Authors: Bradley A. Wallace, MD; Todd Taylor, MD, Emory University School of Medicine, Department of Emergency Medicine
Editor: Matthew Tews, DO, MS; Medical College of Wisconsin
Both vascular access and bedside ultrasound are vitally important aspects of Emergency Medicine and can often be used in conjunction with one another. Whenever there is difficulty in obtaining peripheral intravenous access by traditional means (i.e., sight or palpation), bedside ultrasound can be a useful adjunct to the procedure and can often succeed when other methods fail. Additionally, using ultrasound at the bedside when obtaining central venous access has become commonplace within Emergency Medicine and throughout the medical field. As vascular access as a whole has been described elsewhere on this site (https://cdemcurriculum.com/vascular-access/), this chapter will focus almost exclusively on using bedside ultrasound as an adjunct when obtaining vascular access.
Ultrasound-Guided Peripheral Intravenous Access
Patients on which to consider ultrasound-guided IV access
- Self-proclaimed “hard sticks”
- Patients with end-stage renal disease
- Patients with a history of IV drug abuse
- Obese patients
- Patients with significant edema
- Patients with sickle cell anemia or other blood dyscrasias
- Severely dehydrated patients with poor landmarks
Selecting a Vessel
Location: Sites that are specifically good for ultrasound guided access include:
- Antecubital fossa
- Basilic vein of the medial upper arm
- External jugular vein
Identifying the Vessel
After placing a tourniquet on the patient’s upper arm, use the linear ultrasound probe to evaluate for an appropriate vein making sure to differentiate between vein and artery. The characteristic differentiation between veins and arteries on ultrasound is collapsibility. When applying direct downward pressure with the ultrasound probe, veins should collapse easily while arteries will keep their cross-sectional circular shape.
Clip 1. When gentle downward pressure is applied with the ultrasound probe, veins will easily collapse while arteries will remain patent and often exhibit pulsatility.
Additionally, arteries will have thicker, hyperechoic walls as well as pulsatility when compared to veins.
Image 1. An artery (A) will have thicker, hyperechoic walls (arrows) when compared to veins (V).
If you have identified a vessel that you believe to be a vein but are still uncertain, it can be useful to turn on the ultrasound machine’s color flow. When color flow is turned on, a vein will have a low flow continuous color (or may sometimes be anechoic) while an artery will exhibit a higher velocity pulsatile flow.
Clip 2. The vessel at the center of the clip exhibits pulsatile color flow, indicating that it is an artery. The other vessels in the clip remain anechoic when color flow is turned on, indicating that they are veins.
Once you have identified a vein, it is important to evaluate its depth and size.
According to a 2010 study by Witting et al., ultrasound-guided IV access is more likely to be successful when the vein is:
- Less than 1.5 cm below the skin
- Greater than 0.4 cm in diameter3
When attempting to locate an appropriately sized vein, it can be useful to adjust the depth on the ultrasound machine to 2.0 cm or less. The advantages of this are twofold: it decreases attempts at IV placement on veins that are too deep as well as making superficial veins appear larger on the screen and therefore easier to successfully puncture.
In addition to evaluating the vessel’s depth and size it is a good idea to scan along the vessel lengthwise to determine its degree of tortuosity. If the vein is exceedingly tortuous it can be difficult to thread the IV catheter. Be sure to scan proximally and distally to your proposed puncture site to evaluate the trajectory of the vein.
Once you have identified an appropriate vessel as above, there are two views that can be used on the ultrasound machine for peripheral IV placement: short axis (cross-sectional) or long axis (longitudinal). Each method has its individual advantages and disadvantages, which will be discussed shortly. The supplies needed are the same for either method.
- High frequency linear ultrasound probe
- Sterile gel/lubricant
- Adhesive dressing (e.g., Tegaderm®)
- IV catheter (ideally longer than 1.16 inches)
- Antiseptic solution
Image 2. Supplies needed for an ultrasound guided IV insertion.
Short Axis (Cross-Sectional) Approach
- Apply tourniquet to upper arm
- Cleanse the skin with antiseptic solution
- Place adhesive dressing over ultrasound probe
- Apply sterile gel/lubricant to ultrasound probe over adhesive dressing
- Place ultrasound probe on skin perpendicular to the previously identified vein making sure to keep the cross-section of the vein at the center of the screen
- Ensure that the ultrasound probe indicator is pointing to the patient’s right—i.e., the ultrasound operator’s left—so that the left side of the ultrasound screen corresponds to the ultrasound indicator
Image 3. Orientation of ultrasound probe for short-axis approach. Note the probe indicator pointing to the patient’s right (the operator’s left).
6. Pierce the skin at a 45O angle with the catheter at the center of the probe
7. Identify the hyperechoic needle tip on the screen
- It may be useful to push the catheter up-and-down or fan the probe back-and-forth to help identify the needle tip on the screen
Clip 3. The hyperechoic needle tip is visualized proximal/superficial to the blood vessel. Note that when the needle is gently moved back-and-forth it can be more easily identified.
8. Pierce the vein looking for the “target sign” or “bull’s eye sign” (the hyperechoic needle tip in the center of the anechoic vessel)— you should see a corresponding flash of blood in the catheter once the needle tip has pierced the vessel
Image 4. Hyperechoic needle tip localized in blood vessel in short axis. This is called the “target sign” or “bull’s eye sign.”
9. Once the target sign is visualized, thread the catheter in the usual manner and secure the catheter to the skin with an adhesive dressing
10. The IV should now flush easily and painlessly if placed correctly
Long Axis (Longitudinal) Approach
- Use the same technique as described in steps 1-4 of the short axis approach above
- Place the ultrasound probe on the skin parallel to the axis of the previously identified vein with the probe indicator facing towards the patient’s head
Image 5. Orientation of ultrasound probe for long-axis approach. Note that the probe indicator is pointing towards the patient’s head.
3. Pierce the skin at a 45O angle just distal to the ultrasound probe with the needle at the center of the probe
4. Identify the hyperechoic needle tip on the right side of the screen
5. Advance the needle tip until you visualize it piercing the wall of the vessel on the screen— you will see a corresponding flash of blood in the catheter once the needle has pierced the vessel
Image 6. Hyperechoic needle tip localized in blood vessel in long axis.
6. Thread the catheter in the usual fashion and secure the catheter to the skin with adhesive
7. The IV should now flush easily and painlessly if placed correctly
Comparison of Methods
Both the short axis and long axis approaches have advantages and disadvantages. The main advantage of the short axis method is better lateral resolution (i.e., after piercing the skin, one is able to tell if the needle tip is lateral to the vein). The main drawback to the short axis technique is the requirement of moving the ultrasound probe dynamically to keep the needle tip on the screen.
Image 7. In a short axis view, the location of the ultrasound probe can result in the needle appearing to be in multiple different positions. Though the needle in the image above has gone entirely through the vessel, the needle appears to be proximal to the vessel using position 1, within the vessel using position 2, or through the back wall of the vessel using position 3.
Compared to the short axis method, the long axis technique allows the operator to visualize the entirety of the needle and see in real time as it enters the vein in profile, as illustrated in Image 6 above.
While the short axis method has good lateral resolution, the long axis method can be more technically challenging due to its poor lateral resolution (i.e., the needle can appear to be in the same plane as the vessel despite being just lateral to the vessel). Furthermore, with the long axis approach it can be easy to lose sight of the vein and accidentally re-focus the probe onto an adjacent artery with very small moves of the ultrasound probe.
If one is learning the technique for ultrasound-guided IV access for the first time, the short axis approach has been shown to be easier to learn than the long-axis approach for novice operators.4 Furthermore, a 2011 study demonstrated that the short axis method both resulted in a higher success rate and took less time than the long axis approach.5
The Videos in Clinical Medicine series by The New England Journal of Medicine provides a review of ultrasound-guided IV placement: http://www.nejm.org/doi/full/10.1056/NEJMvcm1005951
Ultrasound-Guided Central Venous Catheter Placement
While many patients in the emergency department can be successfully resuscitated with only peripheral access, some patients will require central venous access. Though central venous catheters have been associated with certain complications (e.g., pneumothorax, arterial puncture, bleeding, and infection), there have been multiple prospective, randomized controlled trials and several meta-analyses that have shown that the use of real-time ultrasound guidance during catheter placement has reduced the number of complications as well as reducing the number of cannulation attempts when compared to using landmarks alone.6-9
Note: Central venous access is discussed in depth elsewhere on this site; as such, this chapter will focus on using ultrasound to locate and cannulate central veins. For further information on central venous catheter placement, including indications, contraindications, and the individual steps required for the entirety of the procedure, please refer to the Vascular Access chapter (https://cdemcurriculum.com/vascular-access/).
The three traditional locations for central venous line placement are the internal jugular vein, the femoral vein, and the subclavian vein. The technique for ultrasound-guided central line placement into the internal jugular vein and femoral vein is nearly identical; as such, the discussion here will focus mainly on placement into the internal jugular vein as it tends to be the favored location for central line placement. While the use of ultrasound for subclavian central line placement is becoming more popular, this is a more advanced technique and will not be discussed in this chapter.
Image 8. Anatomy of major neck vasculature. Both the internal jugular vein and common carotid artery are located in an anatomic triangle formed by the two heads of the sternocleidomastoid muscle and the clavicle. (Image courtesy of Sierra Beck, MD.)
As discussed in the ultrasound-guided peripheral IV access section above, the ultrasound machine can be used to visualize blood vessels in both short axis and long axis. The materials needed are the same for both, though the technique varies slightly. The short axis approach will be discussed first.
- Central line kit (including drape)
- Sterile gown/gloves/cap
- Probe cover kit (with sterile gel)
- Ultrasound machine with linear probe
Image 9. Supplies needed for ultrasound guided central line insertion.
Short Axis Approach—Internal Jugular Vein
- Standing at the head of the bed, place the ultrasound machine to patient’s right or left depending on which internal jugular vein you plan to cannulate. Some operators prefer the machine on the ipsilateral side to the internal jugular vein that is being accessed while others prefer the ultrasound machine on the contralateral side— this is largely a matter of personal preference
- Place patient in Trendelenberg position
- Have patient turn head contralaterally to the desired puncture site
- Apply gel to linear ultrasound probe
- Place probe on patient’s neck just above the clavicle, making sure to have the indicator pointing to the patient’s (and the operator’s) left side so that the left side of the probe corresponds to the left side of the ultrasound machine
- Walk probe proximally and distally in an attempt to find a site where the internal jugular vein is largest and relatively remote from the carotid artery. Keep in mind that movements of the patient’s head may alter vascular anatomy greatly
- Remember that arteries are typically thick-walled, pulsatile, and non-collapsible when applying pressure with the ultrasound probe while veins are thin-walled, non-pulsatile, and collapse easily when applying pressure with the probe (see Clip 1 and Clip 2 above for how to better differentiate arteries and veins).After locating an appropriate puncture site, remove gel from patient’s neck and apply appropriate sterilizing solution (e.g., Chlorhexadine, betadine, etc.)
- Open central line kit, don sterile gown, hat, mask and gloves, and open ultrasound probe cover
- While you hold the ultrasound probe cover, have an assistant apply ultrasound gel to ultrasound probe and drop probe into cover making sure to keep probe cover sterile
Image 10. Sterile gloved hand holding sterile probe cover open while an assistant places the ultrasound probe into the probe cover.
10. Place sterile ultrasound gel on outside of probe cover
11. Anesthetize skin overlying the puncture site
12. Place ultrasound on patient’s neck perpendicular to orientation of vasculature
13. Pierce skin at 45o angle at the center of the ultrasound probe (keeping the vessel in the middle of the screen) making sure to continuously aspirate immediately after piercing skin
Image 11. Ultrasound operator in foreground with sterile gloves piercing skin at 45o angle to the skin at center of the ultrasound probe. Note that the operator is continuously aspirating given that the needle tip has pierced the patient’s skin. In the background of the image, note that the ultrasound image is centered on the hypoechoic internal jugular vein in short axis as the operator is advancing the needle towards the vessel.
14. Identify the hyperechoic needle tip in relation to the internal jugular vein. It may be useful to fan the probe back-and-forth or gently bounce the needle up-and-down in the soft tissue when attempting to locate the needle tip. Be sure to keep the needle tip on the screen by advancing the ultrasound probe along the skin as you advance the needle—this will ensure the you do not inadvertently cannulate the wrong vessel (viz., the artery)
15. Once you note the bull’s eye or target sign (see Image 4 above) you should have aspiration of blood into the syringe
16. When aspiration of blood is confirmed, place the ultrasound probe on the sterile drape, remove the syringe from the needle, and advance the guidewire
17. Remove the needle from the skin
18. Grab the ultrasound probe and place it on the patient’s neck to obtain a longitudinal view of the internal jugular vein. If the wire is appropriately positioned, you will be able to visualize a hyperechoic structure (the wire) in long axis on the ultrasound machine
19. Complete placement of the central venous catheter using the Seldinger technique and secure the catheter to the skin
20. Obtain chest X-ray to confirm appropriate positioning of central venous catheter
Long Axis Approach—Internal Jugular Vein
- Carry out the same steps as above (steps 1-13)
- Place ultrasound probe on skin parallel to venous structures when surveying vascular anatomy. Ensure that the probe indicator is oriented towards the patient’s head, corresponding to the left side of the ultrasound screen
- When piercing the skin at 45o angle, be sure that the entire vessel is visualized on the screen
- With the probe indicator oriented towards the patient’s head, you should see the needle tip enter the left side of the screen after piercing the skin
- Once you visualize the needle tip enter the vessel (see Image 6 above), you should note aspiration of blood into the syringe
- Place probe onto sterile drape, remove syringe, and thread guidewire
- Place ultrasound probe back onto skin in long axis, attempting to visualize the guidewire within the vessel in long axis— it is critical to verify the location of the guidewire prior to dilation (see Image 12 above)
- Complete placement of the central venous catheter using the Seldinger technique and secure the catheter to the skin
- Obtain chest X-ray to confirm appropriate positioning of central venous catheter and ensure that there is no iatrogenic pneumothorax
Note: The femoral vein can be accessed using the same steps as above. When surveying femoral anatomy, keep in mind that the femoral vein is located medially to the femoral artery.
While both peripheral venous access and central venous access were traditionally performed using palpation or anatomic landmarks, the use of ultrasound for both procedures has become more prevalent in Emergency Medicine. Using ultrasound guidance while performing peripheral IV placement has been shown to be a robust alternative to traditional approaches on patients whom venipuncture has proven difficult while also helping to improve patient satisfaction. Similarly, ultrasound guided central line placement has been shown to decrease both number of attempts at cannulation and complications of the procedure. As such, the ultrasound machine should be a consideration whenever contemplating venous access strategies in the emergency department.
- Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D. Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access. Ann Emerg Med. 1999 Dec. 34(6):711-4.
- Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med. 2005 Nov. 46(5):456-61.
- Witting MD, Schenkel SM, Lawner BJ, Euerle BD. Effects of vein width and depth on ultrasound-guided peripheral intravenous success rates. J Emerg Med. 2010 Jul. 39(1):70-5.
- Blaivas M, Brannam L, Fernandez E. Short-axis versus long-axis approaches for teaching ultrasound-guided vascular access on a new inanimate model. Acad Emerg Med. 2003 Dec. 10(12):1307-11.
- Mahler SA, Wang H, Lester C, Skinner J, Arnold TC, Conrad SA. Short- vs long-axis approach to ultrasound-guided peripheral intravenous access: a prospective randomized study. Am J Emerg Med. 2011 Nov. 29(9):1194-7.
- Leung J, Duffy M, Finckh A. Real-time ultrasonographically guided internal jugular vein catheterization in the emergency department increases success rates and reduces complications:a randomized, prospective study. Ann Emerg Med. 2006;48:540-547.
- Karakitsos D, Labropoulos N, De Groot E, et al. Real-time ultrasound guided catheterization of the internal jugular vein: A prospective comparison to the landmark technique in critical care patients. Crit Care. 2006;10:R162.
- Randolph AG, Cook DJ, Gonzales CA, Pribble CG. Ultrasound guidance for placement of central venous catheters: A meta-analysis of the literature. Crit Care Med. 1996;24:2053-2058.
- Hind D, Calvert N, McWilliams R, Davidson A, Paisley S, Beverley C, Thomas S. Ultrasonic locating devices for central venous cannulation: Meta-analysis. BMJ. 2003;327:361.