This video demonstrates an overview of radial arterial cannulation in a pediatric patient using real-time ultrasound (US) guidance. Ultrasound imaging is a useful tool in the armamentarium for guiding arterial line placement, and its use has become commonplace due to increased accessibility and improved technology. Ultrasound imaging facilitates the detection of abnormal anatomy and abnormal findings (e.g. thrombosis). It also allows for real-time guidance for arterial cannulation, which is especially valuable during difficult insertions such as in neonates or small infants, patients with weak or absent pulses or landmarks, and those with multiple prior cannulations. There is evidence of higher success rates with first attempts and decreased complications compared to the traditional landmark and palpation techniques.
Traditionally, the landmark with palpation approach has been the technique used to guide arterial line placement. At present, the use of ultrasound (US) for guiding placement has become commonplace due to increased accessibility, improved technology, and evidence of increased first-attempt success rates and decreased complications. The proficient use of US allows for the detection of abnormal anatomy or findings (e.g. thrombosis) and allows for real-time visualization, which is especially helpful during difficult insertions, absence of landmarks, and in challenging patient groups such as in small infants..
Setup
- Catheter of chosen size and length
- Introducer needle
- Guidewire Syringe
- Suture and needle
- Sterile saline (heparinized) flushes
- Sterile gauze
- Sterile skin cleansing solution such as chlorhexidine
- Sterile drapes
*For the operator: Surgical mask, head covering, antiseptic hand wash, sterile gloves. Sterile gowns are also often utilized.
*For the cleaned ultrasound probe: Sterile ultrasound gel and a sterile ultrasound probe cover
Procedure
Hold procedure time-out to identify the correct patient, procedure, and site of the procedure.
Pre-scan the wrist with the US prior to skin preparation and draping to identify the radial artery and relevant anatomy, vessel patency, size, and course before the procedure starts, and exclude abnormalities. Note the pulsatility.
Properly position the arm and wrist.
Prepare for an aseptic procedure: Surgical mask, head covering, antiseptic hand wash, sterile gloves. Sterile gowns are also often utilized.
Cleanse the skin over the puncture site with chlorhexidine-alcohol-based solutions or alternatives.
Cover the patient with sterile draping, exposing only the cleaned site for cannulation.
Open and prepare the equipment for arterial cannulation.
Remove all air bubbles from the catheter, flushes, or monitoring tubing.
Place the US probe and gel in a sterile sheath in a sterile fashion with the help of an assistant.
Secure the US probe so it does not slide off the sterile field. A high-frequency (5-15 MHz) linear ultrasound transducer is appropriate as the artery is superficial. Both short- and long-axis views are helpful for guiding and verifying desired placement as the structures of interest are imaged in two different views. The short-axis view provides a cross-sectional visualization of the artery, while the long-axis view shows a longitudinal image of the vessel. In small infants, an initial short-axis view may be preferable and more ergonomic for puncture and tracking of the needle during arterial cannulation, followed by a long-axis view for confirmation and visualization of its course. Ensure that the US probe orientation is aligned with the screen (a mark on the side of the probe corresponding to a mark on the scan sector or touching the side of the probe to match the orientation on the screen).
Select the site of puncture where the artery is most accessible for puncture and follows a relatively straight course.
Under ultrasound guidance, puncture the skin while visualizing the tip. Using the short-axis view, visualize the needle tip contact the artery, and then drop the angle of the needle until it is almost parallel to the vessel before advancing the needle tip into the lumen. Once the tip is visualized inside the lumen, try keeping the tip in the center of the lumen like a “bull’s eye target.” Move the US probe away from the tip until it disappears, and then advance the tip of the needle into view. Repeat until most of the needle has been advanced into the vessel.
Thread the catheter and remove the needle. Blood should be flowing out. If exchanging for another more definite catheter, thread the guidewire through the catheter using the Seldinger technique.
Advance the new catheter over the guidewire and remove the guidewire.
Attach the tubing and transducer, aspirate for blood return, and flush through with saline or heparinized saline.
Make sure no air bubbles are present in the tubing or flushes.
Secure into place and place a sterile dressing over the site.
Practitioners who are familiar with the landmark/palpation technique for arterial line catheterization, but who have not incorporated US into their practice, adding US technology requires training and exposure for proficiency, so that it actually improves the practitioner's first-attempt success rates and decreases complications. In addition to developing technical proficiency, one must understand aspects of ultrasound technology such as imaging capacity (e.g. imaging depth associated with probe frequency) and limitations (e.g. artifacts, 2-dimensional view). Failure to understand the technology may lead to improper interpretation of the images; for example, the needle shaft may be mistaken for the needle tip, resulting in missteps and complications. In practice, ultrasound operation requires good hand-eye coordination, and in small infants, the physical size of the probe relative to the body site and the small size of structures of interest may be limiting to its utility. Indications include monitoring for beat-to-beat arterial pressure and blood sampling. Contraindications to arterial cannulation include abnormal anatomy, skin infection over the site, thrombus inside the artery, or lack of collateral circulation to the extremity. Severe coagulopathy is a relative contraindication. In this situation, ultrasound-guided arterial cannulation is the method of choice for these patients at high risk of bleeding and hematoma formation. Although the use of real-time ultrasound guidance can significantly decrease the complication rates of this procedure, it is important to remain aware of the ultrasound limitations in addition to those intrinsic to the catheterization process. Possible complications include catheter malposition, subcutaneous hematoma, hand ischemia, and air embolism. The use of real-time ultrasound guidance can significantly decrease the complication rates of this procedure. When blood flow from a catheter is not brisk, and a guidewire is used to gain improved vessel entry and cannulation, do not force the guidewire on insertion to avoid vessel damage or inadvertent tearing of surrounding structures. Additionally, prevent air emboli by keeping the catheter, tubing, and saline flushes free of any air bubbles. In summary, the proficient use of US for arterial catheterization facilitates real-time visualization, which is especially helpful during difficult insertions, absence of landmarks, and in challenging patient groups such as in small infants.
Review Ultrasound-Guided Arterial Catheterization in a Pediatric Patient.