ppt Fetus to Newborn: Physiologic Adaptation to Extrauterine Life Flashcards
Lung Development
Canalicular Phase
17-27 weeks
Saccular Phase
26-36 weeks
Alveolar Phase
36 weeks – 3 years
Delineation of pulmonary acinus
Type II cells begin to differentiate, capillary network begins
Canalicular Phase
17-27 weeks
Lung Development
26-36 weeks
Thinning of interstitial space, closer association of endothelial and type I cells
Saccular Phase
26-36 weeks
Lung Development
36 weeks – 3 years
Presence of true alveoli
Lengthening and sprouting of capillary network
Alveolar Phase
Surfactant basics
Phospholipid-protein complex (90% lipid, 10% protein)
Decreases work of breathing (improves compliance, DV/DP)
Surfactant Function
hydrophilic head and a hydrophobic tail which extends into the air space
if air space collapses, the tails are densely packed, leading to mutual repulsion, opposing collapse
Treatment of Surfactant Deficiency
Oxygen
Continuous positive airway pressure (nasal CPAP)
Intubation and mechanical ventilation
Surfactant replacement
Clearance of Fetal Lung Fluid
Air-liquid interface moves distally with each inspiration, if inspiration is strong, and little or no fluid re-enters during exhalation
Failure to Breathe
At birth, we assume it’s secondary apnea, and intervene quickly
Requires rescue with positive pressure ventilation to establish lung inflation and begin regular respirations
Blood from descending Ao to placenta
Umbilical artery
Blood from placenta to inferior vena cava
Umbilical vein
Shunt from pulmonary artery to descending Ao
Ductus arteriosus
Shunt from umbilical vein to inferior vena cava
Ductus venosus
Allows blood flow between RA and LA
Foramen ovale
Closes when systemic pressure (LA) is greater than pulmonary pressure (RA)
Foramen ovale
