Lecture lung abscess and pleural effusion

2021-09-18 07:04 AM

Lung abscesses can be classified based on the duration of the disease and the cause. Acute abscesses when less than 4-6 weeks or more than 6 weeks are considered chronic.


Pleural effusion diagnosisbook

Pleural effusion


Lung abscess is the necrosis of lung parenchyma and cavernous formation of necrotic tissue and fluid caused by infection. The multiple formations of small abscesses (<2cm) are commonly referred to as necrotizing pneumonia (or lung gangrene). Both lung abscess and necrotizing pneumonia have similar pathological progression.

Lung abscesses can be classified based on the duration of the disease and the cause. Acute abscesses when less than 4-6 weeks or more than 6 weeks are considered chronic.

Primary lung abscess is an infection caused by inhalation or pneumonia in people with normal immune systems; Secondary abscesses are caused by comorbid conditions such as obstruction, bronchiectasis with or without immunodeficiency.

Lung abscess is more common in the right lung than in the left lung, usually develops 1-2 weeks after inhaling fluid.

Pleural effusion is the presence of pus in the pleural cavity, which is a typical complication of pneumonia. However, it can also develop from a thoracic injury, rupture of the oesophagus, after a pleural puncture or drainage, or from the spread of abscesses below the diaphragm and side of the spine.


In most cases, the lung abscess originates from inhaled anaerobic pneumonia in the oropharynx, these patients predominantly have oral disease. The process of necrosis of the lung parenchyma begins 7-14 days after aspiration pneumonia. Other mechanisms leading to pulmonary abscesses include sepsis, endocarditis, and infectious embolism in the lungs.


In lung abscesses, anaerobic bacteria account for 89% of cases. Common anaerobic bacteria include Pepto streptococcus, Bacteroides, Fusobacterium species, and microaerophilic streptococcus.

There are also other bacteria such as Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae (rare), Klebsiella pneumonia, Hemophilus influenza, Actinomyces spices, Nocardia species, and gram-negative bacilli.

Non-microbial agents such as parasites (Paragonimus, Entamoeba), fungi (Aspergillus, Cryptococcus, Histoplasma, Blastomyces, Coccidioides), and Mycobacterium.


In the United States, the prevalence in the general population is unknown, the overall death rate due to pulmonary abscesses is about 4-7%. The mortality rate in immunocompromised or bronchial obstruction is quite high 75% (Pohlson, 1985), the mortality in lung abscess for both gram-negative and positive infections is about 20% (Hirshberg, 1995).

Age: This usually occurs in the elderly.


Asking about the disease, the following facts suggest a diagnosis

Pneumonia has been diagnosed and treated recently.

Previous history of chest piercing wound.

Sputum, rotten or bloody.


Shortness of breath.

Anorexia, weight loss.

Night sweats.

Pleural chest pain.


Fever, usually no more than 102oF (38.8oC).

Fast breathing.


Goats squeak, pipe blowing.

Reduce negative sound, knock chisel.

Most causes of abscesses and pleural pus are inhaled, so it is important to be aware of patients with risk factors such as:

Oral disease.



Coma, general anesthesia.

There are underlying lung diseases such as pulmonary embolism, vascular disease, lung cancer with cavitation, or fibrosis of the lung.


Complete blood count (CBC)

The leukocyte formula turns left.


Gram stain, inoculate to orient pathogenic bacteria.

Blood cultures

Image study

Chest X-ray:

Chest X-ray will help to identify and differentiate pneumonia, lung abscess, pleurisy. This has important implications for treatment because lung abscess and pneumonia respond well to internal treatment, while pleural pus is often indicated for surgical treatment.

The classic abscess image is a solitary cavernous watermark with an image of the water-vapor level, the edge of an unknown, surrounded by infiltrative lesions. Common locations are the posterior upper lobe (2) and the apical segment of the lower lobe (6). However, it should be differentiated from abscess lung cancer.

During pleural effusion, visualization of the water-vapor level at the chest wall. Comparison of water-vapor diameter on straight film and tilt film helps to distinguish parenchyma blurred mass (lung abscess) or pleura (pleural pus).

Diaphragmatic angular blurring also suggests effusion or pleural pus, estimated to be approximately 175 ml (on linear film).

Chest computational tomography (CT scan of the chest): helps distinguish the peripheral lung abscess and focal pleural pus. The abscess has an irregular margin, creating a sharp angle in the pleura, not displacing blood vessels and bronchi. In addition, a CT chest scan also helps identify necrotic lung cancer.

Other tests

Pulse oximetry, arterial blood gas: helps assess respiratory conditions.

Transbacheal aspiration culture if sputum testing does not help diagnose.

Pleural fluid.

Gram stain, culture, acid-resistant bacteria should be done.

Cytological test if lung cancer is suspected.

Biochemistry test of pleural fluid, with consideration of pleural pus when:

Macroscopic purulent fluid.

pH < 7.2.

WBCs> 50,000 / L.

Glucose < 60 mg/dl.

LDH > 1.000IU/mL.

One factor that indicates pleural fluid being studied is TNF- a (Tumor necrosis factor), if> 80 pg / mL, pleuritic pus or parenteral effusion complications should be considered.


Supportive ventilation: depending on the degree of respiratory failure and hypoxemia, choose an oxygen supply device, consider intubation of the ventilator when indicated.

The schematic approach of patients with sub inflammatory pleural effusion and pleurisy.

Risk factors for sub inflammatory pleural effusion have indications for pleural effusion.

Clinical signs

Symptoms persist.

There is another disease attached.

Failure to treat with antibiotics.

Pathogens (anaerobic bacteria, highly virulent bacteria).

Visual signs

A large amount of fluid (≥ 1/2 of the field).

Create partitions.

Steam level.

Thickened pleura.

Echo mixed.

Signs of pleural fluid

General: turbid, pus-smelling fluid.

Low pH <7.2.

Glucose low < 40mg/dL.

LDH high > 1.000 IU.

Gram stain or inoculate (+).

Treatment in place

If the new fluid is slightly cloudy or the pus is diluted, it is only necessary to actively aspirate and rinse with an isotonic salt solution. Using a 20cc syringe connected to the needle with a rubber tube (if there is no triple lock), the tube is clamped after each suction so that air does not enter the pleural cavity, rinsing until clear water. Advocate therapy 2 times a day to prevent pleural thickening.

If the pus thickens, the pleura must be minimized. Drainpipe connects to the tube soaked in the tank, the end of the tube is submerged in the water 3 cm, the tank is connected to the low-pressure machine. Every day, after washing the pleural drive to suck under pressure - 50cm of water to expand the lungs, 2 times a day, 2 hours each time. The retention time depends on the time the lungs expand close to the chest wall, filling the sockets. Only when there is clear drainage (10-15ml / day) can withdraw the tube. Do not wash antibiotics because it irritates the pleura and easily thickens.


The initial use of antibiotics in a pulmonary abscess is empirical therapy, which can often be initiated with a combination of Cephalosporin + Gentamycin (if you think gram-negative), Flucloxacillin (Staphylococcus aureus), Benzylpenicillin + Metronidazole (bacteria Anaerobic). Currently, there are many highly effective antibiotics such as clindamycin, cefoxitin, ticarcillin, or piperacillin/tazobactam. In pleural pus the first thing is to drain the pleura and combine antibiotics, antibiotics are often experienced as imipenem or piperacillin/tazobactam.

Dosage of drugs used

Clindamycin (Lincosamide group): 600 mg IV every 6-8 hours.

Cefoxitin (Cephalosporin II group): 2g IV every 6-8 hours.

Penicillin G: 2 million units every 4 hours.

Ticarcillin/clavulanate (Timentin): 3.1g IV every 4-6 hours.

Piperacillin / tazobactam (Tazocin): 3.375g IV every 6 hours.

Imipenem: dose varies from 250 - 500mg IV every 6 hours to a maximum of 3-4g / day.

Vancomycin: 500mg to 2g / day IV divided 3-4 times / day.


Pleural fibrosis.

Restrictive ventilatory defect.

Trapped lung.

Bronchial pleural fistula.

Skin pleural leakage.

Related articles:

A pleural effusion is an accumulation of excessive fluid in the pleural space

Fluid in the Chest (Pleural Effusion)

Pathology Basis of Occupational Lung Disease