NPS Neonatal Physiology and Pathophysiology Flashcards

What is the normal fetal hemoglobin (HbF) percentage in a term newborn at birth?

Answer: 60–80%

At birth, fetal hemoglobin (HbF) comprises approximately 60–80% of total hemoglobin in term newborns, gradually replaced by adult HbA over the first year.

The transition from fetal to neonatal circulation after birth involves which critical change?

Answer: Closure of the foramen ovale and ductus arteriosus as pulmonary vascular resistance falls

With the first breath, pulmonary vascular resistance falls, pulmonary blood flow increases, and functional closure of the foramen ovale and ductus arteriosus occurs.

Which electrolyte abnormality is most common in preterm neonates in the first 24–48 hours of life?

Answer: Hypernatremia

Hypernatremia (or hyperchloremia) occurs in the first days of life due to high insensible water losses from immature skin and inadequate free water intake.

Hyperbilirubinemia in neonates becomes concerning when bilirubin crosses the blood-brain barrier, causing which condition?

Answer: Kernicterus (bilirubin encephalopathy)

Kernicterus results from unconjugated bilirubin depositing in basal ganglia and brainstem nuclei, causing acute bilirubin encephalopathy with potential permanent neurological damage.

A neonate born at 26 weeks gestation has a brain ultrasound showing blood in the lateral ventricles without dilation. This is classified as which grade of IVH?

Answer: Grade II

Grade II IVH (Papile classification) involves blood within the ventricles without ventricular dilation, indicating bleeding into the ventricular system from the germinal matrix.

What is the underlying pathophysiology of necrotizing enterocolitis (NEC) in preterm neonates?

Answer: Intestinal ischemia, bacterial translocation, and inflammatory cascade

NEC results from mucosal ischemia in the premature gut, triggering bacterial invasion, inflammatory mediator release, and progressive intestinal necrosis.