Pleural Effusion

00:01 So now let's talk a little bit about pleural effusion, a very common abnormality that's found within the chest.

00:06 Pleural effusion is accumulation of fluid within the pleural space.

00:11 Pleural fluid is physiologically produced at the capillary bed of the parietal pleura but it's usually absorbed by the parietal pleural, lymphatics and the visceral pleura.

00:21 There are different causes of pleural effusion including increased rate of formation, decreased rate of absorption and direct extension from the peritoneum through the diaphragm.

00:34 So let's just take a look at the anatomy one more time, so we have here the lung which is surrounded by the visceral pleura which is right here, the inside layer.

00:47 The outside layer is called the parietal pleura and in between the two is the pleural space where the fluid accumulates.

00:55 So pleural effusions are characterized by their protein content, they can be transudative in which they have a very low protein content and this is usually the result of an increase in hydrostatic pressure or decrease an osmotic pressure and causes include congestive heart failure, cirrhosis, nephrotic syndrome or any cause of hypoalbuminemia.

01:17 They can also be exudative or have a high protein content and these are usually the result of an inflammatory or an infectious process like pneumonia. They could be cause by any kind of cancer within the lung.

01:29 Hemothorax is considered as high protein content diffusion.

01:33 Empyema which is the collection of infected fluid or possibly a pulmonary embolism that results in infraction.

01:41 So the infracted tissue can result in a pleural effusion that has a high protein content.

01:46 Pleural effusion are also characterized by whether they're bilateral or unilateral.

01:52 The most common bilateral effusions are caused by CHF and a little bit less commonly lupus.

01:58 Unilateral pleural effusion are often caused by malignancy, infection, trauma, pulmonary embolism or cirrhosis.

02:06 And again these are somewhat general categorizations so each of these can also cause the opposite type of effusion.

02:12 So what is a subpulmonic pleural effusion? Within the pleural space, that's just above the diaphragm, there could be an accumulation of fluid which is really best seen on an upright film.

02:24 So you can see here that there's elevation of the right hemidiaphragm much significantly higher than the left hemidiaphragm and this is really the only finding of a subpulmonic effusion.

02:35 So if you see a symmetric elevation of the hemidiaphragm one of the things to consider is a subpulmonic pleural effusion.

02:42 Often pleural effusion start in the subpulmonic location because of gravity and then they arise and move up to the sides.

02:49 So there are two different categories of pleural effusion in terms of location.

02:54 One is a free-flowing effusion and this is a normal gravity dependent flow within the pleural space. These are usually the most common and the fluid redistributes based on patient's positioning.

03:06 So on the left, we see an image of a patient that supine and you can see that the fluid layers throughout the right lung.

03:13 The entire right lung appear somewhat hazy with the apex being a little bit less hazy because more of the fluid is located inferiorly.

03:21 On the right, you have a semi-upright film which is obtained a few minutes later in the same patient.

03:26 And you can see that the fluid has now dropped down inferiorly because the patient has gone into a semi upright position.

03:32 And so now the fluid because of gravity is a little bit more inferiorly located.

03:37 Pleural effusion can also be loculated or walled off and this is usually a cause of adhesions in which you have no change in shape or location with changes in patient position.

03:48 So it's a small collection of fluid that really can't move around at all and you can see an example of it here.

03:53 The patient has bilateral loculated pleural effusions with even though the patient is upright in this position you can see that the fluid remains in the upper part of the lung on both sides.

04:04 So these cannot be drained as well as the free-flowing effusion.

04:09 So it's important to recognize these for therapeutic reasons because they're walled-off and they often contain multiple septations eventhough you try to drain it not all of the fluid will come out.