Peripheral Venous Access - Real Time IV Access
Real Time IV Access
In the Vascular Access - Basics Module, we talked about the techniques of both the Short Axis and Long Axis approaches. Here, we shall apply them for peripheral venous access. As a reminder, Real Time US signifies maintaining the needle tip in view during the entire process.
1. Short Axis Approach
2. Long Axis Approach
In the Vascular Access - Basics Module, we talked about the techniques of both the Short Axis and Long Axis approaches. Here, we shall apply them for peripheral venous access. As a reminder, Real Time US signifies maintaining the needle tip in view during the entire process.
1. Short Axis Approach
2. Long Axis Approach
1. Short Axis Approach
The vessel of interest is imaged in its short axis, and the needle is guided into the vascular lumen with this view. The needle, also, is imaged in its short axis as well with this approach. On the monitor, the vessel will be displayed as a circular/ovoid anechoic structure, and the needle tip will be an hyperechoic dot.
The vessel of interest is imaged in its short axis, and the needle is guided into the vascular lumen with this view. The needle, also, is imaged in its short axis as well with this approach. On the monitor, the vessel will be displayed as a circular/ovoid anechoic structure, and the needle tip will be an hyperechoic dot.
a. Staggered Sliding:
- Center the vein
- Introduce the needle
- Look for the hyperechoic dot
- Look for the needle tip
- Advance the probe until the needle tip fades
- Advance the needle forward until the hyperechoic dot reappears
- Repeat until the hyperechoic dot is in the vessel
- Advance the tip until it is in the center of the lumen to ensure the angiocath's sheath is, also, in the lumen
b. Posterior Wall Pass
In reality, and in particular for peripheral veins due to their small diameters and low pressures, the needle will often collapse the entire vessel such that the anterior and posterior walls are in contact. As a result, when one advances the needle, the posterior wall will be penetrated - passed beyond the lumen.
If that is the case, in real time, very slowly and gently withdraw the needle until the tip is in the lumen.
In reality, and in particular for peripheral veins due to their small diameters and low pressures, the needle will often collapse the entire vessel such that the anterior and posterior walls are in contact. As a result, when one advances the needle, the posterior wall will be penetrated - passed beyond the lumen.
If that is the case, in real time, very slowly and gently withdraw the needle until the tip is in the lumen.
2. Long Axis Approach
The vessel of interest is imaged in its long axis, and the needle is guided into the vascular lumen with this view. The needle, also, is imaged in its long axis as well with this approach. On the monitor, the vessel will be displayed as a tubular anechoic structure, and the needle will be seen along its length.
This is a more challenging technique as most peripheral superficial veins are not straight - it is not easy to find a segment of vein that is straight enough to run across the entire screen. However, if you have a "decent" length of the vein imaged on the screen, it should be doable.
The vessel of interest is imaged in its long axis, and the needle is guided into the vascular lumen with this view. The needle, also, is imaged in its long axis as well with this approach. On the monitor, the vessel will be displayed as a tubular anechoic structure, and the needle will be seen along its length.
This is a more challenging technique as most peripheral superficial veins are not straight - it is not easy to find a segment of vein that is straight enough to run across the entire screen. However, if you have a "decent" length of the vein imaged on the screen, it should be doable.
a. Fixed Imaging
- Image the vein in at its WIDEST diameter in the long axis
- Steady the probe-hand once the ideal image is attained
- Introduce the needle IN PLANE with the probe
- Advance the needle forward until the hyperechoic tip is in the vessel
- Advance the tip until it is in the center of the lumen to ensure the angiocath's sheath is, also, in the lumen
Key Messages:
- Real time US demands visualization of the needle TIP during the entire guidance process
- Short axis: beware of advancing the needle in a windy trajectory which can KINK angiocath once the needle is withdrawn
- Long axis: need a decent length of vein imaged on its long axis though not always easy to find
- Ensure the needle tip and the angiocath's sheath are in the vascular lumen