Suturing an arterial line involves anchoring the catheter hub to the skin with a nonabsorbable suture so the line stays in place during monitoring. The technique is straightforward but requires attention to sterile practice, proper tension, and site-specific considerations. Whether you’re securing a radial or femoral arterial catheter, the goal is the same: keep the line stable without compressing the vessel or creating an infection risk at the entry site.
Equipment You Need
The standard suture material for arterial line securement is a nonabsorbable suture, most commonly silk. For femoral arterial lines, 2-0 silk is the typical choice. For radial lines, 3-0 or 4-0 silk or nylon works well given the smaller catheter and thinner skin. You’ll also need a needle driver, toothed forceps, suture scissors, and sterile gloves.
Local anesthesia is used before catheter insertion, not just for the arterial puncture but also to numb the skin where the suture will pass. The standard is 1% lidocaine without epinephrine, drawn into a 3 to 5 mL syringe with a 25 to 27 gauge needle. If the line is already in place and the skin wasn’t pre-anesthetized at the suture site, a small subcutaneous wheal of lidocaine at the planned suture point keeps the patient comfortable.
Step-by-Step Suturing Technique
Once the arterial catheter is confirmed in place (pulsatile blood return, transducer waveform verified), you’re ready to secure it. Clean the surrounding skin with antiseptic if not already prepped.
Take a bite of skin approximately 5 mm from the catheter insertion site, entering and exiting on the same side. Pull the suture through, leaving a tail long enough to tie. Loop the suture around the catheter hub or through the hub’s built-in suture wing, depending on the catheter design. Tie a square knot snug enough to hold the hub against the skin but not so tight that it bunches or blanches the tissue. Most clinicians place three to four throws to ensure the knot holds. Cut the tails to about 5 mm.
Some catheters have a molded wing or eyelet specifically designed for suture passage. Thread the suture through this before tying. If the hub has no wing, loop the suture around the hub itself, making sure the loop sits in the groove where the hub narrows. This prevents the suture from sliding off.
For added security, especially on femoral lines, a second suture can be placed on the opposite side of the hub. This prevents rotation and lateral movement. After suturing, apply a sterile transparent dressing over the insertion site so you can monitor for bleeding, swelling, or skin changes without removing the dressing.
Radial vs. Femoral: How the Site Changes Your Approach
Radial arterial lines use a smaller catheter, typically 20 gauge and under 5 cm in length. The radial artery sits superficially over the radius bone, which makes compression easy and bleeding less of a concern. Many radial lines can be adequately secured with a transparent dressing and adhesive strips alone, though suturing adds an extra layer of security in patients who are restless or diaphoretic.
Femoral arterial lines are a different situation. The catheter is longer (15 cm or more), the artery is larger and deeper, and the groin is a high-movement area prone to moisture. Femoral lines should be sutured. The bigger catheter and soft tissue depth mean there’s more leverage for accidental dislodgement, and losing a femoral line carries a higher bleeding risk because the artery is harder to compress. It sits deep, surrounded by soft tissue without the firm bony backstop that the radial artery has. Use 2-0 silk and consider two separate suture points to prevent both axial pullout and lateral shifting.
Suture vs. Adhesive Securement Devices
The CDC recommends sutureless securement devices as a Category II recommendation for intravascular catheters, meaning the evidence supports their use to reduce infection risk. A comparative study of central venous catheters found that adhesive securement devices had a total complication rate of 21.3%, compared to 47.2% in the sutured group. The sutured catheters had significantly higher rates of local infection signs, catheter displacement, and catheter-associated bloodstream infection.
These findings apply most directly to central venous catheters, and the data for arterial lines specifically is less robust. In practice, many ICUs still suture femoral arterial lines because of the mechanical forces at the groin, while using adhesive devices or dressings alone for radial lines. If your institution uses a commercially available securement device (such as a StatLock or similar product), it clips onto the catheter hub and adheres to the skin, eliminating the need for a skin puncture and the bacterial colonization pathway that sutures can create.
Complications to Watch For
The suture itself introduces a small puncture wound adjacent to the arterial access site, which creates a potential entry point for bacteria. Keeping the suture site clean and covered with a transparent dressing lets you monitor for redness, swelling, or purulent drainage. If the dressing becomes soiled or loses adhesion, replace it promptly.
Tying the suture too tightly can compress the skin against the catheter hub, restricting blood flow to the skin edges and potentially causing localized necrosis. This is more of a concern at the femoral site, where larger hubs and deeper soft tissue can create uneven pressure. Aim for a tension that holds the catheter without dimpling the surrounding skin.
Vasospasm is another risk, though it’s related to the catheter itself rather than the suture. When the catheter diameter exceeds roughly 50% of the artery’s internal diameter, spasm becomes more likely. This is particularly relevant in pediatric patients and small adults. Signs include pallor or mottling distal to the insertion site. If skin discoloration appears during or after suturing, it may indicate spasm or thrombosis and warrants immediate assessment. In children, the reported complication rate for femoral artery cannulation (including ischemia, thrombosis, embolism, and infection) ranges from 0.1% to 14%.
Multiple insertion attempts and accidental transfixion of the posterior arterial wall increase the risk of vessel injury and downstream complications. A clean, single-wall puncture on the first or second attempt is the best way to minimize endothelial damage that can trigger clot formation and spasm.
Keeping the Line Secure After Suturing
Once the catheter is sutured and dressed, secure the IV tubing to the patient’s skin or gown with tape or a clip. A common cause of arterial line dislodgement isn’t suture failure but tubing that gets caught on bed rails, equipment, or during patient repositioning. Creating a stress loop in the tubing near the insertion site absorbs tension before it reaches the catheter hub.
For femoral lines, pay extra attention to leg movement. Hip flexion and extension put cyclical stress on the catheter. Positioning the tubing so it exits toward the patient’s feet and taping it along the thigh reduces the angle of pull on the hub. For radial lines, splinting the wrist in slight extension (about 20 degrees) with an arm board limits wrist flexion that could kink or dislodge the catheter.
Check the suture at each dressing change. Silk sutures in moist environments can loosen over days, and the knot may slip. If the catheter appears to have migrated outward or the suture has loosened, re-secure it rather than pushing the catheter back in, which introduces bacteria from the external segment into the vessel.