24 – Anesthesia for Intra-Abdominal Procedures




24 Anesthesia for Intra-Abdominal Procedures


Raymond Park and Edward Cooper



Introduction


Abdominal procedures constitute a large percentage of operating room cases in the neonatal and infant population. Therefore, it is vital for anesthesiologists caring for pediatric patients to be knowledgeable regarding general surgical conditions common to this specific patient population, as well as their typical presentation, associated comorbidities and perioperative management strategies. Patients presenting for surgery often have associated syndromes or genetic abnormalities that predispose them to abdominal complications, and the anesthesiologist should be cognizant of the other associated systemic manifestations of the underlying disease.


Foremost among the considerations in evaluating patients presenting for intra-abdominal surgery is the potential for either altered or frankly obstructed gastrointestinal emptying. In children, there are currently no noninvasive methods to reliably discriminate patients with full stomachs from those with relatively intact gastric emptying. Therefore, common practice is to assume that the patient is at high risk for aspiration during induction and emergence, unless actively tolerating oral feeding without complications. Rapid sequence induction should be considered, though with this approach neonates and infants may develop hypoxemia during the time period needed for adequate muscle relaxation due to their higher baseline oxygen consumption (>5 ml kg–1 min–1 vs. 2–3 ml kg–1 min–1 in adults) and decreased apneic functional residual capacity compared with adults [1,2]. Due to these considerations, many practitioners choose to utilize a modified rapid sequence induction with cricoid pressure and low-pressure mask ventilation prior to intubation. Though use of a modified rapid sequence technique can mitigate risk of hypoxia during induction, application of cricoid pressure can potentially obscure airway anatomy and hinder mask ventilation. Despite these precautions, judicious mask ventilation with pressures as low as 10 cmH2O has still been shown to result in gastric insufflation, though applying cricoid pressure can increase this threshold [35]. Additionally, use of a nasogastric tube, placed prior to induction, can be used to decompress the stomach. The potential benefit of this maneuver must be weighed against the possibility that the stomach may still not be fully empty and the possibility of additional patient agitation. Though studies in infant and adult cadavers demonstrated effective esophageal occlusion with cricoid pressure of up to 100 cmH2O in the presence of a nasogastric tube, concerns with leaving a nasogastric tube in place during induction include potentially interfering with esophageal sphincter function and serving as a “wick” for regurgitant contents [6,7]. Consequently, if a nasogastric tube is placed for gastric evacuation, whether it should be removed prior to induction is not clear.


In addition to addressing the direct anatomical and surgical concerns of intra-abdominal injury, the pediatric anesthesiologist must be acutely aware of and thoroughly investigate the potential systemic manifestations of abdominal pathology. Patients will often have signs consistent with sepsis and capillary leak syndrome pre-, post-, and intraoperatively secondary to underlying bowel ischemia or perforation. These patients will often require aggressive fluid resuscitation and will occasionally require the use of vasoactive medications when vasoplegia is present. Perioperative management can also be complicated by florid intra-abdominal inflammation and fluid retention, leading to abdominal compartment syndrome. Depending on the degree of abdominal swelling and concerns for postoperative abdominal compartment syndrome, abdominal closure may not be immediately possible or advisable at the end of the procedure. Airway edema secondary to rapid fluid administration, ongoing hemodynamic instability, and unfavorable acid–base status may preclude safe extubation and result in subsequent difficulty with ventilation. These concerns coupled with increased relative evaporative losses in the neonate with an open abdomen can make these cases particularly challenging from a fluid management perspective. Regional anesthetics for postoperative analgesia such as epidural, caudal, and transversus abdominis plane catheters can be considered, but expected duration of postoperative ventilation, future and present coagulation status, and risk of postoperative infection should be considered prior to placement.


Increasingly, many intra-abdominal procedures are being performed laparoscopically, and understanding the physiological changes that occur with abdominal insufflation is important. Carbon dioxide is the preferred gas for laparoscopy due to the fact that it is not readily flammable, clears quickly from the peritoneum, and does not expand within closed spaces. Carbon dioxide is readily absorbed across the peritoneum and necessitates an increase in minute ventilation to maintain normocapnia. The insufflated abdomen can lead to cephalad displacement of the diaphragmatic, to compression of dependent lung areas and to subsequent V/Q mismatch and hypoxemia. Higher airway driving pressures may be needed to compensate for reduced pulmonary and thoracic compliance with laparoscopy [8]. Hemodynamically, higher insufflation pressures can lead to reduction in cardiac output [9,10]. If insufflation pressures exceed venous pressure in the setting of open abdominal venous channels, clinically significant carbon dioxide embolism can occur [11]. Intracranial pressure can be increased by a combination of increased abdominal pressure, hypercarbia, and head-down positioning, and therefore the risks and benefits of laparoscopy should be carefully considered in patients with elevated intracranial pressure or an existing ventriculoperitoneal shunt [12,13].



Specific Conditions



Gastrointestinal Duplications


Gastrointestinal duplications are rare congenital lesions that occur in approximately 1 in 4500 live births [14]. Duplications have been described at all points along the gastrointestinal tract as proximally as the mouth and as distal as the anus. The etiology of gastrointestinal duplications is unclear, but they are thought to occur between four and eight weeks during embryonic development. Existing theories to explain their occurrence include errors in recanalization of the primitive intestine, failure of regression of embryonic diverticuli, and errors of notochord splitting [15,16]. Gastrointestinal duplications can either occur as an isolated occurrence or involve multiple locations. Duplications generally do not communicate with adjacent gastrointestinal structures, though this is not universally the case. Similar to the case of many congenital malformations, there are often associated systemic abnormalities that should be identified and evaluated [17,18].


With the advent of and improvements in prenatal imaging, most gastrointestinal duplications are detected in utero and have in only rare instances required fetal intervention. Most pediatric surgeons advocate resection of the duplication, though for asymptomatic patients the optimal timing of surgery remains unclear, and presently there are no concrete data to aid in guiding practice [14]. Patients who develop sequelae of duplications usually do so in the context of secretions that accumulate in noncommunicating and closed space duplications, leading to pain and compression of adjacent structures. Such developments are of particular concern when the compression of adjacent vasculature leads to bowel ischemia. The duplication can also serve as a lead point for the bowel to telescope around surrounding intestinal segments, leading to intussusception. Ulcerations resulting in bleeding can occur in the duplication itself secondary to ectopic gastric tissue or in adjacent tissue [19].


Anesthetic considerations for gastrointestinal duplications include localization of the duplication, identification of any associated abnormalities, and the clinical manifestations of the duplication. Potential for airway obstruction may require the use of rigid bronchoscopy, and bowel obstruction will mandate full stomach precautions.



Pyloric Stenosis


Pyloric stenosis is a relatively common condition requiring surgical intervention in infants and occurring in approximately 2–5 out of 1000 live births [20]. The etiology of pyloric stenosis is not entirely clear, though likely multifactorial. The condition occurs four times more commonly in males than in females and has a higher prevalence in first-born children [21]. Unlike many other gastrointestinal abnormalities, patients with pyloric stenosis are otherwise generally healthy, though a familial genetic predisposition is observed.


The pathological finding in pyloric stenosis is hypertrophy of the muscularis layer of the pyloric sphincter, leading to gastric outlet obstruction. Patients typically present with immediate, nonbilious, nonbloody, postprandial projectile vomiting at the age of 3–12 weeks [22] that often increases with intensity over time. The severity of dehydration and electrolyte abnormalities generally correlates with the degree and duration of symptoms prior to presentation [23]. In general, patients will present with a chloride-sensitive, hypochloremic, hypokalemic, metabolic alkalosis with some degree of hyponatremia secondary to volume depletion and paradoxical aciduria. However, if there is longstanding volume loss without correction, patients can present with metabolic acidosis as a result of both lactic acidosis and renal dysfunction.


Pyloric stenosis can often be diagnosed by history alone, but supporting physical exam findings include an olive-shaped mass in the right upper quadrant. Diagnosis is typically confirmed with an abdominal ultrasound, though barium studies have also been utilized [24].


Pyloric stenosis is not a surgical emergency, though definitive treatment is surgical pyloromyotomy, which can often be performed laparoscopically. Prior to surgical intervention, acid–base status and electrolyte abnormalities should be corrected. Patients with persistent or untreated metabolic alkalosis are at increased risk of postoperative apnea [25]. Metabolic alkalosis is often corrected after hospital admission and preoperatively with saline administration that corrects volume status, replenishes total-body sodium and chloride, and promotes excretion of urine bicarbonate. Secondary to dehydration, patients may present with renal insufficiency, and potassium repletion should be initiated only with the establishment of urine output. Serum chloride concentration can be followed to gauge the adequacy of rehydration and correction of the underlying metabolic alkalosis. Studies by Goh et al. and Shanbhogue et al. demonstrated that a serum chloride concentration greater than 106 meq L–1 predicts correction of alkalosis in the majority of patients with pyloric stenosis [26,27].


Due to functional gastric outlet obstruction, patients with pyloric stenosis are at high risk for aspiration during induction. The stomach should be emptied with a large-bore orogastric tube, sometimes with several passes, prior to induction. This does not necessarily guarantee an empty stomach. The airway should be secured by means of a (modified or standard) rapid sequence induction or awake intubation. Anesthesia can be maintained with nondepolarizing neuromuscular blockade and volatile anesthetics, though Davis et al. showed decreased postoperative respiratory events with the use of a remifentanil-based anesthetic [28]. For longer cases, a dextrose infusion should be started. Surgeons may ask that an orogastric tube be used to insufflate the stomach to rule-out luminal perforation following repair. Adequate analgesia can generally be obtained with rectal or intravenous acetaminophen combined with local anesthetic via caudal block or local infiltration by the surgeon. Sparing use of intermediate and long-acting opioids is advocated. The patient should be awake and vigorous at the end of the case prior to extubation. In addition to remaining metabolic alkalosis, hypothermia, hypoglycemia, residual neuromuscular blockade, and previous opioid administration can all further increase the risk of postoperative apnea, and every attempt should be made to avoid these conditions [21,29].



Necrotizing Enterocolitis


Necrotizing enterocolitis (NEC) is characterized by ischemic necrosis of the intestinal mucosa, leading to gut translocation of enteric organisms and to potential local and systemic complications. Necrotizing enterocolitis occurs in approximately 1 out of 1000 live births, is inversely related to birth weight and rarely occurs spontaneously in full-term neonates unless associated with predisposing conditions, such as congenital heart disease, sepsis, or hypotension, that lead to compromise of intestinal blood flow [30,31]. Mortality from NEC is 15–30 percent, and survivors often suffer from long-term sequelae such as short-gut syndrome, parenteral nutrition dependence, and growth and neurodevelopment deficits [30,32].


Necrotizing enterocolitis classically develops in the second to third week of life after the initiation of feeding, though it can develop in patients prior to initiation of feeding and has been rarely observed in patients who have tolerated feeding for a significant length of time. NEC often initially presents with constitutional symptoms such as lethargy, temperature instability, hypotension, and apnea in conjunction with or followed by gastrointestinal symptoms such as feeding intolerance, emesis, abdominal distention, or bloody stool. As the disease progresses, worsening abdominal distention, increased abdominal tympany, palpable bowel loops, and periumbilical abdominal wall erythema and ecchymosis can develop. Imaging studies can help to confirm diagnosis, although NEC is a clinical diagnosis and radiographic findings are not always appreciated. Findings that are highly suspicious for NEC include pneumatosis intestinalis, pneumoperitoneum, and evidence of air within the portal system. Patients may concurrently experience deterioration of other organ systems by avenues such as hematologic abnormalities (disseminated intravascular coagulation, thrombocytopenia, coagulopathy), metabolic acidosis, respiratory failure, and septic shock.


Initial management includes supportive measures such as bowel rest, nasogastric tube decompression, broad-spectrum antibiotics, and hemodynamic and respiratory support if necessary. Medical management is continued with serial monitoring of abdominal exam and radiographic studies. If there is high suspicion or frank evidence of intestinal perforation, surgical intervention is indicated and includes laparotomy with resection of affected bowel segments and/or bedside peritoneal drainage. Between 20 and 40 percent of NEC cases require surgical intervention [31,33], with Guthrie et al. showing a mortality rate of 23 percent for surgical NEC patients compared with 4 percent for medically managed NEC patients [33].


Patients who present requiring surgical treatment will often have multi-organ dysfunction that will complicate perioperative management. Existing hematologic abnormalities may require ongoing treatment with appropriate blood component therapy. Hypotension secondary to intravascular volume depletion and septic vasoplegia is common in the presence of intra-abdominal fluid sequestration and distributive shock. Consequently, the patient may require additional or initiation of vasoactive infusions and continued fluid administration to maintain blood pressure. A primarily narcotic-based anesthetic may be better tolerated from a hemodynamic perspective than one that utilizes higher concentrations of volatile anesthetics. In addition, delivery of volatile agents may be limited if an ICU ventilator is utilized for transport and better control and monitoring of respiratory parameters. If the airway is not already secured, consideration should be given to a rapid sequence induction or to an awake intubation. Venous access should take into account the likely need for administration of large amounts of volume and vasopressor therapy. Obtaining arterial access for hemodynamic monitoring and blood sampling is optimal but should not unduly delay definitive surgical treatment in a clinically deteriorating patient.



Meconium Ileus


Meconium ileus (MI) is characterized by bowel obstruction, generally at the level of the terminal ileum and ileocecal valve secondary to accumulation and failure of passage of thick, desiccated meconium. Patients with cystic fibrosis (CF) in particular have a propensity to develop MI due to secretion of highly viscous meconium that adheres to the intestinal lumen. Twenty percent of CF patients who develop MI represent 80–90 percent of the total MI cases [34,35]. Meconium ileus is categorized as simple or complex. Simple MI presents clinically with abdominal distention, failure to pass meconium and, in some cases, emesis. Roughly 50 percent of cases of MI are classified as complex. Meconium ileus is classified as complex if there is associated gastrointestinal pathology such as perforation, peritonitis, atresia, or volvulus. Volvulus and other ischemic insults that occur in utero may manifest postnatally as bowel atresia. Simple MI is treated with nasogastric decompression, correction of any fluid or electrolyte abnormalities, and administration of serial hyperosmolar enemas [36]. Repeat enema administration is common but increases the risk of perforation and other complications with each additional attempt [37,38]. Simple MI that is refractory to more conservative medical management requires surgical intervention.


Preparation for the operating room should identify and initiate correction of electrolyte abnormalities and volume depletion as a result of potential dehydration, hyperosmolar enema therapy, or fluid shifts associated with bowel injury or obstruction. In CF patients, the lung pathology is generally not a concern until after several years of life [39], unless the clinical presentation is associated with previous aspiration or secondary lung injury due to sepsis or systemic inflammatory response syndrome. Stomach contents should be decompressed with an orogastric tube prior to induction to minimize the risk of aspiration during anesthetic induction. Rapid sequence induction or awake intubation with local anesthetic should be employed to secure the airway. Anesthetic can be maintained with neuromuscular blockade and, depending on hemodynamic status, with volatile versus an opioid-based anesthetic. Vasoactive infusions should be readily available to treat potential hypotension.



Malrotation


Malrotation results from in utero arrest of normal rotation of the embryonic gut, leading to narrowing of the mesenteric base and to a predisposition to mesenteric twisting and consequent volvulus. With malrotation, there can also be abnormal attachments, known as Ladd’s bands, that form in the process of attempting to affix the bowel in the peritoneal cavity and that can lead to duodenal obstruction. Symptomatic malrotation occurs in approximately 1 in 5000 live births [40], and 50–70 percent of cases are associated with other congenital abnormalities. Gastrointestinal anomalies are most common, though cardiac, orthopedic, and central nervous system anomalies also frequently occur [41,42]. Intestinal atresia can be seen in cases in which malrotation occurs in utero during bowel development. In children with malrotation requiring surgery, up to 65 percent present during the first month of life [42].


Patients with malrotation can clinically present with either volvulus or nonischemic intestinal obstruction due to Ladd’s bands or atretic bowel. Patients with volvulus present with bilious emesis, symptoms of bowel obstruction, and potentially an acute abdomen. Grossly bloody stool can also be seen and usually indicates a more severe presentation with significant bowel ischemia. Diagnosis of malrotation in a clinically stable patient can be made radiographically with plain film or fluoroscopic upper gastrointestinal series with small-bowel follow-through or an abdominal ultrasound to determine the relative orientation of mesenteric vessels [43].


A patient with suspected or confirmed volvulus requires prompt surgical treatment to salvage affected bowel segments. Because volvulus is a surgical emergency, every effort should be made to safely proceed as quickly as possible to surgery with the goal of saving any viable bowel. The airway should be secured using full-stomach precautions. Arterial access can be obtained as needed, though doing so should not delay surgery and relief of ischemic bowel. As with many other ischemic abdominal pathologies, patients may present with a combination of intravascular depletion due to intra-abdominal inflammation and swelling along with vasodilation from sepsis. Treatment for hypotension may therefore require both fluid and blood component therapy in addition to vasoactive infusions. In cases in which abdominal compartment syndrome is present, concern should be exercised upon surgical decompression of the peritoneal cavity. With the relief of elevated abdominal pressures, subsequent systemic washout of lactate and products of cell ischemia, such as potassium, can result in rapid clinical deterioration.



Intestinal Atresia


Intestinal atresia is the complete congenital obstruction of the lumen of a hollow viscus. Intestinal atresia can occur at any point of the intestinal tract, with the small intestine being the most common site of pathology. Of the cases of small-bowel atresia, the majority occur within the jejunum and ileum. The atresia can also be present in the large bowel, though these cases constitute only 7–10 percent of all cases of intestinal atresia [44].


Intestinal atresia is classified into types I–IV using the following definitions:




  • Type I: Intact muscularis and serosa, with the lumen obstructed by an intact diaphragm or membrane.



  • Type II: Obvious gap in bowel with the proximal and distal segments connected by a fibrous band.



  • Type III:




    1. a. Obvious gap in bowel with no connection between proximal and distal segments.



    2. b. Proximal small-bowel atresia, absence of mid-small bowel that would normally be supplied by the superior mesenteric artery and a large gap in small-bowel mesentery.



  • Type IV: Multiple II or IIIA atresias.


In many cases, intestinal atresia can be diagnosed prenatally and is often accompanied by polyhydraminios. Patients with intestinal atresia present with abdominal distention, emesis, and failure to pass meconium. With bowel obstruction, there can be increased enterohepatic circulation of bilirubin and resultant jaundice. Patients with partial obstruction or stenosis will often present later than those with complete intestinal atresia. Diagnosis should exclude other intra-abdominal pathologies, and additional radiographic studies can help to confirm the diagnosis, particularly plain film or fluoroscopy with and without contrast imaging.


Patients with duodenal atresia should be screened for other associated abnormalities, with particular attention to the heart, kidneys, spine, and hepatobiliary system. There are associated chromosomal abnormalities in approximately 30 percent of cases of duodenal atresia, most often trisomy 21 [45]. Though the majority of patients with jejunal and ileal atresia are otherwise healthy, it can be associated with coexisting disease such as CF, gastroschisis, and, less commonly, omphalocele [44]. Patients with CF are predisposed to develop in utero bowel ischemia due to volvulus or perforation; the resultant necrotic bowel is resorbed, leaving behind an atretic segment of gut. Patients with colonic atresia are generally healthy, though they can also be affected with pathology such as gastroschisis and Hirschsprung’s disease (HD) [44].


Initial management of intestinal atresia involves discontinuation of feeding, decompression with a nasogastric tube, and correction of fluid and electrolyte abnormalities. Patients with duodenal atresia should be evaluated for possible comorbidities, while those with jejunal or ileal atresia should be tested for CF.


Emergent surgery for intestinal atresia is generally not indicated, and clinical stability should be established and further evaluation of potential associated abnormalities should be completed prior to bringing the patient to the operating room. Patients with intestinal atresia by definition have a full stomach, and appropriate measures should be taken during anesthetic induction to minimize risk of aspiration. Adequate peripheral intravenous access should be obtained and an arterial line placed if needed in the setting of associated cardiac abnormalities.



Hirschsprung’s Disease and Anorectal Malformations


Hirschsprung’s disease results from failure of neural crest cells to migrate during intestinal development, leading to a segment of aganglionic colon and, in approximately 7–10 percent of cases, to complete involvement of the colon, resulting in depressed gut motility [46,47]. In rare cases of HD, the entire colon and a portion of the small bowel may also be affected. Males are disproportionately affected, with a male:female gender ratio of 3–4:1 cases [48]. Multiple specific genetic mutations are associated with HD. Furthermore, HD is often associated with chromosomal abnormalities and monogenic syndromes [49].


The majority of cases of HD are diagnosed in the neonatal period when affected individuals develop symptoms of distal intestinal obstruction such as vomiting, abdominal distention, and the failure to pass meconium and stool within the first 48 hours of life. Older patients typically present with symptoms of chronic constipation, failure to thrive, and abdominal distention. Hirschsprung’s disease patients can also present acutely with enterocolitis, toxic megacolon, and associated sepsis, fever, and abdominal distention [50]. Rarely, volvulus can also occur in patients with HD due to twisting of feces or meconium-filled, enlarged bowel segments.


Patients with enterocolitis may require immediate surgical intervention, though it is preferable to stabilize the patient and obtain a definitive diagnosis of HD prior to surgery and then proceed with a single-stage definitive surgery rather than with a diverting colostomy and the need for a later pull-through procedure. Stable patients with suspected HD should undergo an appropriate diagnostic workup consisting of a rectal suction biopsy, though abdominal radiographs, contrast enemas, and anorectal manometry have all been used to provide supportive diagnostic information. Definitive treatment for HD involves surgical resection of affected bowel segments with an anal sphincter-preserving re-anastomosis of normal ganglionic bowel. Even after definitive surgical treatment for HD, patients can present later with enterocolitis [39,49].


Patients with HD presenting for surgery should be carefully evaluated for comorbid disease and syndromes that could potentially impact anesthetic management. Anesthetic induction should take into account the degree of abdominal obstruction. Patients with HD enterocolitis may require aggressive fluid resuscitation, vasoconstrictive drug infusions such as dopamine, and arterial access for monitoring of hemodynamics and metabolic status. Pull-through procedures may require lithotomy positioning, which can limit placement of intravenous catheters to the upper extremities and in rare cases has been associated with complications such as lower extremity compartment syndrome.


A similar surgical condition that the pediatric anesthesiologist may need to treat is anorectal malformations. Anorectal anomalies manifest with a wide spectrum of severity and have an incidence rate of 1 in 2500–4000 live births [51,52]. These anomalies arise from failure of normal development of the cloaca into the urogenital and rectal structures [53]. Consequently, the correction of these congenital defects will often require a multidisciplinary surgical approach.


Presurgical planning is centered on definitively defining the anatomy and identifying associated defects that may require more immediate treatment. Pre-procedure studies should include evaluation of the heart, kidney, urinary collection system, spine, and remainder of the GI tract [54]. Surgical approach will be dependent on the nature of the anomaly and on whether it is amenable to repair via a simple anoplasty, pull-through, or temporizing staged colostomy. Given the often elective nature of these procedures, anesthetic concerns similar to those entertained in HD should be considered. After corrective surgery, postoperative course often requires serial dilations that may also require the services of an anesthesiologist.



Intussuseption


Intussuseption is the invagination of one segment of intestine into another, leading to compromised lymphatic and venous drainage. Eighty-five percent of patients with intussuseption are under three years of age [55] and are generally otherwise healthy. Intussuseption is the most common cause of intestinal obstruction in the pediatric population. The site of intussuseption is often in close proximity to the ileocecal junction, though bowel segments in both the large and small intestines can be affected. If left untreated, intussuseption results in progressive bowel edema, ischemia, and possible perforation. Though the majority of cases of intussuseption have no clear etiology, commonly associated predispositions include viral illness, viral or bacterial enteritis, and identifiable “lead points” for intussuseption such as Meckel’s diverticulum, lymphoma, duplication cysts, inflamed Peyer’s patches with concurrent Henoch–Schonlein purpura, and vascular malformations [39].


Patients with intussuseption present with sudden intermittent cramps, severe paraoxysmal colicky abdominal pain, and progressive lethargy often out of proportion to abdominal exam. The classic presentation of pain, a palpable sausage-shaped mass, and currant jelly stool is observed only in a minority of patients [56]. Abdominal plain film can be suggestive of intussuseption, but abdominal ultrasound is generally the preferred modality of diagnosis [56], though computed tomography (CT) can be helpful if prior workup has been unrevealing.


Surgical intervention is indicated for patients with evidence of perforation. Otherwise, patients should be stabilized with intravenous fluids and decompression with a nasogastric tube and reduction attempted with hydrostatic or pneumatic enema. Nonoperative reduction has a success rate of 80–95 percent and can be repeated, but does carry a 1 percent risk of perforation [57] and a recurrence rate of 5–7 percent [58]. Surgical intervention is necessary if nonoperative intervention is not successful or results in perforation.


Anesthesiologists may be asked to provide anesthesia or sedation during nonoperative or surgical reduction. Patient with intussuseption should be considered to have full stomachs, and appropriate precautions should be taken during anesthetic induction. Similar to considerations for other intra-abdominal surgical emergencies, intravenous access, hemodynamic monitoring, and need for vasoactive medications and fluid resuscitation will be contingent on the severity of clinical presentation.



Biliary Atresia


Infants born with biliary atresia (BA) are most often treated with a hepatoportoenterostomy or Kasai procedure that allows for bile drainage from small bile ducts into the small intestine. There are three common types of BA: type 1 – atresia restricted to the common bile duct; type 2 – atresia of the common hepatic duct; type 3 – atresia of the right and left hepatic duct. If the Kasai procedure is performed in the first two months of life, greater than 80 percent of infants will achieve some bile drainage, although a majority of these eventually will require a liver transplant.


A hepatoportoenterostomy or Kasai portoenterostomy is a surgical treatment performed on infants with biliary atresia to allow for bile drainage. In these infants, the bile is not able to drain normally from the small bile ducts within the liver into the larger bile ducts that connect to the gall bladder and small intestine.


The surgery involves exposing the porta hepatis (the area of the liver from which bile should drain) and attaching part of the small intestine to the exposed liver surface. The rationale for this approach is that minute residual bile duct remnants may be present in the fibrous tissue of the porta hepatis and thus provide direct connection with the intrahepatic ductule system to allow bile drainage [1].



Prognosis




  • If performed before 60 days of age, 80 percent of children achieve some bile drainage.



  • Prognosis is progressively worse the later surgery is done.



  • Postoperatively, cholangitis and malabsorption are common.



  • Many children with biliary atresia will require liver transplantation despite the attempted surgical repair.



  • In type I, atresia is limited to the common bile duct, and the gallbladder and hepatic ducts are patent (i.e., “distal” BA). In type II, atresia affects the hepatic duct, but the proximal intrahepatic ducts are patent (i.e., “proximal” BA). Type II is subgrouped in type IIa, where a patent gallbladder and patent common bile duct are present (sometimes with a cyst in the hilum, i.e., “cystic BA”), and in type IIb, where the gallbladder as well as the cystic duct and common bile duct are also obliterated. In type III, there is discontinuity of not only the right and left intrahepatic hepatic ducts, but also of the entire extrahepatic biliary tree (i.e., “complete” BA). The French classification is similar, but the designation of the above types IIa and IIb as types 2 and 3 results in a total of four types [3].



  • Most often, BA is complete (Japanese/Anglo-Saxon type III, 73 percent) or subcomplete (type IIb, 18 percent), with “cystic” BA and “distal” BA being infrequent (types IIa and I, 6 percent and 3 percent, respectively) [4].




References


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