Central Venous Access

A central line provides rapid access to the right side of the heart, which would allow drugs to be rapidly delivered to the rest of the body. A central line has many applications, including: a chemotherapy port, emergency delivery of drugs or large volumes of fluid, total parenteral nutrition, pacemaker leads, etc.

Objectives

Orientation

Let's begin with the skeleton. We've omitted the clavicles and sternum. Rib 1 is the only rib included. From the first and second costocartilages you can infer the position of the manubrium and the sternal angle of Louis. At any time, feel free to add back skin or rotate the image. Remember to use mouse-overs with the "highlight" tool activated to identify things. In the sectional images, identify the first rib and clavicle.

Let's look at the major veins that lead to the superior vena cava. The subclavian veins and internal jugular veins are commonly used for the central line. Relate them to the clavicle and first rib in the sectional images. The veins have different names based on location. To see where the same vessel changes names, use mouse-overs to trace the veins from the thorax to their origins.

Part I: Subclavian vein lines

This Youtube video discusses the instrumentation and techniques for infra- and supra-clavicular approaches to the subclavian vein. The anatomy of the procedure is discussed between minutes 5:40 and 7:35.

Test your recall of the video by answering the questions embedded in this more detailed exploration of the anatomy.

We will work on the left side. To give an unobstructed view when you choose to rotate the image, we'll omit the right-side structures. Add in the clavicle. Your target is the subclavian vein, between the clavicle and first rib. Rotate the image 60° to the left to see the flight path of your needle into the vein Add back some skin to see where you are.

Now let's add some structures you want to avoid. First the arteries. (Remember to use mouse-overs to identify them) Rotate the image through 360° to confirm that the axillary artery and vein are very close together throughout their distal course beyond the first rib.

Click on the green box to see the answer. To activate a link in the answer right, or control, click of the link and choose "open"

Where do you see a gap between the subclavian vein and artery?

Right! When you rotate the image to 90° to the left or 90° to the right. Look where the vessels cross the rib.

On the sectional images, use mouse-overs with the highlight tool activated and identify the muscle that separates the artery and vein.

Add in the anterior scalene muscle. Rotate thru 360° to confirm how the anterior scalene separates the the subclavian artery and vein.

Now look at 0° as we remove the clavicle and then remove the subclavian vein. Mouse-over the axial image to see the relationship of the clavicle, vein, muscle and artery. Therefore, you can inject the vein where it crosses the first rib and the anterior scalene muscle will protect the artery from your needle, should you go too deep.

What else would be protected by the anterior scalene muscle?

Add in the brachial nerve plexus. These nerves supply the arm and shoulder. Your patient will let you know if you hit it!

What nerve lies on the anterior surface of the anterior scalene muscle and would be at risk of injury by your procedure?

Add in the phrenic nerve (controls the phrenic diaphragm and one's ability to breathe).

See how the Lung extends above the first rib. It your needle goes deep you can enter the pleural cavity.

What would be the result of puncturing the lung?

A pneumothorax, which would let air enter to the pleural cavity thereby decreasing lung capacity. Because of this you would not do this procedure if the contralateral lung was compromised by pneumothorax, hemothorax, or dysfunctional hemidiaphragm.

Lastly, note a major lymphatic vessel that drains most of the body, the thoracic duct.

What would injuring this vessel cause?

A chylothorax, which allow lymph to enter pleural cavity thereby decreasing lung capacity.

Let's add back the entire skeleton for one final look. Rotate this around as much as you like!

Now try to apply your knowledge and interpret the following sonographic images used for the ultrasound-guided approach to the placing a central line.

Part II: Jugular vein lines

This Youtube video reviews the anatomical principals and demonstrates three different approaches to the Jugular vein.

Test your recall of the video by answering the questions embedded in this more detailed exploration of the anatomy.

Let's begin with the bones and the sternocleidomastoid muscle on one side. Now, we'll add the internal jugular vein and common carotid artery on both sides. Rotate the main image and examine the sectional images to answer the following questions.

Which vessel has the closest relationship to the sternocleidomastoid muscle?

The internal jugular vein is just deep the muscle throughout its course.

Which vessel is medial to the other?

The common carotid artery.

There are several ways to locate the internal jugular vein.

Now try to apply your knowledge and interpret the following sonographic images used for the ultrasound-guided approach to the placing a central line.

The next movie provides more clinical details.

Summary