Technique
Techniques for USG PIV placement vary and can be adapted to best suit the user.
Techniques include:
- Static vs dynamic
- Single vs dual operator
- In-plane vs out-of-plane
Static vs Dynamic
In the static approach US is used solely to identify vessels and the overlying is marked. In a dynamic approach the US is used to guide the placement of the catheter into the vessel from skin puncture to cannulation. The static approach has significant limitations in terms of success due to movement of skin and subcutaneous tissues in relation to the underlying vessels. The dynamic use of US to guide needle placement is the preferred method in PIV access but can be more technically challenging to learn.
Single vs Dual Operator
USG PIV access can be performed with either single or dual operators – one person performs the ultrasound while the other performs the procedure. This provides the advantage of freeing up the proceduralist’s hands for IV placement alone. This technique also does not require the dual hand eye coordination of directing the ultrasound transducer as well as performing the procedure.
The dual operator technique is particularly useful in the situation where the operators have different skills sets, such as a nurse with good cannulation skills but limited US experience or a doctor who is comfortable identifying veins on US but lacks confidence in advancing and securing catheters. In such cases a dual operator approach may be preferred. Yet, with two operators, coordinating the ultrasound image relative to the needle can be technically challenging, so there is no preferred approach.
Out-of-plane vs in-plane
Finally, ultrasound guided procedures can be performed with either an out-of-plane or in-plane technique. Each has it advantages and drawbacks. The out-of-plane approach (figure 9) is generally preferred by novice users and has similar success rates compared to the in-plane approach, but special care must be taken to visualize the needle tip and avoid posterior wall puncture [14]. In pediatric patients a dynamic out-of-plane approach has been found to be successful and may be easier for novices [8,15].
Figure 9: Out-of-plane technique
The in-plane technique (figure 10) allows for visualization of the needle along its entire path and can reduce the risk of puncture of the posterior vessel wall, but it is a technically more challenging approach as keeping the vessel and needle in plane is difficult and the technique can be limited by vessel characteristics, operator experience, and patient movement.
Figure 10: In-plane technique
