Empyema: Clinical sciences

Empyema is a collection of purulent fluid within the pleural cavity but outside of the lung. This occurs when there is inoculation of bacteria or other microorganisms within the pleural space leading to the development of frank pus. Pneumonia is the most common cause of empyema, but it can result from blunt or penetrating chest trauma, esophageal rupture, hematogenous seeding of infection, or mediastinitis.

Empyema goes through three stages: exudative, fibrinopurulent, and organizing. In the exudative stage, fluid accumulates in the pleural space. Next, in the fibrinopurulent stage, invasion of bacteria activates the immune response that leads to septations. After a few weeks, the organizing stage occurs. In this stage, there is a formation of a thick connective tissue on both pleural surfaces that prevents the lung from fully expanding. This is known as pleural rind or peel. Empyema can quickly progress to a systemic infection so it should be diagnosed and treated promptly.

When a patient presents with a chief concern suggesting empyema, your first step is to perform an ABCDE assessment to determine whether the patient is unstable or stable. If the patient is unstable, stabilize the airway, breathing, and circulation. Consider intubation for patients with signs of impending acute respiratory failure. Then, obtain IV access and initiate IV fluids for resuscitation, while continuously monitoring vital signs like pulse oximetry, blood pressure, and heart rate.

Once you have initiated the acute management, your next step is to obtain a focused physical examination and order labs including CBC, CMP, CRP, and albumin. On history, patients typically report symptoms of severe infection, such as fever, chills, malaise, loss of appetite, and weight loss. Be sure to ask about any symptoms they had prior, since empyema takes time to develop. They might report respiratory symptoms in the previous weeks or even months like cough, pleuritic chest pain, and dyspnea.

In severe cases, physical exam might reveal altered mental status, hypotension, tachycardia, and tachypnea, which are signs of systemic infection. On examination of the chest, you can expect to find dullness on percussion, decreased breath sounds, and decreased fremitus. Labs will likely show leukocytosis, hyponatremia, elevated CRP, and low albumin. If your patient presents with these findings, suspect empyema with a systemic infection or sepsis. These patients need to be dealt with promptly because the disease can rapidly progress.

Now, let's discuss the work-up. The diagnostic tests you need to order are a chest x-ray and pleural ultrasound. On chest x-ray, you will likely see pleural thickening, blunting of the costophrenic angle, and a loculated effusion.

Now, here’s a catch! Your average chest x-ray with posteroanterior view might not help you distinguish a loculated effusion from some other pathology. You’ll have to obtain a lateral decubitus x-ray. If the fluid stays in place and doesn’t flow down to the gravity-dependent position, it is a loculated effusion.

On pleural ultrasound, you can expect to see a loculated pocket of fluid with or without septations, or hyperechoic debris as well as pleural thickening. These radiologic findings help you confirm your diagnosis of empyema with systemic infection or sepsis.

Alright, now that you have made the diagnosis, let’s talk about management. Your first step is to start empiric IV antibiotics. Then, place a large bore chest tube sometimes under ultrasound guidance to locate the loculation and drain the empyema. Finally, make sure to continue treating the underlying infection or sepsis that might be present.

Now that we’ve treated the unstable patients, let's switch gears and talk about the stable patients. Your first step in evaluating a stable patient is to obtain a focused history and physical, as well as labs such as CBC, CMP, CRP, and albumin. Stable patients often report symptoms of infection like fever, malaise, loss of appetite, and weight loss; in addition to respiratory symptoms like cough, pleuritic chest pain, and dyspnea. Sometimes patients might have had pneumonia recently, or are currently suffering from one. This is a very important clue to determine in which stage the empyema is, which will help you treat it. History might also reveal one or more risk factors including a history of aspiration, poor dental hygiene, alcohol or substance use disorder, and immunosuppression.

On physical exam, you can expect to find dullness on percussion, decreased breath sounds, and decreased fremitus of the chest. Finally, labs might reveal leukocytosis, hyponatremia, elevated CRP, and a low albumin. If your patient presents with these findings, you should suspect empyema.