Video-assisted Thoracic Surgery for Congenital Diaphragmatic Hernia Compared With Conventional Open Surgery in Infants

This study aimed to evaluate the effectiveness of video-assisted thoracic surgery for the treatment of congenital diaphragmatic hernia (CDH) in a larger series compared with conventional open surgery. Additionally, we summarized the experience of thoracoscopic surgery in the treatment of CDH in infants.


Abstract Background
This study aimed to evaluate the effectiveness of video-assisted thoracic surgery for the treatment of congenital diaphragmatic hernia (CDH) in a larger series compared with conventional open surgery.
Additionally, we summarized the experience of thoracoscopic surgery in the treatment of CDH in infants.

Methods
We retrospectively analysed the clinical data of 109 children with CDH who underwent surgical treatment at the Department of Cardiothoracic Surgery of Children's Hospital of Chongqing Medical University from January 2010 to January 2019. According to the surgical method, the children were divided into an open group (62 cases) and a thoracoscopy group (47 cases). We compared the operation time, intraoperative blood loss, postoperative mechanical ventilation time, postoperative hospital stay, postoperative CCU admission time and other surgical indicators as well as the recurrence rate, mortality rate and complication rate of the two groups of children.

Results
The index data on the operation time, intraoperative blood loss, postoperative mechanical ventilation time, postoperative hospital stay and postoperative CCU admission time were better in the thoracoscopy group than in the open group. The difference between the two groups was statistically signi cant (P<0.05). Compared with the number of incision infections, pulmonary infections, atelectasis, pleural effusion and chylothorax between the two groups, the number of children in the open group was greater than that in the thoracoscopy group, and the total postoperative complication rate (51.61%) was higher than that in the thoracoscopy group (44.68%). The recurrence rate of the thoracoscopy group (8.51%) was higher than that of the open group (3.23%). In the open group, 2 patients died of respiratory distress after surgery, and no patients died in the thoracoscopy group.

Conclusions
Thoracoscopic surgery and open surgery can effectively treat CDH. Open surgery has advantages in patients with unstable haemodynamics, large diaphragm defects and abdominal malformations.

Background
Congenital diaphragmatic hernia (CDH) is due to developmental disorders or dysplasia of the diaphragm.
The contents of the abdominal cavity herniate into the thoracic cavity and compress the lungs and heart, Page 3/10 which can lead to pulmonary dysplasia and pulmonary hypertension. The incidence of CDH is approximately 1:2500-1:5000 [1], and the fatality rate of CDH is as high as 40%~60% [2][3]. The current treatment still requires surgical repair of the diaphragm defect, including open surgery and minimally invasive surgery. Open surgery generally involves traditional laparotomy or thoracotomy, and minimally invasive surgery is divided into laparoscopic and thoracoscopic surgery. Related studies have suggested that the operation time, hospitalization time, postoperative mechanical ventilation time and postoperative analgesic use of children after minimally invasive surgery are better than those after open surgery but that it may cause hypercapnia and hypoxia. Additionally, the recurrence rate after minimally invasive surgery is also higher [4]. However, comparative studies between minimally invasive surgery and open surgery have not been conducted extensively due to wide discrepancies in the severity of pulmonary hypoplasia and pulmonary hypertension between patients as well as different management protocols, For the open surgery group, the right CDH was treated by a transthoracic approach, and the left CDH was treated through an abdominal approach. Through the thoracoabdominal approach, we removed the weak diaphragm and used intermittent nonabsorbable sutures to ensure that the cut diaphragm had a shingled shape to strengthen the weak area of the diaphragm. We once again sutured the ventral muscle layer of the diaphragm with intermittent mattresses and removed the hernia sac if it was combined. For the thoracoscopic group, a 5 mm trocar was placed on the lower edge of the scapula tip using the three-hole method, and two operation holes were made in the fourth intercostal space on both sides of the trocar.
The thoracic cavity pressurizes the abdominal organs into the abdominal cavity and fully exposes the diaphragm defect to observe the size of the diaphragm defect. If there was a hernia sac in the child, it was pushed into the abdominal cavity, and a purse-string suture with a needled suture was used to repair the diaphragmatic defect, close the CDH, restabilize and suture the edge of the defect with barbed sutures. In addition, a chest drainage tube was placed after surgery.
We observed the operation time, intraoperative blood loss, postoperative mechanical ventilation time, postoperative hospital stay, postoperative CCU admission time and other surgical indicators as well as the recurrence rate, mortality rate and complication rate of the two groups of children.

Results
This study included 109 children with CDH. According to different surgical methods, 47 children who In the open group, 10 cases were complicated with other malformations, including 3 cases of cryptorchidism, 2 cases of pectus excavatum and 5 cases of right heart shift. In the thoracoscopic group, 15 cases were complicated with other malformations, including 3 cases of cryptorchidism, 4 cases of pectus excavatum, 3 cases of right heart shift and 5 cases of congenital intestinal malrotation. There was no signi cant difference in sex, age, weight, location of disease or other preoperative data between the two groups (P > 0.05), indicating that the two groups were comparable (Table 1). All children in the open group completed the operation successfully, and 3 cases in the thoracoscopy group were converted to open surgery due to severe thoracic adhesions and abdominal organs obstructing the surgical eld. During the operation, the ori ce diameter of the CDH was 2-12 cm, and the average area of the diaphragmatic muscle defect was 18.12±6.43 cm 2 . The 89 cases with left CDH mainly herniated into the following organs: small intestine, stomach, colon, mesenteric and spleen. The 20 cases of right CDH mainly herniated into the right lobe of the liver, small intestine and colon.
We analysed the data of the relevant surgical indicators in the two groups. The index data on the operation time, intraoperative blood loss, postoperative mechanical ventilation time, postoperative hospital stay and postoperative CCU admission time were better in the thoracoscopy group than in the open group. The difference between the two groups was statistically signi cant (p<0.05) ( Table 2). Compared with the number of incision infections, pulmonary infections, atelectasis, pleural effusion and chylothorax between the two groups, the number of children in the open group was greater than that in the thoracoscopy group, and the total postoperative complication rate (45.16%) was higher than that in the thoracoscopy group (36.17%). Both groups of children were followed up for 1 month to 9 years after surgery. Three patients in the thoracoscopy group relapsed, and 2 patients in the open group relapsed.
The recurrence rate and mortality of children in the thoracoscopy group were not signi cantly different from those in the open group (P>0.05) ( Table 3). Two cases in the open group died after surgery, and the causes of death were respiratory failure, pulmonary dysplasia and severe pulmonary hypertension. The rest of the children were followed up for growth and breathing in outpatient clinics or by telephone. After discharge from the hospital, 13 children were lost to long-term follow-up, and 96 patients were followed up for 1 month to 9 years. All the children recovered well without death or serious complications. Postoperative chest radiograph and gastrointestinal angiography showed that the abdominal organs were in normal positions (Figure 1).

Discussion
CDH is a congenital disease that causes a defect in the diaphragm due to abnormal embryonic development, causing abdominal organs to herniate into the thoracic cavity and causing a series of pathophysiological changes. Generally, CDH occurs more often on the left side than the right side with the incidence ratio on the left and right sides being approximately 6:1, and CDH is rare on both sides with an incidence rate of approximately 2% [5]. In this study, the number of children with CDH on the left side (81.65%) was far greater than that of children with CDH on the right side (18.35%), which was consistent with literature reports. The incidence of CDH combined with other malformations is 30%-70%, including cardiovascular formations (27.5%), genitourinary system malformations (17.7%), skeletal muscle system malformations (15.7%) and central nervous system malformations (9.8%) [6]. In this group, congenital pulmonary dysplasia (53, 48.62%) and congenital heart disease (45, 41.28%) were the main malformations in this study. Other combined malformations included cryptorchidism, pectus excavatum, right shifted heart and congenital intestinal malrotation, which was consistent with literature reports.
The traditional treatment for CDH is transthoracic or transabdominal diaphragmatic hernia repair. In the open group, 56 patients underwent transabdominal diaphragmatic hernia repair, and 6 patients underwent transthoracic diaphragmatic hernia repair. We believe that transabdominal surgery has the following advantages: easy to reset abdominal organs; easy to suture the edge of the diaphragm; and easy to deal with abdominal deformities, such as intestinal rotation malrotation. Therefore, transabdominal surgery is recommended for left-side diaphragmatic hernias. Transthoracic surgery is used for right-side diaphragmatic hernia due to liver obstruction because the diaphragm is clearly exposed during transthoracic surgery. Additionally, transthoracic surgery addresses thoracic adhesions and other combined chest deformities. However, in the open group, 5 children with right CDH without thoracic malformations were treated with transabdominal diaphragmatic hernia repair, which also achieved satisfactory clinical results. Therefore, we believe that the choice of approach is mainly based on the characteristics of the patient's CDH lesions and which approach the surgeon is more familiar with. In this study, 47 patients had stable haemodynamics, no severe pulmonary dysplasia and pulmonary hypertension. In addition, thoracoscopic diaphragmatic hernia repair was used. A purse-string suture with a needled suture was used to repair the diaphragmatic defect, close the diaphragmatic hernia, restabilize and suture the edge of the defect with barbed sutures. We believe that compared with ordinary absorbable sutures, continuous suturing of the diaphragm with barbed sutures has the following advantages: less bleeding, absorbability, no knot response, tight sutures and no knots during the suture process, which greatly shortens the operation time. Moreover, re-strengthening the diaphragm reduces recurrence.
With the development of minimally invasive technology, thoracoscopy has gradually been used in the treatment of CDH. We  [7]. In this study, the overall incidence of postoperative complications in the open group (45.16%) was higher than that in the thoracoscopy group (36.17%), which was equivalent to the incidence reported in the literature [8,9]. In this study, the main complications of the open group were lung infection, pleural effusion and respiratory failure. The main complications of the thoracoscopy group were respiratory failure and pneumothorax. The incidence of complications in the open group was higher than that in the thoracoscopy group, but there was no signi cant difference between the two groups (P>0.05).There were 6 cases of pleural effusion and 7 cases of pneumonia in the open group. Open surgery has a larger traumatic area than thoracoscopic surgery and more exudation, which is likely to cause pleural effusion. Moreover, children are young and have poor resistance to lung infections. Two children in the open group died of respiratory failure after surgery. The possible causes were that the children had unstable haemodynamics before surgery, severe pulmonary dysplasia, poor cardiopulmonary function after surgery and could not tolerate open surgery.
This study compared the postoperative recurrence rate of the thoracoscopy and open groups. The recurrence rate of the thoracoscopy group (8.51%) was higher than that of the open group (3.23%), but the difference was not statistically signi cant. Some scholars have compared open surgery and thoracoscopic surgery, suggesting that the recurrence rate after thoracoscopic surgery for CDH is higher [10,11] and that intraoperative hypercapnia and acidosis are more serious. The recurrence rate of thoracoscopic diaphragmatic hernia repair is reported to be between 0% and 25%. Most authors have reported that the recurrence rate is higher than 15% [12,13]. The recurrence rate in this study was lower than that reported in the literature, which may be attributed to the thoracoscopic diaphragmatic hernia repair being only performed in patients with a small diaphragm defect (defect diameter <3 cm). If a large defect was found under thoracoscopy, it was converted to open repair. In the open group, there were 2 cases of recurrence, which may have been due to poor development of the diaphragm, suture not reaching the edge of the normal diaphragm and a long-term increase in intra-abdominal pressure. The 2 cases of recurrence may have also been related to the large defect of the diaphragm, high tension of the diaphragm suture and loose suture. There were 4 cases of recurrence in the thoracoscopy group. We found that all recurrences occurred in the early stage of the use of thoracoscopy. The postoperative recurrence may have been related to several factors. (1) The surgical operation was performed under thoracoscopy, and the surgical eld was enlarged. In addition, the surgeon could not accurately estimate the suture distance. As a result, the suture distance of each stitch was large, and the defect could not be closed well. (2) The diaphragm muscle tension was too large when sutured, and the sutured diaphragm muscle tissue was not thick enough, causing the diaphragm to tear. (3) The use of continuous sutures led to loose knots. In the later period, a purse-string suture with needled suture was used to repair the diaphragmatic defect, close the diaphragmatic hernia, restabilize and suture the edge of the defect with barbed sutures to achieve better clinical results. Scholars at home and abroad have also proposed the use of special equipment to assist in knotting and have achieved good results [14].

Conclusions
Thoracoscopic surgery and open surgery can effectively treat CDH. Open surgery has advantages in patients with unstable haemodynamics, large diaphragm defects and abdominal malformations. Availability of data and materials: The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.
Competing interests: The authors declare that they have no competing interests.  Tables   Table 1.Comparison of general clinical data of the two groups of children (n=109).

General information
Open group(n=61)