Duodenum

The duodenum is a portion of the small intestine that extends from the pylorus to the jejunum and transitions from a retroperitoneal structure to an intraperitoneal structure at the ligament of Treitz. Pancreatic and hepatic enzymes (bile) enter the second portion of the duodenum through the sphincter of Oddi. These enzymes work to neutralize acidic chyme and promote digestion. The duodenum is the primary site for absorption of iron, trace metals, and water-soluble vitamins.

Jejunum

The jejunum lies between the duodenum and ileum and comprises approximately half of the small bowel. Ninety percent of nutrients and 50% of water and electrolyte absorption is completed by the jejunum.

Ileum

The ileum connects the small intestine to the colon. Its functions include absorption of vitamin B₁₂ and bile salts and completion of any remaining nutrient absorption. The ileocecal valve is situated between the ileum and the colon. This valve delays entry of intestinal contents into the colon and prevents reflux of colon contents back into the small intestine.

Carbohydrates

Carbohydrates are consumed as disaccharides, oligosaccharides, and polysaccharides. These are digested, absorbed, and transported through the body primarily as glucose, which is the primary metabolic fuel.

Fats

A variety of lipids (fats) are consumed in the diet; the highest quantity is in the form of triglycerides. Dietary triglycerides are a major source of energy; they have a higher caloric density than the other macronutrients (i.e., carbohydrates and proteins). Adequate dietary lipids are needed to allow for the absorption of fat-soluble vitamins A, D, E, and K.

Protein

Dietary proteins are necessary for maintaining body proteins and increasing protein mass associated with growth. If dietary protein is inadequate, growth is retarded. Renal and liver disease, cancer, and infections are associated with loss of body proteins.

Indications for Parenteral Nutrition

PN is most often is used as a supportive rather than a definitive therapy for infants and children with complex illnesses and structural GI anomalies. Indications for the supportive use of PN in the neonatal period include: congenital GI anomalies requiring extensive resection of the small bowel, intestinal obstruction, and necrotizing enterocolitis. Beyond infancy, indications for PN include: severe malnutrition, acute pancreatitis, fulminant liver failure, inflammatory bowel disease, extensive burns, malabsorption syndromes, refractory anorexia nervosa, and other disorders causing intestinal failure (see the Intestinal Failure section in this chapter).

Parenteral Nutrition Solutions

PN solution consists primarily of glucose (as a source of carbohydrate), amino acids (as a source of protein), and fat emulsions. Dextrose provides 3.4   Kcal/g and constitutes 60% to 70% of the total PN caloric intake. Protein can be administered as Trophamine (recommended for infants younger than 1 year and for children with liver failure), or as Clinisol or Travasol (for children older than 1 year). Protein provides 4   Kcal/g and should constitute 14% to 20% of the total PN caloric intake. Fat emulsions (Intralipid) may be administered as a separate solution to provide a major source of calories (20% solution provides 2   Kcal/mL) and should constitute 30% to 50% of the total PN caloric intake. Providing adequate calories from fat (0.5   g/kg per day) prevents essential fatty acid deficiency states. Electrolytes, vitamins, minerals, and trace elements are added to these solutions to meet the child’s known nutritional requirements.

The PN orders are individually tailored to deliver appropriate amounts of fluid, nutrients, and electrolytes. The critically ill child’s fluid requirements often change and may differ from estimated maintenance fluid requirements. In addition, it may be necessary to alter electrolyte content based on the child’s clinical condition or changes in medications. For example, medications such as furosemide (Lasix) will increase the daily potassium requirements; if the furosemide dose is reduced, the child will require less supplementary potassium.

When PN is initiated, there is gradual titration of additives until goal calories are achieved. The goal calories should be determined by the healthcare provider in consultation with a dietitian or pharmacist.

Nursing Responsibilities

The nurse must closely monitor the child’s clinical appearance and fluid and electrolyte balance to prevent and detect complications of PN as soon as possible. This monitoring requires documentation of the quantity and content of the child’s fluid intake and output and evaluation of the child’s fluid and electrolyte status and daily weight. A sample monitoring schedule for children receiving PN is provided in Table 14-5.

Table 14-5 Sample Monitoring Schedule for Children Receiving Parenteral Nutrition: Must Be Tailored to Child’s Clinical Status

Monitoring	Frequency
General and Anthropometric Measurements
Vital signs	Every 4   hours, or more often as patient condition warrants
Weight	Daily
Strict intake and output	Constant
Caloric intake	Daily
Height	Weekly
Head circumference	Weekly (for children younger than 2 years)
Blood Sampling
Glucose	Initial + Daily until stable (more often in neonates)
Electrolytes	Initial + Daily until stable
BUN, Creatinine	Initial + Weekly
Ca2+/ionized calcium, , Mg2+	Initial + Weekly (, Mg2+should be checked daily if values not within reference range)
Alkaline phosphatase, AST, ALT	Initial + Weekly
Total and direct bilirubin	Initial + Weekly
Total protein, albumin	Initial + Weekly
Prealbumin	Initiation
Triglycerides, cholesterol	Weekly
Zinc, copper, selenium, manganese, iron	Monthly
Glucose point-of-care testing	When PN is abruptly discontinued, cycled, or if signs or symptoms of hypoglycemia or hyperglycemia suspected
CBC count with differential	When febrile
Blood culture	When febrile

ALT, Alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; Ca²⁺, calcium; CBC, complete blood count; Mg²⁺, magnesium; PN, parenteral nutrition; phosphorous.

Whenever the child receives concentrated glucose solutions, the nurse must verify that the fluid volume and content are appropriate for the child’s estimated daily requirements. Before every new bag of PN solution is infused, the nurse should confirm that the prepared solution is accurate and consistent with the order by checking the solution content against the provider’s original order. Reduction in the PN administration rate (e.g., if the intravenous [IV] catheter malfunctions or with the initiation of enteral feedings or feeding advancement) will reduce the child’s fluid, glucose, and electrolyte intake unless enteral feedings provide the difference.

Potential complications of PN include electrolyte abnormalities, infection, cholestasis leading to hepatic dysfunction, and hyperlipidemias (with triglyceride administration). In critically ill children, there is an association between hyperglycemia and organ dysfunction.³³

Because PN solution contains a high concentration of glucose, it provides an excellent medium for bacterial growth. When hanging a new bag of PN solution and tubing, the nurse must use strict aseptic technique to prevent line contamination. Many hospitals require that the entire tubing system (between PN solution and the patient, including infusion pump tubing) be changed every 24   hours to decrease the possibility of significant bacterial growth. The dressing over the catheter insertion site should be changed when it is no longer occlusive (per hospital policy), using sterile technique and an occlusive dressing. The nurse should assess the catheter insertion site for evidence of inflammation (erythema or exudate) and should report any abnormalities to the appropriate provider. Wound exudate should be cultured and sent for gram stain analysis as ordered (or per protocol). Nurses should be careful to follow the healthcare institutional policies and protocols to prevent central venous catheter-associated blood stream infections (see Chapter 22, Box 22-6 for further information).

Monitor the child’s temperature at least every 4   hours (or according to hospital PN policy). Blood cultures are typically ordered if the child’s temperature rises above 38.5°   C or if the child develops signs of infection. The child may be placed on empiric antibiotics until culture results are available. The antibiotics are then adjusted if the culture is positive and the bacterial sensitivities or susceptibilities support a change. Often the catheter is maintained during an attempt to clear an existing infection, because if the child requires long term PN it may be difficult to achieve and maintain venous access. Therefore existing access sites are salvaged if possible.

When PN is initiated, a low glucose concentration and a low rate of infusion are used, and then both are increased gradually so that the child’s insulin production can accommodate the glucose load. Once the PN infusion is established, providers should maintain the infusion at a uniform rate as ordered; it should not be decreased or increased, because hypoglycemia or hyperglycemia can result. Once goal calories are achieved, it may be appropriate to stop the PN for increasing time intervals, allowing intervals without the PN. When neonates or children are receiving high dextrose compositions, dosing may need to be decreased and increased (with a gradual decrease in rate of administration before and gradual increase after the off cycle) to prevent hypoglycemia or hyperglycemia. To discontinue PN, the glucose concentration and the rate should be weaned gradually.

When PN infusions are initiated, serum glucose measurements can be performed several times per day. Point-of-care glucose measurements may be performed every 4 to 8   hours in infants if unit or hospital policy allows such testing. The presence of either glucosuria or ketonuria should be reported to an on-call provider, and the child’s serum glucose level should be checked. Glucosuria usually indicates the presence of high serum glucose levels that exceed the renal threshold of 150 to 200   mg/dL blood.

If the PN catheter infiltrates or becomes occluded, providers should promptly insert a temporary IV catheter to continue glucose administration and avoid the development of hypoglycemia that could result from a sudden cessation of glucose infusion. Monitor the child closely for clinical evidence of hypoglycemia (e.g., lethargy, irritability, tremors, diaphoresis, tachycardia, headache, vomiting, dizziness, blurred vision) until the PN infusion is resumed. Point-of-care glucose measurements can be obtained from infants to rule out hypoglycemia. An additional source of IV glucose administration may be needed if the PN solution contains a dextrose concentration of greater than the maximum 12.5% dextrose solutions that can be infused peripherally.

Because serum magnesium, phosphate, and calcium levels may fall during PN therapy, providers will monitor the concentration of these elements at least weekly. Trace element deficiencies are more likely to develop with long-term PN therapy or when PN therapy is used in premature infants. The signs and symptoms of copper deficiency include anemia, neutropenia, loss of taste (obviously difficult to assess), and rash. Zinc deficiency can produce an erythematous maculopapular rash (called acrodermatitis enteropathica) over the face, trunk, and digits; poor wound healing; hair loss and loss of taste; and a functional ileus.⁶² A chromium deficiency can produce a diabetes-like syndrome.⁶²

Complications of the PN catheter may also develop. Cardiac arrhythmias can occur if the central venous catheter migrates into the heart, particularly into the right ventricle. Venous thrombosis can develop if a clot is allowed to form at the catheter tip. Superior vena caval thrombosis can complicate PN therapy, particularly in infants who require prolonged PN therapy. An air embolus can be caused by careless coupling of the IV line or stopcock.

Because the central venous PN catheter is inserted into a relatively large vein, a loose or cracked tubing connection can rapidly result in significant loss of blood (i.e., hemorrhage). It is important that the nurse check all tubing and catheter connections at least every hour. Because insertion of a central venous catheter creates risk of significant complications, the nurse must ensure that the catheter is secured in place with no possibility of dislodgement. If catheter misplacement or migration is suspected, a chest radiograph may be needed to verify placement (for further information, see Chapter 10).

Fat emulsions are typically piggybacked into the PN line just before the solution enters the vein. This practice evolved during the initial years of parenteral alimentation using fat emulsions and arose from a concern that prolonged contact between the PN amino acids and the lipids would cause emulsification of the fat and result in the production of fat emboli.

Administration of fat emulsion is contraindicated in neonates with jaundice. Lipid binds with albumin and will displace bilirubin, resulting in an increased risk of hyperbilirubinemia.

Children who receive prolonged PN frequently demonstrate abnormalities in liver function studies (i.e., elevation of the liver enzymes and bilirubin values). Many of these abnormalities are transient and resolve shortly after PN nutrition is discontinued; however, if these abnormalities are noted, the child should be weaned from the PN as clinically appropriate.

Cholestatic jaundice is a serious but incompletely understood complication of PN that is associated with periportal fibrosis, bile duct proliferation, and bile stasis. This complication contributes to morbidity and mortality in younger infants and children with short gut syndrome (SGS) following intestinal resection.¹⁰ The first sign of cholestatic jaundice is elevation in concentrations of liver enzymes (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]). In addition, the bilirubin will begin to rise and the child may appear jaundiced; cholestasis is defined as a direct bilirubin greater than 2   mg/dL. Risk of cholestatic jaundice can be reduced by cycling and limiting lipid administration to 1   g/kg per day or using alternate day dosing of the fat emulsion. If cholestasis is present, treatment includes administration of ursodeoxycholic acid.

Etiology

The etiologies of intestinal failure can be categorized as congenital anomalies with bowel loss or resection (e.g., complicated gastroschisis, malrotation with volvulus, multiple intestinal atresias), postsurgical complications (e.g., NEC, trauma), dysmotility disorders (e.g., chronic intestinal pseudoobstruction, total intestinal Hirschsprung disease), inflammatory bowel disease (e.g., Crohn’s disease), and congenital enteropathies (e.g., microvillus inclusion disease, intestinal epithelial dysplasia, secretory diarrhea).

Pathophysiology

Each child with intestinal failure is unique, because there are no absolute criteria for the amount and type of bowel needed to sustain absorption of nutrients for appropriate growth. The normal estimated bowel length at birth is 250 ± 40   cm.²² After the loss of a bowel segment, the intestine undergoes a process termed intestinal adaptation. As a general rule, infants can experience acceptable intestinal function with less than 15   cm of intestine if the ileocecal valve is intact, and with 30 to 45   cm of intestine if the ileocecal valve is absent or does not function.¹⁷ It is unlikely that children with less than 20   cm of remaining bowel will be able to grow and develop with enteral nutrition alone. Intestinal transplantation may offer hope to these patients.

Many children with SGS no longer have a functioning ileocecal valve; this results in more rapid intestinal transit and decreased absorption of nutrients. Small bowel distension results in stasis and bacterial overgrowth. Small bowel bacterial overgrowth can result in bacterial translocation and sepsis that contributes to morbidity and mortality in this patient population. For these reasons, enteral antibiotics, and most recently probiotics (bacteria administered to support healthy intestinal flora), are often prescribed for children with SGS to minimize small bowel bacterial overgrowth.

Intestinal adaptation is characterized by increasing intestinal mass, lengthening of villi, and improved absorption at the epithelial level.^10,22 This process allows for the remaining intestine to compensate for the loss of the bowel by increasing its surface area and functional abilities.¹⁰ Successful adaptation is described as the ability to achieve normal growth, fluid balance, and electrolyte concentration without PN.⁵³ The time frame required for adaptation is unclear and dependent on the etiology of the SBS and the functional state of the remaining bowel, although adaptation can occur over weeks to months.^10,22 Children have been transitioned to enteral feedings exclusively over periods as long as 8 years. There are a number of metabolic derangements that occur after loss of bowel that are summarized in Table 14-6.

Table 14-6 Metabolic Derangements and Consequences in Children with Short Gut Syndrome

From Cohran VC and Kocoshis SA: Short bowel. In Baker S, Baker R, David A, editors: Pediatric nutrition support, Sudburry, MA, 2007, Jones and Bartlett.

Management

The care of patients with intestinal failure includes complementary medical and surgical interventions with the goals of optimizing oral or enteral diet, PN prescription, treatment of bacterial overgrowth, and use of stool bulking agents. Surgical procedures include bowel lengthening procedures and intestinal transplantation.

In order for the bowel to adapt it must be fed; therefore initiation of early enteral feeding is paramount. Enteral feeding can start with a continuous infusion of nutrition administered through a nasogastric, gastrostomy, or transpyloric feeding tube. Appropriate fluid administration is as important as caloric intake. Many of these children will require 150% to 160% of maintenance fluid to remain hydrated. Once a continuous rate of feeding is tolerated, the time interval can be shortened and feedings can be consolidated if larger volumes are tolerated. Once a consolidated hourly feeding schedule is tolerated, the child can be advanced to bolus feeding.

Often 20   Kcal/ounce feedings are initiated and can be advanced to higher caloric density (to as high as 30   Kcal/ounce [1   Kcal/mL]) as tolerated. Usually these children are fed with casein hydrolysate formulas and elementary amino acid-based formulas such as Pregestimil (Mead Johnson, Evansville, IN), EleCare (Abbott Nutrition, Columbus, OH), and Neocate (Nutricia North America, Gaithersburg, MD) in infants and Peptamen Jr (Nestle Nutrition, North America, Minneapolis, MN) and Neocate Jr.(Nutricia North America, Gaithersburg, MD) in older children. These formula types are easier to digest and are less likely to trigger an immune response, so they will enhance bowel adaptation.¹⁰

The eventual goal of medical and surgical therapy is appropriate growth with enteral intake alone, without the need for PN. Promotion of oral food intake should be encouraged; many of these children will have an oral aversion.

When children are unable to achieve appropriate growth with enteral feedings, they may be considered surgical candidates for procedures to restore normal bowel diameter, lengthen the bowel, or both. The goals of surgical intervention include reducing stasis, improving motility, and increasing the effective mucosal surface area.²⁹ The most common short bowel procedures are the Bianchi, Kimura, and the serial transverse enteroplasty procedure.

The Bianchi procedure is the oldest procedure and involves a longitudinal incision to create two tubes to lengthen the bowel (Fig. 14-5). The Kimura procedure (Fig. 14-6) is an alternative procedure for patients with SGS and inadequate mesentery who are not candidates for the Bianchi procedure. The serial transverse enteroplasty (STEP) procedure augments bowel length by stapling dilated bowel in a zigzag fashion to achieve more effective bowel surface area (Fig. 14-7).

Fig. 14-5 The Bianchi intestinal lengthening procedure. The bowel is divided in a longitudinal plane to create two tubes, which after reanastomosis results in doubling of the intestinal length at the expense of halving the bowel wall circumference.

(From Warner BW: Short-bowel syndrome. In Grosfeld JL et al, editors: Pediatric surgery, ed 6, Philadelphia, 2006, Mosby.)

Fig. 14-6 The Iowa (Kimura) intestinal lengthening procedure. The antimesenteric bowel wall is pexed to the undersurface of the abdominal wall. A seromyotomy along the bowel wall and mechanical abrasion of the abdominal wall before pexing promote neovascularization of the antimesenteric bowel, based on the systemic-derived abdominal wall. Several months later, the bowel may be longitudinally divided into two limbs. The first is based on the systemic blood supply to the antimesenteric limb, and the other is based on the mesenteric blood supply. These two limbs are then reapproximated to double the intestinal length.

(From Warner BW: Short-bowel syndrome. In Grosfeld JL et al, editors: Pediatric surgery, ed 6, Philadelphia, 2006, Mosby.)

Fig. 14-7 The serial transverse enteroplasty procedure. Multiple fires of an anastomotic stapling device to alternating sides of the bowel wall result in decreased bowel caliber with an increased length of enteral nutrient transit.

(From Warner BW: Short-bowel syndrome. In Grosfeld JL et al, editors: Pediatric surgery, ed 6, Philadelphia, 2006, Mosby.)

With advances in surgical techniques and immunosuppressive therapy, intestine transplantation is successful as an isolated procedure and when combined with transplantation of other organs.⁵⁴ A major reason for the increased success of intestinal transplantation is the availability of more potent immunosuppressants such as tacrolimus (Prograf). The major limiting factor that prevents widespread use of transplantation is the lack of available organs for transplantation. Because children with less than 15   cm of bowel are not likely to tolerate enteral feeding and thrive, they should be referred to an intestinal rehabilitation and transplant program as soon as possible.

The ideal intestine donor has the same blood type, weighs within 10% of the recipient’s body weight, and is close in age to the recipient. All intestine recipients have a stoma to allow for bowel surveillance and access for endoscopy and biopsy. Figure 14-8 shows the technical details of isolated intestine transplant procedure and intestine transplant in combination with other organs.⁵⁴

Fig. 14-8 The three basic intestinal transplant procedures (the graft is shaded): Isolated intestine transplant, Intestine transplant combined with liver transplant, and multivisceral transplant. With the isolated intestine transplant, the venous outflow may be to the recipient portal vein (center), to the inferior vena cava (left), or to the superior mesenteric vein (right).

(From Reyes JD: Intestinal transplantation. Semin Pediatr Surg 15:228-234, 2006.)

The priorities of care for patients with liver-intestine failure (so-called “ABCs” of care) in the pediatric critical care unit include aeration, bowel integrity, and caloric or hydration requirements. As with any critical care patient, the nurse will assess and support the child’s airway, breathing, and circulation. Bowel integrity is initially assessed by evaluating the physical appearance of the stoma (normal stoma appears pink and moist) and enteric output. Initially caloric requirements are met with PN. Enteral feedings are initiated as soon as possible after the transplant.

Critical care goals are to support the patient to be hemodynamically stable, with adequate oxygenation and ventilation, free of requirement for mechanical ventilation support. Airway clearance and spontaneous ventilation may be ineffective as a result of the lengthy abdominal surgical procedure (and resultant need for anesthetic administration during the long procedure), visceral edema, and pain. With the postoperative resolution of coagulopathies, aggressive chest physiotherapy is initiated. Intestine recipients generally require mechanical ventilation longer than isolated liver recipients (see Liver Transplantation in Chapter 17), because intestine recipients typically are in poor health before the transplant and often have a precarious fluid balance. Additional challenges include open abdominal wounds and potential need for surgical reexploration for complications such as perforation or bleeding.

Complications of intestine transplant procedures include rejection, infection, and posttransplant lymphoproliferative disease (PTLD). Signs and symptoms of intestinal graft rejection include a pale or dusky stoma, an increase or decrease in enteric output, abdominal pain, and guaiac positive output. Postoperative endoscopic biopsies of the transplanted bowel are made through the child’s stoma on a routine and as needed basis. Rejection is not usually a visual finding during endoscopy, and there are no known confirmatory laboratory tests. Endoscopy with biopsy is the gold standard.

Infection is a common complication following intestine transplant. Viral infection is the most threatening infection for the intestine recipient. Primary infections are typically more serious and occur when the recipient has had no previous exposure to a virus and becomes infected in the posttransplant period. A secondary infection represents reactivation of a previous latent virus.

The most common infecting organisms are cytomegalovirus and Epstein-Barr virus. For the isolated intestine recipient efforts are made to match the recipient and donor cytomegalovirus status. The donor-recipient serology relationship is important because prophylactic therapy is initiated based on viral titers.

Post-transplant lymphoproliferative disorder (PTLD) is one of the most underrated complications of immunosuppression. PTLD is the development of continually proliferating B-lymphocytes, presumably under the influence of Epstein-Barr virus. Diagnosis is made by clinical examination and histologic review. Clinical signs and symptoms include fever, lymphadenopathy, GI symptoms, and weight loss. If the biopsy specimen is diagnostic for PTLD, treatment includes holding or reducing immunosuppression and initiating IV antiviral therapy and immunoglobulin therapy (see Chapter 17 for additional information).

PTLD is a difficult complication to treat following intestine transplantation, because rejection can develop following withdrawal of immunosuppression. Therefore careful titration of immunosuppression is imperative to promote recovery, although the graft may be lost to preserve the child’s life.

Etiology and Pathophysiology

GI bleeding in children can result from inflammation of the intestine, congenital or acquired visceral or vascular anomalies, trauma, esophageal varices, ulcers, or coagulopathies. The incidence of acquired GI bleeding in critically ill children receiving mechanical ventilation has been reported to be as high as 51.8% in some series.^14,47 Identified risk factors include a pediatric risk of mortality 2 score of 10 or higher, operating room procedures longer than 3   hours, hepatic insufficiency, coagulopathy, respiratory failure, and high-pressure ventilator settings of greater than or equal to 25   cm H₂O.^14,47

Upper GI bleeding originates proximal to the ligament of Treitz. Causes include gastritis, peptic ulcer disease (from nonsteroidal antiinflammatory use and from Helicobacter pylori infection), esophageal or gastric varices, and vascular malformations.

Lower GI bleeding is the result of mucosal disruption distal to the ligament of Treitz and can be caused by Crohn’s disease, intussusception, or ischemic injury. Common causes of GI bleeding in children are listed in Table 14-7.

Table 14-7 Causes of Gastrointestinal Bleeding in Infants and Children

GI, Gastrointestinal.

Data from Arensman RM, Browne M, Madonna MB: Gastrointestinal bleeding. In Grosfeld JL et al, editors: Pediatric surgery, ed 6, Philadelphia, 2006, Mosby; Martin SA, Simone S: Gastrointestinal system: In Slota MC, editor: Core curriculum for pediatric critical care nursing, ed 2, St Louis, 2006, Mosby-Elsevier.

Microscopic bleeding may cause no symptoms and may be detectable only through analysis of GI secretions or feces. Significant GI bleeding may result in hypovolemia and low cardiac output, shock, and death (see also Shock, in Chapter 6). See the section on Gastrointestinal Bleeding in the Chapter 14 Supplement on the Evolve Website for additional information about the pathophysiology of GI hemorrhage.

Clinical Signs and Symptoms

The appearance of the child with GI bleeding varies considerably, and it is affected by the amount and rapidity of blood loss. Usually the child is brought to the provider’s office or emergency department for treatment after vomiting blood, passing black, tarry stools (melena), or passing bright red blood per rectum (hematochezia). Bright red vomitus indicates recent or ongoing upper GI hemorrhage, whereas coffee-ground vomitus indicates partial digestion of the blood.

The color and the source of the bleeding often help to identify the location of the bleeding. Bright red vomitus usually results from esophageal or gastric bleeding, and bright red blood in the stool results almost exclusively from rectal bleeding. Maroon, black, or tarry stool often indicates the presence of upper GI bleeding; the color derives from blood that is partially digested during passage through the bowel.

The patient with sudden, significant bleeding is more likely to demonstrate faintness, pallor, tachycardia, thready pulses, diaphoresis, thirst, apprehension, and other signs of acute blood loss. The child with gradual bleeding, however, may experience only weakness and faintness; the child may be aware of passing black stools, but may not know that significant blood loss has occurred.

The child with GI bleeding may have a normal systolic blood pressure, particularly in the recumbent position, despite significant intravascular volume loss and shock. Signs of decreased peripheral perfusion are usually the earliest signs of severe hemorrhage and include tachycardia; cool, pale, mottled skin; decreased peripheral pulses; and oliguria (urine output averaging less than 0.5-1.0   mL/kg per hour despite adequate fluid intake) or anuria.

Arterial constriction makes blood pressure measurement by cuff difficult or inaccurate, because automated oscillometric blood pressure cuffs may provide falsely high readings in the presence of shock with or without hypotension. The arterial waveform displayed from an indwelling arterial line usually is dampened in appearance, with a narrow pulse pressure.

Metabolic acidosis and a rise in serum lactate may be noted. Oxyhemoglobin desaturation may not be present or detected by pulse oximetry, because existing hemoglobin may be saturated with oxygen. The oximeter device may have difficulty detecting a signal if the child’s pulses are weak. The nurse should notify an on-call provider immediately of these findings, because the patient’s status is critical (see Chapter 6 for more information about recognition and treatment of shock).

Digested blood has a specific odor that may be noted on the patient’s breath even before the onset of melena or the first expulsion of hematemesis. This odor is qualitatively the same as that of melena, but it is usually fainter. To detect early evidence of GI bleeding, all GI fluids and stools of patients at risk should be tested for the presence of blood (hemoprotein). The presence of occult blood in gastric fluid may be determined with point-of-care (bedside) testing such as the use of Gastroccult (Beckman Coulter, Brea, CA).

During the first days of life, the Apt test (named for Leonard Apt) may be performed to distinguish between swallowed maternal blood and GI bleeding as a cause of blood in the newborn’s stool.⁴ The Apt test is performed by placing blood from the neonate on filter paper with 1% sodium hydroxide (a reagent that reacts with fetal hemoglobin).⁴ Maternal blood will appear rusty brown, whereas the neonate’s blood that contains fetal hemoglobin will remain pink or red.⁴ The pink or red color is a positive result, indicative of presence of blood from the neonate.

Management

The three phases of management of the child with GI bleeding are resuscitation, specific diagnosis, and specific treatment. A diagnostic algorithm for upper GI bleeding is presented in Fig. 14-9.

Fig. 14-9 Diagnostic algorithm for upper gastrointestinal (GI) hemorrhage. PPI, Proton pump inhibitor; PUD, peptic ulcer disease.

(From Arensman RM, Browne M, Madonna MB: Gastrointestinal bleeding. In Grosfeld JL, O’Neill JA, Coran AG, Fonkalsrud EW, editors: Pediatric surgery, ed 6, Philadelphia, 2006, Mosby.)

During resuscitation and replacement of intravascular volume, nursing observations may help to determine the source of the child’s bleeding. If saline lavage through a nasogastric tube reveals grossly bloody or red-tinged aspirate, ongoing upper intestinal bleeding is present. Nursing interventions during resuscitation of the child with GI bleeding are summarized in Box 14-1.

Proton pump inhibitors and histamine-2 receptor antagonists are the most commonly used pharmacologic agents to prevent the development of GI bleeding (Table 14-8). Although only a small number of critically ill children will develop gastric bleeding, the associated morbidity justifies the common practice of prophylaxis.

Upper GI endoscopy is indicated when bleeding is significant. It can be performed in the critical care unit and is the diagnostic procedure of choice. Push endoscopy is one method, and newer diagnostic tools include video capsule endoscopy. For diagnosis of small bowel bleeding, video capsule endoscopy can be a valuable diagnostic tool. A minute endoscope is embedded in a capsule that is swallowed. The capsule is propelled by peristalsis and captures images that are recorded on a hard drive attached to the patient’s belt.

Indications for urgent surgical intervention include the development of intestinal perforation (identified by the presence of free air on an abdominal radiograph) or severe hemorrhage unresponsive to blood replacement therapy. If GI bleeding is stopped effectively with medical management and after resuscitation is complete, further studies will be performed to determine the origin of the bleeding and whether the patient is stable. Surgical intervention may be required at that time.

Etiology

Bilirubin is the major byproduct of hemoglobin breakdown. Hyperbilirubinemia is an elevation in the level of total serum bilirubin (TSB); it results from an imbalance between bilirubin production and excretion. An increase in bilirubin production can result from increased red blood cell (RBC) breakdown (such as hemolysis or decreased RBC life span in the neonate), or impaired bilirubin excretion (such as decreased capacity for elimination in the neonate or cholestatic liver disease). This section addresses hyperbilirubinemia in the neonate; hyperbilirubinemia in the older child is included in the liver failure section.

When the neonate’s TSB is elevated, the bilirubin can cross the blood-brain barrier, causing acute bilirubin encephalopathy or the chronic form of bilirubin encephalopathy, kernicterus. Kernicterus is a yellow staining and brain tissue damage with degenerative lesions, resulting from central nervous system exposure to high concentrations of unconjugated bilirubin. Hyperbilirubinemia is commonly associated with prematurity, breast feeding, and other factors summarized in Box 14-2.

In the first week of life, it is estimated that approximately 60% of normal newborns will become clinically jaundiced.⁴² Newborns are now discharged from the hospital at approximately 24 to 48 hours after birth, before the typical TSB peak at 48 to 96 hours. As a result, hyperbilirubinemia is the most common reason for hospital readmission of the neonate. A sentinel event alert was issued by the Joint Commission in 2001, because an increased number of cases of kernicterus were being diagnosed in otherwise healthy newborns.

Pathophysiology

When RBCs reach the end of their 120-day life span, they normally are sequestered in the spleen. The cells are destroyed, and the heme portion of the hemoglobin molecule is oxidized, and bilirubin is formed. Bilirubin is bound to albumin in the plasma and taken up in the liver, where it is combined with a sugar through the action of the enzyme, bilirubin uridine diphosphate glucuronosyltransferase, making conjugated bilirubin.¹¹ Conjugated bilirubin is water soluble, it cannot cross the blood-brain barrier, and it is normally excreted in bile (Fig. 14-10). Free bilirubin, called unconjugated (indirect) bilirubin, is lipid soluble and not water soluble. Because unconjugated bilirubin is thought to diffuse freely into the brain, high concentrations of this form of bilirubin may be neurotoxic and cause kernicterus.

Fig. 14-10 The pathophysiology of neonatal hyperbilirubinemia.

(From Colletti JE, et al: An emergency medicine approach to neonatal hyperbilirubinemia. Emerg Med Clin N Am 25:1117-1135, 2007.)

Increased TSB concentrations can result from an elevation in conjugated or unconjugated bilirubin. An elevation in the level of conjugated bilirubin is known as direct hyperbilirubinemia. It most commonly results from biliary tree obstruction or liver disease, although it also may occur with metabolic disorders, sepsis, meningitis, or drug reactions.

Elevation of unconjugated bilirubin levels is known as indirect hyperbilirubinemia. It most commonly occurs as a result of excessive bilirubin production in the neonatal period. Premature and critically ill neonates bind bilirubin less effectively than do healthy infants, so indirect hyperbilirubinemia is common among premature neonates. In addition, it can result from impaired transport of bilirubin caused by hypoxia, acidosis or the administration of albumin-binding drugs that displace bilirubin from the albumin. Impaired hepatic uptake of bilirubin also may cause indirect hyperbilirubinemia.

Kernicterus is yellow (bilirubin) staining of the basal ganglia in the brain of neonates with severe jaundice. Although the precise mechanisms responsible for the entry of bilirubin into the brain are not known, disruption of the blood brain barrier from increased permeability (e.g., caused by hyperosmolarity or severe asphyxia), prolonged transit time (e.g., caused by increased central venous pressure [CVP]), or increased blood flow (e.g., caused by hypercarbia and acidosis) are thought to be contributory.⁶³

Jaundice (icterus) can usually be detected when the child’s TSB level exceeds 3.0 to 5.0   mg/dL (normally it is less than 1.5   mg/dL). Jaundice is characterized by the accumulation of yellow pigment in the skin and other tissues. In the skin, the jaundice is apparent with digital blanching. Jaundice is usually evident first in the sclera and then progresses in a cephalocaudal distribution. The urine color may become brown as the result of the urinary excretion of conjugated bilirubin. In addition, the stools may become gray or acholic, indicating the absence of normal fecal elimination of bilirubin. Clinical signs that the jaundice is pathologic include persistently elevated direct bilirubin level, dark urine, and acholic stools. Infants with these signs should be evaluated for liver disease.

The neurotoxic sequelae of hyperbilirubinemia are the most worrisome, and a grading for acute bilirubin encephalopathy has been proposed. The earliest signs may include alteration in the tone of extensor muscles (hypotonia or hypertonia), retrocollis (backward arching of the neck), opisthotonus (backward arching of the trunk), and a poor suck.³ The early symptoms may intensify and be accompanied by a shrill cry and unexplained irritability alternating with lethargy.³ Therapy at this stage may prevent advancement of symptoms. Cessation of feeding, irritability, seizures, and altered mental status are later symptoms of acute bilirubin encephalopathy. The final stage is kernicterus and may be irreversible with the development of cerebral palsy, deafness or hearing loss, and impairment of upward gaze. Kernicterus has a significant mortality (at least 10%) and long-term morbidity (at least 70%), and most cases are reported in infants with TSB greater than 20   mg/dL.²⁸

Noninvasive (transcutaneous) bilirubin measurements can be obtained with newer instruments. Published data suggest that in most infants the measurements are within 2 to 3   mg/dL of serum measurements and can replace TSB measurements in most cases.² In infants undergoing phototherapy, this measurement is not reliable and should not be used.

It is possible to measure serum levels of total bilirubin and direct (or conjugated) bilirubin. Current recommendations caution against inferring the indirect (unconjugated) bilirubin from the TSB, because the difference between the total and direct bilirubin is not constant. Current guidelines recommend that providers evaluate the TSB level⁶³; the higher the TSB, the greater the risk of bilirubin encephalopathy. Treatment is indicated for infants with bilirubin levels in excess of 20   mg/dL.

Management

If direct hyperbilirubinemia is present, the nurse should be alert for the appearance of additional signs of liver disease or decreased hepatic function. Additional diagnostic tests are indicated (these tests are reviewed in greater detail in the section, Liver Failure, later in this chapter).