Chapter 96

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1650 PART 5 ■ Anesthetic, Surgical, and Interventional Procedures: Considerations congenitally-acquired disease may be asymptomatic, patients with acquired disease may be symptomatic from a respiratory perspective, owning to the acute change in diaphragmatic function. The diagnosis, regardless of etiology, can be assessed with diagnostic imaging tests, including ultrasound and fluoroscopy of the diaphragm, looking for paradoxical motion of the diaphragm. In the event that the diagnosis continues to be unclear, an upper gastrointestinal series can be obtained. Once a diagnosis is secured, the option of surgical repair is generally considered for all patients who are symptomatic and those patients who are asymptomatic but also have a markedly elevated hemidiaphragm that is compressing the ipsilateral lung. The surgical procedure involves plication of involved diaphragm; infrequently, a redundant portion of the diaphragm will have to be excised. The approach can be via abdominal or thoracic approach and can be via an open or thoracoscopic/laparoscopic technique. The latter technique has been slowly gaining favor among surgeons. A number of case reports and small case series have been published that advocate for the use of the laparoscopic/thoracoscopic techniques. 48 A study by Sato et al. noted that all of the cases were successfully completed with the thoracoscopic technique and there were no recurrences in long term follow-up. ANOMALIES OF THE LUNG AND AIRWAY Anomalies of the lung and airway are an area of pediatric surgery that is undergoing changes with respect to optimal treatment and management. Some authors have suggested that not all of these lesions need to be surgically excised and some can be safely monitored. 49 Aziz et al. have suggested that asymptomatic congenital cystic adenomatoid malformations can be observed. Other authors, such as Azizkhan et al., have suggested that all of these asymptomatic lesions be surgically excised. 50 This remains a very controversial area and there remains considerable disagreement on this topic. This section will focus on the current treatment options for these largely congenital anomalies and will mention areas of controversy where it alters clinical management; included in this section is a discussion of spontaneous pneumothorax, which may be congenital or acquired in origin. Congenital Pulmonary Airway Malformation These lesions are referred to as congenital cystic adenomatoid malformations (CCAMs) or more recently as congenital pulmonary airway malformations (CPAMs). They can be macrocystic, macrocytic, or solid masses which may involve all or a portion of the lobe of the lung; they communicate with the airway and usually do not have anomalous blood vessels. There are a number of histologic subtypes, which embryologically contain no cartilage and arise from the excessive proliferation of bronchial structures without alveoli. 51 These lesions are now diagnosed in three clinical settings: (1) on antenatal ultrasound examination, (2) when the child presents with symptoms related to respiratory distress or pulmonary infection (pneumonia and/ or intrapulmonary abscess), or (3) when the lung anomaly is discovered incidentally on diagnostic chest imaging. The former examinations have demonstrated that these lesions can have dramatically distinct clinical courses, including complete resolution of the lesion before birth, little change in the size of the lesion, progressive enlargement of the lesion, and in utero demise related to compression of the heart with impairment of central venous return, ultimately leading to hydrops. The primary preoperative indications for surgical resection of these lesions are: (1) respiratory distress from direct compression of adjacent intrathoracic structures, (2) prevention of pulmonary infection (or recurrent pulmonary infection), and (3) prevention of possible pulmonary malignancy. The latter indication is one of the most controversial, because it is unclear whether these malignancies have arisen from a benign congenital lung lesion or whether the diagnosis of the benign congenital lung lesion has been in error and the lesion is, in fact, a malignancy. These lesions are optimally assessed with CT scan imaging, although ultrasound can be used for lesions that are fluid-filled or solid and are adjacent to the chest wall. Figure 96–13 illustrates a CPAM in the right chest that is primarily cystic with a small solid component. The surgical approach usually involves complete resection of the congenital lesion including the surrounding lobe of the lung via an open or thoracoscopic technique. The latter technique has been advanced with devices that effectively seal large vessels and can also go through a 5-mm port; the stapling devices that are now available are too long for most hemithoraces in small children and require a 12-mm port. In addition, it has become common for pediatric surgeons to use low-pressure intrathoracic insufflation (3–7 mmHg) to safely compress the ipsilateral lung, instead of one-lung ventilation. which is prone to technical difficulty given the small airways of children. Various authors have reported low conversion rates to open procedures and overall good success rates with the approach. Albanese et al. have noted maximal conversion rates of 2%, few other intraoperative complications, and lower mean hospital lengths of stay. 52 Figure 96-13. Computed tomography scan (axial) of a congenital pulmonary airway malformation in the right chest, which is primarily cystic with a small solid component.
CHAPTER 96 ■ Thoracic Surgery: Surgical Considerations 1651 Pulmonary Sequestration These lesions are also referred to as bronchopulmonary sequestrations (BPSs). They classically have anomalous arterial and pulmonary or systemic venous blood supply and do not formally communicate with the normal tracheobronchial tree. The former arterial vessels which arise from the thoracic (85–90%) or abdominal aorta (10–15%) can be very large, resulting in a large arteriovenous shunt and possible high-output cardiac failure; moreover, these vessels, if not properly ligated and divided at the time of surgical resection, can result in major intraoperative hemorrhage and can occasionally retract into the subdiaphragmatic space (if they originate from the abdominal aorta). There are two types of BPS, intralobar BPS and extralobar BPS. They differ based on their location within the lung parenchyma; intralobar BPS, which is more common (making up 90% of BPS), lies within the parenchyma of the lobe and indirectly communicates with the adjacent normal lung parenchyma via the pores of Kohn; these pores create an opportunity for infection of the BPS. Extralobar BPS is separate from the adjacent lung parenchyma and is invested with its own visceral pleura but does similarly have systemic arterial and pulmonary or systemic blood supplies. As such, it rarely becomes infected but is at risk for creating an arteriovenous shunt, causing high-output cardiac failure. Unlike intralobar BPS, extralobar BPS is associated with congenital diaphragmatic hernias and can be anatomically located in the thorax (more commonly on the left side) or the subdiaphragmatic space. BPS lesions can be imaged with transthoracic ultrasound, chest CT scan, or MRI. These lesions tend to occur more in the lower portion of the chest; they are differentiated from other congenital lesions by identification of a lung mass with an adjacent large arterial vessel which can be followed to the aorta. Preoperative indications for surgical resection of intralobar and extralobar BPS include recurrent pulmonary infection, congestive heart failure, or resection for diagnosis of a paraspinal mass (to differentiate if from a neoplasm as a neurogenic tumor). As with CCAM/CPAM, they can be resected via open or thoracoscopic techniques and authors have noted equal success with resection of these lesions with minimal access techniques. 52 Intraoperative considerations include the rare risk of major hemorrhage if the arterial blood vessel if not properly ligated; moreover, approximately 15% of BAS lesions will have more than one arterial blood vessel which can be inadvertently missed leading to unanticipated blood loss. 51 Congenital Lobar Emphysema Congenital lobar emphysema (CLE) has multiple etiologies that lead to overdistention (air trapping) of the lobe of lung, resulting in compression of adjacent normal lung parenchyma. Some have implicated the embryologic absence of cartilage in the involved bronchus, leading to a ball-valve effect of progressive over inflation of the lung tissue, and others have implicated the polyalveolar lobe syndrome, which involves the development of abnormally high numbers of alveoli, leading to gigantic alveolar units. 51 Clinically, these children present with respiratory symptoms such as tachypnea; some of these symptoms will resolve with time averting the need for surgery. Optimal diagnostic imaging is achieved with a chest CT scan; the upper and middle lobes are most commonly involved. Figure 96–14 illustrates a child with left-sided CLE on CT scan. Bronchoscopy can also be used to identify abnormal areas Figure 96-14. Computed tomography scan (axial) of a child with left-sided, posterior congenital lobar emphysema with compression of adjacent normal lung parenchyma. of absent cartilage in the tracheobronchial tree. Intraoperative complications can occur at the time of induction of anesthesia, because positive pressure ventilation can cause acute over distention of the lobe involved with CLE. Strong consideration should be given to an anesthetic based on spontaneous ventilation and the surgeon should be in the operating room at the time of induction in case an emergent thoracotomy is required to relieve compression of adjacent intrathoracic structures. Bronchogenic Cysts Bronchogenic cysts are noncommunicating cystic structures adjacent to the tracheobronchial tree which usually exist at the level of the carina or main stem bronchi. They lack normal alveolar structures but do contain a ciliated columnar epithelial lining that produces mucus; as the cyst collects mucus, it extrinsically compressed the adjacent normal bronchial structures. Although this compression can cause air trapping, resulting in a clinical picture of CLE, many of these cysts are asymptomatic at diagnosis and are only noted incidentally on diagnostic chest imaging. Preoperative indications include surgical excision of the cysts to address respiratory compromise, to prevent infection of the cyst, to prevent the unusual occurrence of acute hemorrhage into the cyst causing acute extrinsic compression of the trachea, and to prevent the rare case of adenocarcinoma. These patients are often ideal candidates for a thoracoscopic approach for resection of the cyst, provided that the ipsilateral lung is not over inflated. Many authors have demonstrated the benefit of thoracoscopic resection over open thoracotomy. 53–55 The complication of injuring the adjacent airway at the time of resection is now lessened as it is recognized that the entire cyst wall need not be resected to achieve a low recurrence rate, if the remaining mucosal lining is cauterized.
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Chapter 96

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