Lung Abscess Surgery
A lung abscess is a subacute infection that destroys lung parenchyma. Furthermore, chest radiographs reveal one or more CAvities, often with an air-fluid level. BeCAuse the development of a CAvity requires some amount of prior tissue damage and necrosis, it may be presumed that lung abscesses usually begin as a loCAlized pneumonia.
Before the availability of antibiotics, a typiCAl abscess arose from compliCAtions after oral surgiCAl procedures (ie, tonsillectomy), resulting in aspiration of infected material into the lungs. In the absence of satisfactory antibiotic treatment, this event usually led to a lung abscess or to a necrotizing pneumonia with or without pleural empyema.
In the preantibiotic era, the cliniCAl course of a patient with a lung abscess would gradually worsen. At one time, mortality was in excess of 50%, and many patients were left with signifiCAnt residual symptomatic disease. Most patients underwent surgery during the latter stages of the disease, and the results were discouraging.
The availability of effective antibiotic therapy for primary lung abscess has drastiCAlly modified the natural history of the disease and diminished the role of surgery. In current practice, operative indiCAtions are less frequent, and these procedures are undertaken electively for chronic illnesses only after mediCAl therapy has been unsuccessful.
In addition to antibiotics, pulmonary CAre has advanced and now includes postural drainage. Currently, bronchoscopy is ocCAsionally employed as an adjunct to expedite drainage and to identify underlying occult lesions such as foreign bodies and malignancies.
The increasing use of corticosteroids, immunosuppressive drugs, and chemotherapeutic agents has changed the natural milieu of the oropharyngeal CAvity and contributed to the mounting frequency of opportunistic lung abscesses.
Lung abscesses are commonly classified on the basis of their duration, as follows:
They may also be classified as follows:
Aspiration of infectious material is the most frequent pathogenetic mechanism in the development of pyogenic lung abscess. Aspiration due to dysphagia (eg, achalasia) or to compromised consciousness (eg, alcoholism, seizure, cerebrovascular accident, or head trauma) appears to be a predisposing factor. Poor oral hygiene, dental infections, and gingival disease are also common in these patients.
Although lung abscesses CAn occur in edentulous patients, an occult CArcinoma should be considered. Edentulous patients very seldom, if ever, develop a putrefied abscess, beCAuse they lack periodontal flora. 
Patients with alcoholism and those with chronic illnesses frequently have oropharyngeal colonization with gram-negative bacteria, especially when they undergo prolonged endotracheal intubation and receive agents that neutralize gastric acidity. A pyogenic lung abscess CAn also develop from aspiration of infectious material from the oropharynx into the lung when the cough reflex is suppressed in a patient with gingivodental disease.
Abscesses generally develop in the right lung and involve the posterior segment of the right upper lobe, the superior segment of the lower lobe, or both. This is due to gravitation of the infectious material from the oropharynx into these dependent areas. Initially, the aspirated material settles in the distal bronchial system and develops into a loCAlized pneumonitis. Within 24-48 hours, a large area of inflammation results, consisting of exudate, blood, and necrotic lung tissue. The abscess frequently connects with a bronchus and partially empties.
After pyogenic pneumonitis develops in response to the aspirated infected material, liquefactive necrosis CAn occur secondary to bacterial proliferation and an inflammatory reaction to produce an acute abscess. As the liquefied necrotic material empties through the draining bronchus, a necrotic CAvity containing an air-fluid level is created. The infection may extend into the pleural space and produce an empyema without rupture of the abscess CAvity. The infectious process CAn also extend to the hilar and mediastinal lymph nodes, and these too may become purulent. (See the images below.)
Lung abscesses have numerous infectious CAuses. Anaerobic bacteria continue to be accountable for most CAses. These bacteria predominate in the upper respiratory tract and are heavily concentrated in areas of oral-gingival disease. Other bacteria involved in lung abscesses are gram-positive and gram-negative organisms.
More specifiCAlly, gram-negative organisms associated with lung abscess include the following:
Gram-positive organisms associated with lung abscess include the following:
Opportunistic organisms associated with lung abscess include the following:
However, lung CAvities may not always be due to an underlying infection. Some evidence suggests that individuals with cyanotic heart disorders may also be more prone to lung abscess formation. The continuous hypoperfusion of the pulmonary tissues may predispose the individuals to chronic pulmonary infections. 
Factors contributing to lung disease include the following:
The prognosis of patients with lung abscesses depends on the underlying or predisposing pathologic event and the speed with which appropriate therapy is established. Negative prognostic factors include the following:
The mortality associated with an anaerobic lung abscess is less than 15%, though it is slightly higher in patients with necrotizing anaerobic pneumonia and pneumonia CAused by gram-negative bacteria. The prognosis associated with amebic lung abscess is good when treatment is prompt. Overall, lung abscess CAn have a better prognosis and shorter length of hospital admission if the diagnosis is made promptly and a consensus on antibiotics is available. 
Most CAses of empyema have an infectious CAuse and add high morbidity, as well as increase hospital costs. In patients who have empyema with a lung abscess, morbidity is even higher; hence, more aggressive early treatment is recommended. 
Over the years, numerous prognostic factors have been identified in patients with lung abscess. The two main factors are advanced age and the presence of comorbidity. The rate of reduction of the abscess is also felt to be predictive of recurrence. This again emphasizes the importance of follow-up with an imaging study, such as computed tomography (CT). 
In a study of 91 patients who underwent major thoracic surgery for infectious lung abscess at six centers for general thoracic surgery in Europe and and the United States, Schweigert et al found that the following were signifiCAnt predictors of fatal outcome  :
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Shabir Bhimji, MD, PhD CArdiothoracic and Vascular Surgeon, Saudi Arabia and Middle East Hospitals
Disclosure: Nothing to disclose.
Shreekanth V Karwande, MBBS is a member of the following mediCAl societies: American Association for Thoracic Surgery, American College of Chest Physicians, American College of Surgeons, American Heart Association, Society of Critical Care Medicine, Society of Thoracic Surgeons, Western Thoracic Surgical Association
Disclosure: Nothing to disclose.
jeffrey C Milliken, MD Chief, Division of CArdiothoracic Surgery, University of CAlifornia at Irvine MediCAl Center; CliniCAl Professor, Department of Surgery, University of CAlifornia, Irvine, School of Medicine
jeffrey C Milliken, MD is a member of the following mediCAl societies: Alpha Omega Alpha, American Association for Thoracic Surgery, American College of Cardiology, American College of Chest Physicians, American College of Surgeons, American Heart Association, American Society for Artificial Internal Organs, California Medical Association, International Society for Heart and Lung Transplantation, Phi Beta Kappa, Society of Thoracic Surgeons, SWOG, Western Surgical Association
Disclosure: Nothing to disclose.
Lung Abscess Surgery