What is the recommended technique for ultrasound-guided femoral access?

Ultrasound-Guided Femoral Access Technique

Ultrasound-guided dynamic guidance should be routinely used for femoral venous access to improve success rates and reduce complications, particularly inadvertent arterial punctures. 1

Pre-Procedural Assessment

• Use a high-frequency linear transducer with sterile sheath and sterile gel 2
• Perform pre-procedural ultrasound evaluation to:
  • Identify anatomical variations and vessel relationships
  • Confirm absence of vascular thrombosis
  • Evaluate target vessel size and depth
  • Apply color Doppler to differentiate between venous and arterial vessels 3
  • Locate the optimal puncture site (near the inguinal ligament at the level of the common femoral artery) 1

Procedural Technique

Equipment Setup

• Position the ultrasound machine on the side opposite to the operator for optimal screen visibility
• Use a high-frequency linear transducer (typically 7-12 MHz)
• Apply sterile gel and cover the probe with a sterile sheath 2

Vessel Identification

1. Place the transducer in the inguinal region to identify the femoral vessels
2. Visualize the femoral vein (typically medial to the femoral artery)
3. Apply gentle compression to confirm venous structure (veins are compressible, arteries are not)
4. Use color Doppler to further differentiate between arterial and venous flow 1

Needle Approach Options

• Transverse (short-axis) approach:

  • Position the probe perpendicular to the vessel
  • Advance the needle toward the vessel while visualizing the needle tip as a hyperechoic dot
  • Most commonly used for femoral access 1

• Longitudinal (long-axis) approach:

  • Position the probe parallel to the vessel
  • Advance the needle in-plane with the ultrasound beam
  • Allows visualization of the entire needle shaft and tip 1

Critical Steps

1. Puncture the femoral vein close to the inguinal ligament at the level of the common femoral artery 1
2. Visualize the needle tip entering the vessel in real-time
3. Confirm venous access by observing dark, non-pulsatile blood return
4. Visualize guidewire placement within the target vein before dilation 2
5. Use low abdominal compression if needed to facilitate vein puncture 1

Benefits and Advantages

• Reduces risk of inadvertent arterial puncture (from 15.8% to 7.1% with inexperienced operators) 1
• Improves first-attempt success rates (92.9% vs 55.3% compared to landmark technique) 1
• Decreases total procedure time (45.1 ± 18.8s vs 94.6 ± 61.7s) 1
• Reduces overall complication rates (1.4% vs 3.4%) 4
• Particularly valuable during cardiopulmonary resuscitation (reduces arterial catheterizations from 20% to 0%) 1

Common Pitfalls and How to Avoid Them

• Vessel compression: Apply minimal pressure with the ultrasound probe to avoid collapsing the femoral vein
• Needle visualization issues: Use echogenic needles or needle guides to improve visibility 2
• Anatomical variations: Structures in the inguinal region are less echogenic than in the neck region; careful pre-procedure scanning is essential 1
• Iliac vein thrombosis: If no increase in diameter occurs with compression, suspect iliac vein thrombosis 1
• Inadequate training: Ensure proper training before attempting the procedure independently 2

Special Considerations

• For pediatric patients, ultrasound guidance is particularly important as femoral veins can be difficult to visualize in infants 1
• In obese patients or those with difficult access, ultrasound guidance significantly improves success rates 1
• During cardiopulmonary arrest, ultrasound guidance reduces needle passes and arterial catheterizations 1

Ultrasound-guided femoral access represents a significant advancement over traditional landmark techniques, with clear benefits for patient safety and procedural success. While experienced operators may achieve similar success rates with landmark techniques in routine cases, the evidence strongly supports using real-time ultrasound guidance as the standard approach for femoral vascular access.