What is Parapneumonic Pleural Effusions and Empyema Thoracis?
A parapneumonic effusion is a medical term for a buildup of fluid around the lungs that’s linked to a lung infection, mainly pneumonia. Basically, when bacteria from pneumonia infects the lungs, the body responds by sending in fluid to try and flush it out. The fluid primarily accumulates around the same side as the lung infection.
This fluid buildup is often associated with bacterial infections and grouped into two types:
- Uncomplicated parapneumonic effusions: This type has fluid with high white blood cell count (neutrophilic), and the fluid is an exudate, which means it has high protein content. The fluid’s glucose level is above 60 mg/dl, its pH is above 7.20. The fluid does not have any bacteria present, as shown by a ‘gram stain’ a bacterial detection test which is negative.
- Complicated parapneumonic effusions: This situation occurs when bacteria enters the protective lining around the lung (pleura). With this type, the glucose level decreases and the fluid becomes acidic (pH below 7.20). Though the fluid doesn’t show any bacteria due to their quick clearance from the area or a low bacterial count. This situation is termed as ‘complicated’ because it requires drainage of the fluid to be resolved.
If the infection continues to worsen, it may lead to a severe condition called empyema thoracis. This means that there’s actual pus in the area around the lungs, or a bacterial infection is confirmed in the lung-area fluid either through a ‘gram strain test’ or by the fluid testing positive for bacteria.
It is common for patients who have pneumonia to develop a fluid buildup around their lungs. In fact, about 40-60% of people with bacterial pneumonia will experience this. While we don’t see as many cases nowadays because of effective and timely antibiotic treatment, in some patients, the fluid that builds up becomes thick (fibrinous) and can even get infected, resulting in empyema.
What Causes Parapneumonic Pleural Effusions and Empyema Thoracis?
Pneumonia, or lung inflammation, frequently leads to two conditions known as parapneumonic effusions and empyema thoracis, which involve fluid build-up and infection in the space around the lungs. Empyema, an accumulation of pus in this space, may also occur as a result of complications from heart or lung surgery. Other causes of infection in this space include injuries, and spreading of infection from the blood or other parts of the body.
It’s important to know that both viruses and bacteria can lead to parapneumonic effusions. However, it is bacteria that most frequently cause empyema thoracis, an infection in the space that separates the lung from the chest wall.
Certain people are more likely to develop empyema. Risk factors include age and medical conditions like diabetes, alcoholism, GERD (a chronic type of acid reflux), frequent hospitalizations for pneumonia, and advanced age.
Different types of bacteria have been known to cause empyema. The Streptococcus pneumoniae and Staphylococcus aureus are the most common types found in infections caused by air-loving, or aerobic, gram-positive bacteria. Klebsiella, Pseudomonas, and Haemophilus species are commonly found in gram-negative cultures. Bacteroides and Peptostreptococcus species are the most common types of bacteria that don’t need air, or anaerobic bacteria, causing infection. Empyema thoracis associated with aspiration pneumonia, a lung infection caused by inhaled food or drink, often involves a mix of aerobic and anaerobic bacteria. After surgery, the infection is usually caused by S. aureus.
Injuries that cause bleeding in the chest, or hemothorax, can often lead to an infection if the blood is not fully removed. Other causes of empyema include mediastinitis (inflammation in the central chest area), a ruptured esophagus, pericarditis (inflammation of the pericardium, a sac-like tissue that surrounds the heart), pancreatitis (inflammation of the pancreas), and abscesses hidden away below the diaphragm.
Risk Factors and Frequency for Parapneumonic Pleural Effusions and Empyema Thoracis
Parapneumonic effusion, a condition that develops alongside pneumonia, affects roughly 20% to 40% of patients hospitalized with pneumonia. This results in approximately 1 million cases each year in the United States. However, despite the prevalence of this condition, less than 10% of patients will need to undergo aspiration – a procedure to remove the effusion.
posteroanterior chest x-ray reveals a pleural effusion of the right lung.
Signs and Symptoms of Parapneumonic Pleural Effusions and Empyema Thoracis
Parapneumonic effusion or empyema, which are conditions related to pneumonia, can produce different symptoms based on factors like when the patient seeks help or how aggressive the bacteria causing the illness are. The typical signs of bacterial pneumonia with parapneumonic effusion are a cough, spitting up mucus, increased body temperature, chest pain that worsens with breathing or coughing, and trouble breathing.
During a physical examination, doctors usually find the following indicators:
- Fever, rapid breathing, and a faster than normal heartbeat
- Pleural effusion (which can be recognized by a dull sound when the doctor taps on your chest, decreased vibration when speaking, and weakened or no sounds of breathing)
- Inflammation in the lungs next to the effusion (symptoms might include crackling sounds or abnormal breathing sounds on inhalation)
Testing for Parapneumonic Pleural Effusions and Empyema Thoracis
If a doctor suspects that fluid is building up in your chest cavity (a condition known as pleural effusion), there are several tests they might perform. One of these is a plain chest x-ray. This common procedure can easily detect any fluid that’s collecting in your chest space. If the x-ray shows different densities in this fluid, that might suggest that it’s not evenly distributed or “loculated”.
Another way to detect this fluid buildup is with a chest ultrasound. This is a type of imaging that uses sound waves to make a picture of the organs inside your chest. It can help your doctor see if the fluid is free-flowing or if it’s trapped in pockets (loculated). Ultrasound can also guide doctors during thoracentesis – a procedure where a needle is inserted into the chest to remove excess fluid.
In adults with possible empyema (infected fluid in the chest) or if the fluid is loculated, a CT scan with a special dye could be performed. This dye enhances the picture so that the linings of the chest cavity (the pleurae) can be seen more clearly, and can detect underlying abnormalities in lung tissue.
Typically, when the fluid layer is more than 10-mm thick on a chest x-ray, your doctor might recommend thoracentesis. This procedure involves using a needle to remove fluid from the chest cavity, both for relief and for further testing. Ultrasound or a CT scan could be used to guide the needle, especially if the fluid isn’t evenly distributed.
The fluid taken out in this procedure would then be tested in a lab. It would undergo a microbiologic analysis to check for infection, as well as a total and differential cell count to measure the numbers and types of cells in the fluid. The fluid’s protein, lactate dehydrogenase (an enzyme), glucose (sugar) levels, and pH (acidity) would also be tested for.
The fluid can also be checked for biomarkers, substances in the body that can indicate certain conditions. These include C-reactive protein, procalcitonin, and STREM-1 (substances produced by your body in response to inflammation and infection). They may help differentiate between complicated and uncomplicated cases of fluid buildup in the chest related to pneumonia. However, these aren’t necessarily superior to traditional tests.
If needed, additional tests could be done to rule out other causes of fluid buildup in your chest.
Treatment Options for Parapneumonic Pleural Effusions and Empyema Thoracis
Parapneumonic effusion is a condition where excess fluid collects in the space between your lungs and chest wall due to pneumonia. Treating this condition generally involves the use of appropriate antibiotics, along with draining the fluid if necessary.
The severity of parapneumonic effusion is categorized into four groups based on the risk level, which helps choose the optimal treatment. These categories are:
- Category 1 (very low risk): The fluid is very small and flows easily. There’s no need to remove the fluid.
- Category 2 (low risk): The fluid, small to moderate in size, flows easily and is not infected with bacteria. There’s no need to remove the fluid.
- Category 3 (moderate risk): The fluid is large or trapped, the lining of the chest wall may appear thick in CT scans, and/or the fluid is infected with bacteria. In such cases, removing the fluid is recommended.
- Category 4 (high risk): The fluid becomes pure pus indicating a high infection level. In such cases, removing the fluid is critical.
If a patient falls under category 1 or 2, they might not need fluid removal. But, if they’re in category 3 or 4, fluid drainage is advised. If less invasive drainage methods fail to work, fibrinolytics (drugs that dissolve blood clots), VATS (a type of minimal invasive surgery), or other surgical interventions might be necessary.
The treatment also involves the use of antibiotics, which aim at eliminating the bacteria causing pneumonia. The choice of antibiotic and how long treatment is needed depends on many things such as how sensitive the bacteria are to the antibiotic, the amount of lung and pleural disease, how the disease responds to the initial treatment, and how well the fluid drains.
For patients where the fluid drains freely and hasn’t been tainted by bacteria, inserting a chest tube to drain it is a common method. Such tubes are generally put in place with the help of imaging methods like ultrasound or CT scan. After this process, it’d be necessary to do follow-up imaging within 24 hours to ensure that the tube is located correctly. The tube is normally left in place until the drainage rate decreases and the infection pocket closes.
Sometimes, agents called fibrinolytics are administered in the space between the lung and chest wall to help with draining trapped fluid, but their use is a point of discussion among healthcare professionals.
If antibiotics and chest tube drainage aren’t effective, thoracoscopy might be considered. This is a surgical procedure that can break down the tissue fibers sticking together, allowing the fluid to be drained. But, it’s recommended to do it within two weeks of infection, else it may not be effective and require open surgery.
If the pleural peel, a layer formed on the lining of your chest cavity and lung, persists for more than 6 months leading to significant lung restriction, decortication might be needed. This is a surgical procedure to remove the peel.
Lastly, if all previous methods fail and the patient’s health is too critical to tolerate decortication, an open drainage of the pleural space might be advised. This involves making an incision through the chest wall to allow the fluid to flow out, and a chest tube may be left in place for about two to three months.
What else can Parapneumonic Pleural Effusions and Empyema Thoracis be?
Conditions that have similar symptoms to pleurisy can include:
- Bacterial pneumonia
- Perforated esophagus
- Hemothorax
- Chylothorax
- Lung cancer
- Tuberculosis
What to expect with Parapneumonic Pleural Effusions and Empyema Thoracis
Most people with parapneumonic pleural effusion, a type of lung infection in which fluid collects around the lungs, recover. However, about 10% do not survive. Appropriate antibiotic treatment and draining the fluid from around the lungs are key to getting better.
To help predict which patients might not do as well, doctors use a system called RAPID score. The score helps identify patients with higher chances of negative outcomes.
Other things that make treatment trickier and may lead to higher death rates include being older, having heart or lung problems, having a weakened immune system, and being frail or weak. Older patients especially tend to have higher death rates.
Possible Complications When Diagnosed with Parapneumonic Pleural Effusions and Empyema Thoracis
Complications from pleural empyema (an infection in the space between the lungs and chest wall) can include thickening residual tissue in the pleura, revealed extensive scar tissue known as pleural fibrosis, a passageway that forms between the bronchial tubes in the lungs and the pleural space (bronchopleural fistula), and the development of an increasingly severe condition called empyema necessitans.
Additionally, the surgery to treat empyema can also have a variety of complications, such as pain, recurrence of the infection, a longer stay in the hospital, injuries to the organs in the chest, paralysis of the diaphragm (the muscle that helps you breathe), and even fractured ribs.
Complications of Pleural Empyema and Its Surgery:
- Thickening residual tissue in the pleura
- Pleural fibrosis (extensive scar tissue)
- Bronchopleural fistula (a passageway that forms between the bronchial tubes and the pleural space)
- Empyema necessitans (a more severe condition)
- Pain post-surgery
- Recurrence of infection
- Long hospital stay
- Injuries to the chest organs
- Diaphragm paralysis
- Fractured ribs