Chapt 25

Congenital vs. Acquired Conditions

  • Congenital Disorders

    • Definition: Conditions that are present at birth and typically develop during fetal growth.

    • Causes: These may stem from genetic abnormalities, chromosomal disorders, environmental exposures, infections, or developmental defects occurring during pregnancy.

    • Key Question for Identification: Did the body form incorrectly?

    • Examples:

      • Cleft lip/palate.

      • Spina bifida.

      • Hydrocephalus.

      • Phenylketonuria (PKU).

  • Acquired Disorders

    • Definition: Conditions that develop before, during, or after birth due to specific affecting events.

    • Causes: Usually related to physiologic problems or external exposures rather than structural malformations.

    • Key Question for Identification: Did something happen to the infant?

    • Examples:

      • Respiratory distress.

      • Infection.

      • Hyperbilirubinemia.

      • Meconium aspiration syndrome (MAS).

      • Neonatal abstinence syndrome (NAS).

Respiratory Complications and Transition

  • Normal Fetal to Neonatal Transition

    • Fetal State: The fetus receives oxygen via the placenta; lungs are fluid-filled and do not participate in gas exchange.

    • Post-Birth Requirement: The newborn must rapidly clear lung fluid, expand the alveoli, and begin independent breathing.

  • Respiratory Distress

    • Primary Respiratory Distress: Caused by issues within the respiratory system itself.

    • Secondary Respiratory Distress: Caused by non-respiratory issues such as infection, hypoglycemia, hypothermia, or cardiac disease.

  • Assessment at Birth: The Four Critical Questions

    1. Is the infant term?

    2. Does the infant have good muscle tone?

    3. Is the infant breathing or crying?

    4. Does the infant have a good heart rate?

  • Thermoregulation Link

    • Respiratory function and thermoregulation are closely connected.

    • Cold Stress: Increases oxygen (O2O_2) consumption, which can significantly worsen respiratory distress.

Hypoxic Ischemic Encephalopathy (HIE)

  • Definition: A condition where the brain receives inadequate oxygen and blood flow before, during, or shortly after birth.

  • Causes:

    • Placental insufficiency.

    • Cord prolapse.

    • Uterine rupture.

    • Severe maternal hypotension.

    • Prolonged fetal distress.

    • Difficult deliveries.

  • Clinical Manifestations:

    • Altered state of consciousness.

    • Poor muscle tone and weak reflexes.

    • Feeding difficulties.

    • Respiratory depression.

    • Seizures.

    • Multi-organ dysfunction.

  • Treatment:

    • Therapeutic Hypothermia (Cooling Therapy): Used to reduce metabolic demands and limit the extent of brain injury.

Specific Respiratory Syndromes

  • Transient Tachypnea of the Newborn (TTN)

    • Definition: Temporary, rapid breathing in term and late preterm infants; it is the most common cause of respiratory distress in this group.

    • Cause: Delayed absorption of fetal lung fluid after birth.

    • Risk Factors: High prevalence in cesarean births without labor, as the infant misses the hormonal and mechanical processes that clear fluid.

    • Clinical Manifestations: Tachypnea, grunting, nasal flaring, mild cyanosis, and retractions.

    • Prognosis: Generally improves within 24−72 hours24-72\,\text{hours} as the fluid is absorbed.

    • Treatment: Supportive care including oxygen, CPAP if indicated, and gavage feedings if the respiratory rate is too high for safe oral feeding.

  • Meconium Aspiration Syndrome (MAS)

    • Cause: Fetal hypoxia or stress stimulates intestinal peristalsis and relaxation of the anal sphincter, causing meconium passage into the amniotic fluid, which the infant then aspirates.

    • Risk Factors: Postterm infants, maternal hypertension, and preeclampsia.

    • Pathophysiology of Aspirated Meconium:

      1. Physical airway obstruction.

      2. Interference with surfactant function.

      3. Inflammation.

      4. Increased risk of persistent pulmonary hypertension.

    • Clinical Manifestations: Immediate respiratory distress (tachypnea, cyanosis, grunting, retractions, nasal flaring), crackles on auscultation, and a barrel-shaped chest due to air trapping.

    • Visual Cue: Meconium in the amniotic fluid may give the newborn's skin a greenish tint.

    • Treatment: Oxygenation and ventilation support, CPAP, mechanical ventilation, surfactant therapy, and ECMO for severe cases.

  • Persistent Pulmonary Hypertension (PPHN)

    • Definition: Failure of the pulmonary circulation to transition from fetal to neonatal circulation; pulmonary vascular resistance remains high.

    • Consequence: Blood bypasses the lungs through fetal shunts (foramen ovale and ductus arteriosus), leading to inadequate oxygenation of tissues despite breathing efforts.

    • Risk Factors: MAS, sepsis, birth asphyxia, tight nuchal cord, diaphragmatic hernia, polycythemia, RDS, and maternal use of NSAIDs or SSRIs.

    • Clinical Manifestations: Severe respiratory distress, tachypnea, and progressive cyanosis that does not improve with oxygen therapy.

    • Treatment: Correcting hypoxemia, mechanical ventilation, inhaled nitric oxide, and ECMO.

Hyperbilirubinemia

  • Physiologic Jaundice: Normal occurrence; appears after 24 hours24\,\text{hours} of life and resolves spontaneously.

  • Pathologic (Non-Physiologic) Jaundice:

    • Timing: Appearance within the first 24 hours24\,\text{hours} of life is always considered abnormal.

    • Cause: Most commonly hemolytic disease (e.g., RhRh incompatibility) where maternal antibodies destroy fetal RBCs, releasing bilirubin.

  • Major Concern: Kernicterus

    • Unconjugated bilirubin is fat-soluble and can cross the blood-brain barrier.

    • Can lead to bilirubin encephalopathy (kernicterus) and permanent neurologic damage.

  • Manifestations: Early-onset jaundice, rapid rise in bilirubin levels, lethargy, poor feeding, hypotonia, and a high-pitched cry.

  • Treatment: Phototherapy

    • Converts unconjugated bilirubin into water-soluble lumirubin for excretion, bypassing the immature liver.

    • Side Effects: Increased insensible water loss, loose green stools, skin rash, and temperature instability.

    • Nursing Care: Protect eyes with shields, frequent feeding to promote stooling/bilirubin elimination, monitor temperature, maximize skin exposure (repositioning), and monitor for dehydration.

Neonatal Infection and Sepsis

  • Timing Classifications:

    • Congenital: Acquired via transplacental transmission (Rubella, CMV, Herpes, Varicella).

    • Early Onset (<48\,\text{hours}): Often from the maternal genital tract (Group B Strep, E. coli, H. influenzae).

    • Late Onset (>48\,\text{hours}): From environment or caregivers (Staph, Pseudomonas, HIV, CMV).

  • Manifestations: Subtle signs including temperature instability (infants often become cold/hypothermic rather than febrile), poor feeding, lethargy, apnea, jaundice, and glucose instability.

  • Diagnosis: Blood and urine cultures, CBC, inflammatory markers, and lumbar puncture.

  • Treatment: Immediate initiation of broad-spectrum antibiotics, adjusted later based on culture results.

Infants of Diabetic Mothers (IDM) and Polycythemia

  • IDM Pathophysiology: Maternal hyperglycemia leads to fetal hyperglycemia; the fetal pancreas produces excess insulin, which acts as a growth hormone.

  • IDM Complications:

    • Macrosomia: LGA infants with round faces, thick necks, and broad shoulders.

    • Hypoglycemia: Maternal glucose ends at birth, but fetal insulin remains high.

    • Other: Respiratory distress syndrome (RDS), polycythemia, hypocalcemia, and hyperbilirubinemia.

  • Polycythemia:

    • Definition: Hematocrit levels > 65\%.

    • Cause: Response to chronic fetal hypoxia.

    • Manifestations: Plethoric appearance (ruddy, dark red), increased risk of hyperbilirubinemia due to high RBC breakdown.

    • Consequence: Thick/viscous blood reduces tissue perfusion.

Substance Exposure and Withdrawal

  • Neonatal Abstinence Syndrome (NAS)

    • Primary Cause: Opioids.

    • CNS Symptoms: Hyperactive tone, tremors, irritability, high-pitched cry, difficulty soothing.

    • GI Symptoms: Poor suck-swallow-breathe coordination, projectile vomiting, diarrhea, poor weight gain.

    • Autonomic Symptoms: Overstimulation/over-arousal.

    • Environment: Low-stimulation (dim lights, reduced noise, swaddling, clustered care).

  • Fetal Alcohol Spectrum Disorders (FASD)

    • Cause: Alcohol crossing the placenta; no safe amount is known.

    • Physical Features: Smooth philtrum, thin upper lip, short palpebral fissures, wide-set eyes.

    • Neurologic Impairment: Learning disabilities and poor impulse control; these effects are permanent.

Genetic and Metabolic Disorders

  • Phenylketonuria (PKU)

    • Definition: Deficiency of phenylalanine hydroxylase, preventing conversion of phenylalanine to tyrosine.

    • Inheritance: Autosomal recessive.

    • Manifestation: Musty/mousy odor to urine, skin, or breath; intellectual disability if untreated.

    • Screening: Performed around 24 hours24\,\text{hours} of age after the infant has ingested protein feedings.

Congenital Anomalies

  • Cleft Lip and Palate: Primary concern is feeding; cleft palate makes generating suction impossible. Requires specialized nipples and upright positioning.

  • Abdominal Wall Defects:

    • Omphalocele: Organs herniate through the umbilical ring but are covered by a membrane/sac.

    • Gastroschisis: Organs protrude through an opening beside the umbilicus with no protective sac; requires immediate coverage with sterile, saline-soaked dressings and plastic wrap.

  • Neural Tube Defects (NTDs): Linked to folic acid deficiency.

    • Anencephaly: Absence of major portions of the brain; incompatible with life.

    • Spina Bifida: Vertebral arches fail to close.

      • Meningocele: Only meninges protrude.

      • Myelomeningocele: Meninges and spinal cord protrude.

      • Nursing Care: Maintain moist, sterile saline dressings on the defect; position the infant prone (never on the back).

  • Hydrocephalus: CSF accumulation in ventricles. Signs include "sunset eyes," bulging fontanelles, and rapid head growth. Treated with a ventriculoperitoneal (VP) shunt.

  • Genitourinary Defects:

    • Hypospadias: Urethral opening on the ventral (underside) of the penis.

    • Epispadias: Opening on the dorsal (upper) surface.

    • Nursing Note: Do not circumcise; the foreskin is needed for surgical repair.

    • Bladder Exstrophy: Bladder is exposed outside the abdominal wall; must be kept moist with sterile, nonadherent coverings.