Paediatric Urology

26. BASIC PRINCIPLES OF LAPAROSCOPIC SURGERY IN CHILDREN

26.1. Epidemiology, aetiology and pathophysiology

The use of laparoscopy and robot-assisted laparoscopic surgery is rapidly increasing and has gained widespread acceptance for many urological surgeries in children [1517]. Laparoscopy is commonly performed for nonpalpable testis, nephrectomy, heminephrectomy, varicocelectomy, pyeloplasty and ureteral reimplantation. This expanding scope related to technological advancements allows surgeons to perform more-complex procedures in a minimally invasive fashion even in infants and younger children. Generally, well-established benefits of minimally invasive surgery are decreased pain, shorter convalescence and better cosmetics compared to traditional open surgery [837,1518]. When comparing the transperitoneal and retroperitoneal approach, there was no difference in recovery of bowel function [1519]. Additional advantages of robotic surgery over conventional laparoscopy include ergonomics, 3D vision, better manoeuvrability, decreased tremor and easy learning curve. Limitations to be considered are increased operative time, smaller working space at a young age, cost, and experience of the surgeon and anaesthesiologist. While the success and complication rates are comparable for nephrectomy and pyeloplasty, advantages of laparoscopy and robotic surgery for ureteral reimplantation have not been proven and this can only be recommended for experienced centres.

As worldwide experience increases, there is an accumulating awareness about the physiological consequences related to intra- and retroperitoneal CO₂ insufflation in children. In contrast to traditional open surgery, pneumoperitoneum may have physiological responses which require close monitoring during surgery and should be taken seriously.

26.2. Technical considerations and physiological consequences

26.2.1. Preoperative evaluation

Laparoscopy in children requires specific anaesthetic precautions. Physiological effects of CO₂ pneumoperitoneum, positioning of the patient, and potentially increased operative time must be considered by the anaesthesiology team. Therefore, a detailed medical examination and risk assessment is mandatory pre-operatively. Especially, the cardiac and pulmonary systems should be assessed, as increased intra-abdominal pressure may lead to decreased ventricular preload [1520].

26.2.2. Abdominal insufflation

Abdominal insufflation is the main principle of laparoscopic surgery to create working space for the surgeon. Carbon dioxide is most commonly used for insufflation in laparoscopic centres throughout the world. Other alternatives reported are nitrous oxide, helium, argon and air. However, CO₂ is considered to be the best available gas, as it is colourless, cheap, has high solubility in the vascular system [1521] and is excreted by the pulmonary system, making it the safest option. Smaller children and infants absorb more CO₂ than older children [1522], suggesting the need for more attention both during and soon after laparoscopic surgery for these children.

Most complications of laparoscopy are attributable to gaining access to the abdominal cavity. One study reporting complications of > 5,400 paediatric laparoscopic surgeries showed that there was an overall complication rate of 5.3%, of which 4.2% were related to problematic insufflation (subcutaneous emphysema, gas embolism, injury to the organs and vascular structures, mis-insufflation and so on) [1523]. There are two main and well-established techniques for initial access to the abdomen or retroperitoneum: open technique (Hasson) and Veress needle. Studies comparing these two different access techniques in paediatric laparoscopic urological procedures showed similar complication rates [1524]. The vast majority of the complications were minor and related to lack of surgical experience. Particularly in infants and smaller children, the Panel recommends the open access technique to reduce the chance of complications.

Elasticity of the abdominal wall is age-related and is higher in infants and small children compared to older children [1525].

Pneumoperitoneal pressure (PnP in mmHg) is one of the critical points that laparoscopic surgeons must considered carefully. An RCT compared two different pneumoperitoneal pressure groups (6-8mmHg vs. 9-10mmHg) in infants weighing less than 10kg [1526]. The results of the RCT demonstrated that higher pressures were associated with more pronounced respiratory and haemodynamic changes, as well as increased postoperative pain scores and prolonged time to resume feeding.

26.2.3. Pulmonary effects

After intra-abdominal insufflation, the diaphragm is pushed upwards due to increased abdominal pressure. This leads to decreased total pulmonary compliance. Combined with CO₂ absorption, this may lead to hypercarbia and acidosis, particularly in case of prolonged operative time or low pulmonary reserve such as in infants. Trendelenburg position may also aggravate the situation in operations in the pelvic region, such as antireflux or bladder neck surgeries. Several studies revealed increased end tidal CO₂ (ET CO₂) related to CO₂ absorption [1522,1527,1528]. One study showed a 33% increase in ET CO₂ in the majority of neonatal laparoscopic and thoracoscopic procedures [1529]. Shorter operative time and lower intra-abdominal pressures decrease the risk of increased ET CO₂. Hypoxemia is rarely seen, even in neonates, and can easily be adjusted by increasing minute ventilation. These findings highlight the importance of close monitoring of the children.

26.2.4. Cardiovascular effects

Intra-abdominal pressure, CO₂ absorption and positioning may also affect the cardiovascular system. It has been shown in adults that, after initiation of pneumoperitoneum, cardiac output and stroke volume decrease, while mean arterial pressure, central venous pressure and systemic vascular resistance increase [1530]. Similar outcomes have been reported during paediatric laparoscopy with some nuances. Cardiac output was 30% decreased while blood pressure remained stable during laparoscopic orchidopexy with PnP of 10mmHg in children between the ages of 6-30 months [1531]. When PnP was lowered from 12mmHg to 6mmHg, cardiac index and other vascular parameters normalised [1532]. Using high intra-abdominal pressures in infants with congenital cardiac abnormalities may result in reopening of cardiac shunts such as the foramen ovale and ductus arteriosus [1533]. Although cardiovascular effects of using high PnP are clinically measurable, they may not have a significant clinical impact on healthy children. However, it is clear that using lower pressures is safer, particularly in smaller children.

26.2.5. Effects on renal function

A study measuring renal oxygenation with near-infrared spectroscopy (NIRS) during laparoscopy showed that pneumoperitoneum might have a negative effect on renal oxygenation [1534]. However, this effect was reversible after desufflation. Other studies showed that pneumoperitoneum may also have adverse effects on renal blood flow [1535]. High intra-abdominal pressures and reverse Trendelenburg position may cause decreased glomerular filtration rate and decreased urine output. One study has shown that 88% of infants and 14% of children above the age of one year old develop anuria within 45 minutes after initiation of PnP with 8mmHg [1536]. However, urine output recovers with temporary polyuria after the operation. Although the clinical relevance of decreased urine output seems insignificant, it is important to monitor the fluid and electrolyte balance of the children during and after laparoscopic surgery.

26.2.6. Effects on neurological system

Another effect of pneumoperitoneum is increased intracranial pressure (ICP), which normalises after desufflation of the abdomen [1537]. Trendelenburg position, high PnP and hypoventilation are additional risk factors for increased ICP. Laparoscopy is therefore contraindicated in patients with intracranial space occupying lesions [1538]. Children with ventriculoperitoneal shunts require precautions with regards to shunt drainage, however, laparoscopy is not contraindicated [1539].

26.2.7. Comparison of robot-assisted laparoscopic surgery versus laparoscopic surgery

No physiological differences are expected between the two approaches, since pneumoperitoneum must be achieved in the same manner. However, a systematic review comparing robot-assisted laparoscopic pyeloplasty to conventional laparoscopy in infants and children showed no differences in terms of operative success and redo rates between the two techniques [1540]. As for operative time, length of hospital stay and complication rates, the robotic approach appears to be slightly superior in children [1541,1542]. However, in the infant population, operative time was longer in the robot-assisted approach as compared to conventional laparoscopy, and there was a higher complication rate, mainly due to a higher rate of port-site hernias [1543]. The robot-assisted approach might aid in filling the gap to minimally invasive surgery for paediatric urologists, as it has a shorter learning curve and does not necessarily require prior laparoscopic experience. Downsides to the robotic approach are the size of the instruments, accessibility and costs [1540,1542].

26.3. Summary of evidence and recommendations for laparoscopy in children