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Pleural space problems

Konrad Hoetzenecker and Walter Klepetko

PLEURAL EMPYEMA WITHOUT BRONCHOPLEURAL FISTULA

Pleural empyema is, by definition, a collection of pus within the naturally existing anatomical cavity of the pleura. It is, in most cases, a sequela of a pneumonitis that has gained contact to the pleural cavity. According to demographic studies, it accounts for six out of 100 000 hospitalizations in the United States, with a twofold increase within the last 10 years. Although pleural empyema is a rare clinical condition, it has a high mortality of 7.2%o. ¹

The pathogens traditionally associated with empyema are Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus. The triphasic nature of the disease is well established. In the early phase (Stage I, exudative phase) the pleural cavity is filled with superinfected pleural effusion, or pus. If these fluid retentions are not evacuated, a fibropurulent state (Stage II) develops, which is finally replaced by a fibrothorax (Stage III, consolidated phase). The lung is trapped by a thick peel of inflammatory tissue causing a contraction of the hemithorax, the mediastinum to shift, the diaphragm to elevate, and the spaces between the ribs to narrow (see Figure 22.1).

Preoperative evaluation includes a thoracic computed tomography (CT) scan with contrast agent. It provides information on the location and extent of the empyema, degree of loculation, and the integrity of the underlying lung parenchyma. A contrast-enhanced pleura and a multiloculated pleural collection are a typical picture found in most cases (see Figure 22.2).

The management of pleural empyema is based on a stagewise approach.

Conservative management/Chest tube

In the early phases, an insertion of a chest tube might be sufficient. To completely evacuate all effusion, a chest tube of sufficient size (at least 28 Fr) should be placed directly in the most dependent location, specifically into the costodiaphragmatic recesses and advanced in a posterior direction. ² If the lung does not fully expand after chest tube insertion, a decortication is necessary (see Figure 22.3).

Thoracoscopic decortication

Thoracoscopic decortication should be the treatment option of choice for Stage II empyema. There is sufficient evidence that thoracoscopic decortication has a superior outcome in terms of postoperative morbidity, complications, and length of hospital stay when compared with open decortication for Stage II empyema. When the history of infected effusion is less than 3 weeks, a thoracoscopic approach is usually successful. If the empyema has been present for a longer time, a minimal-invasive approach is more difficult, due to dense adhesions and the presence of a thick visceral peel.

TECHNIQUE

The procedure is usually done with a three-port technique. (see Figure 22.4) The preoperative CT scan helps to place the ports in the right place. One port in the 6th or 7th intercostal space anterior axillary line, one port in the 7th or 8th intercostal space posterior axillary line, and a small working port (3 cm incision) in the 5th intercostal space midaxillary line provide a good exposure of the lower pleural cavity. Care should be taken not to injure the lung when placing the ports. It is advisable to bluntly create a working space in the pleural cavity with a finger before inserting any instruments. First, the pleural space has to be completely visualized by breaking up loculations and by clearing any gelatinous fibrinous deposits. In a next step, the visceral pleura is freed from the beginning cortex with the use of ring forceps, curettes, and peanut dissectors. Special care should be taken not to injure the surface of the lung. Intermittent ventilation helps to visualize the right plane for decortication and to detect any residual trapping of the lung. A complete mobilization is the goal for a good postoperative result, since a residual space is a setup for recurrent infection. Complete reexpansion of the lung to completely obliterate the space is the goal. To accomplish this, it is especially critical to mobilize the lower lobe away from the diaphragm and the anterior aspect of the lung from the mediastinum. Care must be taken to protect the phrenic nerve during this preparation step. If adequate progress is not being made because of too dense adhesions and a complete decortication is impossible with an inadequate expansion of the lung, a conversion to open decortication should be performed. At the end of the operation, complete hemostasis should be achieved and the pleural cavity irrigated with warm water or an antibiotic solution. Two chest tubes are placed and the ports are closed.

Open decortication

Open decortication should be reserved for Stage III or complicated Stage II empyema. The incision is placed in the 5th or 6th intercostal space. Care should be taken to avoid opening an intercostal space that is too low, since the diaphragm is always elevated due to the shrinkage of the pleural cavity. Although a posterolateral approach has traditionally been preferred and facilitates perfect vision, muscle-sparing thoracotomies can be used without impairment of visualization. After the intercostal muscles are dissected a blunt—if necessary, extrapleural—development of the pleural space next to the thoracotomy is advisable before inserting the chest retractor. This releases tension on the ribs in order to avoid fractures during spreading. A resection of ribs, as suggested by some authors, is not necessary in most cases. The thickened parietal pleura and peel are incised with a scalpel until the visceral pleura is identified. Then the thick peel is meticulously removed in a blunt way, taking care to maintain the appropriate plane between the visceral pleura and the peel. (see Figure 22.5) A mild inflation of the lung usually eases this maneuver, since it provides some needed countertraction necessary in maintaining the appropriate plane. A complete mobilization is important, and small superficial injuries of the lung are often unavoidable but usually seal within the first hours after the operation. Deep tears of the lung should be closed with absorbable suture material. At the end of the procedure, hemostasis is obtained, the pleural cavity is irrigated with warm saline or an antibiotic solution, and two chest tubes are placed. In severely compromised patients, a sufficient hemostasis is sometimes impossible to achieve. In these selected cases, packing of the pleural cavity using towels is advisable.

Small abscess formations found during the decortication should be closed by capitonnage with reinforced sutures. Necrotizing pneumonia, extensive pulmonary abscess formations, and lung gangrene are rare situations. They always require resection of all devitalized pulmonary structures. In most cases, an anatomical resection (septic lobectomy, pneumonectomy) is necessary. In these cases, it is of utmost importance to reinforce the bronchial stump with wellvascularized muscle or a pericardial flap.

Open treatment

For multimorbid patients who are considered not fit enough for an open decortication, an open window thoracostomy (Eloesser flap) in combination with a vacuum-assisted closure (VAC) device can be considered. VAC therapy allows an acceptable reexpansion of remaining lung and a sterilization of the pleural cavity in most cases.

Postresectional pleural empyema

Postresectional pleural empyema may occur after anatomical as well as wedge resections. The incidence for postlobectomy empyema is 2%. For wedge resections, it is considerably lower. Infections of the pleural space after lung resections are nearly always associated with prolonged air leaks. In contrast to the pleural space, which is a highly sterile region, the lung itself is often colonized by pathogens. During a prolonged air leak, the pleural space can be contaminated with pathogens resident in the lung breaking the natural antimicrobial barrier of the pleural space. In early stages, a chest tube placement and intravenous antibiotics provide sufficient treatment. In advanced stages, an open window thoracostomy with/without intrathoracic VAC treatment, followed by a muscle transposition, might be necessary.

POSTPNEUMONECTOMY EMPYEMA

Postpneumonectomy empyema (PPE) is a serious complication in thoracic surgery, which carries a high mortality. The reported incidence ranges from 2% up to 7%; however, these numbers may be underestimated because of delayed presentation and occurrence of the disease. ³ In general, PPE can be classified as PPE with a bronchopleural fistula (BPF) or PPE without a BPF, the latter being rather rare (comprising only 15%).

Risk factors for the development of PPE include local (long bronchial stump, disrupted blood supply, preexistent empyema, postoperative mechanical ventilation, right pneumonectomy, neoadjuvant radiotherapy) and systemic factors (poor nutritional status, diabetes). A proper surgical technique is a prerequisite to reduce the risk of a PPE. When performing the lymphadenectomy at the time of resection, special care should be taken to avoid devascularization of the main bronchus and carinal region. The bronchial stump should be stapled at the level of the carina to avoid a long bronchial stump. Right bronchial stumps are at higher risk for the development of a BPF. This is due to minimal mediastinal coverage compared with the left side, where the stump will usually retract in the mediastinum beneath the aorta. The bronchial stump should always be covered with vascularized tissue after a pneumonectomy. This includes, according to local availability, a pedicled pericardial fat pad, a diaphragmatic or an intercostal muscle flap, an azygos flap, or a combination thereof.

PPE can present days to years after the initial surgery. Diagnosis is difficult, since the clinical presentation can be quite subtle, especially in late occurring fistulas. The most reliable diagnostic tool has been shown to be a constantly high C-reactive protein, with a sensitivity of 100% and a specificity of almost 92%. Radiological imaging should always include a chest X-ray and if in doubt a CT scan. Air in the pleural cavity, a convex expansion of the pneumonectomy space, and a reversal of the physiological ipsilateral mediastinal shift are signs highly suspicious of PPE. A bronchoscopy should always be performed to exclude a bronchial stump fistula. It is of note that a small stump dehiscence may be missed easily during bronchoscopy. An injection of methylene blue and monitoring of the drained pleural fluid help to identify a small BPF.

Treatment

DRAINING THE PLEURAL SPACE

As many patients with PPE present with a fulminant course and a preseptic or septic condition, stabilization of the patient is the primary goal. Draining of the pleural space is the most important initial measure. This controls the septic process and prevents aspiration of pleural fluid through the BPF to the remaining lung. The chest tube should be placed above the old thoracotomy to avoid a subphrenic malposition due to the chronic shrinkage of the pneumonectomy cavity. Broad intravenous antibiotic coverage should be started immediately and adapted according to the culture results of obtained pleural fluid specimens. This can be supported by insertion of an irrigation catheter applying topical antibiosis into the thoracic cavity. The most common organisms cultured from PPE specimens are Staphylococcus aureus and Pseudomonas aeruginosa.

The further treatment algorithm is dependent on the following factors: early versus late fistula, large versus small bronchial defects, the patient’s overall condition, and the extent of intrapleural infection. In general, surgical management of PPE includes three different steps.

1 Closure of the BPF

The surgical approach to reach the hilum can be difficult, especially for late fistula, when the hilar structures are covered by a dense cortex. For right-sided problems, a redo thoracotomy is the best option. The old skin incision can be used; however, the chest cavity should be entered one intercostal space higher. This maneuver facilitates the use of an undamaged intercostal muscle flap (if needed) for the buttressing of the reclosed bronchus. For left-sided stump problems, access through a left-sided repeat thoracotomy is not advisable. The stump is usually deeply positioned in the mediastinum below the aorta and very hard to dissect. An alternative approach through a right-sided thoracotomy or a transsternal approach eases the preparation of the stump through a formerly untouched area. ⁴

After exposing the hilum, the bronchial stump is carefully dissected, leaving the blood supply intact. Small fistulas can be visualized by positive airway ventilation under water seal. There are several ways to manage the fistula. If the stump is long enough, a more central reclose with a commercial stapling device can be done. If there is too little space to insert a stapler, the bronchus should be reclosed with interrupted reinforced monofilament sutures. The neostump should be buttressed with either an intercostal muscle flap or a pedicled pericardial flap. For patients with older fistulas, a direct closure without tension is sometimes not possible. In these cases, the bronchial opening is closed by directly suturing a muscle flap or omentum onto the fistula.

2 Debridement and sterilization of the pleural cavity

Sterilization of the pleural cavity is an essential step in the successful treatment of PPE. The postpneumonectomy cavity is a noncollapsible space, which is filled by bradytrophic, contaminated tissue. Due to the advanced scarring, systemic antibiotics only reach the cavity insufficiently and a thorough debridement of all necrotic or infected tissue in the pleural cavity is a prerequisite to reach sterility.

According to the grade of infection, singular or repeated debridements are necessary. Mild infections of the thoracic cavity can be treated by a singular removal of infected material, and a subsequent sealing with viable tissue (myoplasty, omental flap). Omental flaps are—in our opinion—the best option. Although a median laparotomy is required for their preparation, they are able to effectively contain residual minor infection.

In most cases, however, sterility cannot be reached in a single stage, and multiple procedures will be required. The old concept of creating a thoracic window, initially developed for the treatment of tuberculosis, is still the approach of choice in many centers. This procedure combines repeated debridements through a thoracic window (Eloesser flap, open window thoracostomy) with later closure after sterilization is completed. The technique results in a high rate of success, although treatment requires a prolonged hospital stay and the thoracostomy procedure is disfiguring and related to high morbidity. Therefore, alternative procedures have been proposed recently. An accelerated treatment omitting the thoracic window by performing repeated debridements in the operating room and packing with iodine dressings was proposed by Schneiter and colleagues (2008). ⁵ This technique resulted in a definite closure of the chest within 8 days and a success rate of 100%. Alternatively, in cases with only moderate infectious changes of the thoracic cavity, a single thoracic debridement procedure followed by prolonged antibiotic irrigation can be successful. Another novel approach is vacuum-assisted management of the infected pleural cavity. The negative-pressure wound therapy stimulates an accelerated sterilization of the cavity, avoiding prolonged hospitalization and facilitating an early closure of the thoracic window.

3 Sealing of the cavity

Successful sterilization of the pleural space is a prerequisite before the postpneumonectomy cavity can be closed. The cavity should be completely sealed with vascularized vital tissue (muscle flap, omental flap). If the remaining space is too large, this can be combined with a limited thoracoplasty, removing the first three ribs. A complete thoracoplasty is associated with high morbidity and disfiguration and should rarely be performed. Alternatively, if no vital flaps are available, the cavity can be obliterated with antibiotic solution.

ENDOBRONCHIAL PROCEDURES

Endoscopic treatment options to close small BPF have been anecdotally described in the literature. ⁶ The bronchial defects can either be bridged by coated stents or directly closed by glues, coils, balloon catheter occlusion, or by repeated application of silver nitrate. These techniques can be successful for defects less than 3 mm but are not advisable for a larger bronchial stump dehiscence. One must remember that infection in the pleural space is the major issue; closure of the bronchial fistula must be considered strictly as an adjunct to ultimately sterilizing and obliterating the space.

MUSCLE FLAPS AND OMENTAL FLAP

Muscles are an ideal material for filling the pleural space and for covering bronchial stump fistulas. They are well vascularized and can be rotated to nearly any region of the thoracic cavity. The survival of the muscle depends on the preservation of its blood supply during preparation. The following muscles can be used for intrathoracic transposition.

Intrathoracic muscle flaps

DIAPHRAGMATIC MUSCLE FLAP

This flap can be easily used to cover a BPF. Its vascular pedicle is the phrenic artery, which runs below the phrenic nerve on the inferior aspect of the muscle. The flap is prepared in a U-shaped fashion and is rotated to the lung hilum. Care should be taken to avoid a torsion or extensive tension on the pedicle. The remaining rent in the diaphragm is closed with interrupted sutures (see Figure 22.6).

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