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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.
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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 to monitor for aspiration pneumonitis is notoriously inaccurate.
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Several antireflux barriers exist in the region of the lower esophageal sphincter. Beyond intrinsic myogenic tone, barriers such as the cardioesophageal angle, abdominal esophagus (which acts as a flutter valve), mucosal rosette of the sphincter (which acts as a choke valve), and diaphragmatic crura themselves act to prevent reflux of gastric contents.
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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.
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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 gastrointestinal bleeding. In addition to their hemodynamic effects, these agents inhibit gastric acid production. Tranexamic acid may also reduce gastrointestinal bleeding.
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Crohn disease and ulcerative colitis are chronic, relapsing disorders without known causes. The transmural inflammation of Crohn 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.
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An abdominal plain film showing pneumatosis intestinalis, hepatic portal air, or both confirms the diagnosis of necrotizing enterocolitis. 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 bases of medical therapy. Surgical resection is reserved for severe cases when medical management fails and gangrenous bowel develops.
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Abdominal compartment hypertension and syndrome 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 improved outcomes for children admitted to pediatric intensive care units (PICUs). Indeed, the technology available today has 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. This chapter reviews the current approach to gastroenterologic diagnosis and therapy as well as the principles of gastroenterologic physical examination.
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.
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 sign or Grey Turner 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 disease. Similarly, deep fissures or sentinel piles suggest ulcerative colitis or Crohn 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 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. 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 intubation 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 significant cardiac lesion, central venous line, ventriculoperitoneal shunt, or who are immunocompromised. 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 proved therapy for variceal hemorrhage. Percutaneous endoscopic gastrostomy has become a popular alternative to surgical gastrostomy to provide a reliable route for enteral nutrition 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 are 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 patient 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—the procedure uses the principle of physiologic endoscopy via passive movement and does not inflate the bowel, thus, images of the mucosa are captured in a collapsed state. Primary indications include the diagnosis of obscure gastrointestinal bleeding, small bowel tumors, or Crohn 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.
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 impedance monitoring has become the preferred means of measuring gastroesophageal reflux in children, especially among patients who are receiving acid suppression or in whom weakly acidic or alkaline reflux is suspected, as impedance monitoring is independent of pH. 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, 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 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.
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 to the formula, such as blue dye No. 1 or methylene blue. 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; however, 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. Particularly in patients with sepsis, there is an associated increase in mortality in patients who received enteral colorant for aspiration evaluation. The authors recommend against the use of colorants to detect aspiration given the low efficacy in detection of aspiration and increased risk of mortality.
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 that can often be appreciated on 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 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 ICU patients 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, iso-osmolar 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 has advantages and disadvantages (see also Chapter 15 ). 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. 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 the preferred imaging technique. CT also best identifies enlarged periaortic lymph nodes. CT and magnetic resonance enterography are other modalities used to detect small bowel inflammatory disease. Oral hyperhydration can achieve adequate luminal distention, 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. Magnetic resonance elastography is increasingly recognized as a modality for detecting and staging hepatic fibrosis and nonalcoholic fatty liver disease (NAFLD). The use of magnetic resonance elastography may negate the need for liver biopsy in some patients. Alternatively, fibrosis detected on sonographic elastography correlates well with that detected by MRI. However, higher body mass index, presence of ascites, and small intercostal distance limit the utility of ultrasound elastography. The combination of positron emission tomography/MRI can be very useful to evaluate for focal liver lesions and liver metastasis of various childhood neoplasms.
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. Technetium-99 ( Tc) 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, height of the reflux column, and 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.
Three techniques are used to aid in the diagnosis of gastrointestinal bleeding. Tc sulfur colloid and Tc-labeled red cells are used in patients with continuous or intermittent bleeding. The advantage of sulfur colloid is that less than 0.1 mL/min of blood can be detected. 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. Tc pertechnetate scanning does not require active bleeding to localize a Meckel diverticulum. The isotope is concentrated by gastric mucosa, and if a scan reveals an ectopic focus, a Meckel diverticulum can be suspected. Scan results are negative in the 15% of diverticula not containing gastric mucosa. A variety of non-Meckel 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 Tc 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. Leukocytes are extracted from the patient, tagged with a radioisotope in vitro, and reinjected. Scanning of the area in question is then performed. Technetium hexamethylpropyleneamine 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. , They work because hemoglobin oxidizes the reagent to a blue product. The Hemoccult Sensa (Beckman Coulter) slide detects as little as 2 to 3 mL of stool blood loss per day. This slide is virtually 100% sensitive when blood loss equals 10 mL/day.
In the stomach, blood can be denatured, which 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 the 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; sugar more than 0.5 mg/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.
Intensive care unit as a satellite laboratory facility
Regulations of The Joint Commission 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.
Life-threatening complications of gastrointestinal disorders
Systemic
Central line–associated bloodstream infection
Children with intestinal failure who are reliant on parenteral nutrition through a central line are at high risk of central line–associated bloodstream infections (CLABSIs) because of the presence of an indwelling catheter and the generalized inflammation and reduced mucosal barrier of their gut. CLABSIs are the number one cause of mortality among this patient group. These children are frequently admitted to the PICU with septic shock. Children who are younger have a shorter segment of viable bowel (<50 cm), and those receiving a higher dose of parenteral lipids seem to be at increased risk of CLABSIs. The most common bacteria causing these infections are enteric Gram-negative organisms, such as Klebsiella species and Enterobacter species. Enterococcus species and coagulase-negative staphylococci can also be commonly seen, as can Candida species. As such, therapy should start with broad-spectrum Gram-negative and Gram-positive coverage with addition of an antifungal if this is a concern, with narrowing of coverage as soon as species identification and susceptibility testing allow. A goal of treatment for these children is often to salvage their central line, as their life depends on their ability to receive parenteral nutrition, and they may have limited venous access. Loss of vascular access is one of the few indications for small bowel transplant in these patients. Antimicrobial locks are used to eradicate catheter biofilms and consists of antibiotic- and nonantibiotic-based locks. Ethanol locks are an inexpensive method to improve infection clearance rates and increase line salvage rates both in the PICU and in the outpatient setting and may be used in both a treatment and prophylactic approach. Tetrasodium ethylenediaminetetraacetic acid (EDTA) is an antimicrobial lock recently approved in Canada that also significantly reduces biofilms after a 24-hour lock. Although antibiotic antimicrobial locks are available, biofilms are notoriously resistant to antibiotics, requiring high concentration of antibiotics in the lock.
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 the trachea with blind distal esophageal pouch (2%), and (5) interrupted esophagus with both proximal and distal esophagus communicating with the 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. 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 126 ).
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. 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. 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%. Conversely, 25% of patients with significant esophageal burns have no pharyngeal or mouth involvement.
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. 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.
Esophageal foreign bodies
Children can swallow a variety of metallic, wooden, or plastic foreign bodies in a myriad of shapes and sizes. 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. Typically, button batteries are removed within 2 hours of arrival. Historically, CT is recommended if there are any concerns for esophageal injury to evaluate for more serious injuries, such as esophageal perforation, tracheoesophageal fistula, or aortoesophageal fistula. Given experience with serious injury caused by button batteries, the authors recommend obtaining a CT, regardless of esophageal appearance on endoscopy, if the battery was ingested for an unknown period of time. The preponderance of evidence suggests that once a battery has escaped the esophagus, complications from an unretrieved battery are rare.
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, abdominal esophagus (which acts as a flutter valve), mucosal rosette of the sphincter (which acts as a choke valve), and 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 otolaryngologic 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, 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. However, 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, and cough may be present. 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 carbon dioxide 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 99m Tc sulfur colloid on the tongue. Subsequent imaging permits observation of its handling. The 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. 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).
For patients with neurologic impairment, excessive drooling can lead to chronic aspiration, pneumonia, and difficult airway control. Fortunately, there are several treatment options for this issue. The first, and most commonly used, is glycopyrrolate; however, due to its anticholinergic properties, it is often not tolerated or leads to unacceptable thickening of secretions. Another option is injection of botulinum toxin A by a pediatric otolaryngologist or interventional radiologist. Various studies have shown that approximately 60% of patients improve after these injections. If there is improvement, the patient may benefit from subsequent injections. Male sex and cerebral palsy were associated with an increased positive response. The major side effect for botulinum toxin injection is dysphagia. Finally, some patients who are refractory to more conservative management may benefit from surgical intervention by otolaryngology, specifically a submandibular gland excision, ligation of submandibular and parotid ducts (commonly known as a drool procedure), and, in the most extreme of cases, a laryngotracheal separation.
Stomach and duodenum
Gastric volvulus
Acute gastric volvulus may be of two types. When the whole stomach revolves about its long axis, organoaxial volvulus has occurred. When the fundus and pylorus exchange positions, the volvulus is mesenteroaxial. Predisposing factors include paraesophageal hernias or eventration of the diaphragm.
Because a closed obstruction has occurred, the patient is unable to vomit despite severe pain, distention, and retching. Plain radiographs reveal a markedly distended stomach with air-fluid levels, and contrast radiography may reveal cardioesophageal junction obstruction. An immediate operation is indicated.
Gastric ulcer
Whereas some authors suggest that duodenal ulcers outnumber gastric ulcers in childhood, others have reported that young children are more likely to have gastric ulcers. Most gastric ulcers lie at the junction of the gastric fundus and body. Those high in the fundus are usually related to stress. Antral ulcers are often the result of use of nonsteroidal antiinflammatory drugs (NSAIDs).
A well-recognized complication of severe illness requiring admission to the ICU is stress ulceration of the stomach. Bleeding becomes an important source of morbidity and mortality in patients with burns and trauma, as well as in those who have undergone major operations or have systemic disease. Prophylaxis against bleeding is common in the ICU setting. Antacids, H 2 -receptor antagonists (H 2 RAs), proton pump inhibitors (PPIs) such as lansoprazole and pantoprazole, and sucralfate are most often used. Unfortunately, elevation of gastric pH by antacids and H 2 RAs removes one barrier against bacterial colonization and may increase the risk of pneumonia with organisms colonizing the stomach. Large controlled trials, however, have failed to confirm this concern. Sucralfate is equally effective as prophylaxis against bleeding but does not affect gastric pH. If sucralfate is given concurrently with antacids or acid-suppressing medications, its efficacy will be reduced because it requires an acidic environment for optimal effect. Furthermore, sucralfate administered in close temporal proximity to other enterally administered medications may reduce their bioavailability by binding with them within the intestinal lumen.
Most patients with gastric ulcers are hypochlorhydric rather than hyperchlorhydric, because exposure to detergents or toxins such as NSAIDs, pepsin, bile salts, or ethanol erodes the gastric barrier to back-diffusion. A second consistent finding among patients with gastric ulcers is delayed gastric emptying, which may be an epiphenomenon or central to the pathogenesis of ulcers. The association between Helicobacter pylori infection and chronic gastritis as well as gastric and duodenal ulcers is now well established.
Clinical features of gastric ulcer resemble those of duodenal ulcer. Pain predominates and is epigastric in location but usually follows eating more closely. Nausea and vomiting may occur. Milk or antacids relieve the pain. The two complications of gastric or duodenal ulceration most commonly requiring intensive care are perforation and bleeding. Perforation, requiring immediate surgical intervention, produces exquisite pain and rapid development of peritoneal signs in patients without immunosuppression.
Hematemesis heralds gastric ulcer bleeding and may be as massive as that of duodenal ulcer. Careful, repeated assessment of vital signs and prompt restoration of circulating blood volume by large-bore venous catheters are essential. Saline solution or epinephrine gastric lavage through a large sump tube is mandatory. Iced saline lavage offers no advantage and excessively depresses core temperature.
Efforts should also focus on reducing gastric acid production with a parenteral PPI. Continuous intravenous vasopressin infusion, commonly used for control of variceal hemorrhage, reduces arterial flow through the splanchnic bed. Intravenous administration of somatostatin or its synthetic, 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. Tranexamic acid (TXA) is an antifibrinolytic that successfully reduces bleeding in a variety of disease processes, including traumatic hemorrhage, uterine bleeding, and surgical procedures. It has few side effects and is low cost. In cases in which hemodynamic instability occurs and bleeding persists, it may be beneficial to add TXA despite insufficient literature support at this time. Several trials are underway to assess its role in reducing gastric bleeding, including a large, randomized, international trial in adults (HALT-IT). ,
When the patient’s condition is stable, endoscopy may be performed to localize the ulcer. Endoscopic therapy may then be performed on actively bleeding ulcers or those with visible vessels (which tend to rebleed). Ulcer beds may be photocoagulated, electrocoagulated, or thermocoagulated. They may also be injected with hemostatic agents such as epinephrine. Another nonsurgical modality is Hemospray, a powder that forms a barrier and increases local clotting factors; however, the patient must undergo repeat endoscopy within 24 to 48 hours due to the risk of rebleeding. If nonsurgical techniques fail to stop the bleeding, one of several surgical options (including ulcer oversewing or resection, variations of gastric drainage procedures, and vagotomy) must be performed. Fortunately, successful pharmacologic and endoscopic therapies have precluded the need for these surgical therapies in all but the rarest circumstances. One of these rare instances includes Dieulafoy lesions, typically a large, tortuous arteriole in the submucosa of the gastrointestinal tract that can erode and cause severe bleeding. In the pediatric population, these lesions are more likely to be treated with surgical intervention, typically with band ligation or hemostatic clipping of the artery. ,
Duodenal ulcers
The incidence of duodenal ulcer in childhood is unknown. A large series completed before the popularization of endoscopy suggested an incidence of 4.4 cases per 10,000 children per year, which is, no doubt, an underestimation. The male predominance seen among adults is present only among postpubertal children. The risk for patients with blood group O is 1.3 times that expected.
A number of factors have been implicated in the pathogenesis of duodenal ulcers. Unquestionably, excessive acid production plays a major role. Some factors leading to hypersecretion include excessive gastrin or histamine production and increased vagal tone. Approximately half of patients with ulcers are also hyperpepsinogenemic, and their mucosal integrity may therefore be suboptimal. Infection with H. pylori reduces the ulcer healing rate and increases the recurrence rate. Although approximately 90% of adult duodenal ulcers are associated with H. pylori infection, only about 50% of pediatric duodenal ulcers are related to H. pylori . The effects of diet and stress have been minimized in the literature.
Symptoms in children are similar to those of adults. Epigastric pain occurs after meals and often awakens the child from sleep. Vomiting occurs in 40% of patients.
The major life-threatening complications are perforation and hemorrhage, which lead to a surgical abdomen and shock, respectively. Abdominal plain films reveal free air if perforation has occurred. Hemorrhage presents as hematemesis, hematochezia, or melena. Endoscopy is the most sensitive tool to localize the ulcer and to characterize the risk for rebleeding. Ulcers with visible vessels in the crater are at greatest risk of recurrent hemorrhage and may require endoscopic coagulation. Principles of management are identical to those for gastric ulcer. H. pylori is increasingly resistant to conventional antibiotics, such as metronidazole and clarithromycin. Triple therapy with a PPI, amoxicillin, and either clarithromycin or metronidazole for 10 to 14 days is currently recommended. However, in areas with high clarithromycin resistance, clarithromycin susceptibility testing is recommended first.
Small intestine and colon
Malrotation
In embryonic life, the cecum and ascending colon are located on the left side of the abdomen and the small bowel is on the right. During gestation, the midgut transiently protrudes into the umbilicus and rotates 270 degrees; the cecum is moved to the right lower quadrant and the duodenojejunal junction to the left upper quadrant. Incomplete rotation is of little consequence unless midgut volvulus, which can be a catastrophic event, occurs.
Some patients with malrotation experience partial duodenal obstruction because of extrinsic compression by mesenteric bands. Chronic diarrhea and protein-losing enteropathy may be seen, among other conditions, without complete obstruction.
Clinical features of obstructing volvulus include severe abdominal pain, bilious vomiting, and abdominal distention. Surgical treatment requires a Ladd procedure, in which mesenteric bands are divided and the bowel is returned to its fetal position. Failure to promptly relieve the volvulus leads to ischemic necrosis of all the gut supplied by the superior mesenteric artery (proximal jejunum to midtransverse colon). Short gut syndrome results from resection of the affected intestine.
Necrotizing enterocolitis
Necrotizing enterocolitis (NEC) is primarily a disorder of premature infants, affecting 2.5% of neonatal patients in the ICU but only 0.2% of all infants. The most common areas involved are the ileum and proximal colon, but any part of the intestinal tract may be affected. Its pathogenesis is unknown, but bowel ischemia, feeding of hyperosmolar formula, rapid advancement of feeding, reduced immune surveillance, and population of the bowel by excessive quantities of enterotoxin-producing bacteria may all play a role.
The classic clinical features are abdominal distention, bilious vomiting, and bloody stools, but symptoms are more subtle in some infants. If left unrecognized, NEC may become fulminant, leading to shock, disseminated intravascular coagulation, and apnea.
An abdominal plain film showing pneumatosis intestinalis, hepatic portal air, or both may confirm the diagnosis of NEC. 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. Data have emerged suggesting that changes in the neonatal fecal microbiome or production of excessive quantities of volatile organic acids are early markers of NEC; however, the ability to detect these entities is not yet practical for the clinician at the bedside. ,
Perforation may sometimes be managed successfully in infants with very low birth weight, with simple peritoneal drainage performed with the infant under local anesthesia.
Low cardiac output syndrome
Advancements in surgical techniques have led to significant improvement in morbidity and mortality after pediatric cardiothoracic surgery. However, patients remain at risk for decreased cardiac output and impaired systemic oxygen delivery, especially in the early postoperative period. The drop in cardiac output after cardiac surgery is characterized as low cardiac output syndrome (LCOS). LCOS is defined as an inability of the heart to provide adequate oxygen delivery to meet the body’s metabolic demand. It is primarily due to transient myocardial dysfunction compounded by acute changes in myocardial loading. Cardiopulmonary bypass, along with residual cardiac abnormalities, may further aggravate the underlying low cardiac output state. , Although there are several manifestations of this clinical constellation beyond the scope of this chapter, it is important to recognize its clinical signs and symptoms (see Chapter 36 ). Systemic venous congestion may be observed in the gastrointestinal tract. Manifestations include hepatomegaly, ascites, and peripheral edema. Hypoperfusion to the liver can result in hepatic insufficiency and may lead to coagulopathy if severe enough. Furthermore, intolerance to enteral feeding may be evident in these patients with LCOS and central venous hypertension. Feeding difficulties may be further compounded by high-dose inotropes and narcotic infusions. These patients often require parenteral nutrition. Complications such as mesenteric ischemia or NEC may be observed in rare cases and are often fatal. ,
Food allergy
Food allergy can be defined as a reproducible, immunologically mediated reaction to an ingested food protein. Pathogenic events can be classified according to the schema of Gell and Coombs as type I (reaginic, immediate hypersensitivity reaction), type II (cytotoxic reaction), type III (immune-complex reaction), or type IV (delayed hypersensitivity reaction).
Manifestations may be systemic or confined to the gastrointestinal tract. Life-threatening systemic manifestations include acute urticaria and anaphylaxis. Gastrointestinal reactions, which are sometimes severe, include allergic enteritis, allergic colitis, and celiac crisis.
Acute urticaria is usually easily recognized by the classic wheal and flare cutaneous lesions often accompanied by laryngeal edema and angioedema. Anaphylaxis is an antigen-triggered immune reaction that leads to vascular collapse and bronchospasm (see also Chapter 106 ).
Food protein–induced enteropathy is characteristically a disorder of the infant and toddler. The small bowel develops patchy villous atrophy. Symptoms and signs range from those of malabsorption and enteric protein loss to those of profound diarrhea and shock. Colitis caused by food protein sensitivity is seen most commonly among infants younger than 6 months. Bloody, mucoid diarrhea develops several days or weeks after their first oral antigen challenge. Even though this colitis usually takes a benign course, it may be severe enough to mimic NEC.
Although some do not categorize gluten enteropathy as true food allergy, it shares enough features with allergy to justify inclusion with this category of disorders. Celiac crisis is a rare, life-threatening complication that may occur among untreated patients with a large gluten load or in treated patients as a result of dietary indiscretion. Massive fluid and electrolyte loss leads to shock.
The cornerstone of long-term therapy is elimination of the offending food, but emergency measures are also required. Immediate administration of epinephrine and corticosteroids is essential in the treatment of anaphylaxis. Urticaria may require the administration of antihistamines, corticosteroids, and epinephrine. Corticosteroid administration also seems to benefit patients in celiac crisis. Rapid administration of crystalloid or colloid is crucial in the management of any of these reactions.
Hemolytic uremic syndrome
Hemolytic uremic syndrome (HUS) may occur in epidemic or sporadic forms (see Chapter 74 ). It is frequently preceded by enteric infection with bacterial or viral pathogens. Infection with Shiga toxin–producing Escherichia coli precedes a high number of cases. , Instigating factors, such as bacterial verotoxin, cause endothelial damage in the kidney, liver, heart, brain, adrenal glands, and gastrointestinal tract.
Clinical features include a prodrome of abdominal pain, vomiting, and diarrhea, which may be bloody. Patients may have endoscopic, radiographic, or histologic evidence of ischemic bowel disease. As gastrointestinal symptoms improve, hemolytic anemia and thrombocytopenia rapidly appear with associated symptoms of petechiae, epistaxis, gingival bleeding, and pallor. Subsequently, patients become oliguric, hypertensive, and azotemic. Pancreatitis may further complicate the clinical course. Seizures and altered mental status may occur.
The intensivist caring for children with acute, hemorrhagic colitis must pay exceptional attention to fluid balance, hemogram, and renal function studies. Any sudden change in hemoglobin, platelet count, blood urea nitrogen, or urine output should be considered a potential sign of HUS. In the absence of hypovolemic shock, fluid intake should be curtailed if HUS is documented. In the event of severe renal insufficiency, dialysis is necessary.
Atypical hemolytic uremic syndrome (aHUS) presents similarly to HUS, with hemolytic anemia, thrombocytopenia, and renal dysfunction, but is usually not associated with a prior bacterial infection or diarrhea. In aHUS, dysregulation of the complement cascade leads to uncontrolled complement activation. Patients were previously treated with plasma exchange; however, the morbidity and mortality rates remained high. Eculizumab, a monoclonal antibody that targets C5 to block the complement cascade and prevent formation of the terminal complement complex, has been used in children with aHUS with better results than plasma exchange.
Inflammatory bowel disease
Crohn disease and ulcerative colitis are chronic, relapsing disorders without known causes. The transmural inflammation of Crohn 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 latter always involves distal colon, and its contiguous inflammation extends for varying distances from the rectum. The two entities are different enough to usually permit accurate categorization, but there is sufficient overlap in symptoms and distribution that the diagnosis is indeterminate in 15% of cases. Table 95.1 summarizes the clinical, radiographic, endoscopic, and histologic differences between the two.
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