WEDNESDAY APRIL 7 , 2010NICOLE 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 neonatesThe 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:

HypotoniaDecreased activityPallorDecreased oxygen

saturationDecreased perfusionTemperature

instability

Recurrent apnea and bradycardia

Respiratory distressMetabolic acidosisOliguriaCyanosis

Gastrointestinal signs of NEC

Abdominal distentionDecreased bowel soundsFeeding intoleranceIncreasing or bile-stained residual gastric

aspirates Vomiting (bile or blood)Grossly bloody stoolsAbdominal tendernessErythema (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 NICUsOutbreaks 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 40-100%

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 distentionPneumatosis 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 feedingsAdminister NGT attached to intermittent

suction To provide gastric decompression (relieve pressure)

Parenteral therapy Fluid resuscitation (to support circulation) TPN (usually for 14-21 days while intestine heals)

Systemic antibiotic therapy Also institute infection control and proper hand

washingPossible 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 infantsIndications 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

http://www.youtube.com/watch?v=f13bhv7d9gw

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 reactionsUmbilical 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 infectionPolycythemia should be treated promptlyPossibly 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 14-21 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), e878-86

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), 580-584.

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), 287-291.

Perry, Shannon, Hockenberry, Marilyn, Lowdermilk, Deitra, & Wilson, David. (2009). Maternal child nursing care. Mosby, 731-732.

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), e901-6.

Thompson, A., & Bizzarro, M. (2008). Necrotizing enterocolitis in newborns: pathogenesis, prevention and management. Drugs, 68(9), 1227-1238.