Thoracoscopic Surgery for Congenital Lung Malformation Using Miniaturized 3-mm Vessel Sealing and 5-mm Stapling Devices: Single-Center Experience

Introduction

Minimally invasive surgery in the pediatric population has become largely accepted by pediatric surgeons for treatment of more and more pathologies. ¹ This process took considerably longer than the transition for adult general surgery. One of the main reasons for the delay is the discrepancy between limited operative space and the large size of the instruments, particularly in thoracoscopic surgery.

Technological progress is key to the current diffusion of pediatric thoracoscopy. ² The development of instruments that are suitable for children has been crucial to making thoracoscopy feasible in infants, so that even difficult procedures, such as congenital lung malformation (CLM) resection, can be safely performed thoracoscopically. ³ However, CLM thoracoscopic resection remains a challenging procedure, mainly due to the difficulties of fitting traditional instruments in the small chest of neonates and infants. The recent introduction of a 3-mm vessel sealing device and a 5-mm linear stapler might be another step forward for the safety and feasibility of thoracoscopic surgery in infants. ⁴

The aim of the study is to retrospectively evaluate the experience of a single center with the use of these instruments for CLM resection in infants.

Materials and Methods

To achieve this study's aim, all asymptomatic patients who underwent thoracoscopic CLM resection at Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico of Milan between January 2016 and July 2019 were retrospectively reviewed. Symptomatic patients, who were operated on with an open technique in neonatal age, were not included in this study. Only patients who were operated on by fully minimally invasive trained pediatric surgeons were considered.

All patients were treated according to the local protocol for CLM. In cases referred prenatally, a fetal magnetic resonance imaging (MRI) is performed between the 21st and the 30th week of gestation. In asymptomatic newborns, a chest X-ray and a ultrasound are performed on the first day of life and a chest MRI is performed in spontaneous sleep within the first month of life. If a CLM is confirmed, chest computed tomography with contrast is obtained shortly before surgery, which is performed between the fourth and sixth month of life.

Thoracoscopic lobectomy is the Center's customary choice for congenital pulmonary airway malformation (CPAM) and intralobar sequestration (IS); whereas thoracoscopic resection is performed in case of extralobar sequestration (ES) or bronchogenic cyst (BC). The patient is positioned in a modified lateral position on the controlateral side. Lower lobectomies and ES or BC resection are performed in tracheal ventilation. For upper lobectomies, selective ventilation is preferred.

Thoracoscopy is performed by using three accesses: a 3-mm trocar at the tip of the scapula, another 3-mm one in the third to fourth intercostal space on the axillary line, and a 5-mm trocar in the fifth to sixth intercostal space on the axillary line. A 3-mm 30° camera (Storz) is used. Standard 3-mm instruments by Storz are used for dissection. Before 2018, segmental arteries were individually divided during lobectomies by using a 5-mm vessel sealing device (LigaSure^®, Covidien). Pulmonary veins were isolated distally to the bifurcation, closed with a Hem-o-lok^® (Teleflex Medica) clip, and sealed and divided with LigaSure. Segmental bronchi were individually closed with Hem-o-lok clips and divided with scissors. For pulmonary sequestrations, systemic arteries were closed with Hem-o-lok clips, and they were sealed and divided with LigaSure.

In cases of IS, lobectomy was then performed with the same technique. Since 2018, when JustRight^® (Bolder Surgical) instruments became available in Italy, the Center's preferences changed.

In lobectomies, segmental arteries are individually sealed and divided with a 3-mm JustRight Vessel Sealing device; segmental bronchi are divided with a 5-mm JustRight stapler; and veins are closed with a Hem-o-lok clip and sealed and divided with LigaSure. For pulmonary sequestration, systemic arteries are closed with Hem-o-lok clips and sealed and divided with a 3-mm JustRight Vessel Sealing device. An 8F chest drain is always left in the thoracic cavity and it is removed when no air leak or bleeding is observed for 24 hours.

Demographic and clinical data of the enrolled patients have been recorded with specific focus on type of malformation, location of the CLM, and age at time of surgery. Patients were then divided into two groups according to the type of instruments used for surgery: Group 1 (G1, May 2018 to July 2019), including all patients operated on by using JustRight instruments; Group 2 (G2, 2016 to April 2018) consisting of patients operated on by using LigaSure 5-mm Vessel Sealing System for arteries and Hem-o-lok clips and scissors for bronchi.

Population characteristics have been compared to rule out significant differences. Operative time, number of conversions, intra- and postoperative complications (classified with the Clavien-Dindo classification ⁵ ), with special focus on arterial bleeding and air leak, days for chest drain removal, and length of hospital stay were collected and compared between the two groups. Operative times were analyzed according to the type of surgical procedure performed: lobectomies, ES resection, or BC resection. Thus, operative times for lobectomies in G1 were compared with operative times for lobectomies in G2, and the same happened for ES resections.

Continuous variables of the two groups have been compared by using t-test, whereas dichotomic variables have been compared by using Fisher's exact test. A value of P < .05 has been considered as statistically significant.

Results

In the selected period, 34 CLMs have been treated at our institution. Four CLMs were classified as lobar emphysema due to bronchial atresia and were then treated conservatively. The remaining 30 CLMs have been operated, 29 of which underwent thoracoscopic resection. Only one patient was symptomatic at birth and underwent an open pneumonectomy for massive type 1 CPAM of the left lung.

Group 1 consisted of 13 patients, whereas 16 patients were enrolled in Group 2. Patients' demographics and characteristics are shown in Table 1. No significant differences have been found between the two groups.

In Group 1, 7 patients underwent pulmonary lobectomy (3 CPAM, 4 IS), 5 underwent ES resection, and 1 patient underwent BC resection. In Group 2, 12 lobectomies (5 CPAM, 7 IS), 3 ES resections, and 1 BC resection were performed. Of the 7 lobectomies in Group 1, 5 were left lower, 1 was right upper, and 1 was right lower. In Group 2, 8 left lower lobectomies, 1 right middle lobectomy, 1 left upper lobectomy, and 2 right lower lobectomies were performed.

Mean operative times were 120.7 minutes in Group 1 (range 85–160) and 171.7 in Group 2 (range 105–240). Operative times were significantly lower in Group 1 (P = .003). Mean operative times for ES resection were 63 minutes in Group 1 (range 35–95) and 91.7 in Group 2 (range 70–125). Operative times for ES resection were not significantly different between the groups (P = .07). CB resection in Group 1 was performed in 40 minutes whereas the one in Group 2 was performed in 100 minutes.

None of the cases was converted to open. No intraoperative complication has been recorded. No intraoperative instrument failure occurred in either of the groups. Regarding postoperative complications, the patient in Group 2 operated on for BC resection developed a chylothorax that was treated conservatively (Grade III according to Clavien-Dindo Classification of surgical complications). In Group 1, one of the patients with an ES that was prenatally ablated had a postoperative bleeding that resolved after tranexamic acid iv therapy, probably as a consequence of the extensive blunt adhesiolysis between the lung and the ES (Grade II according to Clavien-Dindo Classification of surgical complications).

Chest drains were removed on average after 2.4 days in Group 1 (range 1–5) and 3 days in Group 2 (range 1–11). There is no significant difference in timing of chest drain removal between the groups (P = .47).

Lengths of stay were not significantly different between groups for lobectomies: G1 4.67 days (4–7) versus G2 4.4 (4–6) (P = .61) and for ES resection: G1 3.17 (2–4) versus G2 6.75 (4–14) (P = .18).

Discussion

Thoracoscopy in adult surgery now represents a well-established approach and it is considered by most thoracic surgeons to be the approach of choice for lung resections. One of the main reasons for this transition was the introduction of specific devices for bronchial division and vessel sealing, such as endoscopic surgical staplers and electro-thermal bipolar sealing devices in the late 1990s. ⁶ However, these instruments' dimensions were unsuitable to fit in children's small chests, especially infants. Development of smaller instruments, such as 5-mm LigaSure and 5-mm metal clips or Hem-o-lok, allowed the thoracoscopic approach even in children. Although technological advancement offered the possibility to perform pediatric thoracoscopic lobectomies, ⁷ they still remained challenging procedures, especially in infants.

Dissection and vessel sealing with a 5-mm device in this population required advanced surgical skills due to the considerable length and thickness of the jaws, often disproportionate to the anatomy and operative space of the infant. Further, the closure of bronchi had to be achieved by using clips or suture, with the risk of dislodgement for clips, and the necessity of extreme surgical confidence with intracorporeal suturing. These are some of the main reasons why thoracoscopic lobectomies in infants experienced significant delay in acceptance by the pediatric surgeons' community. ⁴

These limitations necessitated the development of miniaturized instruments, which could facilitate such a challenging operation. In 2016, JustRight Surgical developed a 3-mm Vessel Sealing Device and a 5-mm Stapler that were available in the United States. In the same year, the first report about safety and effectiveness of these instruments for thoracoscopic pulmonary lobectomies in infants was published. ⁴ In 2018, Bolder Surgical started commercializing these instruments in Europe. The authors decided then to adopt them for four pilot cases of CLM resection and, considering the high versatility experienced, decided to select the 3-mm Vessel Sealing Device and the 5-mm Stapler as the instruments of choice for arterial and bronchial division, respectively.

The results of the preliminary experience seem satisfactory. Comparing the results of thoracoscopic pulmonary surgery performed in the population treated with new miniaturized instruments with the one treated with traditional tools, no complications related to the correct working of the new instruments were recorded. In Group 1, the patient who had mild bleeding had undergone a fetal ablation, which led to diffuse pleuro-pulmonary adhesions requiring extensive manipulation and smooth lung dissection. Thus, we believe that this complication ought to be considered a consequence of the malformation rather than equipment malfunction. No differences have been noticed between groups in the number of days before chest drain removal or length of stay. These findings corroborate the finding that the new JustRight Bolder instruments are as safe and effective as the previous ones.

An important reduction of the operating time is evident. Although the differences for extralobar sequestration resections do not reach the level of statistical significance, the difference in time for lobectomies does favor the new instruments. We believe that this reduction in mean time is due to a higher versatility of the JustRight instruments. With only 10 mm of jaw length, compared with the 20 mm of traditional tools, and a curved Maryland-style jaw design, dissecting anatomical structures is easier and quicker and does not risk the sealing being compromised. Indeed, JustRight 3 mm can safely seal vessels up to 5 mm in diameter, which is more than the usual caliber of an infant's segmental vessels. The 5-mm stapler has a staple line length of 25 mm and a staple leg length of 2 mm, which is perfectly adequate to safely pass around the bronchus and then divide it quickly and effectively. Moreover, the reduced dimensions of these instruments occupy less of the surgical field, allowing for better visualization.

Although, in our series, no intraoperative complication has been recorded in either groups, the authors believe that an easier surgery is also safer.

One of the limits of this study is the relatively small number of patients. It has to be considered, however, that CLM are rare malformations and it is, therefore, difficult to gather a high number of patients. On the other hand, the study refers to a short period of time and the enrolled population is homogeneous.

One might speculate that the learning curve would influence our results: Cases performed later could benefit from the greater experience of the surgeon. However, to limit this bias, this study focused its retrospective analysis only on patients operated on by already experienced (fully trained) surgeons.

In conclusion, we believe that the JustRight 3-mm vessel sealing device and 5-mm stapler may represent an important step forward in facilitation and safety for pediatric/infant thoracoscopic surgery. We hope that this innovation will lead to a wider acceptance and use of the thoracoscopic approach for CLM resections among the majority of pediatric surgeons, thus offering more and more patients a less invasive treatment for a rare and delicate congenital malformation.