Parapneumonic effusion and empyema are interrelated, overlapping manifestations of bacterial pleurisy. The most common cause, pneumonia, is present in about 55 % of cases, while bacterial pleurisy complicates pneumonia in 20–57 % of cases. Thus in the majority of cases, the condition presents as pleuropneumonia (Alfageme et al. 1993). Bacterial pleurisy is estimated to account for 20–30 % of all cases of pleural effusion. Serious and debilitating predisposing conditions are observed in up to 82 % of cases, of which compromised immunity due to alcoholism is the single biggest risk factor (Alfageme et al. 1993). The effusion is unilateral in 80 % of cases and may be profuse or sometimes even lead to intrathoracic displacement and compression. The most important differential diagnosis relevant to local treatment is lung abscess, which, however, will not usually require thoracostomy. Contrast-enhanced CT is helpful for making this distinction using the criteria presented in Table 11.3.

The diagnosis of parapneumonic effusion may be straightforward in situations where the clinical background is compatible and the culture is positive, foul smelling turbid effusion has been recovered, or frank empyema is found at thoracocentesis. In the presence of serous clear pleural fluid and negative microbiological findings, further investigations are needed to establish a diagnosis of bacterial pleurisy. Light’s criteria, including pH, glucose content, and LDH, are then commonly recommended for subclassification of bacterial pleurisy into uncomplicated and complicated parapneumonic effusions. Previously, these overlapping conditions were referred to as exudative or fibrinopurulent pleurisy and organizing or chronic empyema. As shown in Table 11.4, empyema and complicated parapneumonic effusion, which are classical high-dependency indications for thoracostomy and drainage, are characterized by low pH (<7.0) and glucose (<2.2 mmol/l (40 mg/dl)) and elevated lactate dehydrogenase (LDH) levels (>10,000 IU/l) and WBC count (>15 × 10⁹/l), with a bacterial culture which is usually positive (Heffner et al. 1995; Maskell and Davies 2003). While uncomplicated effusion warranting noninvasive management is well defined, on the other hand, these criteria may leave a predictive gap for poorly defined intermediate effusions, as is also shown in Table 11.4. Based on the key parameter, pH, and a comprehensive body of evidence from individual studies and meta-analyses, current recommendations of the American College of Chest Physicians (ACCP) propose a more stringent differentiation into four risk and outcome categories (Davies et al. 2003; Antunes et al. 2003):

In broad practical terms, taking into account the clinical presentation and fluid characteristics, thoracostomy with tube drainage is therefore vitally important in one or more of the following conditions:

Any invasive approach that focuses on chest drainage clearly addresses and highlights the use of thoracoscopy (Colice et al. 2000; Loddenkemper and Frank 2006). The rationale of thoracoscopy in empyema and complicated parapneumonic effusion is mainly management related. The diagnostic value of biopsies taken under direct vision in neutrophilic inflammation of bacterial pleurisy is usually negligible – unless differential diagnoses such as tuberculosis or other specific etiologies are being considered.

The role of medical thoracoscopy in the management of empyema and parapneumonic effusion has long been under debate; this indication is only reluctantly accepted by pulmonologists as there is a paucity of evidence-based data and competitive surgical treatment options. Video-assisted thoracic surgery (VATS), in particular, has become a gold standard. For many years, experienced pulmonologists in Western Europe have routinely performed thoracoscopy in the setting of bacterial pleurisy and this has created a body of expertise. However, it remains largely on the evidence level of expert opinion. The “inventor” of medical thoracoscopy himself (Jacobaeus) was the first to report an extensive experience in 100 cases as early as 1925 (Jacobaeus 1925). Boutin and colleagues describe their good results in the preceding edition of this book (Boutin et al. 1991). In Israel, Weissberg successfully performed thoracoscopy in empyema in the early 1970s, using a mediastinoscope (Weissberg 1980). More recently, in a large retrospective series of 127 patients from various hospitals in Switzerland and Italy, all of whom presented with multiloculated empyema, medical thoracoscopy as the first-line intervention under local anesthesia was successful in 91 % of cases, with 94 % of patients being cured by nonsurgical means (Brutsche et al. 2005). In another series of 16 consecutive cases in whom medical thoracoscopy was performed after tube drainage had failed, clinical improvement was achieved in all cases and definitive cure in 12, thus only four cases required surgical debridement (Solèr et al. 1997). In America, Landreneau and colleagues also reported similarly successful use of thoracoscopy in 63 out of 99 patients (Landreneau et al. 1995). In pediatric cases, medical thoracoscopy performed under local anesthesia does not appear to be feasible, and thus video-assisted thoracic surgery (VATS) is considered the intervention of choice and given clear preference over formal thoracostomy (Colice et al. 2000; Davies et al. 2003; Antunes et al. 2003). Medical thoracoscopy is now also becoming increasingly accepted in English-speaking countries and has been adopted as a treatment option by many scientific societies. Surgical thoracoscopy (VATS) for the treatment of bacterial pleurisy is now firmly incorporated into the current guidelines and consensus statements of both the ACCP and the British Thoracic Society (BTS). According to the BTS guidelines, fibrinolysis, VATS, and formal surgery are equally acceptable interventions in empyema, but VATS is preferred to fibrinolysis (evidence level C) (Colice et al. 2000; Davies et al. 2003; Antunes et al. 2003). In this setting, medical thoracoscopy introduces the intriguing additional option of using a combined thoracoscopy/fibrinolysis approach which has the advantage of being only moderately invasive and more cost-effective. This concept is currently under investigation in a European multicenter project.

The technical approach to performing a thoracoscopy in empyema is basically the same as that used for other types of effusion but, importantly, must specifically take into account loculations and membranes, which are typical for and frequently occur in empyema. A careful evaluation with CT and ultrasound, to define safe entry points, is mandatory prior to the thoracoscopy (Figs. 11.1 and 11.2) (Hersh et al. 2003). This is particularly important when sharp obturators are employed, in order to avoid injury to the lung. To define a safe entry compartment in a loculated effusion, an accessible liquid compartment must be firstly identified by fluid aspiration. In our opinion, this should be confirmed by fluoroscopy using gas insufflation (air or better CO₂) to demonstrate gas deposition and thus lung detachment at the intended point of entry. Following entry into the pleural cavity, exploration may reveal widely varying inflammatory patterns.

Drain insertion is a vital procedure which is carried out in the acute phase of empyema, but it is also crucial for optimal long-term results. Another important advantage of thoracoscopy is that it allows visual control and thus also optimal drain placement. Drainage is performed not only to remove fluid but should also usually include irrigation with or without instillation of fibrinolytics. The drainage specifications should therefore give preference to large-bore, double-lumen catheters (≥24 F) to ensure clearance of thick secretions and initiation of closed circuit irrigation. If fibrinolysis is considered, streptokinase and urokinase are equally effective agents. According to several guidelines, the instillation of fibrinolytics is indicated in the presence of:

Fibrinolysis enhances the effects of interventional thoracoscopy and may obviate the need for two or more drains in multiloculated empyema. There will be a transient increase in fluid production due to the resolution and liquidation of pus and membranes. With irrigation and fibrinolysis protocols, the output of mostly turbid fluid will initially exceed the irrigation input. Irrigation is continued until a clear sterile fluid is obtained and the net fluid production falls below 50 ml/day. Our protocol has been well tried and proven in practice and uses a combination of streptokinase and streptodornase (DNAse) (see Table 11.5). The value of the streptodornase component has not yet been firmly established clinically; however, experimental data strongly suggest that the effectiveness of fibrinolysis can be improved by decreasing the DNA-dependent viscosity of the pus (Simpson et al. 2000). The only relevant contraindication to the use of streptokinase is suspected allergy. However, fibrinolytics may also be cautiously applied in the presence of bronchopleural fistula to avoid spilling and contamination of the ipsilateral and contralateral bronchial systems. Adverse effects of both streptokinase and urokinase may include fever >38.5 °C and pain (both up to 7 % of cases). Pleural fibrinolysis is safe as regards systemic effects, and there is no evidence that systemic fibrinolysis occurs at cumulative doses of up to six times the therapeutic level (Davies et al. 1998). A review of the evidence based on fibrinolysis from multicenter studies and meta-analyses reveals that 200,000–250,000 IU streptokinase was equally as effective as 50,000–100,000 IU urokinase (Bouros et al. 1997). Fibrinolysis was significantly more effective than pure irrigation as assessed on the basis of some secondary endpoints such as time to clearance of empyema and radiological resolution (Diacon et al. 2004; Maskell et al. 2005; Tokuda et al. 2006). There were no significant differences between the two procedures as regards the primary endpoints of mortality and surgery. Thus the benefits of fibrinolysis remain to some extent controversial and require further elaboration (Rahman et al. 2011).

Tuberculous pleural involvement may occur at any stage of the disease but is more likely to be associated with a primary pulmonary tuberculous infection. Most patients present with acute fever and the clinical picture mimics bacterial parapneumonic pleurisy, which is also the most important differential diagnosis. Pleuritis exsudativa tuberculosa is the classical term for this form of tuberculosis. The pleural fluid is serous and a high-grade exudate with a protein concentration usually greater than 5 g/dl. Pleural cellularity shows a prevalence of lymphocytes but may become transiently neutrophilic in the acute febrile and initial stages. Exudative pleuritis occurs unilaterally in the vast majority of cases and rarely, if ever, develops profuse or compressive features. Overt concomitant pulmonary involvement is often absent. Exudative pleuritis is unlike tuberculous empyema, which again may mimic nonspecific bacterial empyema. Tuberculous empyema is a sequel and complication of long-standing postprimary pulmonary tuberculosis that may be associated with the rupture of caseous pulmonary lesions, tuberculous fibrothorax, and calcareous pleural thickening.