Percutaneous Drainage of Lung Abscess

Introduction:

Inflammation and infection lead to the destruction of tissues, activation of the immune system, and aggregation of blood cells. All these factors are responsible for pus formation. Pus is nothing but a collection of necrotic tissues with the presence of inflammatory cells and pathogens. When pus is circumscribed in a particular area, it is called an abscess. Abscess in the visible areas can be treated easily. With the help of medicines and surgical drainage such abscesses can be treated easily. Lung abscesses are invisible and often difficult to diagnose. That is why, they may crest severe complications. Different drainage techniques are used for the treatment of lung abscesses.

What Is Lung Abcess?

A well-circumscribed area containing necrotic lung tissues, inflammatory cells, and microorganisms is known as a lung abscess. The necrosis of the lung parenchyma is caused by various types of lung infections and inflammations. Ultimately these abscesses form a cavity within the lung tissues.

A. Types of Lung Abscesses:

• Based on the duration lung abscess can be either chronic lung abscesses or acute lung abscesses. If the duration of the lung abscesses is less than 6 weeks, it is called acute lung abscesses. Such abscesses are not well-circumscribed and are filled with necrotic derbies. These necrotic materials are usually present in the center of the abscesses and are surrounded by various inflammatory cells and blood vessels. The duration of chronic lung abscesses is more than 6 months. Chronic lung abscesses are irregular or star-shaped and well-circumscribed with thick membranes. They usually form a pyogenic membrane around the abscesses through which blood cells infiltrate. The central portion is filled with pus. Around the pus, inflammatory cells and blood vessels can be observed.

• Based on the etiology lung abscesses can be primary and secondary. Primary lung abscess is caused by factors like aspiration of various f oropharyngeal secretions, necrotizing pneumonia, and immunodeficiency conditions. Factors that are associated with oropharyngeal secretion-related lung abscesses are:

1. Dental and periodontal infections.

2. Infection of the paranasal sinuses or sinusitis.

3. GERD or gastro esophageal reflex (a disorder in which gastric juice comes out of the abdomen due to reflex disorder of the esophageal tract).

4. Patients with tracheostomy or nasotracheal or endotracheal intubation.

5. Frequent vomiting.

Necrotizing pneumonia is caused by various bacteria. Gram-positive bacteria like Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumonia, Pseudomonas aeruginosa, and Acinetobacter species are responsible for the formation of lung abscesses. Other bacteria like Mycobacterium species, Haemophilus influenza, and Escherichia coli are also regarded as the causative factor for lung abscesses. Different fungi like Aspergillus species, Cryptococcus spices, Histoplasma species, and Blastomyces species are responsible for lung abscesses.

Secondary lung abscess is caused by several diseases. Conditions like cystic fibrosis (a disorder that damages the respiratory tract and digestive system), bronchiectasis (the airway is damaged, widened, and mucus is accumulated), and congenital malformations like pulmonary sequestration (presence of a non-functional mass in the lung tissues), vasculitis (inflammation of the blood vessels of the lung), cystitis, and cancerous lesions are associated with the formation of lung abscesses. Lung injury responsible for a pulmonary contusion (bruise in the lung) is also the cause of secondary lung abscess.

What Are the Complication Of Lung Abcess?

Lung abscesses if not treated properly may give rise to some serious complications. The complications of lung abscess are:

1. Empyema: This Is one of the most common complications of lung abscess. In this condition rupture of the abscess causes a collection of pus and necrotic tissues in the pleural space. This may lead to fibrosis of the pleura.

2. Fistula Formation: Sometimes these abscesses may rupture and form a communication channel. This is called fistula tract formation. Bronchopleural fistula is formed due to communication with the pleural space and the segmental bronchus. This may lead to the formation of tension pneumothorax (continuous entry of air in the pleural space leading to the shrinkage of the lungs). When this communication involves the subcutaneous tissue it is called pleurocutaneous fistula.

What Is Percutaneous Drainage of Lung Abscess?

The standard treatment procedure for a lung abscess is antibiotic therapy. Antibiotics such as Beta-lactamase inhibitors, Clindamycin, and Vancomycin are used in such cases. Larger-sized lung abscesses are treated with surgical treatment such as lobectomy (lobe of the lung is removed) or pneumonectomy (surgical removal of an entire lung). But in certain cases, percutaneous drainage is indicated. Such conditions are:

1. The size of the abscess is more than six centimeters.

2. Conditions where surgery can not be done due to conditions like increased age, medical contraindications, and the presence of cancer or tumor.

3. As an adjunct to antibiotic therapy.

4. If the abscess cavity is homogeneous and does not contain any air-fluid level, this type of procedure can be done. This is helpful in preventing sudden decompression of the lungs.

5. Drainage of the fistula tract.

Procedure:

The procedure for percutaneous drainage is as follows:

• This procedure is done under local anesthesia.

• The procedure is done under the guidance of fluoroscopic, ultrasonographic, or computed tomography (CT) techniques. The procedures help in the proper positioning of the drainage. In CT guided technique scan is obtained after every one-centimeter insertion. In case of emergency, all these guidance procedures are not followed.

• A Chiba needle (needle used for biopsy procedures or for percutaneous access) is inserted into the abscess cavity along with a 0.018" guide wire.

• After this Chiba needle is taken out and replaced with a stick cannula. The 0.018" guide wire is replaced with a 0.038" guide wire.

• After this, a Pigtail drainage catheter is inserted and the guide wire is taken out.

• Once the catheter is placed, gentle irrigation is done with the help of normal saline. This is done until clear fluid is retrieved.

• The catheter tube is then placed into an underwater seal employing negative pressure.

• The catheter is placed there for seven to ten days. Within this time period, periodic irrigation of the catheter is done to prevent any clogging.

What Are the Complications of Percutaneous Drainage?

1. Clogging of the catheter tube is the most common complication.

2. Bigger size tubes can lead to the situations like pneumothorax (collection of air within the lungs) and hemothorax (collection of blood in the lungs). Puncture of healthy lung tissues during insertion may also lead to such complications.

3. Contamination of the pleural cavity during the insertion of the tube may lead to fistula formation.

Conclusion:

Lung abscesses are caused by infection or by various lung diseases. If not treated this may lead to complications like pleural involvement and fistula tract formation. Percutaneous drainage of the lung abscess is an easy technique to drain the pus from the lungs. This can be used as a substitute technique for surgical intervention.