critical care medicine
How To Do Femoral Artery Cannulation, Ultrasound Guided
Step by Step Description of Procedure
Check that the ultrasound machine is configured and functioning correctly: Ensure that the screen image you are seeing correlates to the spatial orientation of the probe as you are holding and moving it. The side mark on the probe tip corresponds to the teal blue marker dot on the ultrasound screen. Adjust the screen settings and probe position if needed to attain an accurate left-right orientation. Do a nonsterile ultrasound inspection (ie, using an uncovered probe and nonsterile gel) of the femoral artery about 2.5 cm inferior to the inguinal ligament and determine whether the artery is suitable for cannulation. Use a short-axis (cross-sectional) view. Blood vessels are hypoechoic (appear black on the ultrasound screen). Arteries are generally smaller, thick-walled, and round (rather than thin-walled and ovoid) and are less easily compressed (by gentle pressure on overlying skin) than their paired veins. Use color Doppler mode to identify a patent lumen and spectral Doppler mode to identify pulsatile blood flow in the artery.Cannulate the femoral artery at a site of optimal short-axis imaging (ie, large-diameter cross section of the artery, with no overlying vein). Excess hair may be clipped but not shaved from the site. Shaving increases the risk of infection. Place sterile equipment on sterilely covered equipment trays. Dress in sterile garb and use barrier protection. Draw the local anesthetic into a syringe. Attach the femoral artery introducer needle to a 5-mL syringe with 1 to 2 mL of sterile saline in it. Draw sterile saline into a 3- or 5-mL syringe to be used for flushes. Attach the transducer tubing to the blood pressure transducer and flush the tubing with sterile normal saline. Swab a broad area of skin with antiseptic solution, from the anterior superior iliac spine to the midline and extending down 15 cm below the inguinal ligament. Allow the antiseptic solution to dry for at least 1 minute. Place sterile towels around the site. Place large sterile drapes (eg, a full-body drape) to establish a large sterile field. Direct your assistant (nonsterile) to coat the probe tip with nonsterile ultrasound gel and then hold the probe, with the tip pointing up, just outside the sterile field. Insert your gloved dominant hand into the sterile probe cover. Grasp the tip of the probe with your dominant hand (now covered by the probe cover). Use your gloved nondominant hand to unroll the sterile cover over the probe and completely down the cord.Do not touch the uncovered cord nor allow it to touch the sterile field as you unroll the cover. Pull the cover tightly over the probe tip to eliminate all air bubbles. Wrap sterile rubber bands around the probe to secure the cover in place. The covered probe may now rest on the sterile drapes. Apply sterile ultrasound gel to the covered probe tip. Use short-axis ultrasound guidance: Attain an optimal cross-sectional image of the femoral artery about 2.5 cm inferior to the inguinal ligament. Slide the probe transversely as needed to place the imaged artery at the center of the ultrasound screen.When the artery is centered on the ultrasound screen, the midpoint of the probe becomes a surface marker designating the luminal center of the underlying artery. Keep the probe in this spot. On the ultrasound screen, measure the depth to the center of the artery.When using short-axis ultrasound guidance, insert procedural needles (local anesthetic and introducer needles) into the skin at a point distal and perpendicular to the midpoint of the probe by the same distance as the arterial depth. Then, initially advance the needle into the skin at a 45° angle directed toward the midpoint of the probe. Keep gentle negative pressure on the syringe plunger as you advance. Place a wheal of anesthetic at the needle entry point and then inject anesthetic into the skin and soft tissues along the 45° path leading toward the artery. Slightly tilt the probe fore and aft as you advance the anesthetic needle to continually identify the needle tip and keep it safely distant from the artery and vein. Continue to use short-axis ultrasound guidance (as described above for the local anesthetic injection). Insert the introducer needle (with needle bevel facing up). Maintain ultrasound visualization of the needle tip as you advance by continually tilting the probe slightly fore and aft (the needle tip appears and disappears as the ultrasound plane sweeps back and forth over it). If the needle tip strays from the artery,adjust the lateral direction of the needle to keep the needle tip above the center of the artery.If the needle tip is approaching the artery too slowly,withdraw the needle a bit, increase the angle of insertion, and readvance. As the needle tip approaches the artery, temper your speed and angle of insertion so the needle will enter with as much control as possible.The superficial wall of the artery will indent when the needle tip encounters it. The needle then pops through the wall to enter the lumen, accompanied by a flash of bright red (if normally oxygenated) blood in the barrel of the syringe. Hold the syringe motionless in this spot and visualize the tip of the needle at all times. Displacement is common, and even a slight movement may displace the needle tip from the artery. Remove the syringe from the needle using your dominant hand. Note the flow of pulsatile bright red blood. Then immediately put your thumb over the hub of the needle to stop the blood flow (which can be profuse from an arterial cannulation) and to prevent air from entering the arterial system. Optional: If the accessible femoral arterial segment is long enough to accommodate the long axis of the probe, you may prefer to use the short-axis (cross-section) view first to aim the needle at the artery and then rotate the probe 90° to attain the long-axis (in-plane, longitudinal) view of the needle and artery, which provides better imaging of the arterial puncture. Move the probe as needed to keep both the needle and the artery in sight (in-plane). Press lightly with the probe tip so the artery remains under the tip and does not roll to the side. Continue to hold the introducer needle motionless. Insert the J-curved end of the guidewire into the introducer needle with the J curve facing up. You may use ultrasound guidance (either short- or long-axis) to verify the guidewire entering the artery. Advance the guidewire through the introducer needle and artery. Do not force the wire; it should slide smoothly. Under long-axis ultrasound guidance, you may carefully flatten the needle insertion angle while keeping the needle tip within the artery, which facilitates passage of the wire. Advance the wire until at least about 8 to 10 cm is within the vessel. If you feel any resistance as you advance the guidewire,stop and use ultrasound guidance to check the position of the wire and the needle. Try to gently withdraw the wire slightly, rotate it slightly, and then readvance it, or try to gently withdraw the wire entirely, reestablish the needle tip within the artery (confirmed by venous blood return), and then reinsert the wire. However, if you feel any resistance as you withdraw the wire,terminate the procedure and withdraw the needle and guidewire together as a unit (to prevent the needle tip from shearing through the guidewire within the patient). Then use 4 × 4 gauze squares for 10 minutes to hold external pressure on the area to help prevent bleeding and hematoma. Once the guidewire has been inserted, continue to hold it securely in place with one hand and maintain control of it throughout the remainder of the procedure. First, securely hold the guidewire distal to the needle as you pull the needle from the skin. Then, securely hold the guidewire at the skin surface as you slide the needle down the remaining length of the guidewire to remove the needle. Using the scalpel, make a small stab incision (< 5 mm) into the skin insertion site, avoiding contact with the guidewire, to enlarge the site and allow it to accommodate the larger diameter of the femoral arterial catheter. Advance the catheter over the guidewire to the skin surface: Hold the guidewire fixed at the skin surface, thread the catheter tip over the distal end of the guidewire, and slide the catheter down to the skin surface. The distal end of the guidewire should now be protruding from the port hub. If the distal end of the guidewire is not protruding from the port hub,inch the guidewire outward from the skin surface while holding the catheter tip close to the surface until the guidewire protrudes. Advance the catheter into the artery: Grasp and control the guidewire where it protrudes from the hub. Hold the catheter near its tip and insert the tip through the skin. Then, using a corkscrew motion as necessary, incrementally advance the entire length of the femoral arterial catheter. Use ultrasonography to verify intra-arterial placement of the catheter. Maintain your grasp on both the guidewire and the catheter. Remove the guidewire: Withdraw the guidewire while holding the catheter securely in place at the skin surface. Cover the hub with your thumb. Attach the arterial pressure transducer tubing (pre-flushed with saline) to the catheter hub and verify an arterial pressure waveform on the monitor screen. If the patient is awake or minimally sedated, use 1%lidocaineto numb the skin at the planned suture locations. Place achlorhexidine-impregnated disk on the skin at the catheter insertion point. Suture the skin to the mounting clip on the catheter. Apply a sterile occlusive dressing. Transparent membrane dressings are commonly used. 