Minimal Access Surgery in the Neonate

摘要

After completing this article, readers should be able to: Historically, pediatric surgeons were slow to adapt to minimal access surgery (MAS) techniques compared with the adult surgical community. However, MAS now is widely established in infants and children. Differences in size and physiology have necessitated a number of surgical and technological modifications to apply MAS techniques to this population. This review outlines the important differences between children and adults with respect to MAS and provides examples of the use of MAS for diseases seen in infants.The physiologic response to pneumoperitoneum in children is more pronounced than in adults. Peritoneal insufflation with carbon dioxide has been shown to cause hypercarbia, acidemia, and decreased oxygenation in the pediatric piglet model. (1) In infants, however, there is no detrimental effect on blood pressure, heart rate, or oxygen saturation during short periods of pneumoperitoneum, and elevations in end-tidal CO2 can be counteracted readily by increasing the minute ventilation. (2) Hypercarbia-induced pneumoperitoneum in infants is associated with changes in cerebral blood flow and cardiac output. Nevertheless, laparoscopic procedures have been performed safely with proper anesthetic management in children who have even severe congenital cardiac abnormalities such as hypoplastic left heart syndrome. (3) Hypothermia also can be a concern due to rapid insufflation of unwarmed CO2 gas, mandating the moderation of flow rates. (4)A number of anatomic factors set children apart from adults and must be accounted for when performing laparoscopic surgery in this age group. Young children and infants have thinner abdominal walls than adults, so extreme care must be exercised when placing trocars. Due to the small size of the abdomen, the working space is generally smaller, making the choice of trocar sites vitally important. Often very little space is afforded to perform some complex maneuvers. Infants tend to have large livers and spleens, horizontally oriented stomachs, and intra-abdominal (rather than pelvic) bladders, which may limit the intra-abdominal working space further.The early generation of laparoscopic instrumentation was large and difficult to work with in small children (Fig. 1), but there is now dedicated pediatric instrumentation that is significantly smaller than that used in adults (Fig. 2). Although instrument sizes range from 1 to 12 mm and trocar sizes from 2 to 5 mm, neonatal procedures typically use 3.5- and 5-mm instruments. Endoscopes and cameras are lighter, and the shafts of the instruments are considerably shorter, allowing finer manipulation in a smaller space. A radially expanding trocar system has been a tremendous advancement because it allows for a tighter fit in the thinner chest or abdominal wall of the infant and minimizes sliding movement of the ports. Trocar and instrument sizes are selected according to the surgeon’s preference and infant size.Pediatric thoracoscopy has been used in a wide variety of diagnostic and therapeutic procedures, although ventilation has been a considerable obstacle. Because of the inability for double-lung ventilation in smaller children, thoracoscopic procedures often rely on mainstem intubation and low-pressure, low-flow insufflation of the chest cavity to allow adequate visualization of the operative field. Other techniques are available to achieve single-lung ventilation, such as placement of a bronchial blocker or Fogarty catheter in a mainstem bronchus. Controlled pneumothorax can be achieved with low-flow (1 L/min) and low-pressure (3 to 5 torr) CO2 to collapse the lung fully, providing a larger operative space.Minimal access procedures require general anesthesia. Patients are secured to the table, the stomach is emptied by nasogastric or orogastric suction, and the bladder is decompressed by the Credé maneuver. Positioning of the infant is critical to maintain endotracheal tube placement, avoi