Disorders and Diseases of the Gastrointestinal Tract and Liver

Chapter 86 Disorders and Diseases of the Gastrointestinal Tract and Liver



Scottie B. Day, Samuel A. Kocoshis



Pearls



• So much reliance is placed on electronic monitoring of patients that physicians are often tempted to perform only a cursory examination or go days without laying hands on the patient. Regrettably, adopting such an approach deprives the clinician of an adequate perspective on the patient’s day-to-day condition and deprives the patient of optimal care.

• When compared with a scintiscan of the lungs after administration of a radiolabeled meal or with the discovery of lipid-laden macrophages after bronchoalveolar lavage, the use of colorants is notoriously inaccurate.

• Several antireflux barriers exist in the region of the lower esophageal sphincter. Beyond intrinsic myogenic tone, barriers such as the cardioesophageal angle, the abdominal esophagus (which acts as flutter valve), the mucosal rosette of the sphincter (which acts as a choke valve), and the diaphragmatic crura themselves act to prevent reflux of gastric contents.

• The association between Helicobacter pylori infection and both chronic gastritis and duodenal ulcer is well established, but the role of H. pylori in the pathogenesis of gastric ulceration remains somewhat speculative.

• Intravenous administration of somatostatin or its synthetic analogue, the active octreotide moiety, has been effective in stemming variceal hemorrhage and may work for other causes of bleeding. In addition to their hemodynamic effects, they inhibit gastric acid production.

• Crohn’s disease and ulcerative colitis are chronic, relapsing disorders without known causes. The transmural inflammation of Crohn’s disease may affect any portion of the alimentary tract in a patchy distribution, whereas the inflammation of ulcerative colitis is confined to the mucosa of the colon.

• The diagnosis of necrotizing enterocolitis may be confirmed by an abdominal plain film showing pneumatosis intestinalis, hepatic portal air, or both. A random breath hydrogen/carbon dioxide ratio greater than 8 ppm/mm Hg strongly suggests the diagnosis. Because the pathogenesis is unknown, treatment must be symptomatic. In most centers, feedings are discontinued for 48 hours to 2 weeks depending on the severity of symptoms. Fluid resuscitation and broad-spectrum parenteral antibiotics are the basis of medical therapy. Surgical resection is reserved for severe cases when medical management fails and gangrenous bowel develops.

• Abdominal compartment hypertension and sydrome are two distinct entities becoming increasingly recognized in the intensive care setting. Prompt recognition of clinical symptoms and signs may prevent vital organ compromise.


Gastrointestinal Evaluation of the Critically Ill Child


Dramatic advances in pediatric critical care have resulted in improved outcomes for children admitted to pediatric intensive care units (PICUs). Indeed, the improved technology available today has resulted in improved management strategies for a variety of conditions. So much reliance is placed on electronic monitoring of patients that physicians are often tempted to perform only a cursory examination or go days without laying hands on the patient. Regrettably, adopting such an approach deprives the clinician of an adequate perspective on the patient’s day-to-day condition and deprives the patient of optimal care. Daily physical examination is of paramount importance in the assessment of children with either life-threatening gastrointestinal disease or gastrointestinal manifestations of multisystem disease. The current approach to gastroenterologic diagnosis and therapy as well as principles of gastroenterologic physical examination are therefore reviewed in this chapter.



Abdominal Examination


Astute clinicians recognize that the abdomen extends from “the neck to the knees.” A thorough examination of the head, neck, and chest is essential when patients with abdominal symptoms are evaluated. For example, pneumonia may be discovered by chest auscultation in the child who has abdominal pain. All too often, a child whose abdominal symptoms are due to pneumonia undergoes exploratory laparotomy for a purportedly “surgical” abdomen.


The abdominal examination, which can be difficult to perform on young children without life-threatening illness, is made more difficult in the ICU setting. Pain and fear limit cooperation. Patients who are obtunded by narcotics, sedatives, or an underlying central nervous system (CNS) disorder display inconsistent responses to abdominal palpation. Neuromuscular blockade abolishes abdominal guarding. Children with multisystem trauma may not localize pain. These impediments notwithstanding, the observant clinician can glean a great deal of information from a carefully performed examination. Simple inspection of the child’s abdomen can reveal generalized distention; abnormally prominent abdominal wall veins (which signify portal hypertension); or anterior and lateral abdominal wall ecchymoses, such as Cullen’s sign or Grey Turner’s sign (which herald acute pancreatitis). In addition, because of the child’s relatively undeveloped abdominal musculature, visceromegaly or abdominal masses may be apparent on inspection.


Auscultation will ascertain the frequency and quality of peristaltic sounds. They normally occur every 10 to 30 seconds and are low pitched. High-pitched, frequent bowel sounds suggest enteritis or obstruction. In obstruction, bowel sounds characteristically reverberate and seem to originate “from a deep well.” Bowel sounds are absent in paralytic ileus or peritonitis. Ancillary findings include venous hums, which suggest portal obstruction, or bruits that may denote arteriovenous malformations.


In pediatric patients, palpation should generally precede percussion because it is less threatening. The child should be in the supine position, and when possible the hips and knees should be comfortably flexed to enhance abdominal wall relaxation. The abdomen should be palpated through all phases of respiration in all four quadrants. The examiner should lightly palpate to judge guarding and tenderness and should use gentle ballottement. Deeper palpation better localizes organomegaly or masses.


Percussion permits estimation of visceral size and helps to diagnose obstruction, peritonitis, or ascites. Excessive tympany implies that bowel loops are distended with air, whereas dullness suggests that excessive fluid or a solid mass is present. Shifting dullness is relatively easy to detect in cooperative children with percussion of the abdomen with the child in the supine, left lateral, and right lateral positions. When the child with ascites is in the supine position, dullness is found primarily over the flanks. The dullness moves to a new level nearer the midline when the child is moved to each lateral position. It is essential to perform a digital examination of the rectum in children with gastrointestinal dysfunction. Inspection of the perineum may reveal perianal or perirectal abscesses, which may be the first sign of acute leukemia, chronic granulomatous disease of childhood, or Crohn’s disease. Similarly, deep fissures or sentinel piles suggest ulcerative colitis or Crohn’s disease, and hemorrhoids can be found in portal hypertension. The digital examination should be performed in the alert, older child only after its purpose is explained. Any material that returns on the examining finger should be evaluated for occult blood. Absence of stool in the vault can corroborate Hirschsprung’s disease in an infant with abdominal distention and a history of obstipation. Rectal masses related to pelvic abscesses or tumors may be digitally palpated. Rectal tenderness signifies mural or extramural inflammation or infection.



Gastrointestinal Endoscopy


The development of flexible fiberoptic endoscopes appropriately sized for use in infants and children has greatly expanded the value of endoscopy in diagnosing and treating a variety of gastroenterologic disorders in critically ill pediatric patients. For example, pediatric endoscopes with an outside diameter of 5 mm can now be used for diagnostic purposes in newborn infants. Electrocautery, injection therapy, or variceal banding of gastrointestinal bleeding sites can also be performed with devices that now fit within the biopsy channels of a standard 9.4-mm pediatric endoscope. Upper gastrointestinal endoscopy (esophagogastroduodenoscopy [EGD]) is performed most often with the child under deep sedation or general anesthesia, although some clinicians report successful unsedated upper endoscopy in very young infants. Many pediatric endoscopists in North America use a combination of narcotic sedative and benzodiazepine to achieve acceptable sedation analgesia.1 Other agents commonly used for sedation are propofol and ketamine. General anesthesia with endotracheal intubation is appropriate when the side effects of sedation or the endoscopy pose an undue risk of respiratory compromise (e.g., when underlying pulmonary disease, upper airway disease, or disorders of respiratory control are present) or if the patient is at risk for aspiration of gastric contents (e.g., when massive upper gastrointestinal hemorrhage is present or when an emergency foreign body extraction is performed on a child with a full stomach). In an ICU setting, patients supported by ventilators should receive additional sedation and neuromuscular blockade if the endoscopist anticipates that the procedure will be lengthy or excessively difficult.


Advantages of elective endotracheal intubation for EGD also include control of both the airway and ventilation during the procedure. In very small patients, the relatively large endoscope may partially obstruct the glottis. Distention of the gut with air may interfere with diaphragmatic movement. The risk of inadvertent extubation during EGD, however, mandates careful fixation of the endotracheal tube and careful monitoring of ventilation during the procedure by a physician from the critical care team.


Because bacteremia may occur during both upper and lower gastrointestinal endoscopy, some endoscopists routinely use perioperative antibiotics for endoscopy in patients with a central venous line or ventriculoperitoneal shunt. In recent years, therapeutic endoscopy has complemented diagnostic endoscopy. Gastrointestinal tract hemorrhage from varices, peptic ulceration, and angiodysplasia may be controlled by injection therapy or photocoagulation, electrocoagulation, and thermocoagulation. Band ligation of esophageal varices is also a proven therapy for variceal hemorrhage. Percutaneous endoscopic gastrostomy has become a popular alternative to surgical gastrostomy for patients in the ICU who cannot take oral alimentation on a long-term basis.


The diagnosis and treatment of oropharyngeal dysphagia can be difficult but is improved with the use of fiberoptic endoscopic evaluation of swallowing (FEES). The endoscope can be passed transnasally to visualize both laryngeal and pharyngeal structures. Both the structure and functioning of the pharyngeal phase of swallowing can be evaluated by giving the patients food and liquid boluses. Sensory testing can also be conducted to elicit the laryngeal adductor reflex. Some studies have suggested a good correlation between FEES and videofluoroscopy.


Wireless video endoscopy or video capsule endoscopy (VCE) is a noninvasive technology used to provide imaging of the small intestine, an anatomic site often difficult to visualize. The images acquired are of excellent resolution and the procedure uses the principle of physiologic endoscopy via passive movement and does not inflate the bowel, so images of the mucosa are captured in a collapsed state. Primary indications include the diagnosis of obscure gastrointestinal bleeding, small bowel tumors, or Crohn’s disease. There is growing experience in the use of this technology for children older than 6 years. Advantages include its noninvasive nature and the ability to examine the small bowel mucosa, which is not possible with push enteroscopy. Disadvantages include the impossibility of any tissue sampling or therapeutic intervention. However, studies have suggested that the overall yield of VCE is superior to push enteroscopy and barium studies.2–4



Gastroesophageal Reflux Monitoring


Like gastrointestinal endoscopy, esophageal reflux monitoring has benefited from technical advances that permit insertion of miniature, flexible electrodes into the esophagus of the smallest children.


Esophageal pH monitoring has been in use since the late 1970s. Esophageal pH is continuously recorded for 24 hours, and the duration of esophageal acidification, defined as decreases in pH less than 4, is quantified. Additional variables including the quantity of reflux in the 2 hours after a feeding and during fasting are determined. Detection of alkaline reflux episodes, which commonly occur in the postprandial period when food buffers gastric acid, is not possible with this technique. The administration of apple juice (pH < 4) rather than formula for feedings during the monitored period has been proposed to circumvent this limitation; however, it is an imperfect strategy insofar as normative data are scarce for older children whose esophageal pH is measured during apple juice feedings. Furthermore, the technique is unreliable for children who have been maintained with histamine-2 (H2) antagonists or proton pump inhibitors. For reliable pH monitoring of such children, proton pump inhibitors must have been discontinued for at least 72 hours and H2 antagonists for at least 48 hours. Critical care physicians may not have the luxury of stopping these agents temporarily in critically ill patients who are at risk for stress ulceration of the gastrointestinal tract.


Esophageal impedance monitoring5 is the preferred means of measuring gastroesophageal reflux among patients who are receiving acid suppression or in whom alkaline reflux is suspected. The intraesophageal impedance device measures total opposition to current flow between two electrodes and expresses the value in ohms. Because air and fluid have different conductivities, the contents of the esophagus can be differentiated at any point in time. Thus when the esophagus is devoid of fluid, a baseline impedance is measured. When a bolus of fluid enters the esophagus from refluxed material or from a swallowed bolus, the impedance changes. These changes in intraluminal impedance thus permit the continuous monitoring of pH neutral or alkaline reflux episodes.


In addition to detecting pathologic quantities of reflux in children who have symptoms suggestive of reflux disease, reflux monitoring is also useful in determining whether a temporal correlation exists between gastroesophageal reflux and pathologic events such as cough, bronchospasm, or apnea. Because it does not determine the cause of vomiting, reflux monitoring adds little to the evaluation of vomiting children.


For the ambulatory child capable of undergoing an endoscopy, a small pH transducer capsule can be deployed and attached to the esophagus, being left in place to monitor esophageal acidification for up to 48 hours with an external sensor before being naturally sloughed. The advantage of this device is that nasoesophageal intubation need not be performed, thereby creating a more “natural” environment. For the critically ill, intubated patient, this device is impractical to place and offers no advantage over traditional reflux monitoring.6,7



Use of Colorants to Identify Aspiration in the Intensive Care Unit


Patients who are obtunded or who have been ventilator dependent for an extended time are at significant risk of pulmonary aspiration. A deceptively simple way of documenting aspiration in patients receiving gavage or gastrostomy feedings in the past has been to add a coloring agent such as blue dye No. 1 or methylene blue to formula. The rationale for this strategy was that quantities sufficient to tint formula should be readily apparent when suctioned from the lungs. The fallacy of the technique is that when compared with scintiscanning of the lungs after administration of a radiolabeled meal or with the discovery of lipid-laden macrophages after bronchoalveolar lavage, the use of colorants is notoriously inaccurate. Furthermore, all colorants are dangerous when instilled into the gastrointestinal tract. They are customarily absorbed in minimal quantities, but among critically ill patients, the gastrointestinal tract becomes porous to all macromolecules and appreciable quantities of dye are absorbed. Once absorbed, even minimal quantities function as metabolic poisons, uncoupling oxidative metabolism, thereby resulting in life-threatening metabolic acidosis among susceptible patients.8



Radiologic Procedures



Plain Films


The abdominal x-ray film provides valuable assistance to the clinician evaluating children with abdominal distention, guarding, or tenderness. Dilated, gas-filled bowel loops, with or without air-fluid levels, can signify obstruction or ileus. Air-fluid levels in a “stepladder” configuration along the length of small bowel suggest obstruction, whereas levels that appear in a parallel configuration suggest ileus. Pneumatosis intestinalis and mucosal “thumbprinting” are signs of bowel wall ischemia and can often be appreciated on the plain film. Pneumoperitoneum can be evaluated with the inspection for air in the lesser sack, air between bowel loops, or a visible falciform ligament. Even though an upright film is optimal for visualizing peritoneal air, lateral decubitus or cross-table lateral films are acceptable substitutes in bedridden patients. Air in an abscess cavity or air in liver parenchyma, biliary tree, or portal venous system should be acknowledged as signs of serious intraabdominal infection.


Abnormal densities such as abdominal masses, ascites, or calcifications can often be identified on plain films. Calcifications in the region of the gallbladder, pancreas, or appendix suggest cholelithiasis, pancreatitis, or appendicitis, respectively. The abdominal contour and the contour of extraperitoneal structures such as lung bases, pelvic organs, and kidneys should always be assessed.



Contrast Radiography


Although endoscopy is more sensitive than single-contrast radiography for identifying mucosal ulceration, contrast radiography remains a valuable procedure in the critical care setting. In general, the upper gastrointestinal tract series and small bowel series are indicated when partial small bowel obstruction is suspected. A contrast enema will document (and possibly treat) intussusception and document Hirschsprung’s disease. The type of contrast agent for a particular examination depends on the clinical condition of the patient undergoing the examination. Although barium sulfate is superior to water-soluble contrast agents for outlining mucosa, its use in typical patients in the ICU is riskier because barium may form a concretion in a patient with ileus and because barium leaking into the peritoneum from a perforated hollow viscus can cause serious peritoneal injury. Hyperosmolar, water-soluble contrast agents are usually not favored because they pose the risk of dehydration. Currently, isosmolar agents are more commonly used for studies on the critically ill patient.



Ultrasonography, Computed Tomographic Scanning, and Magnetic Resonance Scanning


Ultrasonography, computed tomographic (CT) scanning, and magnetic resonance imaging (MRI) each have advantages and disadvantages. For example, in the slim child with little mesenteric fat, ultrasonography is sometimes better than CT scanning of abdominal viscera. Conversely, CT scanning is superior for abdominal imaging of obese individuals.9 MRI is limited by its inability to distinguish bowel loops from adjacent structures and by blurring caused by motion. It is helpful, though, in identifying vascular tumors, which are seen as low-intensity masses on T1-weighted images and high-intensity masses on T2-weighted images. Ultrasonography or CT is used when an intraabdominal abscess, cystic lesion, hepatobiliary disease, tumor, ascites, or pancreatitis is suspected. In the identification of pancreatic lesions, dynamic CT scanning is a most imaging technique. CT also best identifies enlarged periaortic nodes. CT or MR enterography are other modalities used in the detection of small bowel inflammatory disease. Oral hyperhydration can achieve adequate luminal distension often not requiring nasoenteric intubation. Unlike routine CT or MRI, enterography can display mural changes along with perienteric inflammatory changes with much better resolution. These studies are more accurate than the standard small bowel follow-through or enteroclysis.10–13


Ultrasonography of the liver and biliary tract identifies hepatic parenchymal disease, biliary stones, or congenital abnormalities such as choledochal cyst. Intussusception, pyloric stenosis, and acute appendicitis are particularly amenable to ultrasonographic diagnosis. In addition, Doppler flow analysis has significantly aided the preoperative and postoperative evaluation of liver transplant recipients by identifying congenital vascular anomalies and postoperative vascular thromboses.



Radionuclide Scanning


Radionuclide scanning is helpful when patients in the ICU have pulmonary aspiration, gastrointestinal bleeding, intraabdominal abscesses, or cholestasis.


Gastroesophageal reflux and the rate of gastric emptying can be measured with liquid-phase gastroesophageal scintigraphy.14 Technetium-99 sulfur colloid is mixed with formula or another enterally administered liquid. When there is a scan above and below the diaphragm in 30- to 60-second windows during the first postprandial hour after isotope administration, the number of reflux episodes, the height of the reflux column, and the rate of gastric emptying are quantitated. A 4- to 6-hour delayed scan of the lungs determines whether pulmonary aspiration of that meal has occurred.15


Three techniques are used to aid in the diagnosis of gastrointestinal bleeding. 99Tc sulfur colloid and 99Tc-labeled red cells are used in patients with continuous or intermittent bleeding. The advantage of sulfur colloid is that less than 0.1 mL of blood per minute will be shown. Bleeding in a spot near the liver or spleen, however, may be obscured by high levels of activity in those organs. Tagged red blood cell scans detect intermittent bleeding by means of delayed scans, but migration of blood down the gastrointestinal tract over time may preclude exact localization. 99Tc pertechnetate scanning does not require active bleeding to localize a Meckel’s diverticulum. Isotope is concentrated by gastric mucosa, and if a scan reveals an ectopic focus a Meckel’s diverticulum can be suspected. Scan results are negative in the 15% of diverticula not containing gastric mucosa. A variety of non-Meckel’s lesions (most of which require surgical correction) cause false-positive results on pertechnetate scans. The sensitivity of the scan can be increased when acid suppression is given prior to scanning.


Resolution of hepatobiliary scans has improved dramatically since the introduction of derivatives of 99Tc iminodiacetic acid. Scanning can now document cholecystitis when there is no gallbladder uptake or biliary obstruction when there is no excretion into the bowel. Other entities such as biliary leaks or cystic lesions of the biliary tree can also be documented. Furthermore, delayed or reduced hepatocyte uptake can confirm impaired hepatocellular function.


Intraabdominal abscesses and inflammatory intestinal lesions can be localized with radioscintigraphy.16 Leukocytes are extracted from the patient, tagged with a radioisotope in vitro, and are reinjected. Scanning of the area in question is then performed. Technetium hexamethyl propyleneamine oxime (HMPAO) has replaced indium because of improved resolution of HMPAO scans and because HMPAO scans can be completed within 4 hours rather than 72 hours.



Testing for Occult Blood Loss


Occult blood loss is generally determined with the Hemoccult or Gastroccult test; these are modifications of the guaiac test.17,18 They work because hemoglobin oxidizes the reagent to a blue product. The recently marketed Hemoccult Sensa (Beckman Coulter, Inc., Brea, Calif.) slide detects as little as 2 to 3 mL of blood loss per day. This slide is virtually 100% sensitive when blood loss equals 10 mL/day.8


In the stomach, blood can be denatured, and this can lead to false-negative results. Gastroccult, which contains borate-buffered reagent, significantly improves the sensitivity for testing gastric contents. (Urine test tapes should never be used for gastrointestinal occult blood testing because they are too sensitive.) Therefore even physiologic quantities of enteric blood loss (<1 mL of blood per day) will yield positive results.



Stool pH and Reducing Substances


Excessive enteral carbohydrate loads may worsen preexisting diarrhea in critically ill children. Carbohydrate malabsorption can be assessed with the measurement of reducing sugars and pH of stool. The two tests should always be used in conjunction because colonic transit time and quantity or type of colonic flora affect either of these tests. Malabsorbed sugars appear in feces when colonic transit is sufficiently rapid and are detected by Clinitest tablets or reagent strips; more than 0.5 mg of sugar per 100 mL of stool water suggests malabsorption. If the malabsorbed dietary sugar is primarily sucrose, a nonreducing sugar, the Clinitest result is negative unless the stool is first hydrolyzed with hydrochloric acid. Stools can be negative for reducing sugars despite carbohydrate malabsorption if colonic transit is slow enough to permit complete bacterial fermentation. In such an event, pH of fresh stool (measured by nitrazine paper) is consistently below 5.5. The pH of samples not tested for several hours, however, tends to rise over time as short-chain fatty acids generated from sugar fermentation are further metabolized.



The Intensive Care Unit as a Satellite Laboratory Facility


Regulations of the Joint Commission on Hospital Accreditation prohibit testing for occult blood loss or stool testing by anyone other than an individual certified in accordance with the Clinical Laboratory Improvement Act (CLIA). Thus for many pediatric critical care units, “bedside” testing has moved from the bedside to the clinical laboratory. Turnaround time for measuring occult blood in stool has risen from seconds to hours. Furthermore, when fecal samples are sent to the clinical laboratory for measurement of reducing sugars and pH, results are meaningless insofar as bacterial metabolism of sugars continues ex vivo in these samples between the times of collection to the time of testing. Critical care units wishing to perform reliable fecal testing on site must train a cohort of staff in common bedside tests and obtain CLIA certification for each staff member. Furthermore, just as many ICUs have chosen to comply with CLIA regulations and have established approved satellite laboratory facilities, to measure blood gases or serum electrolytes, they can extend the scope of their laboratory activities to include bedside gastroenterologic testing.



Breath Hydrogen Testing


Breath hydrogen testing confirms monosaccharide or disaccharide malabsorption and small bowel bacterial overgrowth. The technique documents intestinal bacterial fermentation of carbohydrates; their byproduct is hydrogen gas. Fasting alveolar hydrogen concentrations greater than 40 ppm suggest bacterial overgrowth. A rise in concentration of 20 ppm occurring beyond 90 minutes after an enteral carbohydrate challenge suggests carbohydrate malabsorption. A peak less than 60 minutes after the challenge is consistent with bacterial overgrowth.


Because of difficulties in consistent alveolar air sampling, some investigators internally standardize by measuring both H2 and carbon dioxide (CO2) and expressing their results as a ratio.


Perhaps breath hydrogen testing is most valuable in the ICU as a screening test for neonatal necrotizing enterocolitis. Cheu et al.19 showed that randomly obtained breath H2/CO2 ratios greater than 8 ppm/mm Hg strongly suggest necrotizing enterocolitis.



Life-Threatening Complications of Gastrointestinal Disorders



Esophagus



Congenital Esophageal Anomalies


Esophageal atresia and tracheoesophageal fistula are true neonatal emergencies. With an incidence of 1 in 3000 live births, they are among the most common congenital anomalies of the esophagus. Five anatomic varieties exist in the following descending order of frequency: (1) blind proximal esophageal pouch with distal esophagus originating at the tracheobronchial junction (80%), (2) blind proximal esophageal pouch with blind distal esophageal pouch (8%), (3) uninterrupted esophagus with H-type tracheoesophageal fistula (4%), (4) proximal esophagus fistulizing into trachea with blind distal esophageal pouch (2%), and (5) interrupted esophagus with both proximal and distal esophagus communicating with trachea (1%).


The embryogenesis of this disorder is unknown, but other cardiovascular, gastrointestinal, skeletal, or urogenital anomalies are present in 50% of cases.


Infants with a blind proximal esophagus have excessive salivation, respiratory distress, and cyanosis. Diagnosis of blind proximal esophagus can be made by the failure to pass a nasogastric tube into the stomach. Complete atresia leads to a gasless lower gastrointestinal tract. An H-type fistula is sometimes seen on contrast radiography or esophagoscopy, but bronchoscopy is usually the most sensitive diagnostic tool.


Treatment is surgical. A simple fistula can be ligated, and a short atresia can be repaired primarily. Long atresia, however, may require staged treatment with initial esophagostomy and gastrostomy and subsequent definitive repair after internal or external traction is applied. Circular myotomy of the esophagus reduces anastomotic tension. Occasionally a “gastric tube” procedure or colonic interposition is required.



Caustic Injury to the Esophagus


Despite widespread efforts by poison control centers to publicize the dangers of household caustics, thousands of inadvertent ingestions occur annually; most occur in children younger than 5 years. Crystalline products produce greater damage to the hypopharynx and upper airway because of prolonged mouth contact and a smaller volume reaching the esophagus. In recent years most household cleaners have been reformulated to contain less lye, but pure liquid lye can be purchased if desired. Its resemblance to milk leads to numerous inadvertent ingestions by children (see Chapter 106).


Tissue damage can be caused by either strong alkali or acid. Deep esophageal burns are more common after alkali ingestion. Alkalis produce rapid liquefaction of esophageal tissue, and burns can range from first to third degree in depth.20 An intense inflammatory infiltrate develops, and blood vessels thrombose to produce ischemic necrosis. Perforation may occur within hours or days. Strictures can occur weeks to years after ingestion.21 Esophageal burns occur infrequently after acid ingestion, but gastric or duodenal erosions have been reported.


Symptoms that predominate are chest pain and the inability to swallow secretions. Children with upper airway damage often exhibit stridor. When mouth burns are present, the chances of esophageal injury are 75%.10 Conversely, 25% of patients with significant esophageal burns have no pharyngeal or mouth involvement.20


Treatment of severe stridor should be directed toward establishing an airway, and emergency tracheostomy should be contemplated. Upper endoscopy within 24 hours is advisable. If burns are minor, no further therapy is necessary, and patients are at low risk of sequelae. Third-degree burns require ongoing intensive care, though. The role of antibiotics and steroids remains controversial.12 Although steroids reduce tissue damage when given before experimental injury, recent double-blind clinical trials show no efficacy of steroids in preventing sequelae.22 When third-degree burns are endoscopically evident, a nasogastric tube should be positioned with endoscopic guidance. This tube will enable early feeding and serve as a guide for future dilations if they become necessary. Some surgeons have advocated early placement of gastrostomies and esophageal stents in patients with third-degree burns.23



Esophageal Foreign Bodies


A variety of metallic, wooden, or plastic foreign bodies in a myriad of shapes and sizes can be swallowed by children. All that are lodged in the esophagus require urgent removal (within 24 hours). Even more urgent endoscopic retrieval is required for button batteries or pennies minted after 1983 that are lodged in the esophagus because both are caustic to esophageal mucosa and may cause damage within 1 to 4 hours. The preponderance of evidence suggests that once a battery has escaped the esophagus, complications from an unretrieved battery are rare.24


Similarly, pennies minted after 1983 are predominantly zinc based and can be nearly as caustic within the esophagus as button batteries. No published epidemiologic studies are available on which to base the approach to zinc-based pennies within the stomach or small intestine.



Gastroesophageal Reflux


Several antireflux barriers exist in the region of the lower esophageal sphincter. Beyond intrinsic myogenic tone, barriers such as the cardioesophageal angle, the abdominal esophagus (that acts as flutter valve), the mucosal rosette of the sphincter (that acts as a choke valve), and the diaphragmatic crura themselves act to prevent reflux of gastric contents. A complex set of factors, including hormonal changes, anatomic relationships, increased or decreased sensitivity to neurotransmitters, and CNS derangements, act to produce inappropriate sphincter relaxation (usually transient), which leads to most episodes of gastroesophageal reflux. With the advent of more sophisticated otolaryngolocal procedures such as the laryngotracheoplasty and slide tracheoplasty, prevention of gastroesophageal reflux is of utmost importance to facilitate surgical healing. Some surgeons advocate the use of aggressive acid suppression postoperatively because acid-induced damage can result in significant cicatrix formation at the site of laryngotracheal surgery.


Life-threatening events such as apnea and pulmonary aspiration are sometimes attributed to reflux. The relationship between infantile apnea and reflux remains in question,25 but both human and animal data suggest that reflux can occasionally be associated with obstructive breathing patterns. Severe pulmonary aspiration of refluxed material can also take place. A number of protective mechanisms such as an active gag reflex, cough reflex, and laryngospasm protect against aspiration,26 but these reflexes may be lost under special circumstances such as obtundation. Symptoms of obstructive apnea often include a brief episode of stridor accompanied by a struggle to breathe, a change in skin color to red or purple, and finally cyanosis and cessation of respiratory effort. Patients who have aspirated massive amounts of fluid become tachypneic and dyspneic shortly after the meal. Food or formula is often found in the nares or mouth. Cough may occur.The diagnostic modality most helpful in documenting a temporal relationship between apnea and acid reflux is 24-hour esophageal reflux monitoring combined with simultaneous electrocardiography, pneumography by chest wall impedance, pneumography by nasal thermistor, pulse oximetry, and end-tidal CO2 measurement. Aspiration is often difficult to document, but the presence of a new infiltrate on chest x-ray films and a consistent clinical history provide strong circumstantial evidence. If repeated aspiration is suspected, an upper gastrointestinal tract series may reveal gastroesophageal reflux and immediate aspiration of barium; however, aspiration of gastroesophageal refluxate that occurs minutes or hours after a feeding may be missed with contrast radiography. A milk scan may be more sensitive than radiography for documenting this type of aspiration. Children who are not fed orally may nevertheless aspirate oral secretions. The scintigraphic “salivagram” is performed with the placement of a drop of saline containing 99mTc sulfur colloid on the tongue.27 Subsequent imaging permits observation of its handling. Appearance of isotope in the trachea and bronchi confirms aspiration.


When recurrent aspiration is suspected but not confirmed noninvasively, bronchoscopy with bronchoalveolar lavage may support the diagnosis by returning fluid-containing lipid-laden alveolar macrophages.28 Aspiration during swallowing and aspiration of refluxed gastric contents cannot be distinguished by this method in patients who are fed orally.


Although some clinicians view one episode of reflux-induced aspiration or apnea as an absolute indication for fundoplication, the decision to perform fundoplication should be based on the severity of the initial episode, underlying conditions that predisposed the child to the episode, risk for recurrence, and the expected natural history of reflux for a particular patient. In other words, some patients may be successfully managed with pharmacotherapy (a proton pump inhibitor with or without a prokinetic agent such as metoclopramide or erythromycin).

< div class='tao-gold-member'>

Related posts:

Default ThumbnailEducating the Intensivist Neonatal Respiratory Disease Pediatric Transport: Shifting the Paradigm to Improve Patient Outcome Life-Threatening Viral Diseases and Their Treatment Gastrointestinal Structure and Function Research in Pediatric Critical Care

Stay updated, free articles. Join our Telegram channel
Tags:
Jul 7, 2016 | Posted by in CRITICAL CARE | Comments Off on Disorders and Diseases of the Gastrointestinal Tract and Liver

Full access? Get Clinical Tree
Get Clinical Tree app for offline access