Central Venous Access - Anatomical Considerations
Anatomical Considerations
Before we can use PoCUS to help us identify veins, we need to have a idea where they are, or how to find them. Unlike the peripheral veins, the location of the central veins of interest are relatively constant.
1. Cervical Approach
2. Femoral Approach (under construction)
3. Subclavian Approach (under construction)
Before we can use PoCUS to help us identify veins, we need to have a idea where they are, or how to find them. Unlike the peripheral veins, the location of the central veins of interest are relatively constant.
1. Cervical Approach
2. Femoral Approach (under construction)
3. Subclavian Approach (under construction)
1. Cervical Approach
Cervical Triangle Surface Anatomy
Recall that the Cervical Triangle is bounded by the two heads of the sternocleidomastoid muscles (clavicular and sternal heads) and the proximal clavicular bone. The internal jugular vein (IJV) and common carotid artery (CCA) can be found fairly consistently within this triangle.
Most textbooks states that the IJV is lateral to the CCA though in reality this is the not the case (see. Pearls).
Cervical Triangle Surface Anatomy
Recall that the Cervical Triangle is bounded by the two heads of the sternocleidomastoid muscles (clavicular and sternal heads) and the proximal clavicular bone. The internal jugular vein (IJV) and common carotid artery (CCA) can be found fairly consistently within this triangle.
Most textbooks states that the IJV is lateral to the CCA though in reality this is the not the case (see. Pearls).
Right IJV - 2D
This image was taken at the right cervical triangle. These are the general structures seen at the level of the thyroid.
This image was taken at the right cervical triangle. These are the general structures seen at the level of the thyroid.
- Position: ie. lateral to the CCA
- Caliber: usually smaller than CCA unless venous pressure is high
- Wall: quite thin
- Dynamic: vary with respiration
- Pulsation: usually no pulsation - if you do, it is quivering due to the puslation transmission from CCA, triphasic waveform, or tricuspid regurgitation
- Compressibility: readily compressible (anterior wall touching posterior wall) with little pressure
Right IJV - Colour
If you put on Colour Doppler at the IJV, usually you will see the signal indicating the flow of blood is into the thorax.
Here you see the doppler signal within the IJV lumen is continuous with no phase variations. However, this may change if there is, for example, a large CV wave due to tricuspid regurgitation.
If you put on Colour Doppler at the IJV, usually you will see the signal indicating the flow of blood is into the thorax.
Here you see the doppler signal within the IJV lumen is continuous with no phase variations. However, this may change if there is, for example, a large CV wave due to tricuspid regurgitation.
Right CCA - 2D
This image was taken at the right cervical triangle. These are the general structures seen at the level of the thyroid.
This image was taken at the right cervical triangle. These are the general structures seen at the level of the thyroid.
- Position: ie. medial to the IJV
- Caliber: usually larger than IJV unless venous pressure is high
- Wall: thicker wall
- Dynamic: does not vary with respiration
- Pulsation: monophasic
- Compressibility: not readily compressible unless in shock (sometimes able to compress during diastole, but not systole)
Right CCA - Colour
Colour Doppler signal will indicate the blood is flowing out of the thorax. You will see a continuous doppler signal (flow occurs during both systole and diastole). However, during systole, you will see a sudden increase in signal intensity.
Colour Doppler signal will indicate the blood is flowing out of the thorax. You will see a continuous doppler signal (flow occurs during both systole and diastole). However, during systole, you will see a sudden increase in signal intensity.
IJV Cannulization Suitability
Before introducing the needle, evaluate the IJV that you have found to see if it is suitable for cannulization:
Before introducing the needle, evaluate the IJV that you have found to see if it is suitable for cannulization:
- Position: Where is it relative to other critical structures (eg. superior CCA?)
- Depth: How deep is it? Is your needle and angiocath long enough to reach the IJV?
- Caliber: Is it small and easily collapsible with pressure? Run along the course of the IJV and see if it narrows (stenosis) - if it is too small, you may not be able to thread the wire (J-tipped) or even the angiocath.
- Patency: Is the IJV lumen occupied by something else? Clot, valve, mass?
- Trajectory: Is the IJV course relatively straight?
- Surrounding: What are the critical structures around the IJV? Are they too close?
Non-patent vein: On first glance, the internal jugular vein looked quite patent though as the probe translated towards the clavicle, it rapidly tapered with an intraluminal mass in situ.
Non-patent vein:
Another case of internal jugular vein occlusion in longitudinal access.