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Minimal Access Surgery

                               
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Introduction of Minimal Access Surgery

Constant evolution undergoes in the field of surgery. The field of surgery truly expanded with the evolution of inhalation anesthetics. Earlier, surgical procedures were avoided and, if performed, were brief. The best surgeon was the fastest surgeon who thereby caused less pain to his restrained and unanesthetized patient.
Since the beginning, to a successful procedure larger surgical incision was an absolute necessity. The key to a safe and successful operation was Exposure. Exposure is still essential for a safe and successful operation, except that it can now be provided with minimal skin incision and the use of a miniature access approach.
Since the early 19th century, Minimal access surgery (MAS) has been in existence. A crude endoscope, which used a candle as illumination, for exploring intra-cavitary organs through external orifices was practiced. By the adult surgeons advantages of MAS were realized long before it was accepted in the pediatric community. Initially, performing MAS in the pediatric population was resisted for the following reasons:

• The cases were thought to take too long to set up and to perform.
• Equipment was not small enough.
• The cost of laparoscopy was believed to be too high.
• Many believed that MAS was not safe, and its efficacy was not proven.
• A widely held belief was that children did not experience pain.
• MAS was believed to be too difficult to perform and too difficult to learn.
• Many surgeons believed that laparoscopic cases did not really apply to children, and the need for cholecystectomy was relatively uncommon in children.
• Pediatric surgeons already prided themselves on the ability to work with small incisions.
  

Poor-quality pediatric laparoscopic instruments and telescopes that were not small enough were perhaps the most hindering in pediatric laparoscopy advancement.
Many of the advances made in pediatric laparoscopy have subsequently been used in adults. Adult surgeons sought the smaller telescopes and instruments that were developed for pediatric MAS.

Physiology of Minimal Access Surgery in Pediatrics
Insufflation of the abdomen or chest cavities for minimal access surgery (MAS) procedures has important physiologic effects. Much of this physiology has been studied in adults, but on this subject very little work has been conducted in children.
For successful laparoscopy Pneumoperitoneum is required in most of the cases. Most surgeons prefer carbon dioxide gas because it is easy to absorb, and, thus, the risk of embolism is reduced compared with other gases. In addition, it suppresses combustion. After the peritoneum is accessed, the abdomen is insufflated with carbon dioxide gas. The pressure limit usually does not exceed 15 mm Hg in adults. It varies in infants and children, and care must be taken to start low (e.g., 1 L/min and pressures of 8-12 mm Hg) and should use only the pressure required to obtain visualization and maintain optimal physiology.
Once the intra-abdominal volume exceeds the ability of the peritoneal cavity to expand without a significant increase in abdominal pressure, increase in pressure leads to harmful physiologic effects. This is especially true when the cavity is small, as in children. The ability of the abdominal cavity to accommodate an increase in pressure depends on the pressure applied and the length of time during which the pressure is maintained. Under normal physiology, the intra-abdominal pressure can be as high as 200 mm Hg during a coughing and defecation episode. The pressures may rise to 2-8 mm Hg during peritoneal dialysis, which has no demonstrable adverse affect.

Increased intra-abdominal pressure interferes with infra-diaphragmatic venous and arterial blood flow, especially to the kidneys. It may also displace the diaphragm into the chest cavity, decreasing total lung capacity and functional residual capacity, adding to the acid-base disturbance. An increase in intra-abdominal pressure effectively acts as a venous tourniquet. Blood flow from the lower limbs and abdomen is decreased while the arterial perfusion is intact. Cardiac output is decreased with increase in the ventricular stroke work and the heart rate. Increase in Pressure on the abdominal aorta leads to increase pressure in the upper body. In children with preexisting decreased cardiac output, increased intra-abdominal pressure may lead to acute cardiac failure.
The ventilatory and circulatory changes can be appreciated within 5 minutes of the onset of insufflation of gas. Pressures of more than 15 mm Hg are associated with significant pathophysiologic effects but are reversible over a 2-hour period. To insufflate adequately yet maintain normal physiologic parameters Pediatric surgeons and pediatric anesthesiologists must work together.

Increased minute ventilation (i.e., increased rate, airway pressure, and/or tidal volume) can compensate for pulmonary mechanical restriction with intra-abdominal pressures of less than 12 mm Hg. Pulmonary arterial pressure and pulmonary wedge pressure both increase with pneumoperitoneum, improving ventilation-perfusion at intra-abdominal pressures of less than 12 mm Hg. This may help explain the lack of effect on pO2 under these conditions. Across the peritoneal surface the carbon dioxide is mostly absorbed, and a rise in its partial pressure can be offset by increasing minute ventilation.
Elevation in carbon dioxide may continue for 3 hours after an operation. This is important to recognize, especially given postoperative narcotic use and the effect of narcotics on ventilation. Continued monitoring of the cardiac, respiratory, and renal systems should be carried out in the immediate postoperative period.
Increase in intra-abdominal pressure can also exacerbate gastroesophageal reflux, adding to perioperative risk of aspiration.
Much work remains regarding the physiologic effects of pneumoperitoneum in children. Coronary, hepatic, mesenteric, and renal flow may be affected, as well as cerebrospinal fluid (CSF) pressure and pulmonary dynamics.

Advantages of Minimal Access Surgery

• Patients stay in the hospital for a shorter period and recover faster.
• MAS results in reduction of postoperative adhesions.
• Smaller wounds are associated with fewer wound complications, less scarring, and better cosmesis.
• Laparoscopy often offers better visualization than open surgery, particularly better visualization of the hiatus and deep structures in the pelvis.
• Minimal access surgery (MAS) offers dramatic advantages in terms of the quality of life after the operation.
• Postoperative pain is reduced, which decreases postoperative narcotic use and its complications. This also aids in lower pulmonary complications.
• Patients are able to return to their normal activities faster (e.g., feeding, school, work).
• A child's quick recovery allows parents to return to work faster.
• Video imaging allows surgical assistants, anesthesiologists, and nurses to view what the surgeon is doing and to actively participate in the procedure in their respective roles.
• Laparoscopy can be performed in infants weighing less than 1.5 kg without significant mortality or morbidity.
  

Disadvantages of Minimal Access Surgery

• Controlling bleeding laparoscopically is difficult.
• Operating time is longer and the complication rate is higher during the learning curve of the procedure.
• With current technology, the video camera can provide only a 2-dimensional image, although 3-dimensional views are becoming available.
• Initial capital cost is associated with laparoscopy because new equipment and training are necessary.
• Loss of tactile sensation occurs, which is perhaps the major disadvantage of minimal access surgery (MAS). Intra-operative ultrasonography is helping to overcome this deficiency.
• The number of instruments and angles in which they can be applied are limited. Robotic applications using wrist technology is improving this problem.
  

Complications of Minimal Access Surgery

Carbon dioxide–related complications

• Hypothermia can also ensue because of cold carbon dioxide insufflation, especially in small infants.
• Another serious, but fortunately rare, side complication is gas embolism; this is minimized by carbon dioxide use as opposed to use of other gases.
• Carbon dioxide can be easily absorbed through the peritoneal surface, leading to hypercapnia. Elevation in carbon dioxide can lead to acidosis, which can have further metabolic and hemodynamic consequences.
• Insufflation of carbon dioxide can also cause cardiovascular compromise because of the previously mentioned venous tourniquet effect.
• These complications can be minimized by low pressure and warm humidified gas insufflation, slight hyperventilation, proper fluid resuscitation, and careful monitoring in the operating room.
  

Technique-related complications

• Complications can also arise from dissection during the procedure. These include direct injuries to hollow and solid organs, as well as thermal injury. These can also be minimized by careful and precise technique.
• Complications can be related to placement of the initial trocar or initial creation of pneumoperitoneum. Underlying vessels or viscera can be injured. These injuries can be minimized by the use of open technique for the first trocar placement.
  

Minimal Access Surgery Applications

Minimal Access Surgery Applications in the Foregut

Esophagus

• Heller myotomy can be performed using the thoracoscopic technique.
• Operations of the esophagus are associated with significant morbidity directly related to the thoracotomy or laparotomy. Minimal access surgery (MAS) techniques offer a very good alternative to these morbid procedures.
• Thoracoscopic repair of esophageal atresia and tracheoesophageal fistula has been reported by Rothenberg. Significant technical skills are required in fine suturing of the esophageal anastomosis. In the future robotic surgery may play a role in this procedure.
• Heller myotomy with Dor anterior fundoplication via a laparoscopic approach is ideal for patients with achalasia. Many surgeons are performing this procedure. When the diagnosis is made, some wait until recurrence occurs after a single pneumatic dilatation. An anterior myotomy is performed 4 cm above the gastroesophageal junction and extending onto the stomach for 2 cm. A Dor fundoplication is performed, suturing anterior fundic patch to both edges of the myotomized extra-mucosal incision. Simultaneous upper endoscopy is performed to ensure adequate myotomy.
  

Gastrostomy tube

• MAS-assisted percutaneous endoscopic gastrostomy tube placement assures proper location in the stomach and avoids injury to surrounding structures, particularly the transverse colon.
• In many children internal access with a gastrostomy feeding tube is necessary. Some are unable to swallow, and others take in inadequate calories because of neurologic impairment. Children with cystic fibrosis, malignancies, neurometabolic diseases, and cardiac malformations may also require exogenous internal feeding.
• A MAS technique can be used for this procedure. A mini laparoscope (1.6 mm) with a single 5-mm trocar at the exit site for the gastrostomy button is used, and no special instrumentation or kits are needed.
  

Nissen fundoplication

• In children, a previous gastrostomy tube and contractures in patients with cerebral palsy can create additional technical challenges.
• The morbidity of the surgical procedure, particularly complications, return of feeds, and hospital stays, is reduced with the laparoscopic approach.
• The laparoscopic technique is similar to the open technique and is typically performed with 5 ports, including the camera port. An angled (30° or 45°) scope is used.
• To the adult and pediatric surgeons the indications for and the technique of open surgery are well known. However, laparoscopic fundoplication offers excellent visualization of the hiatus, and after the initial learning curve, it can be expeditiously performed.
• Significant respiratory advantages of an MAS approach to this procedure are recognized, particularly in pediatric patients with mental retardation. Likelihood of extubation following the procedure, time spent in the recovery room, time spent in the ICU, and time spent intubated are all reduced with a MAS approach.
• This procedure can also be combined with gastrostomy feeding tube if necessary.
  

Pyloromyotomy

• The cosmetic results, when compared with the traditional right upper quadrant incisions, are superior.
• Laparoscopic pyloromyotomy is typically performed with 3 stab wounds without trocars. The average operating time is approximately 15 minutes.
• Most (>90%) of the patients are discharged home within 24 hours.
  

Cholecystectomy

• Similar to its adult counterpart, pediatric laparoscopic cholecystectomy is performed with 4 ports, including the camera port. The size of these ports ranges from 2-10 mm.
• This is one of the most common laparoscopic procedures performed in adults. However, because of lower incidence of gallstones it is less common in pediatric patients. Many of the pediatric patients who require this procedure have blood dyscrasias and form pigment stones.
• Laparoscopic cholecystectomy has been shown to be safe, even in an infant (<19 mo).
• Biliary dyskinesia, which is less common than symptomatic biliary colic but is certainly encountered by pediatric surgeons, is aided by a laparoscopic cholecystectomy.
  

Minimal Access Surgery Applications in the Midgut

Small bowel

• Small bowel can be resected if necessary, with intra- or extra-abdominal anastomosis, using the miniature access technique.
• As with the feeding gastrostomy, a jejunostomy tube can be placed laparoscopically.
• Laparoscopy has been used to treat intestinal malrotation, intussusception, adhesiolysis, Meckel diverticulum, and small-bowel atresia.
  

Appendectomy

• Three ports (2-5 mm) are typically used, although single-trocar appendectomy has also been practiced.
• Laparoscopic appendectomy is being performed in increasing numbers throughout the Western world.
• The laparoscopic approach allows better visualization of the rest of the abdominal cavity, allows better irrigation of the peritoneal cavity, and offers a lower wound infection rate.
• Laparoscopic appendectomy is even more useful if diagnosis of appendicitis is in question, especially in girls.
• Laparoscopy in children with chronic abdominal pain is valuable and can often cure patients if they are experiencing chronic appendicitis.
  

Minimal Access Surgery Applications in the Hindgut

Colon

• Laparoscopy offers superb visualization of the pelvic structures, making working in the deep pelvis easier and safer.
• To treat diseases of the entire colon Laparoscopy has been used. Laparoscopy also takes advantage of the excellent collateral blood supply of the colon, which makes mobilizing large segments possible.
• Once the colon is mobilized, it can be resected with intra- or extra-abdominal anastomosis. The specimen can also be removed via the anus, and anastomosis can be performed transanally from the outside.
• Laparoscopic pull-through for Hirschsprung disease is as follows:
  
  • Classically, Hirschsprung disease has been treated by staged procedures involving biopsy, colostomy, pull-through, and colostomy takedown over a period of 6-12 months.
  • However, with the help of MAS, it can be performed as a single-stage procedure in most patients.
  • Laparoscopic pull-through has been shown to be safe in infants as young as 1 week and as small as 2.3 kg.
  • The procedure is carried out with 3-4 small (3.5-5 mm) ports in the mid abdomen. Seromuscular biopsies are taken to check for mature ganglion cells in the proximal colon. The blood supply (inferior mesenteric artery [IMA]) of the distal colon is ligated. The colon is then mobilized down to the levator musculature in girls and the prostate in boys.
  • The dissection is then begun transanally, and colon is removed to the level of biopsy-proven ganglionic cells, and if possible, a 2- to 5-cm margin is created. Anastomosis between the anus and neorectum is performed above the dentate line.
    

Imperforate anus

• The laparoscopic approach is even more attractive because it allows the repair of the defect without laparotomy, without colostomy, and with minimal pain.
• Most surgeons without a colostomy repair a perineal fistula primarily in the newborn period. For all other anorectal defects, most defer to the 3-step approach, consisting of diverting colostomy shortly after birth, the main repair at a later date, and finally, colostomy closure.
• More recently, a trend to repair congenital malformations earlier in life has developed, and an increasing trend to perform primary procedures without a protective colostomy has developed.
• This procedure has particular application to patients with imperforate anus and recto–bladder neck fistula. The rectum can be mobilized off of the bladder with a laparoscopic approach. Long-term results from this approach are not yet available to determine patient's ability to achieve fecal continence.
  

Minimal Access Surgery Applications in Hernia and Other Surgeries

Herniorrhaphy

• Laparoscopic hernia repair has a theoretical advantage with recurrent hernia because the surgical planes have not been previously violated. This avoids the risk of operating through scar tissue and injuring the testicular vessels or the vas deferens. It also has a theoretical advantage in girls because ovaries can be visualized adequately, especially if they are incarcerated.
• Conventionally, hernia surgery in children is performed via high ligation of the hernia sac. This requires incision over the inguinal canal and dissection through the abdominal wall, opening of the inguinal canal, dissection of the cord from the hernia sac, high ligation of the hernia sac, and closure in layers. Assessment of the contra-lateral side can be a diagnostic dilemma with this type of approach.
• Laparoscopic repair has been reported via transabdominal approach. The peritoneal cavity is entered at the level of the umbilicus, and a trocar is placed. The peritoneal cavity is insufflated with carbon dioxide. Two 2-mm trocars are then placed under direct vision slightly superior and medial to the anterior superior iliac spine. Both internal rings are inspected, and direct and indirect hernias are visualized easily. These hernias are repaired, and, if a contra-lateral hernia is visualized, it is also repaired.
• The repair consists of ligating the sac from the inside at the level of the internal ring. Injury to the gonadal vessels and vas deferens should be avoided during the closure of the hernia defect. This repair does not take care of a distal hydrocele.
• With a laparoscopic approach, minimal or no dissection of the cord structure occurs; therefore, the likelihood of injury to the testes is low.
• In females, the laparoscopic inversion ligation herniorrhaphy (LILH), using peritoneal inversion and high ligation, is a technique that is increasingly used.
  

Varicocele

• This procedure is usually performed with 1-3 trocars.
  

Nonpalpable testes

• Once located, intra-abdominal testes can be treated by MAS-assisted orchidopexy.
• MAS techniques must be used if the cryptorchid testis is not palpable in the inguinal canal after induction of anesthesia.
• Laparoscopy allows localization of intra-abdominal testes, identification of absence of testis and presence of canalicular testis. This localization is easily accomplished by following the course of vas and testicular vessels.
• The nonpalpable testes are usually found between the internal ring and the external iliac vessels.
  

Ovarian pathology

• Patients do extremely well and are able to return to their preoperative activity sooner.
• In teenage girls with abdominal pain, diagnostic laparoscopy is invaluable.
• Laparoscopy has been used successfully to manage a wide variety of gynecologic problems, including tubal torsion, adnexal torsion, and oophorectomy.
• It can be performed easily with 2-3 ports and provides excellent operative view.
  

Minimal Access Surgery Applications in Solid Organs

Splenectomy

• Patients do extremely well postoperatively, and most are able to return home within 48 hours.
• Indications for laparoscopic splenectomy are the same as they are for open procedure unless malignancy is suspected.
• Laparoscopic approach offers a much-improved view without an extensive incision. Most of the dissection has been facilitated by development of better energy modalities and improved stapling devices.
• Patients are usually placed in a supine position or in a 45° right lateral decubitus position. Typically, 4-5 trocars of varying sizes (5-12 mm) are used.
• The spleen is placed in a bag, which is exteriorized and removed after breaking it with a finger or sponge stick.
• Splenopexy has been performed for a wandering spleen in a 2-year-old girl.
• Partial splenectomy, splenopexy for wandering spleen, and splenic cyst excision all have been reported.
  

Nephrectomy

• Transperitoneal or retroperitoneal approaches have been used.
• This approach can be used for renal biopsy, nephrectomy, heminephrectomy, nephroureterectomies, nephropexy, adrenalectomy, and pyeloplasty.
• The retroperitoneal approach completely avoids the peritoneum, thereby decreasing the related complications. The incidence of postoperative ileus and postoperative adhesions are also avoided. It is also ideal in patients who have had previous abdominal surgeries.
• The retroperitoneum is dissected using balloon, saline, finger, or direct vision. Angled scopes provide a much better view because of the limited operational space. This approach is limited in small children.
• Laparoscopic donor nephrectomy has improved the operation for the donor and has increased the use of the living related renal transplantation.
  

Adrenalectomy

• The MAS approach can be transperitoneal or retroperitoneal. MAS offer an excellent view of the surgical anatomy and the vasculature.
• The MAS approach can be applied to adrenal tumors, such as pheochromocytoma, and incidentally found adrenal masses.
• This approach is similar to the laparoscopic nephrectomy.
  

Minimal Access Surgery Applications in the Thorax
Thoracoscopy

• Patients are placed in a lateral position with the operative side up, as in the open technique. Three trocars are used in most cases.
• Thoracoscopy is safe and effective, even in infants weighing less than 1.5 kg, without significant morbidity or mortality.
• Thoracoscopy is useful for the following:
  
  • Diaphragm plication
  • Assessment or resection of mediastinal or lung masses
  • Pericardial drainage
  • Lung biopsies
  • Tumor biopsies
  • Closure of patent ductus arteriosus
  • Vascular rings
  • Resection of subpleural blebs
  • Pleurodesis
  • Drainage of empyema
    

看起来真困难。