Where is the landmark for a central venous catheter insertion?

For over a century, clinicians have relied on anatomical knowledge to place central venous catheters. Understanding where is the landmark for a central venous catheter insertion? is critical for safe and effective central line placement, especially in emergency situations.

Quick Summary

Central venous catheter insertion landmarks vary by site, with the internal jugular vein accessed at the sternocleidomastoid triangle's apex, the subclavian vein beneath the mid-clavicle, and the femoral vein medial to the artery in the groin crease.

Key Points

• Internal Jugular Vein: Insert at the apex of the SCM muscle triangle, typically lateral to the carotid artery, aiming toward the ipsilateral nipple.

• Subclavian Vein: Insert 1-2 cm inferior and lateral to the clavicle's medial/middle third junction, aiming toward the sternal notch.

• Femoral Vein: Insert medial to the femoral artery pulse, 1-2 cm below the inguinal ligament, using the NAVEL mnemonic.

• Confirmation: A chest X-ray must confirm the final catheter tip position, using the carina as a reliable landmark to ensure the tip is in the SVC, not the heart.

• Ultrasound Guidance: Now the standard of care for many insertions, ultrasound provides superior accuracy and reduces complications compared to landmark-only techniques, although landmark skills remain vital.

The use of anatomical landmarks is a cornerstone of medical procedures like central venous catheter (CVC) insertion, though modern practice increasingly integrates ultrasound guidance. This guide details the specific landmarks for the most common insertion sites, the traditional landmark techniques, and how they compare with modern ultrasound-guided methods.

Internal Jugular (IJ) Vein Landmarks

The internal jugular (IJ) vein is a frequent and often preferred site for CVC placement due to its accessibility and relatively low complication rates, especially on the right side which provides a more direct path to the superior vena cava (SVC). The primary landmarks for the central approach are based on the sternocleidomastoid (SCM) muscle.

• The SCM Triangle: The SCM muscle has two heads: a sternal head and a clavicular head. These heads form a triangle with the clavicle at the base. The apex of this triangle is the primary site for needle insertion.
• Central Approach: For this technique, the puncture site is at the apex (superior angle) of the SCM triangle. The needle is inserted at a 30-40° angle to the skin, aiming toward the ipsilateral nipple.
• Artery vs. Vein: The IJ vein typically lies superficial and lateral to the pulsatile common carotid artery. Gentle palpation of the carotid pulse can help orient the clinician to the vein's location. However, anatomical variation is common, making real-time ultrasound guidance a safer standard.

Subclavian Vein Landmarks

The subclavian vein runs beneath the clavicle and offers a valuable alternative access site, particularly in trauma cases where neck access might be limited. The infraclavicular approach is most commonly used for landmark-guided insertion.

• The Clavicle's Break: The clavicle, or collarbone, is the main landmark. Clinicians identify the junction of the medial and middle thirds of the clavicle, often referred to as the "break".
• Puncture Site: The needle insertion point is typically 1-2 cm inferior and lateral to this junction.
• Needle Direction: The needle is advanced, keeping it parallel to the floor, and aimed toward the sternal notch or the operator's index finger placed there. This trajectory allows the needle to pass under the clavicle, into the subclavian vein.
• Limitations: This site is non-compressible, and complications like pneumothorax are a greater risk with landmark-based methods.

Femoral Vein Landmarks

The femoral vein in the groin is another option, favored during resuscitations when upper body access is difficult. It offers an easily compressible insertion site.

• The Femoral Triangle: The boundaries of this triangle are the inguinal ligament (superior), the sartorius muscle (lateral), and the adductor longus muscle (medial).
• NAVEL Mnemonic: A key anatomical landmark relationship is remembered with the mnemonic Nerve, Artery, Vein, Empty space, Lymphatics, from lateral to medial within the triangle. The femoral artery is typically palpated at or just medial to the midpoint of the inguinal ligament.
• Puncture Site: The needle is inserted 1-2 cm medial to the palpable femoral artery pulse, approximately 1-2 cm inferior to the inguinal ligament. It is crucial to insert below the inguinal ligament, as insertion above this point enters the retroperitoneum, where bleeding is difficult to control.

Ultrasound vs. Landmark Technique: A Comparison

For decades, the landmark technique was the sole method for CVC insertion. However, ultrasound guidance has emerged as a superior method for many central line placements, particularly for the IJ vein.

Feature	Landmark Technique	Ultrasound Guidance
Accuracy	Dependent on anatomical knowledge and palpation, with significant risk of variation.	Real-time visualization of the vein, reducing reliance on external anatomy and accounting for variation.
Complications	Higher rates of arterial puncture, hematoma, and pneumothorax, especially in the subclavian site.	Significantly lower rates of complications, including arterial puncture and hematoma.
Speed	Potentially faster in urgent scenarios if the operator is highly experienced and venous access is clear.	May add a short amount of time for setup and visualization but increases overall procedural safety.
Equipment	Requires no special equipment beyond the CVC kit.	Requires a portable ultrasound machine and sterile probe cover.
Best Use	Appropriate when ultrasound is unavailable or in dire emergencies where an experienced operator can gain rapid access.	Recommended standard of care for most CVC insertions, particularly for IJ access, to maximize safety and success.

Final Catheter Tip Position: Using the Carina as a Landmark

Regardless of the insertion site or technique, the ultimate placement of the CVC tip must be confirmed radiographically, typically with a chest X-ray. The final destination for the catheter tip is usually the superior vena cava (SVC), ideally just above its junction with the right atrium (RA).

• The Carina: This is the point where the trachea divides into the left and right main bronchi and is visible on a chest X-ray. Since the pericardial sac ends below the carina, ensuring the catheter tip is above this level minimizes the risk of cardiac tamponade from catheter-related trauma.
• Right vs. Left CVC: Catheters inserted on the right side have a more direct path. Left-sided catheters must traverse the brachiocephalic vein at an angle to reach the SVC, which may require deeper insertion to avoid vessel wall trauma. The position relative to the carina will guide safe placement.

To learn more about the technical aspects of these procedures, you can consult authoritative medical sources like the National Institutes of Health.

Conclusion

While ultrasound has become the gold standard, understanding anatomical landmarks remains a foundational skill for all clinicians. These landmarks—including the SCM triangle for the IJ, the clavicle's break for the subclavian, and the femoral artery pulse in the groin for the femoral vein—are essential guides for safe CVC insertion. Always verify proper tip placement using imaging, such as referencing the carina on a post-procedure chest X-ray, to confirm optimal positioning in the SVC. This combination of anatomical knowledge, technique, and confirmatory imaging ensures patient safety and procedural success.

Frequently Asked Questions

Is using a landmark for a central venous catheter insertion outdated?

While landmark-guided techniques are still used, particularly in emergencies, modern medical guidelines recommend ultrasound guidance whenever possible. Ultrasound offers improved visualization, higher first-attempt success, and significantly reduces complication rates, especially with the internal jugular vein.

How do you use landmarks for internal jugular vein access?

For the central approach, the needle is inserted at the apex of the triangle formed by the two heads of the sternocleidomastoid muscle and the clavicle. The internal jugular vein is located lateral and superficial to the carotid artery, which can be gently palpated as a landmark.

What is the NAVEL mnemonic for femoral access?

NAVEL is a helpful tool for recalling the order of structures in the femoral triangle, from lateral to medial: Nerve, Artery, Vein, Empty space, and Lymphatics. The vein is medial to the palpable femoral artery pulse.

Why is the carina an important landmark for a central venous catheter?

The carina is the point where the trachea divides into the main bronchi. It is a visible landmark on a chest X-ray and is reliably located above the pericardial reflection. Placing the CVC tip in the superior vena cava above the carina minimizes the risk of cardiac tamponade.

Which landmark technique is considered the riskiest?

The subclavian landmark approach carries a higher risk of complications, such as pneumothorax (collapsed lung), because the vein is close to the lung apex and obscured by the clavicle, making it difficult to compress if complications occur. Ultrasound guidance is particularly beneficial for this site.

What happens if a CVC is inserted above the inguinal ligament during a femoral insertion?

Inserting a CVC above the inguinal ligament means accessing the external iliac vein, which is a retroperitoneal structure. Bleeding in this area is difficult to control with external pressure, making proper landmark identification critical.

What is the Seldinger technique in relation to landmarks?

The Seldinger technique is a wire-guided method for placing a catheter. It begins with a needle stick guided by anatomical landmarks or ultrasound. A guidewire is advanced through the needle, which is then removed, allowing a dilator and the catheter to be threaded over the wire into the vessel.