Pleural effusion: Clinical sciences

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Introduction0:00–0:57

Pleural effusion refers to a fluid that accumulates between the parietal pleura and visceral pleura, known as the pleural space, and can be caused by conditions such as congestive heart failure, pneumonia, cancer, cirrhosis, and kidney disease, to name a few.
Depending on the fluid characteristics and how it accumulates, pleural effusions are broadly classified as either transudates or exudates.
Transudate occurs when too much fluid starts to leave the capillaries, either because of increased hydrostatic pressure or decreased oncotic pressure.
On the other hand, exudate is typically associated with inflammation, which allows immune cells and large proteins to leak out of the capillaries.
Based on the type of fluid and etiology, exudates can be further subdivided into parapneumonic effusions, malignant effusions, inflammatory effusions, and chylous effusions.

Unstable branch0:57–1:24

Now, if you suspect a pleural effusion, first perform an ABCDE assessment to determine if your patient is unstable or stable.
If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and provide supplemental oxygen, if needed.
Finally, put your patient on continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry.
Alright, now let’s go back to the ABCDE assessment and take a look at stable individuals. If the patient is stable, you should start with acute management, like obtaining IV access, providing supplemental oxygen, and initiating continuous vital sign monitoring.

Stable branch1:24–2:16

Next, you should perform a focused history and physical, and order labs, including a CBC.Individuals with pleural effusion typically report cough, shortness of breath, and pleuritic chest pain, which is typically described as a severe, sharp pain that worsens with breathing.
Some patients may also report a fever. On the flip side, physical exam findings usually include dullness to chest percussion, as well as decreased tactile fremitus and absent basilar breath sounds on the affected side.
On labs, CBC might show leukocytosis. At this point, you should suspect pleural effusion, so order an imaging study.

Suspect pleural effusion2:16–3:46

Including a chest X-ray, point of care ultrasound or POCUS, or a CT to confirm the diagnosis. If the chest X-ray reveals blunting of the cardiophrenic and costophrenic angles, it indicates a pleural effusion.
You may also see a meniscus sign, which is when accumulated fluid completely surrounds the base of the lung. A chest X-ray might not show a pleural effusion until at least 250 ml of fluid has accumulated.
Often, a lateral decubitus X-ray can more accurately demonstrate a smaller effusion, and might also help you determine if the fluid is loculated.Alternatively, you can use POCUS, which can detect as little as 5 mL of fluid!
POCUS will typically reveal a fluid-filled, or anechoic, collection just above the diaphragm. You may also see a spine sign, which refers to the visualization of the part of the thoracic spine due to the presence of fluid that is typically obscured by air in the lungs.
Lastly, you can order a CT to further characterize the effusion, help find the underlying cause, and aid in potential treatment such as thoracentesis or chest drains.
Your imaging studies should confirm the presence of pleural effusion. If the imaging findings are inconsistent with pleural effusion, you should consider an alternative diagnosis.Now, once you confirm the presence of a pleural effusion, your next step is to determine the cause.

CHF3:46–4:49

First, assess whether or not your patient has congestive heart failure, or CHF for short. Physical exam findings, such as tachypnea, jugular venous distension, peripheral edema, rales, or an S3 heart sound are highly suggestive of CHF.
In this case, start CHF management, typically with diuretics. Next, assess the patient’s response to treatment.
If there’s an adequate response to the diuretics, meaning the amount of pleural fluid is reduced, continue current management!
However, if your patient has an inadequate response, with no reduction of pleural fluid, proceed with a therapeutic thoracentesis.Here’s a clinical pearl!
Large effusions may reaccumulate despite therapeutic thoracentesis. If this is the case, your patient may need to be evaluated by the surgery team for a chest tube or video-assisted thoracoscopic surgery, or VATs for short.Ok, now let’s take a look at individuals that present with findings inconsistent with congestive heart failure!

Thoracentesis4:49–5:47

In this case, proceed with diagnostic and therapeutic thoracentesis! This includes removing accumulated fluid from the pleural cavity, and sending it for lab analysis.
Be sure to order a cell count with differential, total protein, LDH, glucose, and cholesterol and triglycerides. At the same time, order serum total protein and LDH.
Okay, so once the lab results are back, analyze the pleural fluid by using the “Light’s Criteria fluid analysis”. This will determine whether the pleural fluid is a transudate or an exudate.
There are three criteria, which are the ratio of pleural protein, or “pProtein” to serum protein or “sProtein”, the ratio of pleural LDH or “pLDH” to serum LDH or “sLDH”, and pleural fluid LDH levels.So, in transudates, the ratio of pleural protein to serum protein is less than 0.5; pleural LDH to serum LDH is less than 0.6; or pleural fluid LDH is less than 2/3 of the high-normal level for serum LDH.

Transudate5:47–6:52

If any of these conditions are present you can diagnose disease specific effusion. Transudative fluid is often a result of conditions that can lower oncotic pressure, and increase hydrostatic pressure in the pleural space, such as CHF, cirrhosis, or nephrotic syndrome.
If the patient has a transudate, it’s important to treat the underlying cause.Here’s a clinical pearl to keep in mind! If the patient has a transudate but it’s still not clear whether they have CHF, you can order a test called the pleural NT-proBNP.
If the value is greater than 1300 to 4000 pg/mL, it confirms a CHF diagnosis. Otherwise, other potential causes include hypoalbuminemia, hepatic hydrothorax, or peritoneal dialysis.Ok now that we’ve reviewed transudates, let’s switch our focus to exudates.

Exudate6:52–11:32

In this case, the ratio of pleural protein to serum protein is greater than 0.5; the ratio of pleural LDH to serum LDH is greater than 0.6; or pleural LDH is greater than 2/3 of the high-normal level for serum LDH.
Keep in mind that a pleural effusion is considered an exudate if any of those three criteria are met. An exudate occurs when there’s increased capillary permeability and compromised lymphatic drainage.
Important causes of exudative effusion include malignancy, pneumonia, tuberculosis, ARDS, pancreatitis, or trauma.If the effusion is an exudate, your next step is to determine the type of exudate.
The most common ones include parapneumonic effusion, malignant effusion, inflammatory effusion, or chylous effusion. So order additional pleural fluid studies like cytology and gram stain.
You may also need to order pleural fluid amylase and rheumatoid factor. First, let’s start with parapneumonic effusion, which developed in the pleural space due to adjacent pneumonia.
In this case, the pleural fluid cytology shows no malignant cells, but the gram stain typically demonstrates organisms. Additionally, the cell count shows elevated WBCs with a neutrophil predominance.
Next, pleural fluid glucose is usually low; pleural fluid LDH is high, often above 1000 IU/L; and pleural protein is elevated.
Lastly, you should look at the pleural fluid pH; a pH higher than 7.2 means uncomplicated parapneumonic effusion, while a pH lower than 7.2 indicates complicated parapneumonic effusion.
These findings would confirm your suspicion of parapneumonic effusion. Most commonly, this occurs in the setting of bacterial infection from Streptococcus pneumoniae or Staphylococcus aureus.
Remember, if the pleural protein is extremely high, you should think of tuberculosis. If you suspect tuberculous pleural effusion, you can test adenosine deaminase or ADA levels in the pleural fluid.
Once you diagnose parapneumonic effusion, you need to start treatment with antibiotics. In addition, patients with complicated parapneumonic effusion need a chest tube for drainage.Next let’s look at a malignant effusion.
Cytology will be positive for malignant cells, but there will be no organisms on gram stain. The cell count will show increased WBCs with a lymphocyte predominance.
The glucose might be decreased, while the pleural LDH is typically elevated, often over 1000 IU/L. Keep in mind that once you diagnose malignant effusion it’s essential to identify and treat the underlying malignancy, which is usually identified with cytology, but inconclusive cases may require additional imaging and biopsy.Now, moving on to an inflammatory effusion.
Cytology will show no malignant cells, and the Gram stain will be negative for organisms. The cell count often shows elevated WBCs.
In underlying inflammatory conditions, such pancreatitis and ARDS, the pleural fluid amylase might be elevated. In autoimmune diseases systemic lupus erythematosus or rheumatoid arthritis the rheumatoid factor could be positive.
Once you diagnose inflammatory effusion, you have to treat the underlying condition as well as the effusion. Finally, lets look at a chylous effusion.
Cytology will reveal no malignant cells, and the Gram stain will be negative for organisms. However, the pleural fluid cholesterol and triglycerides are often elevated.
In addition, you may notice a milky-white pleural fluid, as opposed to the normal straw-colored pleural fluid. This is typically due to a chylothorax, or leakage of lymphatic fluid into the thoracic cavity.
If so, diagnose chylous effusion and treat the source of chylous fluid as well as the effusion. One last clinical pearl!
Other tests can be performed on the pleural fluid to determine etiology. If you suspect esophageal rupture, the presence of amylase in pleural fluid is diagnostic.
On the other hand, a diagnosis of hemothorax can be made if the pleural fluid hematocrit is more than 0.5 times that of serum hematocrit.Alright, as a quick recap… If you suspect pleural effusion, order imaging, such as a chest X-ray, POCUS, or CT to rule out or confirm the diagnosis.

Review11:32–12:42

Once you confirm the diagnosis, assess for underlying causes like CHF. If physical exam findings are consistent with CHF, treat with diuretics and assess the patient’s response.
If adequate, continue current management, and if inadequate, perform a therapeutic thoracentesis. On the other hand, if there are no signs of CHF, perform diagnostic and therapeutic thoracentesis, using Light’s criteria to see if the fluid is a transudate or exudate.
Transudative effusions are typically associated with CHF, cirrhosis, or nephrotic syndrome, so make sure to treat the underlying cause.
On the flip side, exudative effusions include parapneumonic effusions caused by bacterial infections; malignant effusions caused by underlying malignancy; inflammatory effusions caused by ARDS, pancreatitis, or autoimmune diseases; or chylous effusions from chylothorax.
In any case, treat the underlying cause as well as
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