Short and mid-term results of thoracoscopic surgery for esophageal atresia in low birth weight infants:A single-center clinical experience

Purpose: To evaluate the short-term safety and long-term ecacy of thoracoscopic surgery for esophageal atresia(EA) in low birth weight infants. Methods: From January 2011 to December 2019,a retrospective analysis on clinical data of 48 cases of low birth weight infants of EA. The clinical data were divided according to surgical methods: Thoracoscopy group A and thoracotomy group B. Variables of intra-operation, postoperative complications and mid-term postoperative complications were compared between the two groups. Results: 3 were discharged due to treatment abandoning. there were 17 cases in thoracoscopy group A and 28 cases in thoracotomy group B. The operation time of group A(172.41±20.00min)was longer than B(149.82±13.91min),the difference was statistically signicant (P<0.05).the intraoperative blood loss of group A(7.41±2.83ml) was less than B(18.61±3.60ml),the difference was statistically signicant (P<0.05).postoperative mechanical ventilation time, thoracic drainage time, hospital stay were not signicantly different between the two groups. the incidence of anastomotic stenosis in group B(58.82%) was higher than in A(28.57%),the difference was statistically signicant (P=0.045).There was no signicant difference in the incidence of esophageal anastomotic stula and recurrent tracheoesophageal stula. After 3 years of follow-up, the incidence of thoracic deformity in group B(25%) was higher than in A(0%).The difference was signicant(P=0.034).However, no signicant difference was observed among the gastroesophageal reux, symptomatic stenosis, tracheomalacia. Conclusion: Compared with thoracotomy, thoracoscopy in low weight infants with EA has the advantages of smaller incision, fewer intraoperative bleeding, and less incidence of thoracic deformities. Thoracoscopy might be

group A(7.41±2.83ml) was less than B(18.61±3.60ml),the difference was statistically signi cant (P<0.05).postoperative mechanical ventilation time, thoracic drainage time, hospital stay were not signi cantly different between the two groups. the incidence of anastomotic stenosis in group B(58.82%) was higher than in A(28.57%),the difference was statistically signi cant (P=0.045).There was no signi cant difference in the incidence of esophageal anastomotic stula and recurrent tracheoesophageal stula. After 3 years of follow-up, the incidence of thoracic deformity in group B(25%) was higher than in A(0%).The difference was signi cant(P=0.034).However, no signi cant difference was observed among the gastroesophageal re ux, symptomatic stenosis, tracheomalacia.
Conclusion: Compared with thoracotomy, thoracoscopy in low weight infants with EA has the advantages of smaller incision, fewer intraoperative bleeding, and less incidence of thoracic deformities.
Thoracoscopy might be a feasible surgical option for low weight infants when performed by a surgeon who has rich experience. The major mid-term complications after surgery are esophageal stenosis, gastroesophageal re ux and tracheomalacia.

Background
Congenital esophageal atresia is a serious digestive tract malformation that occurs in 1 in 3000-4000 newborns [1].The incidence in China is slightly lower than that in foreign countries.However,if not treated in time,it will seriously endanger the patient because of the large population. Prenatal color Doppler ultrasound of esophageal atresia often shows excessive amniotic uid.The initial symptoms are foaming at the mouth,coughing,cyanosis,and trouble breathing.If not treated in time,most infants die in [3][4][5] days.At present,many single-center studies at home and abroad have reported that thoracoscopic surgery is a safe and feasible treatment for esophageal atresia,but most infants undergoing surgery have a preoperative weight greater than 2500 grams,who are resistant to thoracoscopic surgery and anesthesia.For infants with low birth weight,the safety and feasibility of thoracoscopic treatment and the long-term clinical prognosis remain under debate.Considering these circumstances,the purpose of this study is to analyze the surgical results of low birth weight infants in a single center,and to compare the e cacy and complications of thoracoscopy and thoracotomy.

General data
Select the clinical data of children with esophageal atresia hospitalized for 8 years from January 2011 to December 2019 in pediatric Surgery of fujian maternity and child health,and retrospectively analyze 48 cases of which received surgical treatment and were born Clinical data of children weighing less than 2500g.3 cases were excluded,who gave up treatment and were discharged automatically due to chromosomal abnormalities and multiple organ abnormalities found in preoperative examinations.With the maturation of thoracoscopic techniques and anesthesia for low birth weight infants,a number of thoracoscopic cases have gradually increased.According to the presurgical evaluation and the partents' willingness,they were divided into thoracoscopic surgery group and thoracotomy group,including 17 cases in thoracoscopy group and 28 in thoracotomy group.In the thoracoscopic group,there were 10 males and 7 females,with a birth weight of 2112.94 ± 0.80g.According to the Gross method,1 case was classi ed as type I,1 case was type II,4 cases were type IIIA,and 9 cases were type IIIB.There were 5 cases of congenital heart disease,3 cases of genitourinary system diseases,3 cases of skeletal limb deformities,and 2 cases of anorectal gastrointestinal malformations.There were 15 males and 13 females in the thoracotomy group,with a birth weight of 2099.29 ± 328.30g.According to Gross method,they were divided into 2 cases of type I,1 case of type II, 6 cases of type IIIA,and 19 cases of type IIIB.There were 9 cases of congenital heart disease,4 cases of genitourinary system diseases,3 cases of skeletal limb deformities,and 5 cases of anorectal gastrointestinal malformations.There were no statistically signi cant differences between the two groups of children in gender,gestational age,age at surgery,birth weight,and whether they received mechanical ventilation before surgery (all P value > 0.05) ( Table 1).Both groups of surgery were performed by physicians in the same treatment group.This study was approved by the Medical Ethics Committee of Fujian Provincial Maternity and Child Health Hospital.The guardians of the children all signed before the operation,con rmed their knowledge and signed the informed consent form for surgical treatment.

Preoperative diagnosis
All children with a gastric tube inserted through the nose were blocked from returning,and the esophagus was con rmed by esophageal angiography or esophageal CT three-dimensional reconstruction.The children were accompanied by various degrees of aspiration pneumonia before the operation.

Surgical methods
Surgical indications:Once the diagnosis of esophageal atresia is clear,surgical treatment is required,and esophageal end-to-end anastomosis can be performed by extrapleural or thoracic route.

Postoperative follow-up
The children are followed up for the rst 3 months after being discharged from the hospital,followed up once a month,during which at least one esophageal barium swallowing examination is performed.
Thereafter,every 3 months to 1 year old,one esophageal barium swallowing examination is performed during the period.After 1 year of age,follow-up visits 1 to 2 times a year,and esophageal barium swallow angiography once a year.During the follow-up period,the esophageal barium swallow angiography was used to understand the status of the esophageal anastomosis,swallowing coordination,re ux,understand the morphological changes of the main trachea and the breathing process,and determine whether there is anastomotic stenosis and leakage,and whether there is gastroesophageal re ux,if necessary Gastroscopy,24-hour esophageal pH measurement,tracheal CT scan.Thoracic deformity is de ned as skeletal deformity of the chest wall,such as depression of the chest wall,high scapula,rib fusion and scoliosis,etc.Anastomotic stenosis is de ned as the presence of clinical symptoms (dysphagia,breathing disorder caused by aspiration or foreign body obstruction)and the stenosis can be found by endoscopy or esophagography (stenosis index ≧ 0.5,SI = 1-stenosis segment diameter/distal normal Diameter of the esophagus).

Statistical processing
Using SPSS 21.0 statistical software for data analysis,measurement data is represented by mean ± standard deviation and range,independent sample t test is used for comparison between groups,and count data is compared by x 2 Test,P < 0.05 indicates that the difference is statistically signi cant.

Two groups of surgery results
All operations were successfully completed,and thoracoscopic surgery patients do not need open thoracotomy.There was no signi cant difference in the preoperative basic data,postoperative mechanical ventilation time, postoperative thoracic drainage time,postoperative hospital stay,etc.between the two groups (P > 0.05).However,the operation time of the thoracoscopy group was (172.41 ± 20.00min) ,and the operation time of the thoracotomy group was (149.82 ± 13.91min).The operation time of the thoracoscopy group was longer than that of the thoracotomy group.The difference in operation time between the two groups was statistically signi cant (P < 0.05).intraoperative blood loss in the endoscopic group (7.41 ± 2.83ml),intraoperative blood loss in the thoracotomy group (18.61 ± 3.60ml),intraoperative blood loss in the endoscopic group than in the thoracotomy group,and intraoperative bleeding in the 2 groups The difference in the amount was statistically signi cant (P < 0.05). (Table 2). Combined with chest X-ray and CT examination. Among the postoperative complications,the incidence of anastomotic stenosis in the thoracoscopic group was 58.82%, and the incidence in the open group was 28.57%.The incidence of anastomotic stenosis in the thoracoscopic group was signi cantly higher than that in the open group,and the difference was statistically signi cant (P = 0.045).There was no statistically signi cant difference in the incidence of esophageal anastomotic stula and recurrent tracheoesophageal stula.After 3 years of follow-up,the incidence of thoracic deformity in the thoracotomy group was 25%,which was signi cantly higher than the incidence of thoracoscopy at 0%.The difference was statistically signi cant (P = 0.034).However,in the gastroesophageal re ux, symptomatic stenosis,The differences in tracheomalacia were not statistically signi cant. (Table 3 and   Table 4).

Discussion
Thoracoscope-assisted treatment of congenital esophageal atresia has a history of 20 years,but it started late in China,and it is still considered by many pediatric surgeons to be a very challenging operation [2,3].Although thoracoscopic surgery has an obvious learning cycle,it has potential advantages,including small surgical incisions and low incidence of thoracic deformities.A meta-analysis of 48 articles found that thoracoscopic surgery to repair esophageal atresia and esophagotracheal stula is safe.Compared with thoracotomy,the mortality rate in the thoracoscopy group did not increase.Although the time of thoracoscopic surgery is longer,the incidence of anastomotic leakage,postoperative esophageal stenosis and gastroesophageal re ux are comparable to those of thoracotomy [4].
At present,many international and domestic experts have proposed contraindications for thoracoscopic surgery,including long-spaced esophageal atresia,low birth weight children,and complicated congenital heart disease and severe pneumonia [5,6].However,in clinical practice,it has been found that for children with low birth weight,if they are not combined with severe congenital heart disease and severe pneumonia,thoracoscopic surgery can also achieve good therapeutic effects [7].Therefore,this article separately analyzes the feasibility of thoracoscopic treatment for children with low birth weight, and also evaluates the long-term clinical prognosis and quality of life after surgery.
Low birth weight newborns pointed out that newborns with a birth weight of less than 2500g,due to the immature anatomy and physiological development of low birth weight newborns,many preoperative complications,poor tolerance to surgical anesthesia,high risk of anesthesia,and low weight This means that the child may have small physical growth and insu cient space for thoracic operation.Therefore,most doctors are unwilling to adopt thoracoscopic treatment.However,with the innovation of intraoperative anesthesia concepts and the maturity of intraoperative endoscopic operations,low birth weight newborns have more opportunities to receive thoracoscopic surgery,and the survival rate is increasing.Therefore,low body weight is not the main factor limiting thoracoscopic treatment.
Hypercapnia is one of the pathological conditions that are likely to occur in neonatal thoracoscopic surgery,especially in neonates with severe pneumonia before surgery or premature infants with pulmonary dysplasia [8,9].In 2017,James K and others pointed out that carbon dioxide insu ation during thoracoscopic surgery may cause hemodynamic changes,such as hypotension and tachycardia.In addition,the establishment of a thoracoscopic pneumothorax may result in decreased blood oxygen saturation [7,10].Finally,the absorption of CO2 by the pleura can lead to hypercapnia,the most serious consequence of which is metabolic acidosis.However,the proposed ventilation strategy for permissive hypercapnia solved this problem for clinicians.When using thoracoscopic surgery, choose a CO2 arti cial pneumothorax pressure of 4-6 mmHg,which has less impact on the vital signs of newborns, is not easy to cause lung collapse,and also ensures a certain amount of chest operation space.There was no signi cant difference in the use time of the ventilator between the thoracoscopy group and the thoracotomy group,which may be related to the use of ventilation strategies for permissive hypercapnia during the thoracoscopy group to reduce lung compression.At the same time,pay attention to pneumonia before operation, clarify whether there is tracheomalacia,pay attention to lung management during operation,and select the appropriate surgical position,which will help improve the anesthesia tolerance of children [11].While ensuring that the surgical eld of vision is not disturbed,the blood oxygen uctuation is maintained at about 90%.
Thoracic surgery is a classic surgical method for the treatment of congenital esophageal atresia.However,the traditional surgical incision is long, the retractor is used to pull the ribs excessively during the operation,and the chest wall tissue is damaged [12].In addition to the long surgical scar left after the operation,the chest wall The incidence of musculoskeletal deformities is high,such as high scapula,rib fusion,and scoliosis [13].while thoracoscopic surgery only needs to make three 5 mm holes in the chest wall,with small incisions,and little damage to the chest wall,intercostal muscles and nerves.The operation time of the thoracoscopy group was 172.41±20.00min,and the operation time of the thoracoscopy group was 149.82±13.91min.The operation time of the thoracoscopy group was longer than that of the thoracotomy group.The difference in operation time between the two groups was statistically signi cant (P<0.05).It is very pro cient with thoracotomy,but thoracoscopic surgery is di cult,requires high anesthesia, and needs to interrupt the operation waiting when the intraoperative percutaneous blood oxygen saturation drops.The intraoperative blood loss in the laparoscopic group was 41±2.83ml,and the intraoperative blood loss in the thoracotomy group was 18.61±3.60ml.The difference in intraoperative blood loss between the two groups was statistically signi cant (P<0.05),which also con rmed the chest cavity The advantages of endoscopic surgery are less damage.The 3-year follow-up showed that the incidence of thoracic deformity in the thoracotomy group was 25%,which was signi cantly higher than the incidence of 0% in the thoracoscopy group,and the difference was statistically signi cant (P=0.034).The thoracoscopy has the function of magnifying the surgical eld of vision,so that the surgeon's eld of vision is clearer, the esophagus is freed more thoroughly, and the esophagus is sutured more nely [14].However,the newborn has a small chest cavity,small operating space,and large interference with the operation of breathing [15].Therefore,the surgeon is required to have skilled endoscopic operation experience and rich knowledge of pathological anatomy.The thoracoscopic technique can effectively preserve the odd veins.Our hospital has reported that esophageal atresia with thoracoscopic preservation of the odd veins can not only reduce the edema of the tissues around the esophagus,but also reduce the occurrence of esophageal anastomotic leakage and accelerate the postoperative recovery of children [16].We found that there was no signi cant difference in the incidence of esophageal anastomotic leakage between the thoracoscopy group and the thoracotomy group in the early postoperative period.It may be di cult to perform thoracoscopic surgery with children with lowweight esophageal atresia.In most cases,it is necessary to ligate the odd vein to facilitate The anastomosis is related to the esophagus,so the advantages of preserving the odd veins cannot be demonstrated.
Postoperative complications of esophageal atresia have been plagued by pediatric surgeons,affecting the quality of life of children.Its common complications include esophageal anastomotic leakage,anastomotic stenosis,gastroesophageal re ux,recurrence of esophageal anastomotic leakage,respiratory diseases and thoracic deformities [17].The main in uencing factors for the occurrence of esophageal stenosis after esophageal atresia are the distance of the esophageal blind end,anastomotic leakage and postoperative gastroesophageal re ux [18]There is a difference in the incidence of early postoperative esophageal anastomotic stenosis between the two groups of thoracoscopy and open surgery.The incidence of thoracoscopy group is 58.82%,which is higher than 28.57% of the thoracotomy group.Insu cient clipping of the proximal end of the anastomosis is related.At the same time,because of the obvious expansion of the proximal esophagus before the anastomosis,there is a certain degree of anastomotic stenosis in the early esophagus after esophageal atresia.Some studies believe that the stenosis(or asymptomatic stenosis)caused by early postoperative changes does not indicate the long-term stenosis formed without preventive dilation [19,20].And most stenosis can be relieved by dilatation of the esophagus,so the two groups are comparable in the incidence of esophageal stenosis at 3 years after surgery.
Of course,our research also has certain limitations.Most of the collected cases of children weigh around 2000g, and there is a lack of research on children with very low birth weight undergoing esophageal atresia surgery.Andreas et al.proposed that the primary repair of type III esophageal atresia and tracheoesophageal stula in very low and ultra-low birth weight newborns was not associated with the increase in intraoperative and postoperative complications compared with high birth weight newborns [21].Therefore,it is not necessary to give priority to staging surgery in these newborns,and should be selected according to the stability and degree of deformity of the child.According to our treatment experience,if the child does not have serious heart malformations and lung infections,even if the birth weight is extremely low,enteral nutrition through jejunostomy can be considered to be suitable for thoracoscopic treatment.
In summary, for low birth weight newborns, as long as there is no serious heart deformity and lung infection before surgery, they can tolerate intraoperative anesthesia, and through thoracoscopic surgery, they can achieve therapeutic effects equivalent to thoracotomy. The long-term curative effect is also comparable. At the same time, thoracoscopic treatment of esophageal atresia has the advantages of small surgical incision, less intraoperative bleeding and less incidence of thoracic deformities. It is safe and feasible, but it requires skilled thoracoscopic operation experience and anesthesiologist during operation. Coordination of airway management.

Conclusions
For low birth weight newborns,as long as there is no serious heart deformity and lung infection before surgery,they can tolerate intraoperative anesthesia,and through thoracoscopic surgery,they can achieve therapeutic effects equivalent to thoracotomy.The long-term curative effect is also comparable.At the same time,thoracoscopic treatment of esophageal atresia has the advantages of small surgical incision,less intraoperative bleeding and less incidence of thoracic deformities.It is safe and feasible, but it requires skilled thoracoscopic operation experience and anesthesiologist to coordination of airway management during operation.

List Of Abbreviations
EA esophageal atresia Declarations