adjacent to major nerves of the arm. For these reasons, it is essential to have a good understanding of the anatomy and have perfected the technique before attempting to cannulate these vessels. Consequently, the deep brachial vein should be lower on the priority list of vessels to cannulate.  The deep brachial and basilic vessels will converge to form the axillary vessel as they are traced proximally towards the axilla.

Indications

Most commonly, USGIVs are used when traditional palpation-based techniques fail. Some facilities have developed policies requiring a certain number of attempts without ultrasound before attempting a USGIV. As long as efforts are made to utilize distal superficial vessels, ultrasound may be used for initial attempts at venous cannulation. Encouraging learners to practice the ultrasound technique on superficial forearm vessels may help develop hand-ultrasound coordination. Once learned, these skills can be extrapolated to help cannulate deeper vessels.

Contraindications

The same contraindications exist for USGIVs as for any PIV. Infection or phlebitis overlying the vein, arteriovenous fistula in the extremity, previous surgeries to the extremity affecting the vasculature, and trauma or burns proximal to the injury would make the vein a less-than-ideal choice.

Equipment

An ultrasound machine with a high-frequency linear probe is necessary to complete a USGIV.  It is essential to use the high-frequency probe to visualize the superficial vessels cannulated during the procedure adequately.

Vessels cannulated with ultrasound guidance will generally be deeper than those cannulated through landmark-based technique. Therefore, it is necessary to use a longer catheter.  Multiple different catheter gauges and lengths are appropriate for ultrasound guidance, but it is critical to use a catheter long enough. When cannulating the basilic and brachial vessels in an adult patient, it is advisable to use a catheter that is at least 2.5 inches long.

Additional equipment needed to start a USGIV includes a sterile probe cover, sterile ultrasound gel, and a towel to wipe the gel. Sterile ultrasound probe covers are available, however clear adhesive film used to secure IVs can also function as a probe cover. Other equipment needed for a basic IV will also be required for USGIVs. These may include a tourniquet, extension tubing, IV cap, and a device to secure the IV.

Personnel

Training requirements and prerequisites may vary by state and facility. Typically, a single nurse trained in USGIVs is the only personnel needed to perform this procedure.

Preparation

Make sure to gather all of the appropriate materials before the procedure. Being comfortable is also important. Try to secure a single line of sight for the operator to look down at the patient’s arm and then directly up to the ultrasound screen. Before penetrating the patient with the IV needle, it is critical to visualize the expected course of the veins. Find one that is adequate for cannulation. Studies indicate that superficial and larger vessels correlate to a higher success rate.  

After identifying an appropriate vein, put a cover on the probe. For peripheral IVs, transparent adhesive films can function as a probe cover. When placing the covers, put them directly on the transmitting surface of the probe. Ensure that there are no air bubbles between the probe and cover.

Technique or Treatment

Transverse, or out-of-plane, and longitudinal, or in-plane, techniques have been described to start USGIVs. The longitudinal method allows the user to visualize the needle as it enters the vessel. However, this procedure is technically more difficult for those without significant ultrasound experience. Therefore, the transverse technique is recommended for beginners.

In the transverse technique, the provider locates the intended vessel with the probe marker towards the operator’s left side. The vein should appear as a black, or anechoic, circle on the screen. Try to get the vein in the middle of the screen so that fewer redirections of the needle will be necessary for cannulation. Many machines have a "guide” or “centerline” function that helps identify the middle of the screen. Likewise, the middle of the ultrasound probe is marked ensuring the needle puncture through the skin is over the intended vein.  

The practitioner should hold the ultrasound probe in their nondominant hand and the IV needle in their dominant hand. Typically, the needle stick will be at a steeper angle than that of a landmark-based PIV. This difference is because most USGIVs utilize deeper vessels than PIVs. While a 45-degree angle is acceptable for most USGIVs, the angle may need to be adjusted based on the depth of the vessel. With the desired vessel in the middle of the screen, penetrate the skin adjacent to the middle of the ultrasound probe.  

When the needle tip crosses the path of the ultrasound beam, it will look like a bright white dot on the screen. It is essential to move the ultrasound probe along the vessel path as the needle advances. It is helpful to keep the probe immediately in front of the needle. As soon as the bright dot of the needle tip appears on the screen, the probe is moved slightly proximal. This adjustment prevents confusing the distal needle tip with more proximal portions of the needle, which can look similar on the machine. As the needle advances, adjust its path left and right to keep it in line with the intended target vessel. Continue to advance the needle until it appears as a bullseye within the middle of the vessel. There will often be a small amount of blood in the chamber of the IV when the needle initially penetrates the vessel wall. However, it needs to insert a little further before attempting to thread the catheter. As the needle advances, adjust its angle to keep the needle tip within the middle of the vessel. This process ensures some of the catheter is in the vessel and not just the beveled needle tip.  

The longitudinal technique is more difficult than the transverse. Therefore, it is not advisable for users without significant experience using ultrasound. For novice sonographers, the probe may slide from a vein to an adjacent artery or fascial planes may be mistaken for the vessel.

To perform this technique, the anechoic lumen of the intended vessel is located in a transverse plane. The probe is then rotated 90 degrees such that the plane of the ultrasound probe follows that of the vessel. In this technique, the needle penetrates directly adjacent to the narrow side of the probe. The needle is then adjusted to match the same direction as the ultrasound probe. The probe is held still over the vein, while adjustments are made to the needle until it is seen coming from one side of the ultrasound screen into the vessel. Advancement and securing of the catheter are the same as described in the transverse technique.

Complications

Complications from USGIVs are similar to those for any PIV. However, the USGIVs are often placed in deeper vessels. This deeper placement can make the findings of a failed IV or complication subtle and difficult to appreciate. An arterial puncture, infiltration, contact with adjacent nerves, and thrombosis are all possible complications. When learning the procedure, it is helpful to practice on superficial veins without a nearby artery to try and minimize complications.

Clinical Significance

USGIVs have the potential to allow faster cannulation of veins in patients with challenging vascular access. They may also decrease the need for invasive central lines. Learning the technique may be frustrating initially, but with practice, it will become a valuable tool utilized in daily practice.

Enhancing Healthcare Team Outcomes

Ultrasound is an invaluable technology for the radiologist and other invasive physicians. The technique can be used to localized vessels, fluids and air in many parts of the body. At least 150 to 200 million peripheral intravenous (PIV) catheters are placed each year in the United States, while up to 80% of patients receive a PIV during their hospital stay.[1][2] Unfortunately, many factors may complicate the process of obtaining PIV access, including obesity, IV drug abuse, hypovolemia, and a variety of chronic medical problems. Staff is becoming trained in ultrasound to help facilitate a PIV in patients with difficult or failed PIV access. The success of ultrasound-guided peripheral intravenous catheters (USGIVs) has been associated with significant reductions in central venous catheter placement in the emergency department[3] as well as enhanced patient satisfaction.[4]