Physiologic Adaptions of the Newborn Flashcards
What is the purpose of the ductus arteriosus?
it shunts blood from the pulmonary artery directly into the descending aorta
What is primary apnea in an infant?
- baby isn’t breathing at delivery, but stimulation easily initiates a cry
- HR and BP are relatively maintained
At birth, the infant takes a breath, causing decreased resistance in the pulmonary vasculature, which causes LA pressure to _____, thereby closing the foramen ovale.
increase
Deoxygenated blood entering the RA from the SVC goes into the RV, then thru the main pulmonary artery, through the ______, and down the descending aorta because of high fetal pulmonary artery resistance.
patent ductus arteriosus
What is the purpose of the ductus venosus?
passes oxygenated blood from the umbilical vein around the liver to the IVC
_____ is a phospholipid-protein complex that lowers surface tension within air spaces, preventing alveolar collapse at end-expiration and allowing easy ventilation (compliant lungs).
Surfactant
Most highly oxygenated blood reaching the heart via the IVC is diverted through the _____ and pumped out the aorta to the head and body.
foramen ovale
What response to suction would earn the baby an APGAR category score of 2?
coughing, sneezing, or crying
How can you tell if an infant has a persistent R to L shunt?
- differential saturation in pre-ductal (R arm) and post-ductal (leg, umbilical arterial catheter) circulation
- oxygen saturation higher in the right arm than in the descending aorta (leg)
Name the phase of lung development:
- 26-36 weeks’ gestation
- thinning of interstitial space
- closer association of capillaries to air spaces and type I cells
Saccular Phase
Prior to 22-24 weeks gestation, the capacity for ventilation is limited by ______ and _____.
- a lack of air spaces
- the distance of capillaries from rudimentary air space
Name the factors that maintain pulmonary vasoconstriction and increase PVR (5).
- low pO2
- low pH
- high pCO2
- leukotrienes
- endothelin
What is the Alveolar Phase of lung development?
- 36 weeks’ gestation to 3 or more years
- presence of true alveoli
______ and decreased prostaglandins cause the ductus arteriosus to close.
Increased oxygen
What heart rate would earn the baby an APGAR category score of 2?
greater than 100
What creates the functional residual capacity (FRC)?
surfactant allowing the airspace to remain partially inflated at end expiration
Surfactant is stored within Type II cells as _____,
lamellar bodies
At birth, the infant takes a breath, causing decreased resistance in the ______, which causes LA pressure to increase, thereby closing the foramen ovale.
pulmonary vasculature
Deoxygenated blood entering the RA from the SVC goes into the RV, then thru the main pulmonary artery, through the patent ductus arteriosus, and down the descending aorta because of _______.
high fetal pulmonary artery resistance
What is Persistent Pulmonary Hypertension of the Newborn (PPHN)?
- increased pulmonary vascular resistance
- decreased systemic vascular resistance (hypotension, shock) –> R to L shunting recurs or continues
Surfactant is produced by _____.
Type II cells
________ blood entering the RA from the SVC goes into the RV, then thru the main pulmonary artery, through the patent ductus arteriosus, and down the descending aorta because of high fetal pulmonary artery resistance.
Deoxygenated
What is the Canalicular Phase of lung development?
- 17-27 weeks’ gestation
- type II cells begin to differentiate
- capillary network begins to form
Name the factors that promote pulmonary vasodilation and lower PVR (6).
- alveolar distension
- high pO2
- high pH
- low pCO2
- nitric oxide
- prostacyclin
What tone would earn the baby an APGAR category score of 2?
active motion
Why do babies with surfactant deficiency grunt?
Grunting provides a positive end expiratory pressure, or PEEP
Blood entering the fetus through the umbilical vein is conducted via the ductus venosus to the ____ to bypass the hepatic circulation.
IVC
What is secondary apnea in an infant?
- baby isn’t breathing at delivery and requires positive pressure ventilation to establish lung inflation and to begin regular respirations
- HR and BP fall quickly
- death will occur without rescue ventilation
What does the ductus venosus become?
the ligamentum venosum
What keeps the PDA open?
prostaglandins E1 and E2
“PGE kEEEEEps it open”
At birth, the infant takes a breath, causing _____ in the pulmonary vasculature, which causes LA pressure to increase, thereby closing the foramen ovale.
decreased resistance
What helps close a PDA?
indomethacin
“ENDOmethacin ENDS patency”
Blood entering the fetus through the umbilical vein is conducted via the ductus venosus to the IVC to bypass the _______.
hepatic circulation
Increased oxygen and decreased prostaglandins cause the _______ to close.
ductus arteriosus
What is surfactant comprised of?
- 90% lipid (phosphatidylcholine, phosphatidylglycerol)
- 10% protein (proteins A,B,C,D)
In the fetus, the pulmonary epithelium secretes fluid by ______.
active Cl secretion
What color would earn the baby an APGAR category score of 2?
completely pink
Name 5 requirements for normal cardiopulmonary adaptation at birth.
- Fetal lung fluid absorption
- Expansion of the lungs with establishment of functional residual capacity
- Increased systemic vascular resistance
- Decreased pulmonary vascular resistance
- Closure of fetal R to L shunts
What is the Saccular Phase of lung development?
- 26-36 weeks’ gestation
- thinning of interstitial space
- closer association of capillaries to air spaces and type I cells
What respirations would earn the baby an APGAR category score of 2?
regular, crying
What do infant lungs with surfactant deficiency look like on CXR?
- diffuse microatelectasis (“reticulogranular pattern” or “ground glass” appearance)
- air bronchograms – very poorly aerated lungs, so called “white-out”
What is the purpose of the foramen ovale?
diverts oxygenated blood from the RA to the LA
Increased oxygen and ______ cause the ductus arteriosus to close.
decreased prostaglandins
Most highly oxygenated blood reaching the heart via the ____ is diverted through the foramen ovale and pumped out the aorta to the head and body.
IVC
At birth, the infant takes a breath, causing decreased resistance in the pulmonary vasculature, which causes LA pressure to increase, thereby causing _______.
the foramen ovale to close
Surfactant is extruded as ______ into the airspace after the lamellar bodies fuse with the cell membrane.
tubular myelin
Name the phase of lung development:
- 36 weeks’ gestation to 3 or more years
- presence of true alveoli
Alveolar Phase
What is a sign that the newborn has hypoglycemia?
they’re jittery
Blood entering the fetus through the umbilical vein is conducted via the ______ to the IVC to bypass the hepatic circulation.
ductus venosus
Name the phase of lung development:
- 17-27 weeks’ gestation
- type II cells begin to differentiate
- capillary network begins to form
Canalicular Phase
Approaching labor signals the absorption of lung fluid: switch to _______ rather than Cl secretion.
active Na absorption
What does the foramen ovale become?
the fossa ovalis
What does the ductus arteriosis become?
the ligamentum arteriosum
Approximately ___% of infants will require some assistance in breathing at delivery.
10%
Failure of fluid absorption leads to retained fetal lung fluid or _____.
TTN (Transient Tachypnea of the Newborn)
