Severe adhesion, fibrous tissue, and inflammation generally occur around the fistula, making rTEF repair surgery difficult. Thoracoscopic surgery provides an enlarged and clearer field. We have performed over 100 thoracoscopic repair surgeries since the first attempt in 2014, with a final cure rate of approximately 84.5% (including early cases). The success rate has been growing year after year by the increase in our thoracoscopic technical experience. The challenges of repair surgery are locating and exposing the fistula while minimizing tissue injury and ischemia. It has been proposed that a guide wire should be left in the fistula to assist in localization [9, 10] and that an endoscopic light source should be used for localization [11]. It was also reported that a fistula can be confirmed if air is seen in the trachea after complete separation of the trachea and esophagus [1]. Endoscopic light localization may interfere with respiratory support. Extra dissection of the esophagus during surgery may injure the vagal nerve and tissue more severely, even leading to lymphatic leakage [12, 13]. We also placed a guide wire prior to the operation to determine the location of the fistula as previously described by Coran [7] for double assurance. However, this may cause friction damage to the trachea and esophagus. In addition, it was difficult to insert the guide wire in some cases because of the poor esophageal condition, airway malformations and irregular fistulae. For esophageal-pulmonary fistulas, as a special type of rTEF, the thoracic infection was usually more severe, so the location could hardly be identified and precludes the use of a guide wire. We therefore attempted to improve rTEF surgery by fluorescent imaging thoracoscopy with ICG. We subsequently applied this method to delayed closure surgery. The patient was diagnosed with esophageal atresia type III with a long gap. Ligation of the tracheoesophageal fistula and gastrostomy were performed at another hospital after birth, and 3 months later, end-to-end anastomosis of the esophagus was performed and failed again. The condition of the thoracic cavity was complex and similar to that observed in patients with rTEF, and ICG helped to identify the esophageal pouch during surgery.
ICG is generated by excitation with near-infrared light (NIR) and becomes visible by the special receiver converter. The thoracoscope system for the surgery had two mode: ordinary light and fluorescence imaging mode.We can switch between two modes to help us during the procedure. We used ICG to visualize fistulae under fluorescence imaging mode during thoracoscopy. ICG is virtually nontoxic [14]. It is usually injected intravenously for the assessment of liver diseases, tumors and other conditions. The clinical application of ICG has mainly been previously reported in adults. Recently, the use of ICG in pediatric surgery has been reported to be safe and effective [6, 15]. No allergic or other adverse systemic reactions to ICG have been reported [8]. Even so, we performed the ICG skin test before surgery in case of rare allergies because the agent contained a small amount of iodine.
ICG is inexpensive and readily available, and the procedure is not time-consuming. Because of the instability of ICG in water, we suggest preparing it immediately prior to use. We obtained a perfect image by fluorescent imaging. The thickness of ICG fluorescence energy across the tissue is generally approximately 1–1.5 cm. We used a lower dose than suggested for intravenous injection, which was 0.5 ml for each operation (concentration of 1.25 mg/ml). To avoid unexpected, uncertain results, we still placed a guide wire for double assurance as the cases allowed. In surgery, fluorescence seemed strong due to the thin fistula tissue. Our fluorescence imaging system can adjust the intensity of fluorescence; thus, we could obtain a clear image. However, in the esophageal pouch, the light was weaker because of the hypertrophic tissue and scarring tissue. It could be enhanced by clamping the tissue. Thus, when the operator was uncertain, the tissue could be extruded slightly and then visualized, or we could use more dose ICG for indication. In all cases, much of the ICG was suctioned, and the rest was excreted directly via the digestive tract or through the respiratory tract as sputum. Even a small amount of drug is absorbed and fully metabolized by the liver.
There are many benefits to the application of green fluorescence indocyanine imaging demonstrated in this study. ICG shows the fistula clearly and distinctly, greatly improving the efficiency of finding the fistula intraoperatively. In addition, it is very helpful for preventing ischemia from wide dissection of the esophagus and trachea during the operation, which may also reduce the duration of the operation. Direct spray of ICG around the fistula can clearly show its location, eliminating the need for guide wire placement, which can save anesthesia time and reduce tissue damage. Moreover, ICG is beneficial for complex cases in which guide wires cannot be placed. Likewise, for in complex esophageal repair surgery, the ICG can be a good indicator.
There are also limitations to the application of ICG. There are few reports on the use of ICG in pediatric surgery. We need more cases to summarize our experience of using ICG to standardize its use and promote its broad application.
