Ultrasound-guided cannulation of the femoral vein uses real-time (dynamic) ultrasound to guide venipuncture and a guidewire (Seldinger) technique to thread a central venous catheter through the femoral vein and into the inferior vena cava.
Femoral venous cannulation has the procedural advantages of a relatively superficial and easily accessed vein as well as nearby anatomy that lacks the complexity and vital structures of the jugular and subclavian regions. However, femoral central venous catheters (CVCs) have higher risks of infection and thrombosis and are appropriate only for bedridden patients.
Ultrasound guidance for placement of femoral lines increases the likelihood of successful cannulation and reduces the risk of complications. When ultrasound guidance and trained personnel are available, this method of placement is preferred.
(See also Vascular Access, Central Venous Catheterization, and How To Do Femoral Vein Cannulation.)
Indications for Femoral Vein Cannulation, US-Guided
- Secure or long-term venous access that is not available using other sites
- Inability to obtain peripheral venous access or intraosseous infusion
- IV infusion of fluids and drugs for patients in cardiac arrest
- IV infusion of concentrated or irritating fluids
- IV infusion of high flows or large fluid volumes if placement of large-bore (eg, 18 or 16 gauge) peripheral venous catheters or other CVCs is not feasible
- Hemodialysis or plasmapheresis
- Transvenous cardiac pacing (see video How to Insert a Transvenous Pacemaker) or pulmonary arterial monitoring (Swan-Ganz catheter)*
- Placement of inferior vena cava filter
- Need for IV access in patients with malignant superior vena cava syndrome
Central venous access above the diaphragm, unless contraindicated, is generally preferred to femoral venous access in patients who require central venous access. Femoral lines are usually used only as provisional access because they have a high risk of infection. They should be exchanged for lines above the diaphragm as soon as possible.
Contraindications to Femoral Vein Cannulation, US-Guided
- Untrained or inexperienced ultrasound operator
- Intra-abdominal hemorrhage or regional trauma (sites that drain into the superior vena cava should be used)
- Unsuitable femoral vein, thrombosed (uncompressible) or inaccessible as seen by ultrasound
- Local infection at the insertion site
- Antibiotic-impregnated catheter in allergic patient
- Coagulopathy, including therapeutic anticoagulation*
- Local anatomic distortion, traumatic or congenital, or gross obesity
- History of prior catheterization of the intended central vein
- Uncooperative patient (should be sedated if necessary)
- Ambulatory patient
* Therapeutic anticoagulation (eg, for pulmonary embolism) increases the risk of bleeding with femoral vein cannulation, but this must be balanced against the increased risk of thrombosis (eg, stroke) if anticoagulation is reversed. Discuss any contemplated reversal with the clinician managing the patient's anticoagulation and then with the patient. Femoral vein cannulation may be preferred for coagulopathic patients because, unlike the subclavian or internal jugular sites, the femoral triangle is readily compressible and vital structures (airway, pleural dome, mediastinum, blood vessels to brain) are distant from the venipuncture site.
Complications of Femoral Vein Cannulation, US-Guided
(See also Complications of central venous catheterization.)
- Arterial puncture
- Retroperitoneal bleeding
- Damage to the vein
- Air embolism
- Catheter misplacement*
- Nerve damage
- Bladder or bowel perforation
* Rare complications due to femoral catheter misplacement include arterial catheterization and retroperitoneal infusion.
Guidewire or catheter embolism also rarely occurs.
To reduce the risk of venous thrombosis and catheter sepsis, CVCs should be removed as soon as they are no longer needed.
Equipment for Femoral Vein Cannulation, US-Guided
Sterile procedure, barrier protection
- Antiseptic solution (eg, chlorhexidine-alcohol, chlorhexidine, povidone iodine, alcohol)
- Large sterile drapes, towels
- Sterile head caps, masks, gowns, gloves
- Face shields
- Ultrasound machine with a high-frequency (eg, 5 to 10 MHz), linear array probe (transducer)
- Ultrasound gel, nonsterile and sterile
- Sterile probe cover to ensheathe probe and probe cord, sterile rubber bands (alternatively, the probe may be placed within a sterile glove and the cord wrapped within a sterile drape)
Seldinger (catheter-over-guidewire) technique
- Cardiac monitor
- Local anesthetic (eg, 1% lidocaine without epinephrine, about 5 mL)
- Small anesthetic needle (eg, 25 to 27 gauge, about 1 inch [3 cm] long)
- Large anesthetic/finder* needle (22 gauge, about 1.5 inches [4 cm] long)
- Introducer needle (eg, thin-walled, 18 or 16 gauge, with internally beveled hub, about 2.5 inches [6 cm] long)
- 3- and 5-mL syringes (use slip-tip syringes for the introducer needle)
- Guidewire, J-tipped
- Scalpel (#11 blade)
- Central venous catheter (adult: 8 French or larger, minimum length for femoral catheter is 24 cm)
- Sterile gauze (eg, 4 × 4 inch [10 × 10 cm] squares)
- Sterile saline for flushing catheter port or ports
- Nonabsorbable nylon or silk suture (eg, 3-0 or 4-0)
- Chlorhexidine patch, transparent occlusive dressing
* A finder needle is a thinner needle used for locating the vein before inserting the introducer needle. It is usually not needed for ultrasound-guided cannulation.
The external diameter of the CVC should be less than or equal to one third of the internal diameter of the vein (as measured by ultrasound) to reduce the risk of thrombosis.
Having an assistant or two is helpful.
- The short-axis (cross-sectional, transverse) ultrasound view is easy to obtain and is the better view for identifying veins and arteries and their orientation to each other. Identifying a needle tip in cross section requires some skill, because the needle appears as an echogenic (ie, white) dot and the tip can be distinguished only by the dot's disappearance and reappearance as the needle tip traverses back and forth across the imaging plane. The short-axis view typically is used to determine a suitable venous impalement site and to guide steeply angled (eg, ≥ 45°) needle insertions.
- The long-axis (longitudinal, in-plane) ultrasound view is technically more difficult to obtain (must keep probe, vein, and needle in one plane), but it shows the needle longitudinally, so the entire needle—including the tip—can be imaged continuously as it approaches and enters the vein; this helps avoid aberrant placement. The long-axis view is helpful when the angle of needle insertion is shallow (eg, in axillary/subclavian cannulations) and to affirm proper longitudinal needle alignment during short-axis insertions.
- Cannulation attempts sometimes fail. Do not exceed 2 or 3 attempts (which increases the risk of complications), and use new equipment with each attempt (ie, do not re-use needles, catheters, or other equipment because they may have become blocked with tissue or blood).
- During cardiopulmonary arrest, or even low blood pressure and hypoxia, arterial blood may be dark and not pulsatile and may be mistaken for venous blood.
- If the femoral artery is errantly cannulated by either the tissue dilator or the CVC, leave the dilator or catheter in place and obtain surgical consultation for possible surgical removal.
Relevant Anatomy for Femoral Vein Cannulation, US-Guided
- The femoral vein and artery are accessible within the femoral triangle, which is defined by the inguinal ligament superiorly, the adductor longus muscle medially, and the sartorius muscle laterally.
- The inguinal ligament is defined as a line drawn between the symphysis pubis and the anterior superior iliac spine.
- The femoral artery is imaged inferior to the midpoint of the inguinal ligament.
- The femoral vein is imaged medially adjacent to the artery. With increasing distance from the inguinal ligament, the vein runs under the artery.
- The desired point of femoral vein impalement is proximal to the saphenous vein entrance and 1 to 2 cm inferior to the inguinal ligament. Bleeding due to a vascular impalement here can be controlled by externally compressing the vessels against the femoral head.
- The retroperitoneal space lies superior to the inguinal ligament. Bleeding due to a vascular impalement here causes retroperitoneal bleeding, and external compression of the vessels is nearly impossible.
- The skin insertion site is influenced by both the imaging and the dimensions of the transducer tip (ie, the skin insertion site for long-axis ultrasound guidance may be several centimeters distal to that for short-axis ultrasound guidance).
Positioning for Femoral Vein Cannulation, US-Guided
- Raise the bed to a comfortable height for you (ie, so you may stand straight while doing the procedure).
- Place the patient supine or in slight reverse Trendelenburg position (bed tilted with the head up) to distend the femoral vein and prevent air embolism.
- Comfortably abduct and externally rotate the leg.
- Retract a pannus or a urethral catheter away from the inguinal area using tape (or an assistant if needed).
Step-by-Step Description of Procedure
Preliminary preparation (nonsterile)
- Check that the ultrasound machine is configured and functioning correctly. Ensure that the screen image 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 vein 1 to 2 cm inferior to the inguinal ligament and determine whether the vein is suitable for cannulation. Use a short-axis (cross-sectional) view. Blood vessels are hypoechoic (appear black on the ultrasound screen). Veins are generally larger, thin-walled, and ovoid (rather than thick-walled and round) and are more easily compressed (by gentle pressure on overlying skin) than their paired arteries. Venous thrombosis may appear as an echogenicity (gray irregularity) in the lumen but often is diagnosed because the thrombosed vein is incompressible. Thrombosis disqualifies the vein as a suitable cannulation site. Cannulate a central vein at a site of optimal short-axis imaging (ie, large-diameter cross section of the vein, with no overlying artery).
- Attach the cardiac monitor to the patient and turn it on.
- Excess hair may be clipped but not shaved from the site. Shaving increases the risk of infection.
Prepare the equipment
- 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 introducer needle to a 5-mL syringe with 1 to 2 mL of sterile saline in it. Align the bevel of the needle with the volume markings on the syringe.
- Pre-flush all lines of the CVC with sterile saline (3 to 5 mL) and then close the ports with caps or syringes.
- When flushing a central line, use a 10-mL syringe (or one of equal or greater diameter) and do not push too hard to avoid rupturing the line.
Prepare the sterile field
- 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.
Place a sterile cover over the ultrasound probe
- 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 or 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.
Anesthetize the cannulation site
Apply sterile ultrasound gel to the covered probe tip.
Use short-axis ultrasound guidance:
- Attain an optimal cross-sectional image of the femoral vein 1 to 2 cm inferior to the inguinal ligament. Press lightly with the probe tip to avoid distorting the image size and shape of the vein.
- Slide the probe transversely as needed to place the imaged vein at the center of the ultrasound screen. When the vein is centered on the ultrasound screen, the midpoint of the probe becomes a surface marker designating the luminal center of the underlying vein.
- Keep the probe in this spot.
- On the ultrasound screen, measure the depth to the center of the vein. 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 vein 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 vein.
- 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 vein and artery.
Insert the introducer needle
- 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 vein, adjust the lateral direction of the needle to keep the needle tip above the center of the vein. If the needle tip is approaching the vein too slowly, withdraw the needle a bit, increase the angle of insertion, and re-advance.
- As the needle tip approaches the vein, temper your speed and angle of insertion so the needle enters with as much control as possible. The superficial wall of the vein will indent when the needle tip encounters it. The needle then pops through the wall to enter the lumen, accompanied by a flash of dark red 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 vein.
Optional: If the accessible vein 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 vein, and then rotate the probe 90° to attain the long-axis (in-plane, longitudinal) view of the needle and vein, which provides better imaging of the venipuncture. Move the probe as needed to keep both the needle and the vein in sight (in-plane). Press lightly with the probe tip so the vein remains under the tip and does not roll to the side.
Assess the blood return
- Continue to hold the syringe motionless.
- Securely grasp the needle hub and also hold it motionless.
- Remove the syringe from the needle hub and briefly let blood flow out to confirm that the blood is venous (ie, dark red and flowing but not pulsatile). Then immediately cover the hub with your thumb to stop the blood flow and prevent air embolism.
However, if the blood is bright red and pulsatile (arterial), terminate the procedure. Remove the needle and use 4 × 4 gauze squares for 10 minutes to hold external pressure on the area and to help prevent bleeding and hematoma.
Insert the guidewire
- 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.
- Advance the guidewire through the needle and into the vein. You may use ultrasound guidance (either short- or long-axis) to verify the guidewire entering the vein. Do not force the wire; it should slide smoothly. Advance the wire 20 to 30 cm.
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 vein (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 and 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.
Remove the introducer needle (after successful guidewire insertion)
- 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.
Widen the insertion tract
- Extend the skin insertion site: Using the scalpel, make a small stab incision (about 4 mm) into the skin insertion site, avoiding contact with the guidewire, to enlarge the site and allow it to accommodate the larger diameters of the tissue dilator and the catheter.
- Advance the tissue dilator over the guidewire: First, grasp the guidewire at the skin and slide the dilator down the length of the wire to the skin. Then grasp the wire just distal to the dilator, hold the dilator near the skin surface, and use a corkscrew motion as needed to stepwise insert the entire length of the dilator. Maintain your grasp on the guidewire at all times during the insertion.
- Remove the dilator: First, securely hold the guidewire distal to the dilator and pull the dilator from the skin. When the guidewire is visible at the skin surface, completely remove the dilator by sliding it down the remaining length of the guidewire.
Place the 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.
- Continue to advance the catheter into the vein: 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, in increments of several centimeters and using a corkscrew motion as necessary, stepwise advance the entire length of the femoral catheter.
- Use ultrasonography to verify intravenous 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.
- Flush each catheter port with saline: First, draw any air from the line and confirm venous blood flow into the hub. Then, using a 10-mL syringe (or one of equal or greater diameter) and nonexcessive force, push 20 mL of saline into the line to clear it.
Dress the site
- If the patient is awake or minimally sedated, use 1% lidocaine to numb the skin at the planned suture locations.
- Place a chlorhexidine-impregnated disk on the skin at the catheter insertion point.
- Suture the skin to the mounting clip on the catheter.
- To prevent pulling on the insertion site, suture the catheter at a second site so that a curved or looped segment of catheter lies between the two sites.
- Apply a sterile occlusive dressing. Transparent membrane dressings are commonly used.
Aftercare for Femoral Vein Cannulation, US-Guided
- If needed (eg, if the femoral catheter is malfunctioning), do a chest x-ray to confirm that the tip of the catheter lies in the inferior vena cava distal to the right atrium.
Warnings and Common Errors
- Never lose grasp of the guidewire.
- During cardiopulmonary arrest, or even low blood pressure and hypoxia, arterial blood may be dark and not pulsatile and may be mistaken for venous blood.
- To help prevent air embolism, CVCs should be inserted (and removed) with the vascular cannulation site positioned dependant to the heart.
Tips and Tricks for Femoral Vein Cannulation, US-Guided
- Femoral lines are usually used only as provisional access because they have a high risk of infection. They should be exchanged for lines above the diaphragm as soon as possible.
Drugs Mentioned In This Article
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