Abstract
This chapter, reviews thoracic surgery for a host of pathologies in children. The author discusses commonly encountered pediatric congenital lung tumors (i.e.. Congenital lobar emphysema and Congenital Cystic Adenomatous Malformations). Anesthetic implications for VATS vs open thoracotomy as well as approaches for one lung ventilation is considered. Treatment of intraoperative pulmonary issues as well as strategies for post-operative analgesia are presented.
Case 1: A six-year-old with a history of osteosarcoma postchemotherapy and resection 18 months prior, presents with a new cough, shortness of breath and expiratory wheezing. The workup reveals a new mass in the right middle lobe as well as a large pleural effusion. Following CT-guided biopsy confirming metastatic disease, the surgeons plan to resect the mass via video-assisted thoracoscopic surgery (VATS).
What Is the Most Likely Cause of This Lung Mass?
Primary lung tumors are uncommon in children, with benign lung lesions being 10 times more common than malignant ones.
Secondary lung tumors are unfortunately more common with metastatic tumors comprising 80% of all lung tumors, of which 95% are malignant. In this patient, despite previous treatment, the most likely scenario of a new lung mass is recurrence of osteosarcoma with lung metastases.
In a child with no history of malignancy, the workup for new solitary lung tumors is quite different. Recommendations are to treat per symptoms, obtaining a baseline chest X-ray and labs. If symptoms persist beyond two to four weeks, a chest CT is warranted as is pulmonology consultation. If the chest CT is negative, treatment is continued for another two to four weeks prior to repeating a chest CT and bronchoscopy. If the CT reveals a lung mass, biopsy is warranted. Peripheral lung lesions are often amenable to open surgical biopsy or percutaneous biopsy in interventional radiology. Central lesions are biopsied via a bronchoscopic approach.
What Are the Differences Between VATS and Open Thoracotomy?
Video-assisted thoracoscopic surgery (VATS) was first performed in children in the mid-1970s. The contraindications to VATS include: (1) empyema with development of fibrosis obliterating obvious space between the ribs and (2) densely adherent tumor infiltrating the chest wall. The advantages of VATS over conventional thoracotomy include:
1. A reduction in postoperative pain from rib retraction during thoracotomy which occurs even if muscle sparing incisions are performed.
2. Reduction in musculoskeletal sequelae, as conventional thoracotomy leads to asymmetry of the thoracic wall from atrophy of the chest muscles as well as the development of ipsilateral scoliosis.
3. Improved recovery, with shorter hospitalizations and faster return to normal activities of daily life.
What Are the Preoperative Considerations Prior to Lung Tumor Resection?
Preoperative evaluation typically includes routine labs, chest X-ray, and CT scan of the chest. Preoperative echocardiography is necessary in settings where external cardiac compression is considered. Type- and cross-matched blood should be available. Despite plans for a thoracoscopic approach, conversion to open thoracotomy with potential for significant blood loss always remains a possibility.
What Are the Options for Lung Isolation?
The primary need for any endoscopic procedure is adequate visualization and space to work. This is achieved by collapsing the operative lung. Lung isolation in small children may prove difficult.
1. Double Lumen Tube (DLT)
This device fuses two tubes of unequal length, with one terminating in the trachea and the other in a bronchus (right or left) allowing for ventilation of one or both lungs. The DLT also helps minimize the risk of contralateral lung contamination and allows for suction and maintenance of positive pressure as needed to either lung. Its limitation is size as the smallest DLT is a 26Fr, acceptable for ages 8–10, with an outer dimeter of 8.7 mm, comparable to a 6.5 mm internal diameter endotracheal tube, preventing its general use in younger pediatric patients.
2. Bronchial Blocker
A balloon catheter is positioned in the proximal main-stem bronchus under fiberoptic visualization. If no true bronchial blocker is available, a Fogarty Occlusion Catheter or balloon wedge pressure catheter may be substituted. Inflation of the balloon blocks ventilation to the distal lobes or entire lung. Disadvantages include difficult placement in small children and frequent dislodgement. In situations where the balloon migrates into the trachea, full ventilatory obstruction may occur. Other issues include potential over-distension of the balloon with resultant tissue damage of the airway, inability to suction the operative lung, and an inability to apply continuous positive airway pressure to the operative lung. A bronchial blocker is often used in young children <8 years.
3. Univent Tube
This is a tracheal tube with a bronchial blocker within a separate lumen, allowing advancement with inflation or withdrawal and deflation should double-lung ventilation be required. These tubes are available for pediatric sizes in 3.5 and 4.5 mm ID, allowing the youngest age of use to be approximately 6 years. This provides an optimal option between ages six and eight, at which point a double lumen tube is the preferred option.
4. Standard Single Lumen Endotracheal Tube with Intentional Mainstem Bronchus Intubation
This is the preferred method for children ages zero to six months, but can be acceptable up to 18 years. A fiberoptic bronchoscope may be passed to confirm placement. Disadvantages include failure to provide an adequate seal, an inability to suction the operative lung, and hypoxemia due to obstruction of the right upper lobe bronchus. The inability to quickly change from one lung ventilation to two lung ventilation is the major drawback of this technique for occlusion of the operative lung.
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