First Aid for the Pediatrics Clerkship, 3 Ed.

Prematurity

 

PREMATURITY

DEFINITIONS

Image Premature infant: Live-born newborn delivered prior to 37 weeks from the first day of last menstrual period.

Image Low birth weigh (LBW): < 2500 g.

Image Very low birth weight (VLBW): 1500 g.

Image Extremely low birth weight (ELBW): < 1000 g.

Image Extremely low gestational age neonate (ELGAN): < 750 g and/or gestational age 26 weeks.

ETIOLOGY

Image Most premature births have no identifiable causes.

Image Identifiable contributors include maternal, fetal, and obstetric:

Image Maternal:

Image Low socioeconomic status.

Image Preeclampsia.

Image Infections (urinary tract infections, group B streptococcus, etc).

Image Chronic medical illness (hypertension, renal disease, diabetes, cyanotic heart disease, etc).

Image Drug use.

Image Fetal:

Image Multiple gestation.

Image Fetal distress (from hypoxia, etc).

Image Congenital anomalies.

Image Obstetric:

Image Incompetent cervix.

Image Polyhydramnios.

Image Chorioamnionitis.

Image Premature rupture of membranes.

Image Placenta previa and abruptio placenta.


Image

Placing a healthy premature neonate in a neutral thermal environment reduces calories burned.


COMMON PROBLEMS IN PREMATURE NEWBORNS

Respiratory Distress Syndrome (RDS; Hyaline Membrane Disease of the Newborn)

ETIOLOGY/PATHOPHYSIOLOGY

Image Occurs secondary to insufficiency of lung surfactant due to immaturity of surfactant producing type 2 alveolar cells.

Image Alveoli are small, inflate with difficulty, and do not remain gas-filled between inspirations.

Image Rib cage is weak and compliant.

Image High surface tension and propensity for alveolar collapse.

Image Alveolar collapse results in progressive atelectasis, intrapulmonary shunting, hypoxemia, and cyanosis.

EPIDEMIOLOGY

Image Usually seen in infants < 32 weeks’ gestational age, but has been seen in full-term infants, especially when the mother has maternal diabetes.

Image The incidence of RDS is inversely proportional to gestational age.

SIGNS AND SYMPTOMS

Image Seen within the first 4 hours of life.

Image Tachypnea.

Image Grunting.

Image Cyanosis.


Image

Production of surfactant can be accelerated by maternal steroid (betamethasone) administration; best if given 24–48 hours prior to delivery.


DIAGNOSIS

Chest x-ray with fine, diffuse reticulogranular or “ground glass” pattern and air bronchograms (see Figure 3-1).

TREATMENT

Image Aggressive respiratory support, including oxygen, continuous positive airway pressure (CPAP), intubation, and mechanical ventilation.

Image To ↓ barotrauma, novel methods of ventilation are sometimes used—high-frequency oscillation, jet ventilation, and liquid ventilation.

Image Exogenous surfactant replacement (instillation via endotracheal tube) has dramatically reduced mortality in infants with RDS.


Image

Most of these neonates also receive antibiotics because clinically and radiographically RDS and congenital pneumonia are indistinguishable.


Bronchopulmonary Dysplasia (BPD)

DEFINITION

Image Chronic lung disease that develops in preterm neonates treated with oxygen and positive-pressure ventilation.

Image Need for supplemental oxygen beyond 28 days of life.

Image Characterized by squamous metaplasia and hypertrophy of small airways.


Image

Antenatal steroids have shown to reduce the incidence of RDS.


Image

FIGURE 3-1. Chest x-ray demonstrating “ground glass” infiltrates consistent with respiratory distress syndrome (with a more focal area of infiltrate or atelectasis in the medial right lung base).

ETIOLOGY

Image Multifactorial.

Image Lung immaturity.

Image Prolonged mechanical ventilation.

Image Barotrauma (from mechanical ventilation).

Image Oxygen toxicity to the lungs.


Image

Infants with bronchopulmonary dysplasia can be wheezing; remember, “not all that wheezes is asthma!”


DIAGNOSIS

Chest x-ray with hyperaeration and atelectasis.

TREATMENT

Image Supplemental oxygen as needed.

Image Oral steroids.

Image Bronchodilators.


Image

BPD occurs in neonates:

Image Born at 22–32 weeks

Image < 1000 g at birth.


Necrotizing Enterocolitis (NEC)

Image

A 32-week-gestation female infant was doing well and advanced to full enteral feeds at 14 days of life. At day 15 of life she was noted to have significant abdominal distention and bloody stools. X-ray of the abdomen is shown in the figure. What is the likely diagnosis and management of the condition shown in this x-ray?

X-ray of this infant is consistent with necrotizing enterocolitis with evident pneumatosis (free air within the bowel wall) in the descending colon area. Management includes serial x-rays to detect perforation of the bowel wall, which requires immediate surgery to seal the bowel. Medical management before perforation includes NPO, IV fluids, and IV antibiotics for a period of 14 days.


Image

Necrotizing enterocolitis carries a mortality of up to 20%.


The most common gastrointestinal emergency in the premature infants.

ETIOLOGY

Image Seen primarily in premature infants, but can occur in full-term neonates (5–25%).

Image Caused by bowel ischemia and bacterial invasion of intestinal wall.

Image More common in premature infants treated with indomethacin for patent ductus arteriosus. Indomethacin may cause splanchnic vasoconstriction.


Image

Most common site: Terminal ileum and proximal ascending colon.


SIGNS AND SYMPTOMS

Image Intolerance of oral feeding (vomiting, bilious aspirates, and large volume residue in stomach).

Image Abdominal distention.

Image Temperature instability.

Image Respiratory distress.

Image Acidosis, sepsis, shock.


Image

Serious sequelae of NEC include intestinal strictures, malabsorption, fistulae, and short bowel syndrome (in case of surgery).


DIAGNOSIS

Image Distended loops of bowel.

Image Abdominal x-ray with “pneumatosis intestinalis”—air bubbles within the bowel wall (see Figure 3-2).


Image

An absolute indication for operative intervention in NEC is pneumoperitoneum.



Image

Most common complication is stricture.


Image

FIGURE 3-2. Necrotizing enterocolitis.

Distended loops of bowel and pneumatosis intestinalis.

Image Air in portal vein.

Image Free air under diaphragm (in case of perforation).

Image Occult blood in stool.

TREATMENT

Image Discontinue feeds.

Image Nasogastric decompression.

Image Intravenous fluids.

Image Antibiotics.

Image Surgery (bowel necrosis, intestinal perforation, pneumoperitoneum, failure of medical treatment).


Image

Currently, severe retinopathy of prematurity is rare due to judicious use of oxygen.


Retinopathy of Prematurity (ROP)

Disease that affects immature vasculature in the eyes of premature infants.

ETIOLOGY

Image Caused by proliferation of immature retinal vessels due to excessive use of oxygen.

Image Can → retinal detachment and blindness in severe cases.

Image Multifactorial; the number one cause has been noted to be hyperoxia.

Image Characterized by neovascularization of retina and vascular congestion that can → retinal detachment and ↓ visual acuity in severe cases.


Image

All infants < 1500 g birth weight or younger than 32 weeks’ gestational age at birth are at risk of developing ROP.


DIAGNOSIS

Image All very-low-birth-weight infants should be screened for ROP with an ophthalmoscopic exam.

Image An ophthalmology evaluation is necessary in all premature infants < 1500 g, < 32 weeks’ gestation.

Image First eye exam:

Image At 27–28 weeks (for 23–24 weeks’ gestational age).

Image At 4th or 5th week (> 25–28 weeks’ gestational age).

Image Before discharge (> 29 weeks’ gestational age).

TREATMENT

Laser surgery may be needed in severe cases.

Intraventricular Hemorrhage (IVH)

DEFINITION

Image Rupture of germinal matrix blood vessels due to hypoxic or hypotensive injury.

Image Most IVHs occur within 72 hours after birth.


Image

All premature, very-low-birth-weight infants should have a cranial ultrasound in the first week of life to look for intraventricular hemorrhage.


PREDISPOSING FACTORS

Image Prematurity.

Image RDS.

Image Hypo- or hypervolemia.

Image Shock.

Image Bleeding disorders.

SIGNS AND SYMPTOMS

Image Most are asymptomatic.

Image Apnea.

Image Hypertension or hypotension.

Image Changes in muscle tone.

Image Lethargy.

Image Poor suck.

Image Seizure.

Image Bulging fontanelle.

DIAGNOSIS

Cranial ultrasound (through anterior fontanelle).

TREATMENT

Image Directed toward correction of underlying conditions (RDS, shock, etc).

Image In cases of associated hydrocephalus, placement of ventriculoperitoneal shunt may be required.

Image Prognosis is dependent on the grade of IVH:

Image Grades I and II: Good outcome.

Image Grade III: Significant cognitive impairment.

Image Grade IV: Major neurologic problems.

SURVIVAL OF PREMATURE NEONATES

Image Disorders related to prematurity and low birth weight (BW) are the leading cause of neonatal death.

Image Only 20% of neonates with BW of 500–600 g survive.

Image Survival of infant with BW of 1250–1500 g is ~ 90%.

Image There is no worldwide, universal gestational age that defines viability.

Image In the United States, chance of normal survival is 50% after 24 weeks.


Image

Ex-preemies can receive RSV prophylaxis with RSV monoclonal antibodies during RSV season (IM injections once a month).


SPECIAL NEEDS OF EX-PREEMIES

Image Heat loss: ↑ susceptibility to heat loss (high body surface area-to-body weight ratio, ↓ brown fat stores, nonkeratinized skin, and ↓ glycogen supply). Minimize heat loss by:

Image Warmed blankets or cellophane wrap.

Image Plastic film over the baby immediately after drying.

Image Hypoglycemia.

Image Fluid and electrolyte imbalance.

Image Hyperbilirubinemia.

Image Due to their bronchopulmonary dysplasia, ex-preemies can experience recurrent wheezing episodes and severe course of respiratory infections, especially respiratory syncytial virus (RSV).

Image Due to ↑ work of breathing and “catch-up” growth, ex-preemies should receive high-calorie diet to allow for this additional caloric expenditure.

Image Routine vaccination should be given based on postnatal (not gestational) age.

Image Early identification and intervention is needed for infants with developmental problems.


Image

Premature infants have proportionally more fluid in the extracellular fluid compartment than the intracellular compartment and are at risk for fluid and electrolyte imbalance.



Image

Optimal parenteral nutrition can be achieved by total parenteral nutrition (TPN)—specialized solution consisting of amino acids, dextrose, minerals, and electrolytes.



Image

Breast milk is the best choice for enteral feeding for premature infants.


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