Neonatal Physiology and Birth Transition Flashcards
6 cards from real NRP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Neonatal Physiology and Birth Transition flashcards as text
During fetal circulation, where does the most highly oxygenated blood flow after entering the right atrium from the inferior vena cava?
Answer: Through the foramen ovale to the left atrium, then to the left ventricle and brain
The most oxygenated blood from the inferior vena cava is directed by the crista dividens across the foramen ovale into the left atrium and left ventricle, then into the ascending aorta to supply the brain and coronary arteries preferentially.
Why is the normal oxygen saturation in the fetus lower than in a term newborn after successful transition?
Answer: Fetal blood is oxygenated by the placenta, which is less efficient than the lungs, resulting in lower SpO2
The placenta is a less efficient gas exchange organ than the lungs, resulting in umbilical venous blood having a PO2 of approximately 35–40 mmHg and SpO2 of about 80% — lower than what is achieved through normal lung ventilation.
What is the clinical significance of persistent pulmonary hypertension of the newborn (PPHN) in relation to birth transition physiology?
Answer: PPHN results from failure of PVR to fall, causing right-to-left shunting and severe hypoxemia despite lung inflation
PPHN occurs when pulmonary vascular resistance fails to fall after birth, maintaining fetal-pattern circulation with right-to-left shunting through the ductus arteriosus and foramen ovale, causing severe hypoxemia refractory to oxygen therapy.
How does fetal hemoglobin (HbF) differ from adult hemoglobin (HbA) in terms of oxygen affinity, and why is this important?
Answer: HbF has higher oxygen affinity than HbA, enabling oxygen loading at the lower PO2 of placental blood
Fetal hemoglobin (HbF) has a higher oxygen affinity than adult hemoglobin due to reduced binding of 2,3-DPG, allowing it to load oxygen efficiently at the lower PO2 of placental blood (~35–40 mmHg).
Which of the following scenarios during birth transition would MOST likely require immediate resuscitative intervention?
Answer: A term infant with Apgar score of 2 at 1 minute who remains apneic with no tone
An apneic, hypotonic term infant with an Apgar of 2 at 1 minute represents failure of the birth transition and requires immediate positive-pressure ventilation and further resuscitation.
What is the role of catecholamines (epinephrine, norepinephrine) released during the birth process in neonatal transition?
Answer: They promote lung fluid clearance, surfactant release, and cardiovascular adaptation to extrauterine life
The catecholamine surge during labor and delivery promotes lung fluid absorption, stimulates surfactant secretion from type II pneumocytes, increases heart rate and cardiac output, and mobilizes fuel substrates to support the transition to extrauterine life.