Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists.
I'm Pradip Kamat. I’m Dr. Ali Towne, a rising 3rd-year pediatrics resident interested in a neonatology fellowship, and I'm Rahul Damania and we are coming to you from Children's Healthcare of Atlanta - Emory University School of Medicine.
Welcome to our Episode a 5-month-old, ex-28 week female with abdominal distention.
Here's the case:
A 5-month-old, ex 28 week, female with a past medical history of severe BPD, pulmonary hypertension, home oxygen requirement, and G-tube dependence presents with hypoxemia and increased work of breathing.
The patient has a history of prolonged NICU stay with 8 weeks of intubation. The patient developed worsening respiratory distress requiring increased support and eventual intubation for hypoxemic respiratory failure. Echo showed worsened pulmonary hypertension with severe systolic flattening of the ventricular septum and a markedly elevated TR jet. The patient had poor peripheral perfusion, and upon intubation was started on milrinone and epinephrine. The patient improved, but the patient then developed abdominal distention and increasing FiO2 requirements prompting an abdominal x-ray. X-ray showed diffuse pneumatosis with portal venous gas. The patient was made NPO and antibiotic therapy was initiated.
To summarize key elements from this case, this patient has NEC.
NEC is not a homogenous disease, but rather a collection of diseases with similar phenotypes.
Some people split NEC into two categories: Cardiac NEC and Inflammatory NEC.
Babies who develop cardiac NEC tend to be significantly older than babies who develop inflammatory NEC (about 1 month vs 2 weeks).
There are three main contributory factors to the development of NEC: gut prematurity, abnormal bacterial colonization, and ischemia-reperfusion injury.
Many cases result from an ischemic insult to the bowel, resulting in translocation of intra-luminal bacteria into the wall of the bowel, but the etiology and course of NEC can be very variable.
This translocation can cause sepsis and death; the ischemia of the bowel can result in intestinal perforation and/or necrosis.

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies in the newborn infant. It is estimated to occur in 1 to 3 per 1000 live births. More than 90 percent of cases occur in very low birth weight (VLBW) infants (BW <1500 g) born at <32 weeks gestation, and the incidence of NEC decreases with increasing gestational age (GA) and BW.
What are key risk factors for the development of NEC?
Prematurity and Birth Weight
NEC incidence is inversely proportional to gestational age.
Congenital Heart Disease
Puts children at risk for NEC due to (1) decreased stroke volume, and (2) improperly oxygenated blood which reduced oxygen supply to the SMA and decreases intestinal wall perfusion.
On the repair of the cardiac lesion, patients develop reperfusion injury due to their now improved perfusion to their gut. This reperfusion causes hyper inflammation via neutrophil activation resulting in NEC.
 NEC primarily occurs in healthy, growing, and feeding VLBW preterm infants. It presents with sudden changes in feeding tolerance (increase in gastric residuals) with both nonspecific systemic signs (eg, apnea, respiratory failure, poor feeding, lethargy, or temperature instability) and abdominal signs (eg, abdominal distension, bilious gastric retention and/or vomiting, tenderness, rectal bleeding, and diarrhea). Physical findings may include abdominal wall erythema, crepitus, and induration.

Other than the immediate risk of death, what are some consequences of NEC long-term?
Higher risk of malnutrition and short gut.
BPD
Developmental delay.

What are some areas of current research and development on the topic of NEC?
Improved biomarkers for early recognition of NEC prior to the development of radiographic findings.
Preventative...