0:01

Are a couple things I want to review that are unique

0:05

in pediatrics in particular.

0:07

I wanna briefly discuss

0:09

what a normal thymus might look like,

0:10

which might be different than what you're used

0:12

to seeing in older children or adults.

0:15

I assume that you already understand the basics of reading

0:18

a normal chest x-ray, so I'm just going to highlight

0:22

what a normal thymus can look like in a young infant.

0:26

Here's an example of an infant with a normal chest X-ray.

0:29

As you can see, we have our expected cardiac silhouette,

0:34

but we have this additional round

0:36

soft tissue density in the upper mediastinum

0:39

In a young child.

0:40

This is a normal appearance for thymus.

0:43

It has smooth convex borders

0:47

and it silhouettes the upper margin

0:50

of the cardiac silhouette.

0:52

This can have a variety of appearances,

0:54

however, this is another infant

0:56

who has an a different normal thymus.

0:59

You can see that there's a triangular opacity overlying the

1:02

right cardiac margin

1:05

and the lower border of

1:07

that thymus has a horizontal appearance.

1:10

This, again, is also a normal thymus.

1:13

There are a variety of additional appearances

1:15

that the thymus can have,

1:17

but these are a couple of the more common ones

1:19

and should not be mistaken for a mass.

1:23

This is in distinction to an abnormally uplifted thymus

1:27

in young babies, particularly infants in the

1:31

neonatal intensive care unit.

1:33

They are sometimes at risk for pneumo mediastinum,

1:36

and this is a patient who does have that note

1:38

that we can see this opacity uplifted from the rest

1:43

of the cardiac silhouette.

1:45

So this is what's called the Spinnaker sail sign,

1:47

where there's uplifting of the thymus off of the heart due

1:52

to air in the mediastinum.

1:54

You can even see the increased lucency underneath it.

1:59

This is different than the prior normal thymus

2:03

that I showed you here, sometimes called the thymic sail

2:06

sign where it looks like a sail on a sailboat,

2:09

but it's not uplifted.

2:10

The uplifted is the spinnaker sail sign,

2:13

and that is abnormal due to pediat.

2:17

The other thing I wanted to mention that is unique in kids,

2:19

particularly in premature young babies, is the presence

2:24

of umbilical catheters.

2:27

These include umbilical arterial lines

2:29

and umbilical venous lines.

2:32

Here's an example of a baby who has a number

2:34

of support devices,

2:35

but we're going to just talk about the umbilical lines.

2:39

You have to have an understanding

2:40

of normal fetal circulation to understand

2:43

where these lines go.

2:46

As you can see, we have two lines coming from inferiorly

2:49

that head superiorly,

2:51

and it's important to know which is which

2:53

because you want to make sure

2:54

that the tip is in the right place

2:56

and you also wanna make sure that the course

2:58

of the entire line is what you would expect it to be.

3:03

The outline that I just showed in the dark red color is

3:05

showing the external portion

3:07

of the umbilical venous catheter.

3:09

So this is outside of the patient,

3:11

probably just draped on their abdominal wall.

3:13

Where this line has stopped is at the level of the umbilicus

3:17

where is going into an umbilical vein.

3:21

I'll then continue this line with a slightly brighter red,

3:24

and that's showing the course

3:26

of the umbilical venous catheter, as we would expect,

3:28

relatively straight superiorly to the level

3:32

of the inferior Cabo atrial junction.

3:34

We expect the tip of this catheter to be about

3:37

where it is in this patient,

3:38

which is approximately at the level of the diaphragm,

3:40

maybe a little bit lower, but where we expect the IVC

3:43

to meet the right atrium.

3:46

On the other hand, an umbilical arterial catheter,

3:50

which we see the external portion of here in the dark blue.

3:54

This has a different course

3:55

and this is how you can tell the difference

3:57

between the umbilical arterial and venous catheters here.

4:00

Once it goes inside the umbilicus, it actually courses

4:03

inferiorly like this before it then goes superiorly.

4:08

And the reason is the umbilical artery first joins the

4:11

internal iliac artery either on the left or right side

4:14

before then coursing up into the aorta.

4:18

The tip of the umbilical arterial catheter

4:22

can have two potential landing zones.

4:25

This particular patient has the tip in the upper landing

4:28

zone, so essentially the mid thoracic region,

4:31

avoiding the major branches of the aortic arch,

4:33

so in the T six to T nine region.

4:36

However, you can also have the tip in the lower lumbar

4:40

region, again, avoiding the major branches

4:43

below the renal arteries around the low L three level.

4:47

Sometimes what institutions will do is they'll aim

4:50

to have the umbilical arterial catheter tip at the high

4:53

level in the mid thoracic region, and if they undershoot it

4:57

and they take a confirmatory X-ray

4:58

and they see that it is too low, they can just pull on it

5:01

until they reach the lower landing zone without having

5:04

to push it back up when we need

5:06

to create a new sterile field.

5:08

So here's a different example of a different patient

5:11

who again has multiple support devices,

5:13

but focusing on the umbilical catheters, we can see

5:16

that the UAC is about where we would expect

5:19

with the tip in the mid thoracic region,

5:22

but the UVC is a little bit high.

5:25

We can see that it's above the level of the diaphragm

5:28

overlying the right atrium.

5:30

This patient had their UVC pulled back a little bit

5:34

and a subsequent X-ray shows that it's been pulled down

5:38

much closer to the IVC right Atrium Junction.

5:42

As we would expect, this is a different patient

5:46

where the UVC has gone awry.

5:48

You can see that the UVC is coming in here

5:51

and it goes superiorly

5:52

and then all of a sudden it takes a hairpin

5:55

turn to the patient's, right?

5:57

And what has happened here is it has gone in

5:59

through into the portal vein.

6:02

Remember, the reason that the umbilical vein

6:05

or the umbilical venous catheter

6:07

can ultimately reach the right atrium

6:10

or the IVC right atrium junction is

6:12

because of the presence of the ductus osis,

6:14

a normal fetal shunt.

6:16

However, because the umbilical vein also communicates

6:21

with the portal vein, if it doesn't get

6:22

through the ductus osis to go into the IVC,

6:24

it can accidentally get into the portal system.

6:27

And this needs to be retracted immediately

6:29

because you don't wanna start putting in medications

6:32

and other fluids into the UVC into the portal vein.

6:36

Sometimes patients who have a UVC in this sort

6:39

of position might end up ultimately having some sort

6:42

of complex fluid collection in the liver

6:44

that can be confirmed by ultrasound, uh, as a result

6:48

of material going through the UVC.

6:51

Also, when it takes a turn like this, it can go either right

6:54

or left.