Lung Abscess: Definition, Causes, Symptoms, and Treatment:
- Lung abscess is an acute or chronic infection of the lung, marked by a localized collection of pus, inflammation, and destruction of tissue.
- It may occur from aspiration of vomitus or infected material ( nasotracheal secretion or blood) from the upper respiratory tract; or secondary to bronchial obstruction due to a tumor, where infection or necrosis within the tumor mass results in accumulation of secretions.
- It may be also a sequel of necrotizing pneumonia, tuberculosis pulmonary embolism, trauma, bronchial neoplasm.
Causes of lung abscess:
The immediate cause of most lung abscesses is an infection caused by bacteria. About 65 % of those infections are produced by anaerobes; remaining cases are caused by a mixture of anaerobic and aerobic bacteria. When the bacteria arrive in the lung, they are engulfed or eaten by special cells called phagocytes. The phagocytes release chemicals that contribute to inflammation and eventual necrosis, or death, of a part of the lung tissue. There are several different ways that bacteria can get into the lung.
- Aspiration refers to the accidental inhalation of material from the mouth or throat into the airway and lungs. It is responsible for about 50 % of cases of lung abscess.
- Aspiration is most likely to occur in patients who are unconscious or semi-conscious due to anesthesia, seizures, alcohol and drug abuse, or stroke
- Patients who have problems swallowing of coughing, or who have nasogastric tubes in place are also at risk of aspiration.
b) Bronchial obstruction
- The bronchi are the two branches of the windpipe that lead into the lungs. If they are blocked by tissue swelling, cancerous tumors, or foreign objects, a lung abscess may form infection trapped behind the blockage.
c) Spread of infection
- Lung abscess can also be caused by the spread of other infections from the liver, abdominal cavity, or open chest wounds.
- Rarely, AIDS patients can develop lung abscess from Pneumocystis caring and other organisms that take advantage of a weakened immune system.
It may take about two weeks after aspiration or bronchial obstruction for an abscess to produce noticeable symptoms. The patient may be acutely ill for two weeks to three months.
In the beginning, the symptoms of lung abscess are difficult to distinguish from those of severe pneumonia.
- Adults will usually have a moderate fever (101 102 °F/38-39°C), chills, chest pain, and general weakness
- Children may or may not have chest pain, but usually suffer weight loss and high fevers
- As the illness progresses, about 75 % of patients will cough up foul or musty-smelling sputum; some also cough up blood, etc.
- History taking: The diagnosis is made on the basis of the patient’s medical history (especially recent operations under general anesthesia) and general health.
- Sputum test: Smears and cultures taken from the patient’s sputum are not usually very helpful because they will be contaminated with bacteria from the mouth.
- Bronchoscopy: This technique is time- consuming and expensive, and requires the patient to be taken off antibiotics for 48 hours. It is usually used only to evaluate severely ill patients with weakened immune systems.
- Chest x-ray: to help distinguish lung abscess from empyema, cancer, tuberculosis, or cysts. In patients with lung abscess, the x-ray will show a thick-walled unified clear space or cavity surrounded by solid tissue. There is often a visible air-fluid level
- CT scan/ MRI: A CT scan/ MRI of the chest is done to have a clearer picture of the exact location of the abscess.
Lung abscess is treated with a combination of antibiotic drugs, oxygen therapy, and surgery.
The antibiotics that are usually given for lung abscess are penicillin G, penicillin V, and clindamycin. They are given intravenously until the patient shows signs of improvement and then continued in oral form. The patient may need to take antibiotics for a month or longer, until the chest x-ray indicates that the abscess is healing Antibiotic treatment is considered to have failed if fever and other symptoms continue after 10-14 days of treatment; if chest x rays indicate that the abscess is not shrinking; or if the patient has pneumonia that is spreading to other parts of the lung.
Oxygen may be given to patients who are having trouble breathing.
- Most patients with lung abscess will not need surgery.
- About 5 % of patients – usually those who do not respond to antibiotics or are coughing up large amounts of blood (500 ml or more) may have emergency surgery for removal of the diseased part of the lung or for insertion of a tube to drain the abscess.
- Initially cough, with a small amount of sputum, a grade fever, and malaise.
- In time, sputum becomes copious and often foul-smelling, sometimes containing blood.
- Pleuritic chest pain.
- Sometimes, the onset is sudden, with chills, high fever, cough, and malaise.
- Because lung abscess is a serious condition, patients need quiet and bed rest.
- Antibiotic administration as indicated.
- Ensure proper nutritional intake.
- Provide emotional support.
- Adequate drainage postural drainage aided by percussion, effective coughing and breathing exercises.
- Assist in the diagnostic procedure (Sometimes, bronchoscopy is needed to drain an abscess).
- Encourage the patient to increase fluid intake to loosen up the secretions in the lungs, and physical therapy to strengthen the patient’s breathing muscles.
- Encourage the patient to take protein, high-calorie diet since chronic infection is associated with a catabolic state.
- Advice the patient to take the full course of antibiotic (duration may be from 6-18 weeks) to prevent relapse.
- Prepare the patient for surgery as advised if medical intervention is inadequate.