Dr Luke Phillips Emergency Physician
Peer review: Dr Rob Buttner
A 65-year-old female undergoing chemotherapy for breast cancer presents to your ED with septic shock and likely febrile neutropenia. She does not have any central access device and tells you that the nurses and doctors always struggle finding her veins. You put the tourniquet on and cannot palpate a vein or visualise one on the back of her hands. Do you try to find a vein blindly, potentially wasting precious minutes and increasing time to antibiotics and fluids/inotropes with multiple attempts, or do you reach for the ultrasound probe? Ultrasound-guided vascular access has been shown to decrease the number of needle puncture attempts, complications, and decrease the requirement for central lines (Blanco, 2019). In the right hands, it can also save time. It is important for clinicians to have adequate cognitive knowledge, workflow understanding, and visuospatial skills to safely execute this procedure. The operator should also be familiar with the anatomical variations, equipment operations, and potential complications and their prevention.
The following video outlines the key steps for ultrasound-guided IV Cannulation (USGIVC):
LIKE WHAT YOU SEE AND WANT TO LEARN MORE POINT-OF-CARE ULTRASOUND SKILLS?
Then join us for our upcoming Ultrasound Courses at Alfred Health. Learn from our expert emergency physicians how to perform lifesaving ultrasound at the bedside. Our core course covers procedural guidance, AAA scanning and eFAST; and our advanced course covers basic Echo and Lung Ultrasound. More information can be found here.
LET’S LOOK AT SOME PRO-TIPS TO HELP ENSURE CORRECT PATIENT SELECTION AND SUCCESS IN YOUR IV CANNULATION.
WHICH PATIENTS REQUIRE ULTRASOUND-GUIDED IV CANNULATION?
The Adult Difficult IV Access (A-DIVA) Scale is a clinical tool that can be used to assess patients at risk of difficult IV access (DIVA) and potentially escalate to early USGIVC. The study identified key variables that were associated with DIVA. These included previous history of difficulty with IV access, failed first attempt, difficulty visualising or palpating a vein or if the patient has spindly, small veins. The more of these variables a patient has, the less likely you are to be successful without ultrasound.
THE A-DIVA SCALE
| Score |
Is there a known history of difficult IV access? | 1 |
Do you expect a failed first attempt or difficult IV access? | 1 |
Is there difficulty visualising a vein? | 1 |
Is there difficulty palpating a vein? | 1 |
Is the largest dilated vein diameter <3mm? | 1 |
The scale consists of 5 questions, with one point for each yes:
Low risk (score 0-1) = 4% failed attempt,
Moderate (2-3) = 37% chance of failed first attempt,
High risk (4-5) = 94% chance of failed first attempt.
A score of three was associated with 55% first-attempt success.
WHAT SIZE AND LENGTH OF CANNULA SHOULD I USE?
Use a long IV cannula even when a vessel is at 1cm depth, as you may still run out of length with the standard IV cannulas. This also ensures a significant proportion of the cannula is in the vessel and won’t dislodge with arm movements. At The Alfred, we use Braun Introcan Safety Deep Access IV catheters.
WHAT VEINS SHOULD I SELECT TO CANNULATE?
The following considerations should be considered when selecting a vein for a USGIVC:
Depth of Vein | Ideally not greater than 1.5cm deep or you will run out of cannula length, and veins that are too shallow may not allow you the opportunity to visualise the needle tip before you enter the vein. |
Diameter of Vein | Veins should be at least 0.5cm in diameter. |
Direction of Travel | Once you have identified a vessel, scan up and down and ensure it is straight, doesn’t branch too early and doesn’t dive too deep. |
Surrounding structures | Nearby arteries, nerves and other veins may make cannulation more challenging. |
TOP TIPS FOR NEEDLE GUIDANCE
Most USGIVCs are inserted using the out-of-plane technique. This involves identifying the desired vein in the transverse plane and using a needle approach over the centre of the vein. The vessel should appear in the short axis as a hypoechoic circle on the screen, with the needle visualised as a hyperechoic point in cross-section. Before needle or catheter insertion, the depth of the centre of the intended vessel should be estimated from the ultrasound image. Choose an angle of insertion that triangulates the path of the needle toward the vessel lumen, ensuring that you don’t run out of cannula length (Think Pythagoras’ Theorem from high school maths). Note that a steeper angle of insertion may make it more difficult to visualise the needle tip.
Figure: Explaining the distance from skin to vessel in ultrasound-guided cannulation. While this distance (d) is estimated in the short axis, the real distance to reach the vein depends on the insertion angle. Assuming a 45° insertion angle, this real distance is equal to d multiplied by 1.4. Of note, the real distance decreases with sloped insertions and increases using shallower insertions
Figure: Real distance from skin to vein measured directly in the long axis. As shown, the shallowest insertions determine the longest pathway to reach the vein, resulting in a large proportion of the catheter dwelling outside the vein and ultimately leading to catheter failure. In contrast, sloped insertions lead to shortening the distance to reach the vein, and aid in increasing the proportion of the catheter dwelling in the vein lumen (Image from Blanco 2019).
Care must be taken to follow the needle tip as it advances to avoid underestimating the depth of the tip. This can be achieved by using the leapfrog method (nicely visualised in the video below by our very own Rob Buttner) where once you have identified the needle tip, the probe is advanced just ahead of the tip before advancing the needle again until it just comes into view. This will limit the likelihood of advancing the cannula through the posterior venous wall of the vein and causing extravasation.
LOST YOUR NEEDLE TIP? DO NOT ADVANCE THE NEEDLE OR JIGGLE IT UP AND DOWN AND FOLLOW THESE STEPS:
Stop and look at your cannula position in relation to the probe. Is it on an angle? Is the probe too far away? If so, then sweep the probe back and adjust your probe angle to better align with the needle.
If everything seems to be good, then fan the probe back towards the needle tip.
Once you have found what you think to be the tip wiggle it from side to side to confirm and then carry on using the leap-frog technique until you have successfully cannulated the vessel.
A lot of these skills are transferrable to other ultrasound-guided procedures. Becoming skilled at ultrasound-guided cannulation and visualising the needle tip will lead to medical mastery in other ultrasound-guided procedures such as nerve blocks, central lines, pleural taps and many more.
PREPARATION IS KEY
Treat USGIV like any other ultrasound-guided procedure (arterial line insertion, nerve blocks), taking adequate time to set up your environment and positioning. You may need an assistant to position the patient’s arm.
Your comfort increases your chances of success. The ultrasound machine should always be directly in your line of sight – this will almost always be on the opposite side of the patient. Even when time-pressured, taking a few moments to optimise these things will increase chances of first-pass success and likely reduce overall time to access.
Consider using local anaesthetic – this is not just for the patient; it is for you. Increased patient comfort will result in less movement and distraction from visualising your needle position.
FURTHER RESOURCES
This video from Kylie Baker a FACEM and ultrasound guru in Ipswich QLD outlines some of the pitfalls encountered when performing ultrasound needle guidance and is a must-watch for anyone doing US-guided procedures.
REFERENCES
AIUM (2019). AIUM Practice Parameter for the Use of Ultrasound to Guide Vascular Access
Journal of Ultrasound in Medicine, 38(3), E4–E18. https://doi.org/10.1002/jum.14954
Blanco, P. (2019). Ultrasound-guided peripheral venous cannulation in critically ill patients: a practical guideline. Ultrasound J11, https://doi.org/10.1186/s13089-019-0144-5
Fields, J. M., Dean, A. J., Todman, R. W., Au, A. K., Anderson, K. L., Ku, B. S., Panebianco, N.
(2012). The effect of vessel depth, diameter, and location on ultrasound-guided peripheral intravenous catheter longevity. The American Journal of Emergency Medicine, 30(7), 1134–1140. https://doi.org/10.1016/j.ajem.2011.07.027
Shokoohi, H., Boniface, K., McCarthy, M., Khedir Al-tiae, T., Sattarian, M., & Ding, R. et al.
(2013). Ultrasound-Guided Peripheral Intravenous Access Program Is Associated With a Marked Reduction in Central Venous Catheter Use in Noncritically Ill Emergency Department Patients. Annals Of Emergency Medicine, 61(2), 198-203. doi: 1016/j.annemergmed.2012.09.016
Van Loon, F., Puijn, L., Houterman, S. and Bouwman, A. (2016). Development of the A-DIVA Scale. Medicine, 95(16), p.e3428.
van Loon FHJ, van Hooff LWE, de Boer HD, Koopman SSHA, Buise MP, Korsten HHM, Dierick-van Daele ATM, Bouwman ARA (2019). The Modified A-DIVA Scale as a Predictive Tool for Prospective Identification of Adult Patients at Risk of a Difficult Intravenous Access: A Multicenter Validation Study. J Clin Med. 8(2):144. doi: 10.3390/jcm8020144.
LUKE PHILLIPS
Emergency Physician
Dr Luke Phillips is an Emergency Physician at Alfred Health who has moved to the greener climes of Ireland. He is a passionate educator and has been fortunate enough to be able to combine this with his love of emergency ultrasound. Luke has a special interest in the use of focused ultrasound for critically unwell patients, in trauma management and in the use of ultrasound to guide procedures and improve patient safety in the ED. He is currently the Co-Chair of the Emergency Medicine Ultrasound Group (EMUGS.org) Board of Directors and holds a number of CCPU units through ASUM. Luke is also involved in the department’s international education program and has developed a Certificate of Emergency Medicine which is currently being run in both Germany and India. He also has interests in human factors, debriefing (particularly after clinical events), and simulation. His Twitter handle is @lukemphillips.
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