Empyema is defined as a purulent pleural collection (Fig. 107-1). Causes include bacterial pneumonia, tuberculosis, postresectional, posttraumatic, and intra-abdominal processes. Approximately 50% of empyemas are caused by bacterial infection. Postresectional causes account for 25%, and an additional 8% to 11% are caused by extension of an intra-abdominal process.10
Empyema is a purulent pleural collection.
The presenting signs and symptoms of empyema are nonspecific. The most common symptoms are shortness of breath and fever. Patients also may complain of cough and chest pain. Sputum production may or may not be present. These symptoms are also present in patients with pneumonia. Empyema should be considered when a patient manifests these symptoms after a prolonged respiratory illness or a lung resection. Laboratory analysis is also relatively nonspecific and usually includes leukocytosis. C-reactive protein levels that exceed 100 mg/L may be useful as a diagnostic indicator of postpneumonectomy empyema, as described by Icard and colleagues.11 Physical examination findings may be underwhelming, although in empyema necessitatis an undrained empyema may track through the soft tissues, causing cellulitis in the overlying skin.
The radiographic workup of postpneumonic empyema should begin with a posteroanterior and lateral chest x-ray (Fig. 107-2). Hsu and colleagues12 showed that an empyema appears as a wide air–fluid level on posteroanterior view and has a narrow anteroposterior width on lateral projection. Bilateral decubitus films may provide information regarding a freely flowing or loculated empyema. Radiographs also may differentiate among empyema, BPF, and lung abscess. In BPF, the air–fluid level is most commonly located in the posterior costophrenic sulcus.13 There is little difference in air–fluid level size between posteroanterior and lateral projections in the case of lung abscess. Schachter and colleagues14 presented the following qualities that distinguish empyema from lung abscess on plain film: (1) The air–fluid level extends to the chest wall; (2) its border tapers near the mediastinum or chest wall; and (3) the air–fluid level crosses the fissure.
This chest film shows a parapneumonic effusion in a patient with left lower lobe pneumonia. The patient ultimately required a left VATS procedure, drainage, and partial decortication.
Ultrasound also may be used to evaluate empyemic spaces. Major advantages include portability and identification of loculations or pleural fibrosis. This modality also may differentiate transudates from exudates.15,16 Ultrasound also may guide catheter-based drainage of effusions, although a major limitation is the operator-dependent nature of this modality.
Chest CT scan is the mainstay in the diagnosis and management of empyema and BPF. CT characteristics specific to empyema include a thin, uniform, smooth wall along the exterior surfaces, in contrast with the irregular walls seen in lung abscesses (Fig. 107-3). The “split pleura” sign, which distinguishes the separated visceral and parietal pleural surfaces, can be seen in nearly 70% of empyemas (Fig. 107-4).17 The presence of empyema fluid separates the two hypervascular surfaces, which are readily identified on contrast-enhanced scans. One major pitfall is the difficulty of differentiating atelectasis or effusion from the diaphragm. Intra-abdominal ascites and subdiaphragmatic abscess also may make proper diagnosis of empyema challenging.
Shown here is a right lower lobe abscess in an alcoholic patient with aspiration pneumonia.
Recurrent right empyema in this patient ultimately required right thoracotomy and decortication.
MRI may be applied to the diagnosis of parapneumonic effusions and empyema. The multiplanar imagery provides details specific to the location and relationship of the empyema to pleural structures. In addition, the pleural surfaces can be visualized adequately to identify a split-pleura sign. Even so, given the availability and current use of CT, as well as the cost of MRI, widespread use of MRI is limited as applied to empyema diagnosis.
As mentioned earlier, parapneumonic effusions account for the majority of empyemas. The approach should include plain films. Antibiotic therapy is the treatment of choice if the fluid thickness on decubitus studies is less than 1 cm.18 Diagnostic and therapeutic thoracentesis is indicated for larger collections and those that persist or enlarge despite medical therapy.
The evolution from parapneumonic effusion to empyema involves three stages. Stage 1, the exudative stage, is characterized by freely flowing fluid. At this point, the pleural surfaces are inflamed and quite permeable. This stage corresponds to the uncomplicated parapneumonic effusion described by Light and colleagues.18 Stage 2, the fibrinopurulent stage, is characterized by bacterial infection and fibrin deposition. The fluid color may progress from clear yellow to purulent. Biochemical fluid analysis can guide management of these fluid collections. A pleural fluid pH of less than 7.00, pleural fluid glucose concentration less than 40 mg/dL, or a positive culture suggests a complicated parapneumonic effusion, and tube thoracostomy is indicated. Frank pus is an indication for tube thoracostomy. The organized phase, stage 3, occurs approximately 1 week after the initial infection. Fibroblastic ingrowth and collagen deposition occur. Progression of this phase over a period of 3 to 4 weeks may result in a thickened membrane, or “peel,” that results in trapped lung and potentially restricts pulmonary function (Fig. 107-5).
In stage 3 empyema, there is fibroblastic ingrowth and collagen deposition that may develop into a thickened membrane, or “peel.”
After chest tube placement and drainage, the patient should undergo surveillance chest x-ray and chest CT scan to assess (1) completeness of drainage and (2) lung expansion. If multiple loculations are present on the chest CT scan, intrapleural fibrinolytics or thoracoscopy should be performed. Daily intrapleural streptokinase 250,000 units/100 mL of saline may be administered via the chest tube, followed by chest tube clamping for 4 hours. This therapy can be discontinued when the volume of drainage is low or after lung re-expansion has been demonstrated.9 Fibrinolytic therapy is most applicable to the fibrinopurulent phase of parapneumonic effusions. Despite the reported success of fibrinolytic therapy, we favor video-assisted thoracic surgery (VATS) over lytic therapy. Thoracoscopy permits adhesiolysis and chest tube positioning under direct vision. In addition, the coagulum may be thoroughly removed, and if necessary, a limited decortication can be performed. The overall condition of the lung also may be assessed and the need for thoracotomy and complete decortication determined.8 During the fibrinopurulent stage of empyema, VATS offers decreased hospital stay, reduced cost, and improved cosmesis in comparison with thoracotomy.19
In the organized phase, a thick fibrous “peel” overlies the visceral pleura. Patients may have a restrictive pattern on pulmonary function testing. Findings suggestive of this phase include the persistence of an empyema cavity after 7 to 10 days of chest tube drainage, failure of full lung expansion on radiographs, and a thick “peel” on chest CT scan or at thoracoscopy.
In cases of empyema complicated by trapped lung, thoracotomy and decortication are indicated. Preoperative workup should include a chest CT scan and pulmonary function testing. Ventilation/perfusion lung scanning may be useful in selected patients when poor ipsilateral lung function may indicate the need for pneumonectomy.20 Contraindications to this procedure include a debilitated, moribund patient, adequate drainage and expansion by lesser procedures, severe cardiopulmonary disease, and little or no perfusion to the affected lung.
The technique of decortication requires general anesthesia, usually through a double-lumen endobronchial tube. Packed red blood cells should be available perioperatively. The patient is placed in a full lateral decubitus position, and a serratus-sparing posterolateral or vertical axillary thoracotomy incision is made. The pleural cavity is entered through the fifth or sixth interspace after removing a portion of the overlying rib. The peel is incised initially with a no. 15 scalpel blade (Fig. 107-6). The peel is grasped, and a meticulous excision is performed using a combination of blunt and sharp separation of the peel and underlying visceral pleura. Some degree of ventilation to the affected lung will assist with identifying the proper dissection plane. The presence of air leaks indicates an incorrect dissection level. As the fibrinous covering is removed, the underlying lung will readily expand when ventilated. The dissection should be thorough and extend into the fissure and diaphragmatic lung surfaces. This extremely tedious procedure requires patience on the part of the surgeon and anesthesiologist.
Decortication is performed to release the trapped lung. The peel is incised with a no. 15 scalpel blade and then grasped and meticulously excised.
Postresectional empyema may occur after pneumonectomy and lesser resections, including wedge biopsy, segmentectomy, and lobectomy. The risk of occurrence is low at 0.01% for wedge resections and up to 2% for lobectomies.21 Postpneumonectomy empyema is more common, with an incidence of 5% after standard pneumonectomy.22 The mortality rate is as high as 50%.23 Empyema from lesser resections usually occurs secondary to persistent parenchymal leak, with a resulting residual space that becomes secondarily infected. Chest tube drainage and directed antibiotic therapy usually are effective management. More extensive procedures, including VATS with drainage, modified Eloesser drainage, and myoplasty, may be needed in refractory cases. Airspace location may determine the muscle type used during myoplasty. Apical airspaces may be obliterated using the pectoralis major, serratus anterior, or latissimus dorsi muscle. The serratus and latissimus also may be used for posterior spaces. The omentum may be mobilized and passed along the anterior diaphragm for inferior spaces.21
Postpneumonectomy empyema (PPE) represents a serious complication that may occur early or late after pneumonectomy. PPE is accompanied by BPF in up to 80% of cases. Several risk factors that cause BPF may ultimately lead to PPE, as shown in Table 107-1. Preventive measures should include aggressive preoperative treatment of pleural sepsis with antibiotics and optimization of nutritional status. Perioperative measures include careful dissection around the bronchial stump with preservation of bronchial blood supply, appropriate stump length, minimization of intraoperative spillage, and liberal use of autologous flaps for stump coverage. Right pneumonectomy is associated with a higher rate of stump dehiscence, empyema, and BPF. This is likely because the stump is exposed to the pleural space on the right. The left bronchial stump usually retracts medially and subaortically, providing some degree of protection.
Table 107-1Factors that Contribute to PPE ||Download (.pdf) Table 107-1Factors that Contribute to PPE
|Preoperative risk factors |
Radiation and/or chemotherapy
Inflammatory diseased lung/destroyed lung
|Intraoperative factors |
Devascularization of stump
Residual cancer at stump
Failure of recognition of BPF before closure
Tension on bronchial closure
|Postoperative factors |
PPE may be insidious in onset. Symptoms of fatigue, cough, weight loss, and pain may be present. Radiographs may be helpful in cases of PPE with concomitant BPF. A decrease in the air–fluid level on plain film in a patient with the preceding complaints and risk factors should prompt further investigation.
Chest CT scan provides information on the volume and homogeneity of the pleural fluid, the position of the ipsilateral diaphragm, and the status of the remaining lung. In cases of PPE with BPF, CT scan may even provide the location of the opening.
Initial management of PPE without BPF is the same as for other types of empyema—tube thoracostomy drainage. Flexible bronchoscopy should be performed to assess bronchial stump integrity. Mediastinal shift and volume loss may alter the dimensions of the pneumonectomy space significantly. Chest CT scan therefore is recommended before tube thoracostomy. Insertion is safest along the fourth interspace in the anterior axillary line.24 The chest tube should be placed to water seal. If the mediastinum is stable but drainage is inadequate, a modified Eloesser flap can be created, as described by Thourani and colleagues25 (Fig. 107-7). Between 3 months (for benign disease) and 12 months (for malignant disease), a single-stage complete muscle flap closure may be performed as described by Miller and colleagues.26 Extrathoracic muscle flaps can be used to close the pleural space. Flaps used in order of decreasing frequency include latissimus dorsi, serratus anterior, pectoralis major, pectoralis minor, and rectus abdominis. Figure 107-8 shows each of these structures with respective blood supplies. The omentum also may be used to obliterate the postpneumonectomy space and may be more useful for bronchial stump coverage in postpneumonectomy BPF.
Technique for performing a modified Eloesser flap.
Extrathoracic muscle flaps and their respective blood supplies.
Nonresectional Postoperative Empyema
Nonresectional postoperative empyema may occur after esophageal surgery with intraoperative spillage or postoperative esophageal leak. Empyema also can complicate intra-abdominal surgery or infection. This may occur after gastric perforation, splenectomy, or pancreatic infection/resection. The management principles are the same as for postresectional empyema.
The worldwide prevalence of tuberculosis caused by bacterial infection with Mycobacterium tuberculosis deserves mention because it relates to empyema and BPF. Tuberculosis causes nearly 3 million annual deaths in adults worldwide.27 In the United States, factors such as HIV infection, IV drug abuse, and immigration patterns led to a 9.4% increase in reported tuberculosis cases in 1990.28,29 The use of collapse therapy, including intrapleural pneumothorax, plombage, and thoracoplasty, was largely supplanted by antituberculous chemotherapy. The development of multidrug-resistant tuberculosis and its complications has led to a small but renewed role for surgery in the treatment of this disease.
Surgery in Tuberculous Empyema
The preoperative approach should include arterial blood gas determination, pulmonary function testing, and quantitative ventilation/perfusion scans. The latter is particularly helpful in determining the need for lobectomy versus pneumonectomy in the case of destroyed lung. Antituberculous chemotherapy should be administered preoperatively in an effort to produce a negative pleural or sputum culture.30,31 Tube thoracostomy may be used to successfully drain small BPFs during this time. Empyema may be drained using a window thoracostomy or Clagett procedure. After several months, a thoracomyoplasty may be performed in patients treated initially by open-window thoracostomy.32 Muscle flap stump closure should be used in all patients undergoing lobectomy with a positive sputum culture, those with anticipated space problems, and all patients undergoing pneumonectomy.30 The latissimus dorsi muscle is favored and used most commonly for this purpose.
Empyema may complicate traumatic hemothorax associated with blunt or penetrating trauma. Hemothorax also may complicate cardiac surgery, especially if one or both pleural spaces were opened at operation. Although a sterile hemothorax usually is reabsorbed after 1 month, secondary infection poses a significant problem. The initial diagnostic approach should include chest x-ray. Chest CT scan may provide useful information about the amount of hemothorax and the condition of the underlying lung.
Thoracentesis should be performed if there is a free-flowing hemothorax. In chronic cases, the hemothorax is clotted, and thoracentesis is of no value. It may provide some information about the presence of infection but will result in inadequate drainage. Tube thoracostomy also may prove insufficient for evacuating a clotted hemothorax. We recommend the early resort to VATS for the treatment of hemothorax. Early thoracoscopic management can be used to adequately evacuate large, infected hemothoraces and obviates the need for thoracotomy and decortication.8 An algorithm for management of empyema and hemothorax is provided in Fig. 107-9.
Management algorithm for empyema and hemothorax. Reproduced with permission from Landreneau RJ, Keenan RJ, Hazelrigg SR, et al. Thoracoscopy for empyema and hemothorax. Chest. 1996;109:18–24.
Extension of a subphrenic abscess may cause empyema. This accounts for a minority of cases. Other miscellaneous causes of empyema include ruptured lung abscess and generalized sepsis. The management depends on the overall patient status and includes control of the underlying condition and use of the approaches described previously.
Ancillary Nonoperative Approaches to Parapneumonic Effusions, Empyema, and Hemothorax
Fibrinolytic therapy with urokinase or tissue plasminogen activator has been increasingly used as an adjunct to tube thoracostomy drainage and video-assisted thoracoscopic drainage of parapneumonic effusions, empyema, and retained hemothorax.33–35 The results of this adjunctive measure have been gratifying with successful nonoperative management (beyond tube thoracostomy) reported in over 80% of patients treated. Currently, the use of these fibrinolytic agents appears to have increasing utility in the management of these pleural problems.