The incidence of this problem has been reported by Bell et al in 22% of TB resections. Wareham et al reported a 20-40% rate of postoperative space after lobectomy procedures. Silver noted a 12% incidence with partial resections. The predisposing factors for postoperative space include:
- Extent of resection, abnormal compliance of the residual lung, underlying parenchymal disease such as pulmonary fibrosis, and emphysema. In addition prior mediastinal radiation or prior surgery can predispose to space problems.
Other causes of this problem include: segmental bare surfaces, incomplete fissures, and persistent air leaks. The problem is more common in left upper lobectomies although the cause is unclear.
- Other factors that may contribute include postoperative atelectasis leading to incomplete expansion. Postoperative spaces can generally be managed conservatively since the majority will close on their own. Maintaining negative pleural pressure, promoting pulmonary reexpansion using incentive spiromerty and chest PT are crucial. IPPB, CPAP masks and intermittent bronchoscopy is also helpful. Placement of patent large chest tubes with high suction if necessary are quite important. Monitoring the degree of air leak and adjustment of the tube, suction as necessary can prevent development of large chronic spaces.
The normal mechanisms after lung resection generally prevent serious problems from occuring. These include:
- Reexpansion of remaining lung, narrowing of the intercostals, elevation of the diaphragm and mediastinal shift. These factors usually help obliterate the air spaces in up to 88% of lung resections. The natural history of these spaces has been well documented by Silver, Barker and others.
- 10-30% of lung resections develop a pleural space postoperatively. 74% of these generally resolve spontaneously. 80% of the time, this occurs within four weeks. 90% of these spaces will disappear within a year. Only 9% of spaces will persist for1-10 years. Approximately 5% of the spaces will get infected. 2% of these will be found to have an associated bronchopleuralfistula. 2% will actually develop an empyema.
- The key to minimizing the morbidity from air space is avoiding their occurrence. There are several simple maneuvers that are important. Careful CT placement can not be overemphasized. When a large resection takes place or results in significant AIR LEAK INTRAOPERATIVELY, two tubes placed anteroapically and posterobasally should be left behind. As noted above aggressive pulmonary toilette is crucial, PA/LAT chest X-ray should be performed if there is a question, in order not to miss a small anterior or posterior loculated space. At the time of resection, stapling of the fissures may result in less air leakage. Use of fibrin glue or pericardial /PTFE buttresses may minimize air leakage although this has not been proven to date. A phrenic nerve crush has been used in the past to help obliterate the postoperative space. Pleural tenting of the apex has received attention again recently. This too has not yet been shown to be of proven benefit.
- When a space is found with an air leak there is a higher chance of infection. Prompt chest tube drainage should be instituted. Once adequate drainage has been achieved, a Heimlich valve can be connected. This will usually result in a shortened hospitalization and less patient discomfort. Alternatively, if the air leak is significant or uncontrolled by the chest tube a VATS exploration can be undertaken. This would allow application of fibrin glue, stapling of the residual air leak and decortication of any trapped lung. Resection of the lung tissue including lobectomy, bilobectomy or even pneumonectomy can be performed.
- Evaluation of the pleural space may allow the surgeon to determine whether there is likely to be closure of the space. Performing a pressure/gas analysis is not commonly done, but this may help to predict resolution. In a closed space there is negative pressure and high CO2. On the other hand, when there is "alveolar seepage", the pressure slowly returns to neutral and the O2/CO2 are similar to that found in the alveoli. If a bronchopleuralfistula is present, there will never be a negative pressure. The gases are the same as in normal inspired gas.
Once an empyema has been diagnosed, the classification by Andrews et al (1962) and Light may help to decide treatment. A Stage I has an exudative effusion (like the "uncomplicated" in Lights classification). Stage II means that there is already fibrinopurulent debris (complicated). Stage III has already developed collagen organization with a resultant peel of the pleura. Some of the sequelae of chronicity include development of a fibrothorax, bronchopleural fistula, empyema necessitans and metastases such as osteomyelitis, brain abcess, and pericarditis. Presently the bacteriology commonly involves MRSA, gram negative aerobes-(64%), anaerobes-(13%), and multiple organisms-(23%).
- Treatment of the postpneumonectomy space represents a special problem. The normal space fills at the rate of 500 cc/day. When more rapid filling occurs, one must consider bleeding which may require a reexploration. If significant mediastinal shift occurs, pleural infection should be ruled out. In addition chylous effusion and malignant collections should be considered. If the pneumonectomy space is noted to be rapidly emptying ,one should consider a bronchopleural fistula.
- The surgical treatment of postoperative spaces is seldom necessary. The key to successful management of the space with surgical techniques is expansion of the underlying lung and drainage of the pleural cavity. Achieving apposition of the remaining lung to the chest wall is sine qua non to successful repair. There are several options including:
- Thoracoplasty using a modified Estlander (extraperiosteal) or Grow-Kergin (extensive-w/pedicle) technique has been reported at the time of resection of two or more lobes. This generally should be reserved for failed conservative treatment. Muscle flaps are helpful in obliterating the pleural space. Intercostal muscle in conjunction with thoracoplasty or alone are well described. Serratus anterior flaps are particularly well suited to the postpneumonectomy space and can be transposed through the second or third interspace. Pectoralis major and omentum pedicled flaps are also excellent means of obliterating the cavity. Other surgical treatments include less invasive procedures such as: pneumoperitoneum utilizing 1000-1500 cc aliquots of air introduced subdiaphragmatically to force the diaphragm upwards. Many groups utilizing the combination of irrigation/debridement with antibiotic irrigation and chest closure have reported the Claret procedure. Likewise when the space can not be controlled by other means the Eloesser flap remains an excellent alternative. Although bronchoscopic closure of bronchopleuralfistula has been reported we have found it useful only for the smallest of holes.
