Empiema

Management o f P l e u r a l Sp a c e : E ff u s i o n s a n d Empyema
Neil A. Christie,
KEYWORDS  Pleural effusion  Pleurodesis  Empyema  Thoracoscopy  Fibrinolysis
MD

Surgeons are commonly called on to evaluate patients with pleural effusions. This article discusses the normal anatomy, physiology, and pathophysiology of the pleural space. The signs and symptoms of pleural effusionsas well as the evaluation of pleural effusions of unknown cause are also reviewed. Although pleural effusions can be seen in a host of medical disorders, the 2 main circumstances that the surgeon is involved with are with malignant pleural effusions and pleural sepsis and therefore the management of theses 2 entities is discussed in detail.
PLEURAL SPACE PHYSIOLOGY

The pleural space liesbetween the visceral and parietal pleura and consists of 2 opposed pleural surfaces separated by 10 to 20 mm of glycoprotein-rich fluid. The normal volume of pleural fluid is low, at approximately 10 mL (0.1–0.2 mL/kg body weight). Pleural fluid contains few cells under normal circumstances.1 The normal pleura is a thin translucent membrane and consists of 5 layers: (1) the mesothelium (flattenedmesothelial cells joined primarily by tight junctions); (2) submesothelial connective tissue; (3) a superficial elastic layer; (4) a second loose subpleural connective tissue layer rich in arteries, veins, and nerves; (5) a deep fibroelastic layer adherent to the underlying lung parenchyma, chest wall, and diaphragm or mediastinum.2 The parietal pleura derives its blood supply from branches of theintercostal arteries. The mediastinal pleura is supplied by the pericardiophrenic artery and the diaphragmatic pleura from the superior phrenic and musculophrenic arteries. The visceral pleura derives most of its blood supply from the bronchial arterial system.2 There exist naturally occurring pores, or stomata, in the caudal portion of the parietal pleura and lower mediastinal pleura that are capableof transferring particulate matter

Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, 5200 Centre Avenue, Suite 715, Pittsburgh, PA 15232, USA E-mail address: christiena@upmc.edu Surg Clin N Am 90 (2010) 919–934 doi:10.1016/j.suc.2010.07.003 surgical.theclinics.com 0039-6109/10/$ – see front matter Ó 2010 Elsevier Inc. All rights reserved.

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Christie

andcells directly into lymphatic channels for removal. Most of the fluid that accumulates abnormally in the pleural space is derived from the lung through the visceral pleura and is absorbed primarily thorough the parietal pleura.3 In disease states, excess production and/or decreased absorption of lymph is responsible for the generation of effusions.
Evaluation of Pleural Effusions

Causes ofeffusions are manifold. They can be classified as transudative with a low protein content (found in congestive heart failure, cirrhosis, nephrotic syndrome) or as exudative with a high protein content (found in cancer, infection, pulmonary emboli, pancreatitis, collagen vascular disease, drug-induced conditions, hemothorax, chylothorax).4 The clinical scenario is helpful in determining the cause ofan effusion. Signs or symptoms of infection, history of malignancy, or associated medical diseases such as cardiac failure or kidney or liver disease can be helpful in determining the cause of an effusion. Small pleural effusions are asymptomatic. Large pleural effusions can cause dyspnea, cough, and chest discomfort. Effusions are generally seen on chest radiograph. Small pleural effusions may beevident as blunting of the costophrenic angle. A lateral decubitus film can confirm an effusion to be free flowing. Loculated effusions are harder to diagnose on a standard chest radiograph. Ultrasound can detect a loculated effusion and also determine an appropriate site for thoracentesis. A computed axial tomography (CAT) scan is useful in the evaluation of pleural effusions. It can determine...