Seminars in Pediatric Surgery 23 (2014) 249–256

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Seminars in Pediatric Surgery journal homepage: www.elsevier.com/locate/sempedsurg

Minimal invasive surgery in the newborn: Current status and evidence Martin Lacher, MD, PhDn, Joachim F. Kuebler, MD, Jens Dingemann, MD, PhD, Benno M. Ure, MD, PhD Center of Pediatric Surgery, Hannover Medical School, Carl Neuberg St. 1, Hannover 30625, Germany

a r t i c l e in fo

Keywords: Minimal invasive surgery Newborn Neonate Laparoscopy Thoracoscopy

a b s t r a c t The evolution of minimally invasive surgery (MIS) in the newborn has been delayed due to the limited working space and the unique physiology. With the development of smaller instruments and advanced surgical skills, many of the initial obstacles have been overcome. MIS is currently used in specialized centers around the world with excellent feasibility. Obvious advantages include better cosmesis, less trauma, and better postoperative musculoskeletal function, in particular after thoracic procedures. However, the aim of academic studies has shifted from proving feasibility to a critical evaluation of outcome. Prospective randomized trials and high-level evidence for the benefit of endoscopic surgery are still scarce. Questions to be answered in the upcoming years will therefore include both advantages and potential disadvantages of MIS, especially in neonates. This review summarizes recent developments of MIS in neonates and the evidence for its use. & 2014 Elsevier Inc. All rights reserved.

Introduction With the widespread implementation of minimally invasive surgery, there has been a revolution in surgical practice over the last decades. While this technology was quickly assimilated in the care of adults, its introduction was much slower in children, and especially in small infants and neonates. The obstacles included a lack of specialized equipment suitable for the size of the patient. Also, technical developments were delayed due to the limited number of surgeons performing these procedures. Currently, both instruments and techniques are adapted that even the most complicated neonatal procedures can be performed laparoscopically or thoracoscopically. Large series could demonstrate safety and feasibility of various minimally invasive procedures in the neonatal period. This review aims to summarize the current state of the art in neonatal laparoscopic and thoracoscopic surgery with special focus on recent developments of the most common indications today.

Physiologic aspects of neonatal endoscopic surgery The immediate postpartum period is a time of significant physiological adaptation, including changes in organ and immune n

Corresponding author. E-mail address: [email protected] (M. Lacher).

http://dx.doi.org/10.1053/j.sempedsurg.2014.09.004 1055-8586/& 2014 Elsevier Inc. All rights reserved.

function. Moreover, the transition from fetal to postpartum blood circulation makes the neonate unique in its physiology. There is limited data regarding the impact of laparoscopy, thoracoscopy, and insufflation of CO2 on the physiologic response of the newborn. Nevertheless, experimental and clinical data point towards a higher sensitivity of the neonate to CO2 insufflation and therefore potential negative effects.1–3 Cardiocirculatory effects Experimental data have demonstrated an increased CO2 absorbance in the young4 and a higher sensitivity of the neonatal cardiovascular system to CO2.2 The increased abdominal pressure during laparoscopy leads to a compression of the vena cava with a decrease in preload and cardiac output. Therefore a sufficient intraoperative hydration is mandatory. However, clinical observations point towards a good tolerance of the neonate to a capnoperitoneum with pressures up to 8–10 mmHg maximum and increased slowly. Experimental data confirmed that a moderate pressure insufflation does not result in any significant decrease of capillary perfusion in splanchnic organs, thereby limiting cardiocirculatory effects of a pneumoperitoneum.5–7 In contrast, laparoscopic procedures with higher-pressure insufflation or operations with a duration over 2 h frequently lead to a decrease in circulatory blood volume, central venous oxygen saturation, and metabolic acidosis.8 To prevent this, the administration of colloidal instead of crystalloid fluids is recommended. It is also important to recognize that not only the insufflation but also the desufflation of

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the pneumoperitoneum and the concomitant decrease in intraabdominal pressure may impair macrocirculation.9,10 Therefore, thorough postoperative monitoring is warranted. One characteristic in the newborn is the persistence of fetal circulation with patent umbilical vessels and potential right-to-left shunts. This puts neonatal patients undergoing laparoscopy at increased risk for severe forms of inadvertent gas embolism, which has been described in several cases.11 Respiratory effects The respiratory system of the newborn is immature as its postnatal development continues through early childhood. Compared to adults the neonatal ratio of alveolar surface to body surface area is only one-third. To account for an increased oxygen demand, alveolar minute ventilation and oxygen consumption in neonates is twice that of the adult. Even under normal physiologic circumstances, the immature cardiac and respiratory systems must function near the limit of their functional reserve to satisfy this metabolic need. Therefore, any rise of intraabdominal pressure with resorption of CO2 may compromise the respiratory function of the neonate. When establishing a pneumoperitoneum, the lung compliance is decreased by 30–50% and by another 20% if the neonate is placed in Trendelenburg position.12 Insufflation of CO2 leads to a decrease of functional residual capacity while increasing oxygen consumption, pulmonary resistance, and alveolar minute ventilation. In addition, an increased intraabdominal pressure is transmitted to the thorax, where it worsens the ventilation/perfusion index with opening of intrapulmonary arteriovenous shunts. A good way for the anesthetist to counteract these patterns is hyperventilation. The adverse effects of neonatal minimally invasive surgery may be even bigger in thoracoscopy. Multiple studies showed that a massive CO2 absorption in the thoracic cavity may be neurotoxic to the neonate.13–16 Recent reports on significant hypercapnia and severe acidosis during thoracoscopic repair of CDH have therefore called into question the safety of this practice and require further evaluation.16 Renal function In contrast to adults, renal perfusion and corresponding urine production appear to be more affected by increased abdominal pressures in neonates. As the majority of infants develop temporary anuria during laparoscopic procedures, meticulous and wellbalanced fluid substitution is mandatory in these patients.17 However, fluid replacements should not be calculated based on urinary output in order to prevent fluid overload.

Laparoscopy in the neonate Pyloromyotomy Laparoscopic pyloromyotomy for hypertrophic pyloric stenosis was first described by Alain et al.18 in 1991. It is usually performed using a three-port technique with 3-mm instruments but can also be conducted in a single-incision laparoscopic approach.19 Several authors reported that laparoscopic pyloromyotomy does have a considerable learning curve and experience in laparoscopy seems to be an important factor to safely perform this procedure.20 In the last decade, several authors with varying experience reported that this operation is associated with potential complications, especially intraoperative perforation and inadequate division of the stenosis.21,22 However, at the same time, several meta-analyses

Table 1 CEBM Levels of Evidence. Level Type of study 1a 1b 2a 2b 3a 3b 4 5

SR/MA of RCTs Individual RCT SR/MA of cohort studies Individual cohort study (including low quality RCT) SR/MA of case–control studies or retrospective comparative studies Individual case–control Study or retrospective comparative study Case-series (and poor quality cohort and case–control studies) Expert opinion without explicit critical appraisal, or based on physiology, bench research or “first principles”

SR: systematic review; MA: meta-analysis; RCT: randomized controlled trial. Adapted with permission from Oxford Centre for Evidence-Based Medicine.126

on laparoscopic versus open pyloromyotomy have been conducted23,24 (Tables 1 and 2). In the most recent one, Oomen et al.23 included four randomized controlled trials with a total of 502 patients. The incidence of complications such as incomplete myotomy, mucosal perforation, and reoperation was 4.9% in the laparoscopic group compared to 2.0% in the open group, which was not significantly different. The mean difference in time to full feeds was 2.3 h in favor of the laparoscopic approach and therefore has limited clinical relevance. In conclusion, laparoscopic pyloromyotomy might be acknowledged as the standard of care with equal safety and effectiveness when performed in centers with expertise. It may be left at the discretion of the surgeon to choose between the two techniques. Ovarian cysts Cystic ovarian masses are common in the fetal and neonatal period. With no spontaneous resolution and increasing size, these cysts have an increased risk of torsion, rupture, intestinal obstruction, hemorrhage, and necrosis. Although there is controversy about the best treatment, depending on their ultrasound pattern and diameter, most authors recommend treatment of cysts larger than 4 cm.25 Potential therapeutic interventions include aspiration, open surgery, or laparoscopic exploration. The main advantage of laparoscopy is that it provides both diagnostic and treatment possibilities. No advanced laparoscopic skills are required to exclude differential diagnoses and provide adequate treatment. The first technique was described by Waldschmidt and Schier26 and reported in a series by van der Zee et al.27 Several technical modifications for the neonatal period have been suggested, including single-incision approaches.28–31 In case of adnexal torsion, the ovary can be detorsed and either resected or preserved.32–34 It has been shown in adolescent girls that the intraoperative assessment of adnexal necrosis by the surgeon is poor and therefore, if possible, the adnexa should be preserved after detorsion.35 However, neonatal ovarian cysts with an origin in the fetal period frequently undergo autoamputation in utero, therefore resection may be the only option in many cases.32 Ultrasound-guided aspiration of suspected ovarian cysts has been reported and might be even less invasive than laparoscopy but carries the risk of false diagnosis including intestinal duplications or cysts of other origin. Simple puncture of those structures may lead to disastrous complications.36 Fundoplication Numerous authors suggest potential benefits of laparoscopic versus conventional fundoplication in infants and children. A meta-analysis performed by Siddiqui et al.37 showed that these advantages include shorter time to full feeding, shorter hospital

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Table 2 Levels of Evidence of neonatal laparoscopic procedures. Study

Indication

Procedure

Study type

Level of Evidence

Advantage laparoscopy

Disadvantage laparoscopy

Pyloromyotomy

MA of RCT

1a

None

None

Pyloromyotomy

MA of RCT

1a

Shorter time to full feeds

None

Templeman et al.28 Thatch et al.40

Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis Ovarian cyst GERD

Resection/deroofing Fundoplication

Case series Retrospective comparative study

4 3b

n/a None

Spilde et al.48

Duodenal atresia

Duodenoduodenostomy Retrospective comparative study

3b

None

Adikibi et al.61 Numanoglu and Millar65 Chan (2013)74 Vick et al.77 Hau et al.83

Malrotation/volvulus NEC

Ladd's procedure Diagnostic laparoscopy

Case series Case series

4 4

n/a Shorter time to full feeds Lower narcotic requirement Shorter time to initial and full feeds Shorter hospital stay n/a n/a

Inguinal hernia ARM Hirschsprung's disease

Herniorrhaphy Primary pull-through Primary pull-through

Case series Case series Case series

4 4 4

n/a n/a n/a

n/a n/a n/a

Jia et al.24 Oomen et al.

23

n/a n/a

GERD: gastro-esophageal reflux disease; NEC: necrotizing enterocolitis; ARM: anorectal malformation; MA: meta-analysis; RCT: randomized controlled trial; n/a: not applicable.

stay, and less 30-day morbidity with equal recurrence rates at 12 months. A randomized controlled blinded trial by McHoney et al.38 found a lower incidence of retching. However, in their study, the intensity of pain, analgesia requirements, time to full feeds, length of hospital stay, dysphagia, and recurrence at 22 months were not significantly different. Studies investigating fundoplication in the neonatal period is scarce. Retrospective data including reports on small infants and neonates suggest that, in experienced hands, laparoscopic fundoplication can also be carried out in the very small, neonatal children with low morbidity and a low rate of complications.6,39 In accordance with these findings, Thatch et al.40 retrospectively compared the outcomes of open and laparoscopic fundoplication performed in patients of the neonatal intensive unit. They found a high efficacy and low complication rate for both techniques. Regarding the different operative methods applied in neonates, Nissen fundoplication appears to be most commonly performed, but others, such as the Toupet or Thal technique, have also been described.41 Duodenal atresia The first successful laparoscopic duodenoduodenostomy in a newborn was reported by Bax et al.42 in 2001 and shortly thereafter by Rothenberg.43 However, in the following years, no similar successful techniques or larger series were presented, which is usually seen after such initial publications.6,44–46 Instead, some authors reported an unacceptably high incidence of anastomotic insufficiency and therefore abandoned the laparoscopic approach for this condition.47 In 2007 and 2008, Spilde et al. presented an alternative technique using U-clips for intracorporeal suturing leading to reduced morbidity. In 15 patients, the authors could show that the time to full feeds and hospital stay were shorter in the laparoscopic group.48,49 Similar favorable results were reported by Kay et al.50 using traditional intracorporeal suturing techniques. In a comparative study of two different time periods, van der Zee et al.47 described further technical modifications of the laparoscopic procedure with corresponding lower rates of anastomotic leakage. In the most recent series by Li et al. including 17 children with duodenal atresia, excellent feasibility was reported, with one patient requiring a reoperation. However, three patients were lost to follow-up.51 In conclusion, no larger patient series of laparoscopic duodenoduodenostomy or prospective trials have

been published so far. Due to its technical challenges, this procedure should be performed in centers with extensive expertise in neonatal laparoscopic surgery. Malrotation Several series on laparoscopic treatment of malrotation in infants and children have been published.52 With regard to the minimally invasive treatment of rotational anomalies in neonates however, data are scarce. In 1995, van der Zee and Bax53 described this technique in a newborn, followed by other small series.54–56 At that time some surgeons restricted the role of laparoscopy to cases without midgut volvulus.54,57–60 Those authors felt that a complete overview on the bowel by “spreading out” the intestinal tract was not possible and therefore this technique was inadequate compared to the traditional open approach. However, in the last decade, several other groups successfully applied laparoscopic techniques in patients with midgut volvulus, even when signs of intestinal ischemia were present.61 These authors emphasized the importance to concentrate on the duodenum and not on the loops of bowel. By running the small bowel down until the entire small bowel has been exposed, the pathologic anatomy was reported to be easily unraveled and an existing volvulus automatically reduced.62 Although the majority of surgeons report an uncomplicated postoperative course, there are no prospective studies and no data on long-term follow-up. A retrospective comparative study on open versus laparoscopic Ladd's procedures including a total of 36 laparoscopic cases showed a significantly shorter time to full feeding. Moreover, the postoperative length of stay was significantly shorter in the patients who had undergone a laparoscopic procedure with an increased readmission rate in the open group.52 However, the interpretation of these results is limited due to heterogeneous patient characteristics and different follow-up periods in both groups. In another retrospective series of Ladd's procedures including 37 children, with 22 aged less than 2 months, Hagendoorn et al.62 described an excellent feasibility with a low rate of conversions or intraoperative complications. Nonetheless, in this study the rate of reoperation due to recurrence was substantial (19%). Based on these data, laparoscopic treatment of rotational anomalies in the neonate is feasible and may offer some benefits to the patients in experienced hands.

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Necrotizing enterocolitis Laparotomy is the first choice for the surgical treatment of necrotizing enterocolitis (NEC), mostly when free abdominal gas or clinical deterioration despite maximal medical therapy are evident. Laparoscopy may offer a potential benefit, particularly when signs of bowel perforation are absent.63 As first reported by Pierro et al.64 in 11 neonates with suspected NEC, laparoscopy may visualize the bowel and determine its perfusion status. Numanoglu and Millar65 reported in a case series of 13 patients that fluorescein laparoscopy may have an additional benefit in identifying necrotic segments. Diagnostic laparoscopy may allow the identification of children who would not need any further intervention, therefore avoiding surgical insult and stress. This may be beneficial in an already compromised, premature neonate. Several other enthusiastic reports on laparoscopic exploration of prematures with suspected necrotizing enterocolitis have been published.66–68 In patients with perforations or necrotic bowel, the authors would then convert to an open procedure. In the case of cloudy peritoneal fluid, laparoscopy allowed a guided placement of a drain. A recent systematic review summarized the current evidence for the use of laparoscopy in NEC based on the analysis of 44 patients with a weight ranging from 0.5 to 2.9 kg.68 Laparoscopy could confirm the diagnosis of NEC in 91% of patients and exclude NEC in 9% patients. In patients with confirmed NEC at laparoscopy, 72% showed perforation and/or gangrene, whereas 28% had neither of these findings. Every fifth patient did not need further surgical treatment after laparoscopy, including 9% without evidence of NEC, 5% with no evidence of perforation and/or intestinal gangrene, and 5% had pannecrosis of the bowel precluding further intervention. In summary, 25 (57%) patients had bowel perforation detectable at laparoscopy. The mortality in this review was 14% due to withdrawal of care in two infants with panintestinal disease, progressive NEC in two patients, and unknown reasons in another two children. The only reported complication was one case of missed perforation at laparoscopy, which was later identified at a subsequent laparotomy for clinical deterioration. This patient had gross intestinal distension that limited adequate visualization of the entire bowel. In conclusion, laparoscopy can be useful in selected premature infants with suspected NEC to avoid unnecessary laparotomy and minimize the surgical trauma. Nevertheless, the evidence supporting this procedure is low with no prospective or comparative data. Inguinal hernia Laparoscopic inguinal hernia repair in children has increased in popularity over the past years, but the benefit of this technique remains to be proven. A meta-analysis on laparoscopic versus open hernia repair was recently performed by Yang et al.69 and included data of three randomized controlled trials (RCTs).70–72 It showed that operative time for bilateral hernia was significantly shorter and the rate of metachronous contralateral hernia was lower in the laparoscopy group. No other differences were found. A second meta-analysis73 included two of the abovementioned RCTs.71,72 The author confirmed the lower rate of metachronous contralateral hernia in the laparoscopic group and found longer operative time for unilateral hernias. Again, no other differences were identified.73 Various key findings of the single RCTs are conflicting. The study from Finland found longer operative times for unilateral hernias and observed significantly higher postoperative pain levels.72 In a RCT from India, delayed immediate postoperative recovery was reported.70 Chan et al.,71 however, found less postoperative pain in children operated on laparoscopically and also confirmed a longer operative time for unilateral hernia. Data on laparoscopic inguinal hernia repair in neonates is scarce.

It has been shown that it is equally feasible and safe even in small premature neonates.74 However, potential morbidity may be caused by the fact that the laparoscopic approach requires general anesthesia and mechanical ventilation. Therefore, the proper selection of patients suitable for this technique is crucial. Children suffering from bronchopulmonary dysplasia (BPD) may be better operated on under regional anesthesia (e.g., caudal block) to reduce pulmonary morbidity. In summary, it is too early to draw final conclusions about clear advantages of either technique in neonates. Anorectal malformation Laparoscopy has been used for the treatment of anorectal malformations (ARMs) since Georgeson et al.75 introduced this technique in 2000. In recent years there is an ongoing discussion on which type of ARM should be repaired via a posterior sagittal approach and which ones require laparoscopy.76 The primary laparoscopic repair of ARM with fistulas to the bladder neck or prostatic urethra has been described in the neonatal period.77 However, there is consensus on the high value of a preoperative colostogram to define the type of ARM first in order to choose the appropriate operative approach. Therefore, and for many other reasons, most authors perform a delayed repair in higher forms of ARM. In those patients the surgical procedure in neonatal period is usually limited to the creation of a colostomy.78 Hirschsprung disease Laparoscopic-assisted endorectal pull-through (LAEPT) was first described by Georgeson et al.79 in 1995. Several series confirmed an excellent safety and feasibility of this approach. It was suggested that LAEPT had advantages over open procedures such as shorter time to feeding, shorter hospital stay, less pain, and better cosmesis.80 However, Langer81 recently emphasized that although LAEPT and pure transanal pull-through operations are often thought of as separate approaches, the techniques are similar in most aspects. The main difference is the preparation of the rectum: laparoscopy allows additional dissection of the rectum from above, whereas by using a transanal technique, the rectum is dissected from below only. The authors further stated that many “transanal” surgeons used laparoscopy for biopsy and/or mobilization of the proximal colon without using it for rectal dissection, making the LAEPT technique a very heterogeneous approach. No study has been published to date comparing LAEPT with pure transanal techniques, however this question has increasingly become less relevant.81 Both techniques may be performed in neonates too. Recent series showed that the Georgeson procedure is safe and effective in any age group.82,83

Thoracoscopy in the neonate Thoracoscopic approaches have been described for a large variety of pediatric and neonatal surgical diseases and safety and feasibility have been demonstrated by multiple authors.84 The benefits include less postoperative pain, shorter hospital stay, better cosmesis, and less long-term musculoskeletal morbidity such as shoulder movement impairment, rib fusions, and scoliosis.85,86 The lower incidence and severity of these sequelae seems to be a specific advantage of minimally invasive techniques in infants undergoing thoracic surgery. Lawal et al.85 recently performed a follow-up study on 62 children who underwent thoracoscopic compared to open surgery. Anatomical parameters such as the alteration of nipple–sternum distance and pre- versus postoperative chest diameter were clearly in favor of thoracoscopy. The

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253

Table 3 Levels of Evidence of neonatal thoracoscopy. Study

Indication

Procedure

Study type

Level of Evidence

Advantage thoracoscopy

Disadvantage thoracoscopy

Borruto et al.90 Lansdale (2010)123 Szavay et al.121 Gander et al.120 Nasr and Bass101

EA/TEF

MA

3a

None

None

CDH

Anastomosis and TEF closure CDH closure

MA

3a

None

CDH

CDH closure

3b

CDH

CDH closure

Lower post OP pCO2 and shorter ventilation Shorter ventilation

CPAM

Lung resection

Retrospective comparative study Retrospective comparative study MA

Longer operative time and higher recurrence rate Longer operative time

3b 3a

Shorter hospital stay and shorter duration of chest tube

Higher recurrence rate None

EA/TEF: esophageal atresia/tracheoesphageal fistula; CDH: congenital diaphragmatic hernia; CPAM: congenital pulmonary airway malformation; MA: meta-analysis.

incidence of grade I scoliosis was 10% versus 50% in favor of thoracoscopy and the cosmesis score was significantly better. However, the level of evidence for neonatal thoracoscopy is low as there are no randomized controlled trials dealing with minimally invasive versus open lung resection, thoracic reconstructive or other intrathoracic procedures87 (Table 3).

Esophageal atresia and tracheoesophageal fistula Since the first thoracoscopic repair of an esophageal atresia with tracheoesophageal fistula in Berlin in 1999, the option of a minimal invasive approach has been widely accepted.88 According to a survey taken at the international scientific meeting of the British Association of Pediatric Surgeons in Edinburgh in 2007, 18% of the participating pediatric surgeons had performed such a procedure, and 50% of the surgeons stated that they intended to continue repairing esophageal atresia thoracoscopically in the future.89 A recent meta-analysis by Borruto et al.90 did not show any significant advantage with regard to overall complications, anastomotic stricture, and leakage. We recently reviewed the evidence for advantages of thoracoscopic TEF repair,87 including three retrospective comparative studies (RCS).91–93 The RCS by Szavay et al.91 revealed longer operative times and higher intraoperative pCO2 in the thoracoscopic group. Lugo et al.92 confirmed longer operative times for thoracoscopic EA/TEF repair and found higher estimated blood loss. Advantages of the thoracoscopic approach were shorter narcotic use, ventilation, hospital stay, time to full feeds, and less anastomotic leakage or stricture.92 However, the lack of a proper statistical analysis in this study makes an interpretation difficult. The third RCS, which also focused on operative time, anastomotic leakage, and stricture did not identify any differences between the two approaches.93 This corresponds to a multinational and multi-institutional retrospective analysis performed earlier by Holcomb et al.94 Treatment of long-gap EA/TEF in which a primary anastomosis cannot be achieved remains a challenge.95 A large number of operative approaches have been proposed. One is the use of mechanical traction to accelerate the growth of the esophageal ends and allow earlier primary anastomosis.96,97 With the introduction of thoracoscopic repair of esophageal atresia, van der Zee et al.98 recently described the repair of long-gap esophageal atresia by thoracoscopic traction of the two esophageal ends and delayed thoracoscopic anastomosis. In summary, the current data suggests that EA/TEF repair can be repaired thoracoscopically without similar overall complications and functional outcome. Advantages of thoracoscopic EA/TEF repair are better musculoskeletal function and cosmesis.99,100

Congenital pulmonary malformations Routine ultrasound scanning during pregnancy increased the chances of detection of multiple intrathoracic malformations such as congenital pulmonary airway malformation (CPAM), lung sequestration, and lobar emphysema. There is consensus that symptomatic lesions need to be operated. However, the majority of these lesions are asymptomatic at birth, which explains the ongoing discussion about when and at what age these lesions need surgery. A recent review on the treatment of congenital thoracic malformations including one meta-analysis of retrospective studies showed no differences regarding complications and operative time between thoracoscopic and thoracotomic procedures.101 Separate analysis of retrospective studies confirmed shorter hospital stay and shorter duration of chest drains in the thoracoscopic group compared with the open procedure.102–105 Additionally, different authors reported on less regional anesthesia,106,107 shorter narcotic use,105 and less overall complications102 in the thoracoscopic group. As a potential disadvantage of the thoracoscopic approach, longer operative times compared with the open approach were reported in two of the retrospective studies.102,106 In the last decade, thoracoscopic resection in the newborn period has been suggested as therapy of choice.108–110 The authors suggested that the early resection of those malformations may avoid potential infections, which make an operation more difficult and operation times longer. Despite these studies, many surgeons tend to operate at a later time point, e.g., at the age of 6 months.111,112 Congenital diaphragmatic hernia (CDH) The first cases of laparoscopic treatment of congenital diaphragmatic hernias were reported two decades ago.113 The technique was initially restricted to late-onset hernias with correction far beyond the newborn period. The age limit was lowered continuously, first to infants and then to truly neonates.114–116 With increasing experience, thoracoscopy was shown to be superior to the laparoscopic approach as the insufflation of the CO2 in the thoracic cavity supported the reduction of the abdominal organs.116–118 In recent years, several studies comparing open versus thoracoscopic CDH repair have been published. Three retrospective studies confirmed a shorter duration of ventilation119–121 and lower postoperative pCO2 in thoracoscopic patients.121 Additionally, Gourlay et al.119 showed that the thoracoscopic group had a faster return to full feeds, less postoperative analgesia, and less severe complications occurred, also accounting for less total hospital charges. Although several series emphasize the good feasibility of the thoracoscopic approach for CDH, the heterogenous selection criteria of the appropriate patients and the

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long-term outcome compared to open surgery are still a matter of discussion. Several studies comparing thoracoscopic procedures used historic controls and suggested equivalent recurrence rates and faster recovery.119–122 In contrast, a systematic review and meta-analysis of thoracoscopic cases by Lansdale et al.123 found higher recurrence rates and longer operation time, compared to open surgery. Despite the initial enthusiasm about the outcome of minimally invasive repair of CDH, other authors are calling into question the safety of this procedure. There is increasing evidence that due to absorption of insufflated CO2 thoracoscopy in neonates may have serious neurotoxic side effects such as severe acidosis. In a recent prospective randomized controlled study, Bishay et al.16 showed that thoracoscopic repair of CDH is associated with prolonged and severe intraoperative hypercapnia and acidosis compared with open surgery. The authors noted that the blood pH decreased to 7.0 during thoracoscopic procedures in newborns. The cerebral oxygen saturation remained at 75% compared to preoperatively for 24 h after operation. The high levels of hypercapnia and acidosis were of such concern that the trial's Data Monitoring and Ethics Committee advised that thoracoscopic repair of CDH should no longer be performed with this type of conventional insufflation and ventilation at this institution. Although the usage of high initial pressures of 7.1 7 0.5 mmHg may partly explain the high CO2 measurements, the effect of thoracoscopy on blood gases during repair of CDH in neonates requires further evaluation. A neurodevelopmental follow-up of these infants is currently under way to determine the effects of the hypercapnia and acidosis in the long term.16

Conclusion Almost every operation has been performed in children using minimally invasive techniques. With an endoscopic equipment of appropriate size and advanced surgical skills, it appears that there is no age or weight limit for minimally invasive interventions. There is an increasing popularity of those procedures in neonates. Obvious advantages include better cosmesis, less trauma, and better postoperative musculoskeletal function, in particular after thoracic procedures. However, the feasibility of minimally invasive surgical procedures does not necessarily translate into a clinical benefit. This was demonstrated for the treatment of biliary atresia, which was shown to have unfavorable outcome if operated on using MIS.124 The aim of academic studies in MIS has therefore shifted from proving feasibility to a critical evaluation of outcome. Prospective randomized trials and high-level evidence for the benefit of endoscopic surgery in the neonatal age group are still scarce.125 Nevertheless we are convinced that MIS has found its place in neonatal pediatric surgery and children will continue to benefit from the advantages of this fascinating technique.

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