Central Venous Access - Guidewire Position Verification
Guidewire Position Verification
Using PoCUS to confirm the location of the Guidewire is without a doubt THE MOST important safety maneuver just prior to THE MOST dangerous step - Vascular Dilatation. As you may recall from the central venous catherization procedure, after the Guidewire has been fed into the vascular lumen and the needle withdrawn (leaving only the wire in situ), the next step is to apply the Dilator. PoCUS allows us to verify where the Guidewire is situated - IJV vs CCA vs other structures - before dilatation.
Using PoCUS to confirm the location of the Guidewire is without a doubt THE MOST important safety maneuver just prior to THE MOST dangerous step - Vascular Dilatation. As you may recall from the central venous catherization procedure, after the Guidewire has been fed into the vascular lumen and the needle withdrawn (leaving only the wire in situ), the next step is to apply the Dilator. PoCUS allows us to verify where the Guidewire is situated - IJV vs CCA vs other structures - before dilatation.
The whole point is to ENSURE the Guidewire is dwelling within the IJV lumen so that the Dilator will be guided to the IJV vascular wall for dilatation - preventing the CCA from being dilated.
The other thing you may evaluate with PoCUS is to see which way is the Guidewire coursing - made a U-turn and traversed up the IJV, or into the thorax.
The other thing you may evaluate with PoCUS is to see which way is the Guidewire coursing - made a U-turn and traversed up the IJV, or into the thorax.
Some studies have shown promise to this technique. Perhaps the most illuminating one is the study on the right (AJEM 2011) - what you can see from this study is that visualizing rate for Needle is poor relative to the visualization of the Guidewire. Real Time US needle tip guidance is not an easy task even for experts, let alone when the novice is internalizing the complex procedure and refining manual dexterity. However, the study demonstrated that Guidewire can be visualized fairly easily. Consequently, as long as the Guidewire is situated within the IJV, whether Real Time US needle tip guidance is employed or not is less pertinent.
1. Short Axis Approach to Guidewire Position Verification Animation
- Place the probe next to the wire
- Situate the probe so that it is imaging the short axis of the vessels
- Slowly slide the probe distally (towards the clavicle)
- Look for the hyperechoic dot (Guidewire body) and note:
- Where is the hyperechoic dot located
- Is the hyperechoic dot the wire
Short Axis Approach to Guidewire Position Verification
Can you the hyperechoic dot?
The Guidewire tends to runs along the posterior vascular wall. Sometimes it can be a bit difficult to see. You can make small movements with the wire (back and forth motion) to help you spot the it via the dynamic motion.
Can you the hyperechoic dot?
The Guidewire tends to runs along the posterior vascular wall. Sometimes it can be a bit difficult to see. You can make small movements with the wire (back and forth motion) to help you spot the it via the dynamic motion.
2. Long Axis Approach to Guidewire Position Verification
The Guidewire may, also, be visualized in its long axis, and you will see its entirety running from the skin, subcutaneous tissue, and within the vascular lumen.
The Guidewire may, also, be visualized in its long axis, and you will see its entirety running from the skin, subcutaneous tissue, and within the vascular lumen.
3. Short vs Long Axis Approach - Which Method?
Know how to do both in case you are having trouble with one particular view.
I personally favour the short axis method for the following reasons:
Know how to do both in case you are having trouble with one particular view.
I personally favour the short axis method for the following reasons:
- Long Axis view may not be easy to find
- Short Axis allows me to see the surrounding structures as well - to see if the Guidewire traversed into another adjacent structure (see animation: sometimes, the angiocath made a double pass without you realizing even with Real Time US needle guidance )
Take Home Messages:
- Verifying the Guidewire is dwelling within the central venous lumen of choice is the key safety mechanism just prior to vascular dilatation
- Use the short or long axis approach to verify the Guidwire's location and trajectory