Guidelines for Thoracoscopic Biopsies in Children
Lung biopsy is an important tool in the diagnosis of interstitial lung disease in immunocompetent children.4 Thoracoscopy is useful for the assessment of respectability, staging and evaluation of metastatic disease.5 Some of the indications for thoracoscopy include blebectomy, mediastinal biopsy, lung biopsy, excision of intrathoracic masses, including bronchogenic cysts.6 Improved technology and decreased morbidity from the thoracoscopic approach allows for a more aggressive approach to obtain tissue for diagnostic purposes in cases of interstitial lung disease and questionable focal lesions.3 Minimally invasive surgery is a safe and accurate means of obtaining tissue in pediatric oncologic patients.7-9 Potential problems with the use of thoracoscopy for biopsy include the inability to palpate lesions and the development of recurrent disease at the port sites.9
Preoperative workup varies based on the procedure performed.6 Most intrathoracic lesions require routine radiographs as well as computed tomography (CT) or magnetic resonance imaging (MRI).6 Thin cut, high resolution CT scan is particularly useful for identifying the most affected areas with interstitial lung disease.6 Occasionally, deep lesions require CT guided needle localization just before the thoracoscopic procedure. This usually involves marking the pleura overlying the lesion with a blood patch or dye and occasionally inserting a wire into the lesion. However, the wire may become dislodged as the lung is collapsed.3, 6
Children with mediastinal masses should be evaluated with pulmonary function and volumetric determination of airway by CT scan prior to performing surgery under general anesthesia. The most important factor in estimating whether tracheal compression will occur after induction of anesthesia is the patient’s preoperative respiratory status, particularly if he/she can lie flat without symptoms. Rarely, avoidance of muscle relaxants is necessary in which case local anesthesia plus mild sedation is used to protect the airway.
The chest x-ray and CT or MRI findings help to localize the lesion and to determine optional patient positioning for the operation.
Lung biopsy is performed with patients in the lateral decubitus position. Posterior pleural biopsies are performed with the patient almost prone and anterior lesions are performed with the patient almost supine. Thus, positioning takes advantage of gravity to allow the lung to fall away from the lesion when the lung is collapsed.3, 6, 11-12
In addition, if necessary, lung biopsy can be obtained by the open technique through a normal posterolateral thoracotomy or small muscle sparing thoracotomy. Mediastinal masses can also be biopsied using thoracotomy, mediastinoscopy, or median sternotomy.
Safe techniques have been identified for thoracoscopic procedures in children. Single lung ventilation is useful in infants and children, but it is difficult to place dual lumen tubes in small children.1, 3, 6, 11-12 Instead, the patient may undergo selective contralateral lung ventilation using ipsilateral bronchial blockers or Fogarty balloon catheters. Use of CO2 insufflation creates a pneumothorax and further collapses the ipsilateral lung. Pressures of 4-6 mm should be utilized.
Entry to the thoracic cavity should be at the fourth interspace as the collapsed lung from single lung ventilation may elevate the ipsilateral diaphragm.
Deep-seated lesions should be localized as previously described. Because the lesion cannot be palpated, the specimen should be sent for frozen section examination and the presence of the lesion should be confirmed before removing the ports.3, 6
Usually three ports are used for biopsy. In larger children, placement of a 12 mm port is recommended for the use of endoscopic staplers. Smaller children can be biopsied with biopsy forceps or after placement of endoloops surrounding the tissue. However, the loops may dislodge and the biopsy site can be secured by sutures.
Mediastinal masses can be approached by thoracoscopy. Single lung ventilation should be achieved by the same methods used for pleural and lung biopsies. For anterior mediastinal masses, a modified supine position is helpful. The positioning allows gravity to keep the lung out of the operative field. Thoracosopy allows visualization of the lesion and determination of the exent of the lesion. The lesion may be biopsied or resected.13
Bleeding can be controlled with cautery, laser, ultrasonic shears or the Ligasure. Reexpansion of the lung frequently controls bleeding.
Placement of tube thoracostomy at the end of the procedure is procedure directed, and is often based on the extent of ventilatory support the patient will require.