Integrating Long-Axis and Short-Axis Views with a Twist for Ultrasound-Guided Vascular Access, Part I: Femoral Approach

Introduction

Ultrasound-guided vascular access has emerged as a ubiquitous tool used by a variety of specialties, including cardiologists, vascular surgeons, emergency room physicians, and critical care specialists. Studies have shown that femoral artery access guided by ultrasound results in safer outcomes.¹ In addition, femoral ultrasound guidance for common electrophysiology procedures has proven to be superior than landmark-guided access to reduce adverse events.^2,3 The most common approach to ultrasound-guided access involves using short-axis (ie, transverse axis) views to guide the needle puncture. This article will describe a hybrid approach using both short-axis and long-axis (ie, longitudinal axis) techniques to enhance visualization of the needle tip into the femoral vessel with a twisting motion to further reduce the chance of inadvertent posterior wall puncture.⁴ 

Equipment

A standard linear array probe (5-15 MHz) made by most ultrasound equipment companies (Sonosite, Philips, etc.) provides the best resolution and depth for femoral vessel access. To enhance visualization, an 18-gauge echo-visible needle should be used with every access attempt. A 21-gauge needle can also be used, and there are echo-visible versions available as well. In my experience, an 18-gauge echo-visible needle has a modest advantage over a 21-gauge needle due to enhanced visualization (and thus, confidence of needle tip position), one less step for wire/sheath introduction, and a better bevel-cutting function with a twisting motion. Ideally, the lab staff should prepare the access needle, J-wires, sheaths, and ultrasound probe in a sterile sleeve near the groin site to minimize the amount that the operator has to move or reach while obtaining access (Figure 1).

Technique

The first step involves a short-axis survey of the femoral artery and vein anatomy, including the bifurcations of each into the superficial femoral and deep branches, the location of posterior bony structures (femoral head and ischial tuberosity), and identification of any superficial crossing vessels to avoid on the path down to the target vessel (Figure 2). The goal is to puncture the femoral vein or artery in the common femoral portion above the bifurcation of the branches and below the inguinal ligament to avoid the inferior epigastric branch of the artery or vein. Given the 3- to 4-centimeter distance of travel from the surface of the skin to the surface of the vessel, it is best to start just superior or at the bifurcation of the intended femoral vessel. Frequently, the femoral vein branches inferiorly to the femoral artery. If the vein is the target, starting at this level (ie, the arterial bifurcation and not the venous bifurcation) is usually necessary, since the superficial femoral artery branch will frequently travel anterior to the vein as the vessels are scanned down inferiorly. 

Next, with the target vessel in the middle of the field of view, an echo-visible needle is also inserted into the middle of the field of view. In Figure 3, Video 1 and Video 2, the right common femoral vein is the target for three separate puncture attempts. Fanning of the ultrasound view in an inferior-to-superior motion as the needle is inserted facilitates visualization of the tip of the needle at all times. The short-axis view is not as optimal for visualizing the needle tip versus the long-axis view; however, given the importance of landing the needle in the center of the target vessel to avoid a glancing injury to any neighboring structures, the short-axis view is preferred for the initial approach of the needle toward the vessel. Using a fine jiggling motion and slow insertion of the needle, the needle tip can be approximated visually as the ultrasound view is fanned superiorly. 

When the needle is at the anterior surface of the vessel, the ultrasound probe is then rotated clockwise 90 degrees to visualize the vessel and needle in long-axis view. Here, maximal tenting is obtained by further slow advancement of the needle. Fine adjustments of the probe and/or tilt of the needle will aid in finding the optimal visualization. After maximal tenting is confirmed, a rapid twisting motion of the needle with consistent forward pressure allows the sharp beveled edge of the needle to cut through the anterior wall of the vessel. This technique avoids the frequently taught jabbing motion, which could inadvertently puncture too far and cause a “through-and-through” injury to the vessel. Once blood flow is confirmed, then the introducer guidewire is inserted under ultrasound guidance by holding the probe in place with the left hand and using the right hand to remove the syringe (slip-tip preferably if one is used), let go of the needle, and insert the wire (Figure 3, Videos 1 and 2). Alternatively, since visualizing the wire enter on ultrasound is not completely necessary for safety, the operator can choose to set down the ultrasound probe and hold the needle in place with the left hand while removing the syringe and inserting the guidewire with the right hand.

If multiple venous access sites are needed — such as the protocol in our lab, which uses three puncture sites into the right femoral vein for all atrial fibrillation and supraventricular tachycardia ablations — the subsequent entry site is attempted about 2-3 millimeters below (inferior to) the prior puncture site (Figure 4). The prior wire is seen on ultrasound but does not usually interfere with seeing the second or third puncture needle tip, especially once switching to the long-axis view. After all punctures have been achieved, a quick ultrasound surveillance in long-axis view can show all three wires cleanly entering the target vessel. 

For femoral artery punctures, the same approach applies with identifying the bifurcation, using short axis for the initial needle approach, and then utilizing the long-axis view to see the maximal tenting while twisting the needle to pop through the anterior wall of the artery (Figure 5). However, it is even more crucial to stay as centered as possible on the artery. With its muscular (and thus, more rigid) vessel wall and higher intravascular pressures, any off-center attempts may result in the needle glancing off the side of the vessel or the tip of the needle only inserting obliquely through the muscular wall and not into or partially into the lumen of the vessel. Trying to insert a wire in this situation could result in dissection of the arterial wall. Therefore, slow advancement, jiggling of the needle, and meticulous fanning of the probe during the approach of the needle will pay dividends in a perfectly centered needle tent before rotating over to long axis. After that, the twisting motion of the needle and continued forward pressure will easily result in quick cannulation into the lumen and brisk pulsatile bright red blood flow back.

Limitations/Challenges

There is a learning curve of approximately 5-10 cases with rotating the probe and finding the best angle to view the anterior wall of the target vessel and the needle tip in long axis. This takes some coordination between both hands, with fine adjustments of both until the needle tip and ultrasound plane are in phase with each other. Therefore, it is best to begin learning with femoral vessel puncture (versus axillary vein or artery puncture), given the wider field to move the probe and the lower serious risk of posterior structure injury (such as pneumothorax). Also, roughly 5-10% of ultrasound-guided femoral access will not have perfect visualization of the anterior vessel wall due to a variety of factors, including body habitus (and thus, deeper vessels, although not necessarily a perfect correlation), presence of renal disease, scar tissue from prior procedures, or poor tissue visualization quality (unclear contributing factors in otherwise normal habitus individuals). Once an operator has performed an adequate number of “normal” attempts (25-50) using this hybrid technique, then safe and successful puncture is still possible due to prior experience, despite suboptimal visualization of the vessel wall and needle tip. Another function that is not used on every case but is valuable to keep in mind is the color Doppler function, which aids in keeping the needle centered and knowing the approximate depth to the vessel when adequate visualization of the vessel is not possible due to superficial tissue characteristics of the patient.

Conclusion

With the availability of ultrasound technology in nearly every procedure lab, ultrasound-guided vascular access should be the first-choice approach for all proceduralists needing to gain femoral artery or vein access. Combining short-axis and long-axis views during needle advancement and using a twisting, cutting motion during maximal tent further optimizes the safety of this approach, and can be easily adopted by all operators at no or minimal additional cost. Future enhancements will involve the integration of a biplane view in all vascular probes to avoid needing to manually rotate the probe. 

Acknowledgments: I would like to thank John Crowell (Abbott EP territory manager) for his superb video and photography skills using my Apple iPhone 11 Pro.

Disclosure: Dr. Salcedo has no conflicts of interest to report regarding the content herein. 

Contact the author on Twitter: @50wattdoc

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1. Seto AH, Abu-Fadel MS, Sparling JM, et al. Real-time ultrasound guidance facilitates femoral arterial access and reduces vascular complications: FAUST (Femoral Arterial Access With Ultrasound Trial). JACC Cardiovasc Interv. 2010;3(7):751-758. 
2. Wynn GJ, Haq I, Hung J, et al. Improving safety in catheter ablation for atrial fibrillation: a prospective study of the use of ultrasound to guide vascular access. J Cardiovasc Electrophysiol. 2014;25(7):680-685. 
3. Sharma PS, Padala SK, Gunda S, Koneru JN, Ellenbogen KA. Vascular complications during catheter ablation of cardiac arrhythmias: a comparison between vascular ultrasound guided access and conventional vascular access. J Cardiovasc Electrophysiol. 2016;27(10):1160-1166. 
4. Spencer TR, Pittiruti M. Rapid central vein assessment (RaCeVA): a systematic, standardized approach for ultrasound assessment before central venous catheterization. J Vasc Access. 2019;20(3):239-249.