Minimally invasive surgery has rapidly emerged as a mainstream technique in infants and children, even largely supplanting many commonly performed open operations. As with conventional surgical techniques, the anesthetic care is dictated by age, coexisting conditions, and acuity of presenting medical condition; therefore, thorough preoperative evaluation and preparation for anesthesia is mandated. Additionally, the unique physiologic perturbations induced by the operating conditions required for minimally invasive techniques impose critical differences in anesthetic management. In the following sections, a brief background about the development of endoscopic surgery, the physiologic impact of minimally invasive surgery, and special anesthetic considerations will be outlined.

      I.   History and background

               A.   Minimally invasive surgery, although relatively new to pediatric procedures, has a long and interesting history.

                       1.   At the end of the 19th century, the use of endoscopy was limited to examination of the bladder, rectum, and pharynx.

                            a.   The development of a device to evaluate and intervene in body cavities previously only accessible by the scalpel is credited to a German physician, Philipp Bozzini (1).

                            b.   Consisting of a tube with an eyepiece, a candle for illumination, and a mirror to reflect the image, the image was of poor quality and the experience quite painful for the patient.

                       2.   In 1902, Georg Kelling, a German gastrointestinal surgeon, examined the peritoneal cavity of a dog using a cystoscope, and by 1910, had performed many successful laparoscopies on patients using the pneumoperitoneum technique (2).

                       3.   It was not until the early 1970s with the development of the Hopkins rod lens system and improved illumination that adequate optics were achieved and “peritoneoscopy” for infants and children was popularized by Stephen Gans and Berci (3).

                       4.   In 1981, Kurt Semm, a German gynecologist, performed the first laparoscopic procedure: a laparoscopic appendectomy.

                            a.   Following his lecture about his procedure, the president of the German Surgical Society wrote to the Board of Directors of the German Gynecological Society suggesting suspension of Semm from medical practice.

                            b.   Subsequently, Semm submitted a paper on laparoscopic appendectomy to the American Journal of Obstetrics and Gynecology, at first rejected as unacceptable for publication on the grounds that the technique reported on was “unethical,” but finally published in the journal Endoscopy (4,5).

                       5.   In 1985, Erich Muehe, a professor of surgery in Boeblingen, Germany, used Semm’s instruments and technique to laparoscopically remove the first gallbladder (6). It was not until the 1990s when laparoscopic surgery became an established, entrusted technique for many abdominal procedures. Now, countless endoscopic or minimally invasive surgeries have been performed in all of the major surgical specialties (Table 37.1).

TABLE 37.1  Minimally invasive surgical procedures

                       6.   Benefits compared to conventional laparotomy include less pain; improved cosmesis; shorter hospital and recovery times; fewer adhesions; decreased blood loss; and decreased pulmonary, wound, and other infections.

                       7.   Moreover, as surgeons have become more proficient and equipment more sophisticated, the number and complexity of minimally invasive procedures performed in infants and children have increased.

     II.   Emerging and innovative surgical techniques

               A.   Traditional laparoscopy is usually carried out through three or more ports that are introduced through different skin incisions.

               B.   Single-incision laparoscopic surgery (SILS) is a novel minimally invasive approach: a single cutaneous incision, commonly in the periumbilical location, is created and a single access device with multiple ports or several single ports adjacent to each other may be placed to laparoscopically approach the abdominal cavity.

                       1.   SILS offers improved cosmesis, but postoperative pain is not reduced, likely because of extensive surgical manipulation of the fascial wall (7).

                       2.   A prospective randomized trial of 50 pediatric patients undergoing surgery for acute appendicitis compared SILS to conventional multiport laparoscopy.

                            a.   No significant difference in postoperative complications or hospital stay could be observed between the two techniques.

                            b.   Significantly shorter operating times and overall costs in pediatric patients undergoing appendectomy with the SILS approach were demonstrated in another study (8,9).

               C.   Natural orifice translumenal endoscopic surgery (NOTES) is another novel minimally-invasive surgical approach.

                       1.   It is currently a developing and experimental alternative to open or laparoscopic surgery (10).

                       2.   NOTES procedures are performed by entering the peritoneal cavity via an endoscopic translumenal approach through a natural orifice.

                            a.   To date, transgastric, transcolonic, transvaginal, and transurethral/transcystic approaches exist.

                            b.   Although NOTES is currently limited to a few academic and research institutions, increasing numbers of NOTES procedures have been performed in humans in the last years.

                            c.   This new concept is driven by the hypothesis that a translumenal approach is less painful than an abdominal wall incision.

                            d.   Potential benefits are considered to be fewer complications such as ileus, abdominal wall pain, hernias, and improved cosmetic outcomes.

                            e.   Better access to certain areas of the peritoneal cavity in specific patient populations (e.g., the obese) might prove to be advantageous with this new technique.

                       3.   So far, the NOTES approach has been largely studied in animal models.

                       4.   Case reports and series of human NOTES are increasing since the technique was introduced in 2004 (11).

                            a.   A case of successful treatment of pediatric gastroesophageal reflux disease using a transoral incisionless fundoplication procedure instead of the standard laparoscopic Nissen fundoplication has been reported (12).

                       5.   To detect complications and potential problems, early outcome databases such as the Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR) registry, the German National Notes Registry, and the Euro Notes Registry have been established by individual medical societies.

                       6.   As of today, only a small number of cases have been purely NOTES.

                            a.   The majority of human case reports are hybrid-NOTES procedures using laparoscopic ports for visualization, retraction, and technical assistance:

                            b.   For example, surgical treatment of Hirschsprung disease successfully combined a laparoscopic-assisted pull-through procedure with transrectal NOTES, minimizing the need for large transabdominal working port sites (13).

                            c.   Pig models show promising results for very delicate long-gap esophageal atresia repair combining laparoscopy and NOTES (14).

   III.   Physiologic alterations during laparoscopic and thoracoscopic surgery. The fundamental differences between children and adults with regard to metabolic, cardiovascular, and respiratory performance are outlined in Chapter 1. Both laparoscopic and thoracoscopic operations mandate the introduction of exogenous CO₂ to the respective body cavity to create a pneumoperitoneum or pneumothorax. The use of muscle relaxants, general anesthetics and the loss of the glottic closure mechanism with endotracheal intubation combined with the supine or Trendelenburg position and the pneumoperitoneum or the lateral position and pneumohemothorax conspire to produce particular challenges for the pediatric anesthesiologist.

               A.   Mechanical effects of insufflation

                       1.   The effects of pneumoperitoneum have been extensively examined in adults (15).

                            a.   Increases of intra-abdominal pressure (IAP) up to 20 cm H₂O are accompanied by increases of central venous pressure (CVP), intrathoracic pressure, and cardiac output.

                            b.   Greater increases of IAP to approximately 40 cm H₂O are accompanied by falls in CVP and cardiac output, with parallel changes in mean arterial pressure and moderate tachycardia.

                            c.   Subcutaneous emphysema has been reported as a result of pneumoperitoneum during laparoscopy; pneumothorax and pneumomediastinum may occur through retroperitoneal entry of insufflating gas into the thorax via anatomic foramina or diaphragmatic defects.

                            d.   A precordial stethoscope may actually be more revealing than an esophageal stethoscope; bilateral stethoscopy should be considered in such cases.

                       2.   Peak airway and plateau airway pressures in adults increase by 50% and 81%, respectively, whereas the compliance of the respiratory system decreases by 47% during the period of increased IAP.

                            a.   Experimental studies suggest that the risk of cardiorespiratory consequences with the development potential fatal emboli is directly related to peak pneumoperitoneal pressures (16).

                       3.   Following release of the pneumoperitoneum, peak and plateau pressures remain elevated by 37% and 27%, respectively, and respiratory compliance is 86% of the preinsufflation value (17).

                       4.   It is somewhat surprising yet consistent that gastroesophageal reflux is rare to nonexistent as assessed by pH probe and direct laryngoscopy as well as clinical signs and symptoms of reflux or aspiration notwithstanding the abdominal insufflation and head-down position (18,19).

                       5.   Occasional case reports of catastrophic cardiovascular collapse occurring during laparoscopy have been attributed to reflex-mediated bradycardia, hypercapnia, anoxia, decreased venous return and cardiac output, gas embolism, and a profound vagal response to peritoneal distension.

                       6.   Pneumoperitoneum alone and together with head-down tilt may shift the endotracheal tube into a deeper position, thereby getting in contact with the carina resulting in airway irritation, possible coughing, or bronchospasm or the endotracheal tube may advance into a right mainstem position resulting in increased inspiratory pressure and decreased exhaled tidal volume (20).

               B.   Monitoring CO₂ insufflation

                       1.   Monitoring of end-tidal carbon dioxide (ETCO₂) is a sensitive method of assessing the combined effects of endogenous and exogenous CO₂ burden during CO₂ insufflation.

                            a.   Strategies that enhance the accuracy of capnography in children are now well recognized, including fast sampling rates and distal airway sampling.

               C.   Effects of CO₂ insufflation

                       1.   Significant amounts of the insufflated gas may be absorbed from the pneumoperitoneum into the blood.

                            a.   CO₂ is the most soluble of the agents employed (CO₂, nitrous oxide, and air) to produce pneumoperitoneum.

                            b.   CO₂ has been well tolerated for angiocardiography in doses up to 7.5 mL per kg in adults, whereas the injection of air in doses of 0.25 mL per kg in cats has resulted in death from coronary artery obstruction.

                            c.   Nitrous oxide is 68% as soluble as CO₂ in blood and, although not flammable, can potentially support combustion directly or make an indirect contribution through bowel perforation and the release of volatile bowel gas (methane, hydrogen) (6).

                       2.   Insufflated CO₂ rapidly equilibrates with tissues; CO₂ pressure in alveolar air as well as arterial blood has been noted to increase within 5 minutes and pulmonary CO₂ elimination increase after 15 minutes (7).

                            a.   In children, after 10 minutes of insufflation, 10% to 20% of expired CO₂ derives from the exogenous CO₂.

                            b.   The percentage of expired CO₂ absorbed rises to 7.7% after 30 minutes of pneumoperitoneum and decreases rapidly after desufflation (8).

                            c.   Hypercarbia may result in elevated endogenous catecholamines accompanied by vasoconstriction, increased CVP, and increased inotropic, chronotropic, and arrhythmogenic effects on the heart.

                            d.   In addition, hyperkalemia, an increase in cerebral blood flow, acidosis, and cardiopulmonary depression may occur.

                            e.   The norepinephrine response has been found to increase with laparoscopic cholecystectomy and this may have particular implications for infants because of the presence of brown fat and its activation by norepinephrine.

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