Lung abscess overview: Difference between revisions
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==Pathophysiology== | ==Pathophysiology== | ||
Aspiration of anaerobic bacteria is the inciting event for the development of lung abscess. Once the aspirate is localized it results in pneumonitis. Inflammatory mediators are released, morphology, resulting in the formation of colliquative necrosis. The right side lung is more commonly affected than the left. On gross morphology, the lesions are well circumscribed filled with necrotic debris and do not demonstrate well-defined borders with the surrounding lung parenchyma. Microscopic examination demonstrates neutrophilic granulocytes with dilated blood vessels and inflammatory edema. | Aspiration of anaerobic bacteria is the inciting event for the development of lung abscess. Once the aspirate is localized it results in pneumonitis. Inflammatory mediators are released, morphology, resulting in the formation of colliquative necrosis. The right side lung is more commonly affected than the left. On gross morphology, the lesions are well circumscribed filled with necrotic debris and do not demonstrate well-defined borders with the surrounding lung parenchyma. Microscopic examination demonstrates neutrophilic granulocytes with dilated blood vessels and inflammatory edema.<ref name="pmid936601">{{cite journal |vauthors= |title=Lung abscess |journal=West. J. Med. |volume=124 |issue=6 |pages=476–82 |year=1976 |pmid=936601 |pmc=1130102 |doi= |url=}}</ref> | ||
==Causes== | ==Causes== | ||
Lung abscess is commonly caused by bacterial infections and these include [[bacteroides]], [[peptostreptococcus]] and [[prevotella]]. | Lung abscess is commonly caused by bacterial infections and these include [[bacteroides]], [[peptostreptococcus]] and [[prevotella]]. | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]
Overview
Lung abscess is necrosis of the pulmonary tissue and formation of cavities (more than 2 cm)[1] containing necrotic debris or fluid caused by microbial infection.This pus-filled cavity is often caused by aspiration, which may occur during altered consciousness. Alcoholism is the most common condition predisposing to lung abscesses.Lung Abscess is considered primary(60%) when it results from existing lung parenchymal process and is termed secondary when it complicates another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into lung.
Historical Perspective
Lung abscess has been a disease entity since the days of Hippocrates. Postural physiotherapy had been the mainstay of treatment until Harold Neuhof described his concept of new one-stage open drainage for the acute abscess in 1930's. With the invention of antibiotics in late 1940's and their promising results led the change in management of lung abscess.[2]
Pathophysiology
Aspiration of anaerobic bacteria is the inciting event for the development of lung abscess. Once the aspirate is localized it results in pneumonitis. Inflammatory mediators are released, morphology, resulting in the formation of colliquative necrosis. The right side lung is more commonly affected than the left. On gross morphology, the lesions are well circumscribed filled with necrotic debris and do not demonstrate well-defined borders with the surrounding lung parenchyma. Microscopic examination demonstrates neutrophilic granulocytes with dilated blood vessels and inflammatory edema.[3]
Causes
Lung abscess is commonly caused by bacterial infections and these include bacteroides, peptostreptococcus and prevotella.
Differentiating Lung abscess from other Diseases
Lung abscess must be differentiated from other lesions that present with similar symptoms such as cough, fever with chills and rigor and chest includes malignancy, tuberculosis, Wegener's granulomatosis, rheumatoid nodules.
Epidemiology and Demographics
The incidence and mortality from lung abscess have greatly declined during the past several decades due to the widespread use of antibiotics and the availability of other treatment options.Lung abscess accounts for up to 4.0 to 5.5 per 10,000 hospital admissions each year in the US.
Risk factors
Factors resulting in the altered level of consciousness and decreased immune response play a key role in the development of lung abscess includes alcoholism, diabetes mellitus, neurological disorder and bronchial obstruction includes alcoholism, stroke, seizure disorder, coma.
Natural history, Complications and Prognosis
Symptoms of lung abscess begin approximately 10 days after aspiration of infected material.Symptoms lasting less than 14 days is considered acute lung abscess, while longer lasting symptoms constitute chronic lung abscess.Acute symptoms include a prodrome accompanied by fever, productive cough, pleuritic chest pain and occasional episodes of hemoptysis.Patients with chronic lung abscess develop weight loss and malaise.The prognosis of lung abscess is good with appropriate antibiotic treatment with a high success rate.Complications include hemorrhage pyopneumothorax pleural empyema and sepsis.
Diagnosis
History and Symptoms
Patient history is important to establish a diagnosis of lung abscess.Common history findings include conditions associated with a risk of gastric content aspiration, a recent history of hospitalization or surgery.Common symptoms include high fever (>101°F [>38.5°C]), productive cough with purulent sputum, and pleuritic chest pain.The presence of a purulent sputum is pathognomic of acute lung abscess.
Physical examination
Patients with acute lung abscess may present with fever, cough with purulent sputum, Gag reflex may be absent in patients with an underlying neurologic disorder such as stroke.Digital clubbing is present in patients with a chronic abscess.On examination of the chest, there will be features of consolidation. Abscess typically localizes in the upper lobes or apical segments of the lower lobes.
Laboratory findings
Diagnosis of lung abscess is made based on clinical symptoms, physical examination, radiographic studies and bacterial culture.Lab findings include increased acute phase reactants (ESR and CRP) levels and leukocytosis with consolidation on lung x-ray.Blood cultures should be performed in all suspected cases.
Treatment
Medical
The mainstay of management for lung abscess is: hospital admission for chest drain and systemic antibiotics.Antimicrobial therapy is based on predisposing host factors and local resistance patterns.The standard duration of the treatment of lung abscess is ≥ 4–6 weeks of parenteral antibiotics.
Surgery
Surgery is considered as the last resort of therapy when both medical and chest drain failed to resolve symptoms.Options for surgery includes: Chest tube drainage and surgical resection of the lung abscess with the surrounding lung tissue.
Reference
- ↑ Bartlett JG, Finegold SM (1972). "Anaerobic pleuropulmonary infections". Medicine (Baltimore). 51 (6): 413–50. PMID 4564416.
- ↑ Neuhof H, Hurwitt E (1943). "ACUTE PUTRID ABSCESS OF THE LUNG : VII. RELATIONSHIP OF THE TECHNIC OF THE ONE-STAGE OPERATION TO RESULTS". Ann. Surg. 118 (4): 656–64. PMC 1617784. PMID 17858299.
- ↑ "Lung abscess". West. J. Med. 124 (6): 476–82. 1976. PMC 1130102. PMID 936601.