Since 1984, ultrasound has been regularly utilized in a wide variety of vascular access procedures, ranging from ultrasound-guided central venous catheterization to femoral artery cannulation to arterial access. ^{1 2} Ultrasound's superior procedural advantages - combined with its cumulative benefits in terms of safety and success- make it a popular tool for practitioners conducting vascular access procedures. ²

Of course, no medical procedure is 100% risk-free, and when it comes to vascular access procedures, it is critically important that everything possible is done to ensure patient safety - including in those procedures that are ultrasound-guided. Below are several categories of ideas, all of which are easily implementable and geared exclusively towards helping to make your ultrasound-guided vascular access procedures even safer for your patients.

Tip #1: Understand how to use ultrasound system features to improve visualization while scanning:

Knowing which buttons on an ultrasound machine to adjust - and when exactly to adjust them - is an important component of performing scans that deliver the clearest images possible for your patients. Here is a breakdown of just some of the more commonly used system features that can be used to improve and optimize the visualization of your image.

• TGC button:

Time gain control (TGC) button. Used to improve the gain of the image (i.e. the brightness), providing the user the ability to adjust the lightness or darkness at different horizontal levels within the image, allowing for a more uniform and detailed image that is easier to see.

• Depth button:

Used to adjust the depth of the image (i.e. specifically how deep the beam is traveling into the patient's body). Increasing the image depth allows the user to see deeper vessels more clearly while decreasing the image depth allows users to better visualize superficial vessels.

• Focal zone button:

Used to adjust the focal zone on an image (i.e. the area of an image that can help with lateral resolution, which assists with helping to visualize side walls and differentiating separate structures). There can be one or multiple focal zones at any given time within an ultrasound image - by using this button, focal zones can be moved as needed to help define individual structures.

• Frequency button:

Used to adjust the frequency of an image (i.e. the overall resolution). Remember: a higher frequency will result in an image that has higher resolution, but lower penetration, whereas a lower frequency will deliver an image with lower resolution, but higher penetration. The general rule of thumb for adjusting frequency: start with the frequency as high as possible, and after you have adjusted all of the other major buttons, lower the frequency until you clearly see the structure that you are trying to focus on.

Tip #2: Understand how to use buttons to improve visualization of the needle during guidance:

Just as important as knowing which of the buttons on your ultrasound machine can help you improve the scan's image quality is knowing which buttons can help improve the visualization of your needle during guidance procedures. Features that can help you to better visualize your needle during guidance include:

• Dynamic Range button:

Used to adjust the contrast/compression of the image. Raising the image's dynamic range creates more shades of gray while lowering it results in fewer grays and higher degrees of black and white. Lowering the dynamic range can be particularly helpful when trying to increase the visibility of the needle tip on the ultrasound image.

• Frequency button:

Used to adjust the frequency of an image (i.e. the overall resolution). Just as the frequency button can be used to enhance the overall quality of an image scan, it can also be used to lower the frequency, which can help to increase the ring-down artifact of the needle tip, increasing needle visibility within the image scan.

• Trapezoid button:

Used to superimpose three individual beams - straight, right, and left - in order to make a rectangular image look like a convex image. Allows for a clearer vision of the needle when using the parallel technique, due to the perpendicular reflection from the needle.

• 2D steer button:

Used to mechanically steer the beam, providing the user with more options on how to angle the beam towards the needle when utilizing the parallel technique. Allows the user a greater degree of control (albeit occasionally at the expense of overall image quality).

• One focal zone button:

Used to increase the frame rate of the image. For interventional procedures, it is usually best to have one focal zone, as multiple zones can potentially slow the image's frame rate, leading to scans that are choppy. Using a single focal zone will typically help to decrease lag in real-time scanning during the biopsy.

Two of the most common methods for conducting ultrasound needle guidance are the "in-plane" and "out of plane" techniques, with both approaches having distinct advantages and disadvantages, depending on when and how they are implemented. Below are brief breakdowns of both approaches, as well as some ideas for each to help you achieve the absolute best results for your patients.

Tip #3: Optimize your in-plane needle guidance approach:

In-plane needle guidance: when the needle is inserted directly parallel to the ultrasound beam, with the needle's shaft being seen as an echogenic white line.

Tips for in-plane guidance approach:

• When guiding a needle using the in-plane approach, make sure that you are positioned directly in the center of the face of the probe as you advance the needle. If you are positioned too far off to any one side, you risk potentially not being able to see the needle.

• Begin your guidance at the center of the long access of the vessel, as opposed to the edges. The advantage of this: if your needle goes slightly off-plane, it will still be firmly located within the vessel.

• Cut the image diagonally to help determine what angle you should use to insert the needle. Angles that are closer to 90 degrees off of the ultrasound beam will result in better visualization. But remember the more vertical your approach, the more difficult it will be to visualize the needle.

• If you have inserted the needle in-plane and still are not able to see the tip, hold the needle still, then slowly sweep the transducer from side to side until you are firmly in line with the needle.

Tip #4: Optimize your out-of-plane needle guidance approach:

Out-of-plane needle guidance: when the needle is inserted directly perpendicular to the plane of the ultrasound beam.

Tips for out-of-plane guidance approach:

• Keep track of where the needle is located at all times. To start, implement a "stepping technique" by placing the vessel in the center of the image, lining up the needle in the middle of the probe, then inserting the needle until you see the tip. Move the probe away from the needle and survey ahead of it, advancing the needle further until it shows up on the image again. If you feel as though you are on the shaft of the needle and not the tip, simply pull the needle back until it disappears, then start stepping forward again.

• Make sure that the needle remains positioned more horizontally for the superficial part of the vessel and is positioned more vertically for the deeper part of the vessel.

• In order to obtain a better reflection of the needle when performing an out-of-plane approach, adjust the probe towards the needle, so that the angle between the needle and the probe is at 90 degrees - this will provide the brightest reflection of the needle tip possible. Remember to also decrease the dynamic range and frequency, which can also help you to visualize the tip even better.

• To locate the needle tip in an out-of-plane approach, slowly sweep the transducer "away" from the needle, until the echo disappears. Then slowly sweep back toward the needle until the tip is identified.

Tip #5: Clean and disinfect your transducer after procedures:

Cleaning and disinfecting your transducer post-procedure is another important step in ensuring that your ultrasound-guided vascular access procedures remain safe for your patients³. There are several easy things that you can implement to help stave off infection and keep your probes contamination-free, which include:

• Cleaning and disinfecting the transducer after each use, avoiding alcohol-based disinfectants and wipes.

• Dry the probe of any residual gel that is left on the transducer (including in any nooks and crannies).

• Performing disinfection in alignment with the probe manufacturer and disinfectants' IFUs, in order to ensure proper reprocessing (for more information on ways that you can ensure your probes receive proper disinfection, check out our blog post, "Top Tips for High-Level Disinfection").

• When rinsing, make sure not to expose the transducer's system connector to moisture.

• Evaluating the transducer and cord for damage, replacing broken probes as needed.

Tip #6: Be on the lookout for probe defects:

Always be on the lookout for defects in your ultrasound probes. It's important to remember that bacteria can, and often will, reside in even the smallest holes, nooks, and crannies of your transducers. To ensure that your probes - and patients - remain safe from contamination, be sure to do the following before and after procedures:

• Check the probe for any seam separation or cracks in the casing of the probe.

• Scan the lens of the probe for punctures, perforations, or delamination.

• Inspect the strain relief (the area of the probe casing that connects to the cord) for dryness.

• Check the cord of the machine for tire-damage.

Tip #7: Handle and store your probes properly:

In recent years, the importance of maintaining proper handling and storage of one's ultrasound probes post-high-level disinfection is something that has received added emphasis by many organizations, including the Joint Commission and AIUM. To help keep your probes safe from potential damage, consider the following "Do's" and "Don't's" whenever handling or storing your transducers:

Do's:

• Do hold the probe by the body when handling.
• Do keep the probe's cord off the floor.
• Do place probes in holders/storage cabinets when not in use.
• Do store your probe in a safe, secure location.

Don'ts:

• Don't hold the probe by the cord
• Don't let the cord get run over by the wheels or drag along the floor
• Don't place probes on beds, tables, or chairs when not in use.
• Don't hang the probe up by its cord.

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References:

1. Maecken, T., & Grau, T. (May 01, 2007). Ultrasound imaging in vascular access. Critical Care Medicine, 35.
2. 2012, The Association for Medical Ultrasound. "AIUM Practice Guidelines for the Use of Ultrasound to Guide Vascular Access Procedures."
3. Magnuson, P. (January 01, 2021). Disinfection of Ultrasound Transducers Used for Percutaneous Procedures: Intersocietal Position Statement. Journal of Ultrasound in Medicine.