What happens in the NICU?

The Neonatal Intensive Care Unit (NICU), in contrast to the newborn nursery, is a highly specialized unit with skilled staff prepared to handle the most dangerous postnatal complications of sick or premature infants. Babies can be found in incubators known as isolettes, which control their temperatures. The  average gestational age (GA) at birth is between 38 and 42 weeks, and an infant delivered before 37 weeks is considered to be "premature". The last trimester (12 weeks) in the womb is an important time for the baby's growth, and underdeveloped organs are vulnerable. The NICU staff, led by a neonatologist, monitors around the clock to identify and manage any problems. Here are a few of the most common:

Apnea: when a baby, typically less than 35 weeks GA, stops breathing momentarily for OVER 20 seconds. This can be central (the brain needs help reminding the baby to breathe, which is treated with caffeine) or obstructive (managed with suctioning and repositioning).

Bronchopulmonary Dysplasia (BPD): when the baby's lungs do not have a change to fully develop, they will need help to breathe until their lungs mature. This may include supplemental oxygen using either a nasal cannula, CPAP, or mechanical ventilation. Typically, OB/GYN doctors help prevent this by giving steroids (betamethasone) to mothers within 24 hours of their delivery if between 24-34 weeks GA. After delivery of a preterm infant, the neonatologist may provide further protection by coating the newborn's lungs in a material called surfactant. BPD is diagnosed if any newborn requires 28 or more days of oxygen support, and is further classified as mild, moderate, or severe depending on how much oxygen he or she is on at 36 weeks GA.

Polycythemia or Anemia: when the baby's hematocrit (ratio of red cells in the blood) is greater than 65% or below 30%, respectively. Anemia of prematurity occurs in the second month of life.

Patent Ductus Arteriosis: persistence of a connection between the right sided chamber of the heart and the aorta, which normally closes at birth. Characterized by tachypnea (fast breathing), cardiac murmur, and a low mean arterial pressure (MAP). Diagnosed with an echocardiogram.

Retinopathy of Prematurity: poor formation of the blood vessels of the eyes, occurs in most infants less than 28 weeks GA, screened for by an ophthalmologist if the baby is <30 weeks GA.

Necrotizing Enterocolitis: when the baby's bowel becomes overwhelmed with bacteria, leading to air in the walls of the intestines and can lead to perforation. Usually occurs in very preterm infants and is characterized by poor feeding, abdominal distension, and bloody stools.

Intraventricular Hemorrhage: when there is bleeding into spaces within the baby's brain known as the ventricles. Usually occurring within the first 3 days of birth and in very premature infants (<1500 grams) who have not fully developed their brains yet.


Problems in full term newborns (>37 weeks) that may require a NICU stay include hypoglycemia, poor feeding, poor tone, meconium aspiration syndrome, transient tachypnea of the newborn, infection, hyperbilirubinemia, and anatomical/chromosomal abnormalities.

Preterm infant mortality falling, prevalence of cerebral palsy rising

A recent study by Vincer et al published in the Journal of Pediatrics and Child Health reported on the rates of preterm infant mortality and cerebral palsy (CP) over the last 20 years. They found that the birth prevalence of CP among very preterm infants (less than 31 weeks) is on the rise, but the reasons are unclear.

CP is a permanent condition caused by damage to motor control centers in the brain before or shortly after birth, resulting in non-progressive impaired movement and permanent physical disability. The affected child typically has problems with uncontrolled spastic movements and/or impaired coordination of movement. Some cases are associated with epilepsy, poor cognition and/or difficulty with communication.

Between 1988 and 2007, very preterm infant mortality steadily declined while CP has been on the upswing. Vincer et al notes that maternal risk factors, anemia and tocolytic use have all been on the rise as well. Whether or not these represent a correlation has yet to be determined.

Reference

Vincer MJ, Allen AC, Allen VM, Baskett TF, O’Connell CM. Trends in the prevalence of cerebral palsy among very preterm infants (<31 weeks’ gestational age). Paediatr Child Health. 2014; 19(4):185-9.

What is Hirschsprung Disease?

Hirschsprung disease, also known as toxic megacolon, is a life threatening intestinal obstruction seen in children.

When a fetus is developing in the womb, each type of cell must successfully migrate to where it belongs and, once there, perform their assigned duties. In this case, the cells, neuroblasts, do not make it to their destination in the distal intestine or they arrive but forget to do their job.

The condition is relatively rare, only occurring in 1 in every 5,000 live births. It is four times more common in males, and the risk is increased in Down syndrome or if a family history is present.

One of the most telltale signs that an infant is suffering from Hirschsprung Disease is the failure of an infant to pass his or her first bowel movement, known as meconeum, within the first 24 hours of life. Other signs include abdominal distention, bilious (yellow bile) vomiting, jaundice and feeding intolerance.

Over 80% of cases occur in infants, but occasionally the condition is seen in older children. In these cases, the child may show signs of chronic constipation, abdominal distention, failure to thrive, fever, diarrhea, vomiting, explosive stools and/or overflow incontinence. These children typically have intermittent problems with having a proper bowel movement, often on laxatives to ease their pain.

The pediatrician will do a physical examination when he or she suspects intestinal obstruction, looking for abdominal distention and a tight anal sphincter. An abdominal x-ray will typically show a dilated section of bowel preceding the area of obstruction. If enterocolitis is ruled out, a contrast enema will be performed, though this test is only 70% sensitive (83% specific). The disease is confirmed by a pathologist following a suction rectal biopsy performed by a surgeon.

If the child is over 12 months old, this condition is very unlikely. Other conditions that may mimic this condition include functional constipation, medication side effects, lead poisoning, sepsis, intussusception, meconeum ileus, meckel diverticulum, hypothyroidism and intestinal malrotation, atresia or stenosis.

Studies have shown that these infants, especially if preterm, also have an increased risk for other congenital abnormalities, such as heart problems, so a doctor may decide to do a thorough workup.

The immediate treatment for Hirschsprung Disease is to “decompress” the bowel obstruction using a nasogastric tube, antibiotics and IV fluids. Once the child is stable, a surgeon will fix the abnormality by removing the affected area of bowel (Pull-through procedure). If the surgery is successful and infection (enterocolitis) is avoided, the prognosis is excellent (<1% mortality) and the child will live a normal life.

Reference

Hirschsprung Disease. DynaMed Database Accessed May 23, 2014, Updated January 24, 2013.

SIRS: The End of a Deadly Disease Spectrum

When an infant or child falls very ill, one of the most feared complications is systemic inflammatory response syndrome (SIRS). 

SIRS is a deadly ending to a spectrum of bloodstream infection which begins when a bacteria or virus enters the bloodstream (bacteremia). In most cases, young bodies can successfully fight off the organism before it causes any serious problems. Unfortunately, this is not always the case. Sometimes, the immune system goes a bit too far and decides to put all of its cards on the table. It releases everything it has, including white blood cells, pro-inflammatory molecules and blood-clotting proteins. This most often leads to the loss of fluids in our blood vessels and the collapse of our circulatory system. Inside the body, the organs (heart, lungs, kidneys, brain) lose vital oxygen and nutrients and begin to shut down. Outside the body, doctors notice signs of shock, which include fever and changes in breathing, heart rate, mental status, blood pressure and temperature regulation. If caught very early, doctors can typically keep the patient alive. In many cases, however, nothing the physician does will save the patient from the downward spiral.

The inci­dence of SIRS is highest in infants (5.16 per 1000), occurring in 20% of low birthweight neonates and resulting in death in over 10% of cases. Studies show that 37% of infections leading to SIRS arise from the respiratory tract, while 25% are primary bloodstream infections (BSIs). 

The management of SIRS is performed in a neonatal intensive care unit (NICU) or pediatric intensive care unit (PICU). Doctors will culture the blood and monitor vital organs while ensuring the body is receiving adequate oxygen. A broad spectrum antibiotic (fights many different infections) is started until a culture comes back from the lab showing what specific organism is causing all the trouble. The antibiotic is then switched to one specifically formulated to kill that bug. One of the most frightening scenarios for a physician is when the culture comes back showing a bacteria that is resistant to all the drugs we have available. This is becoming the case with some gram negative bacteria (Klebsiella and E. coli) that release something called endotoxin and are resistant to our last line of antibiotic defense against them, carbapenems.

Scientists and physicians continue to conduct studies in order to discover ways to prevent SIRS from occurring. Though many different types of treatments have been attempted, the most effective of them continues to be early detection with  prompt antibiotic administration and fluid resuscitation.

• Occasionally, other conditions can trigger SIRS (trauma, ARDS, neoplasm, burn injury, pancreatitis)
• In order to reduce your child's risk, always ensure they are up to date on their vaccinations and be sure to keep them away from undercooked meat, especially beef and chicken.

References

Principles and Practice of Pediatric Infectious Diseases. Judith A. Guzman-Cottrill, Beth Cheesebrough, Simon Nadel, and Brahm Goldstein. Part II, Section A, 11: The Systemic Inflammatory Response Syndrome (SIRS), Sepsis, and Septic Shock. Pg 97-104.