OVERVIEW
Despite the many powerful antibiotics currently in clinical use, pneumonia remains one of the most common diseases. In the United States, pneumonia with pleural effusion ranks as the 2nd leading cause of pleural effusion and the 1st leading cause of exudative pleural effusion. Most pneumonic pleural effusions are self-absorbed with effective antibiotic treatment. However, about 10% of pleural effusions require surgical intervention.
Causes
Pneumonic pleural effusions are often caused by bacterial pneumonia involving the pleura, especially in the elderly, infirm, untreated, immunocompromised, or immunosuppressed. It can also be seen in lung abscesses, bronchiectasis, or lung cancer co-infections.
Any bacteria that can cause lung infection can produce pleural effusions. In the past, pneumonic pleural effusions were most commonly caused by pneumococci or hemolytic streptococci, and after the widespread use of antibiotics, by Staphylococcus aureus. Anaerobic and gram-negative bacillus infections have been on the rise in recent years.
Symptoms
The clinical manifestations of pneumonic pleural effusion are largely determined by whether the patient has an aerobic or anaerobic infection.
The clinical presentation of aerobic pneumonia with pleural effusion and pneumonia without pleural effusion is essentially the same. Patients present with an acute onset of fever, chills, chest pain, cough, sputum, and elevated blood leukocytes with signs of lung inflammation and effusion. The incidence of pleuritic chest pain was 59% in patients with lung infection without pleural effusion and 64% with pleural effusion. The peripheral blood leukocyte count in patients with pneumonia without pleural effusion was 17.1 × 109/L compared with 17.8 × 109/L in those with effusion, which was not significantly different. If the patient is left untreated for a longer period of time, the greater the likelihood that a pleural effusion will occur. If the fever remains for more than 48 hours of antibiotic treatment, it is suggestive of a complicated pneumonic-like pleural effusion. The diagnosis of pneumonic pleural effusion is easier to make if the patient presents first with pneumonia and then with pleural effusion. Patients who are frail and/or receiving glucocorticoids and immunosuppressive drugs may develop the disease without these acute symptoms.
Pneumonia with pleural effusion in anaerobic infections tends to have a subacute onset, with 70% of patients presenting to the doctor more often than 1 week after the onset of the disease, and the later the presentation, the more likely the pleural effusion will be complicated. Many patients had poor oral hygiene and a history of alcohol consumption, loss of consciousness, or aspiration. Most patients have significant leukocytosis (median 23.5 x 109/L) and mild anemia.
Examination
Early pleural effusion may present as aseptic plasmacytoid exudate with pH >7.30, glucose >3.3 mmol/L, LDH <500 U/L, and cellular classification dominated by polymorphonuclear cells. With further aggravation of the disease, the pleural effusion develops into typical pneumonia-like pleural effusion, which shows purulent exudate, pH＜7.10, glucose＜2.2mmol/L, LDH＞1000U/L, and the total number of neutrophils is more than 10×109/L. At this time, the pleural effusion smear with Gram stain or bacterial culture may be positive. Physical examination of the lungs combined with X-ray signs of the chest is easier to determine more than a moderate amount of effusion, while a small amount of pleural effusion can only be determined by meticulous examination. Anteroposterior or lateral chest radiograph with blurred or blunted rib-diaphragm angle or blurred diaphragm suggests pleural effusion, which can be determined by changing the position of fluoroscopy or lateral chest radiograph, in which the fluid is dispersed and the rib-diaphragm angle or diaphragm becomes clearer.CT is more efficient in the diagnosis of pleural effusion, and it can also differentiate between lung and pleura lesions, and understand the location and characteristics of lung parenchymal lesions, which can help to make a differential diagnosis and guide the treatment. In addition, ultrasonography can also determine the presence of pleural effusion and localize it by puncture.
Diagnosis
1. Lung inflammation
It is not difficult to diagnose based on clinical symptoms, signs and chest X-ray examination. Lung inflammation includes bacterial pneumonia, lung abscess and bronchiectasis infection. Sputum culture and drug sensitivity should be performed as early as possible, and if necessary, fiberoptic bronchoscopy, cricothyroid puncture or percutaneous puncture aspiration of secretion culture should be performed to identify the pathogens as far as possible, so as to guide the clinical treatment.
2. Pleural effusion
The initial examination of each patient with pneumonia should note the presence of a pneumonic pleural effusion; it is important to determine whether there is a complicated pneumonic pleural effusion because the presence or absence of intrathoracic tube drainage is associated with mortality.
3. Nature of the effusion
Once the diagnosis of pneumonia-like pleural effusion is confirmed, thoracentesis should be performed as early as possible to examine the pleural fluid routine, biochemistry (e.g., pH, protein, glucose, amylase, and LDH, etc.), bacterial Gram stain and bacterial culture. Then, according to the condition of pleural fluid examination, it will be decided whether chest tube drainage is necessary or not.
Differential diagnosis
It needs to be differentiated from pleural disease, lung abscess, and lung cancer co-infection.
Treatment
The treatment of pneumonia with pleural effusion has two main aspects, one is the selection of antibiotics, and the other is whether or not to drain the chest tube.Light classified pleural effusion into 7 categories according to the development process of inflammatory pleural effusion, which is of great significance in guiding the clinical management.
1.Class I
Meaningless pleural effusion. The amount of pleural effusion is small, and the thickness of the effusion is <10mm on X-ray chest radiograph in lateral position, so thoracentesis is not necessary.
2.Class II
Typical pneumonia-like pleural effusion. Thickness of pleural effusion on X-ray in lateral position is >10 mm. glucose in the effusion is >2.2 mmol/L, pH is >7.20, and gram stain or culture of pleural effusion is negative. Treatment with antibiotics alone.
3.Class III
Borderline complex pneumonic pleural effusion. 7.00 < pH < 7.20, LDH > 1000 U/L and glucose > 2.2 mmol/L. Pleural effusion negative for gram stain or culture. Antibiotic serial thoracentesis.
4.Category IV
Simple complex pleural effusion. pH <7.00 and/or glucose <2.2 mmol/L and/or positive gram stain or culture. The effusion is unencapsulated and non-purulent to the naked eye. Intubation to drain antibiotics.
5.Category V
Complex complex pneumonic pleural effusion. pH <7.00 and/or glucose <2.2 mmol/L and/or positive Gram stain or culture. Multiple encapsulated pleural effusions. Thoracic intubation for drainage of thrombolytic drugs intrapleural injection (usually without thoracoscopy or pleurodesis).
6.VI
Simple pyothorax. The effusion is purulent to the naked eye. Single parcel or free effusion. Thoracic tube drainage pleurodesis.
7.ⅦCategory
Complex pyothorax. Multiple encapsulated effusions. Thoracic intubation and drainage of thrombolytic drugs intrapleural injection. Thoracoscopic treatment or pleurodesis is often required.
The main principle of antibiotic selection is based on whether the pneumonia is community-acquired or hospital-acquired. The recommended antibiotics for community-acquired pneumonia that is not severe are second- or third-generation cephalosporins, or beta-lactam antibiotics/beta-lactamase inhibitors (e.g., ticarcillin/clavulanate potassium) plus macrolide antibiotics (e.g., erythromycin and clarithromycin). Severe community-acquired pneumonia can be treated with macrolides plus a third-generation cephalosporin with antipseudomonas activity (e.g., ceftazidime or cefoperazone). Most hospital-acquired pneumonia is caused by infections with enteric gram-negative bacilli, Pseudomonas aeruginosa or Staphylococcus aureus, and anaerobes. Nafcillin and vancomycin are used for Staphylococcus aureus; third-generation cephalosporins or beta-lactams/beta-lactamase inhibitors plus aminoglycosides are used for Gram-negative bacillus infections. For anaerobic infections, metronidazole or clindamycin may be used.