WEDNESDAY APRIL 7, 2010 NICOLE WITHROW Necrotizing Enterocolitis

Definition NEC is an acute inflammatory disease of the gastrointestinal mucosa Characterized by mucosal or even deeper intestinal necrosis Most common GI emergency in neonates The condition is commonly complicated by perforation  Resulting in the outflow of intestinal contents into the abdominal cavity Although the etiology is unknown, three factors appear to play an important role in the development of NEC  Intestinal ischemia, colonization by pathogenic bacteria, and enteral feedings

Generalized signs of NEC These signs may be indicative of sepsis: Hypotonia Decreased activity Pallor Decreased oxygen saturation Decreased perfusion Temperature instability Recurrent apnea and bradycardia Respiratory distress Metabolic acidosis Oliguria Cyanosis

Gastrointestinal signs of NEC Abdominal distention Decreased bowel sounds Feeding intolerance Increasing or bile-stained residual gastric aspirates Vomiting (bile or blood) Grossly bloody stools Abdominal tenderness Erythema (redness) of the abdominal wall

Abdominal Distention One of the later and more obvious gastrointestinal signs of NEC Bowel perforation and therefore leakage of gastrointestinal contents into the abdominal cavity may cause severe abdominal distention such as this…

Frequency NEC occurs in about 1%to 5% of newborns in NICUs Outbreaks seem to follow an epidemic pattern within nurseries, suggesting an infectious etiology, although a specific causative organism has not been isolated Extremely premature infants (1000 g) are particularly vulnerable, with reported mortality rates of % The mortality rate ranges from 10% to more than 50% in infants who weigh less than 1500 g, depending on the severity of disease, compared with a mortality rate of 0- 20% in babies who weigh more than 2500 g Sepsis occurs in 33% of infants which may also lead to death

Risk factors for developing NEC Preterm birth remains the most prominent risk factor in development of NEC  In the preterm infant the development of NEC may be delayed for up to 30 days  The onset of NEC in the term infant usually occurs earlier, 4 to 10 days after birth Lowered oxygen levels or birth asphyxia during delivery  Lack of oxygen leading to intestinal ischemia and eventually necrosis Infants with polycythemia  Increased amounts of RBCs may thicken blood and therefore hinder transportation of oxygen to the intestines Race  Some studies indicate a higher frequency of NEC in African-American neonates than Caucasian neonates Congenital heart disease  Poor systemic perfusion due to circulatory insufficiency  Patent ductus arteriosus (ductus arteriosus fails to close normally resulting in abnormal blood flow between aorta and pulmonary artery)  Treatment for this condition includes the medication Indomethacin which is related to the development of NEC due to decreased intestinal perfusion

Risk factors for developing NEC “Breast milk contains many factors such as immunoglobulins, particularly IgA, lymphocytes and macrophages (mediate inflammatory response) that potentially mature the intestinal barrier and may prevent the occurrence of NEC” (Barlow B, Santuli T, Heird W, et al. An experimental study of acute necrotizing enterocolitis-the importance of breast milk. J Pediatric Surg. 1984, 9:587) Some studies indicate that infants are at a higher risk for developing NEC if they are formula-fed due to the condition being less common among breast-fed infants…

Diagnosing NEC NEC is confirmed by radiographic examination which may reveal: Bowel loop distention Pneumatosis intestinalis (gas in the bowel wall) Pneumoperitoneum (gas in the abdominal cavity), portal venous air, or a combination of these findings  Pneumatosis intestinalis, pneumoperitoneum, and portal venous air are caused by gas produced by the bacteria that invades the wall of the intestines and escapes into the peritoneum and portal system when perforation occurs

Bowel Loop Distention Radiographic examination reveals bowel loop distention

Diagnosing NEC Laboratory evaluation: Complete blood cell count with differential, coagulation studies, ABG analysis, serum electrolyte levels, and blood culture The white blood cell count may be either increased or decreased  In response to bacterial colonization The platelet count and coagulation studies may be abnormal  Thrombocytopenia (low platelet count) and disseminated intravascular coagulation Electrolyte levels may be abnormal, with leaking capillary beds and fluid shifts with the infection  Hyponatremia

Treatment Discontinue enteral feedings Administer NGT attached to intermittent suction  To provide gastric decompression (relieve pressure) Parenteral therapy  Fluid resuscitation (to support circulation)  TPN (usually for days while intestine heals) Systemic antibiotic therapy  Also institute infection control and proper hand washing Possible surgery  Dependent on severity

Surgery Surgery should be considered for an infant with NEC whose clinical and laboratory condition worsens despite nonsurgical support Extensive involvement may necessitate surgical intervention and establishment of an ileostomy, jejunostomy, or colostomy Surgical intervention is needed in < 25% of infants Indications for surgery include:  Intestinal perforation (pneumoperitoneum)  Signs of peritonitis (absent bowel sounds, tenderness or erythema and edema of the abdominal wall)  Purulent material aspirated from the peritoneal cavity by paracentesis

Necrotizing Enterocolitis An example of necrotic intestinal tissue requiring surgery… Combination liver and small bowel transplantation may also be necessary for severely affected infants who have also acquired life-threatening hyperalimentation hepatitis

Further Complications Some conditions resulting from this disease in surviving infants include short- bowel syndrome, narrowing of the colon with obstruction, fat malabsorption, and failure to thrive secondary to intestinal dysfunction

Preventing NEC Corticosteroid administration  Promotion of intestinal maturity Human milk is thought to provide some degree of protection Use of Indomethacin used during pregnancy (medication relaxes uterine smooth muscle) may cause adverse reactions Umbilical catheters, if required, should be placed below the renal arteries  May cause intravascular clotting or possibly perforate walls and enter pericardial space, may increase risk of infection Polycythemia should be treated promptly Possibly delaying feedings for several days to weeks in premature infants while providing TPN Recent evidence suggests that probiotics (ex: Bifidus infantis, Lactobacillus acidophilus) may help prevent NEC

Case Study L.J. a 36-week SGA African-American infant is admitted into the NICU and begins receiving enteral feedings. The infant’s pulse and respirations are periodically low and the infant has been placed on a warming bed. A diaper change reveals an absence of urinary voiding but also a small amount of grossly bloody stool. The nurse assesses for bowel sounds and hears none and also notices a slightly rounded abdomen. What are some of the evident risk factors? What signs and symptoms in this case may be indicative of NEC? How might the residual gastric aspirates of this infant look? What interventions would follow a diagnosis of NEC?

Case Study Risk factors:  36-week SGA (prematurity)  African-American  Receiving enteral feedings Signs and symptoms in this case:  Pulse and respirations are periodically low  Warming bed (temperature instability)  Absence of urinary voiding (oliguria)  Grossly bloody stool  Lack of bowel sounds  Slightly rounded abdomen (abdominal distention) How might the residual gastric aspirates of this infant look?:  Bile-stained What interventions would follow a diagnosis of NEC?  Discontinue enteral feedings  Administer NGT attached to intermittent suction  Parenteral therapy  Fluid resuscitation (to support circulation)  TPN (usually for days while intestine heals)  Systemic antibiotic therapy  Also institute infection control and proper hand washing  Most likely surgery

Questions?

Resources Bakewell-Sachs, S., Medoff-Cooper, B., Escobar, G., Silber, J., & Lorch, S. (2009). Infant functional status: the timing of physiologic maturation of premature infants. Pediatrics, 123(5), e Cakmak Celik, F., Aygun, C., & Cetinoglu, E. (2009). Does early enteral feeding of very low birth weight infants increase the risk of necrotizing enterocolitis?. European Journal of Clinical Nutrition, 63(4), Ladd, N., & Ngo, T. (2009). Pharmacology notes. The use of probiotics in the prevention of necrotizing enterocolitis in preterm infants. Baylor University Medical Center Proceedings, 22(3), Perry, Shannon, Hockenberry, Marilyn, Lowdermilk, Deitra, & Wilson, David. (2009). Maternal child nursing care. Mosby, Pickard, S., Feinstein, J., Popat, R., Huang, L., & Dutta, S. (2009). Short- and long- term outcomes of necrotizing enterocolitis in infants with congenital heart disease. Pediatrics, 123(5), e Thompson, A., & Bizzarro, M. (2008). Necrotizing enterocolitis in newborns: pathogenesis, prevention and management. Drugs, 68(9),