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QuestionAnswer
What are the 4 phases of lung development?Embryonic stage, pseudoglandular stage, canalicular stage, and terminal sac stage
What forms during the embryonic stage of lung development?lung buds from endoderm, rt and lt mainstem, 10 branches on rt, 9 on left, pulmonary arteries/veins
By the 7th week of the embryonic stage(the end) what has completely formed?diaphragm
What forms during the pseudoglandular stage?conducting airways, 25 generations of branching, cilia, mucus glands, goblet cells, cartilage, smooth muscle and lymphatics
What forms in the canalicular stage?terminal bronchiles, capillary network begins to surround air spaces, epithelium differentiates into Type I and Type II
A viable baby can be born as early as23-24 weeks
What are the 2 stages of the Terminal sac stage?Saccules and Alveolar
What happens during the 1st stage of the terminal sac stage?saccules become subdivided by ridges, capillary layer drawn in increasing surface area for gas exchange
What happens during the alveolar stage of the terminal sac stage?subsaccules to alveoli, maturation of surfactant, 20-150million alveoli, capillary membran thins, lymphatic proliferation
In this stage clustered alveoli split, divide and the capillary bed becomes largercanalicular
In what stage of fetal lung development does the baby show signs of breathing that helps develop resp. muscles?pseudoglandular
Why must lymph system be developed by alveolar stage?it carries away fetal lung fluid
6 factors that affect lung growth:altered metabolic rate in utero, hyperoxia after birth, cigarette smoke in utero, chest wall compression, oligohydramnios, decreased fetal breathing
What usually causes altered metabolic rate in utero?something in the placenta, cord problems, and hypoxia
How does hyperoxia after birth affect lung growth?infants dont have the adequate antioxidant mechanisms and the oxygen causes corrosion of their lung tissue
Smoking while pregnant can cause the fetus to have what?decreases lung volume, decreased DNA content, and structural abnormalities
What is Oligohydraminos and what does it cause?lack of amniotic fluis results in hypoplasia or stiff lungs and trouble ventilating
How does decreased fetal breathing affect baby upon birth?lungs dont stretch and becomes tired easily
When does fetal lung fluid begin?during pseudoglandular stage (70 days)
How much fetal lung fluid is secreted?4-5ml/kg/hr is swallowed or expelled into amniotic fluid
What is the fetal lung fluid composed of?chlorine ions that keep the pH balanced
The total amount of fetal lung fluid is __-__ml/kg and is equaled to____ at birth20-30; FRC
Hormonal changes just before and after birth ___ rate and production of fetal lung fluid?decrease
Surfactant is produced by the Type II cells which are formed during what stage?3rd stage-canalicular
What is the relationship between RDS babies and surfactant?they use it up very quickly and cant produce it fast enough
Where are Lamellar bodies located and what do they do?within type II cells, release tubular myelin
WHat is Myelin?a lattic like structure that forms a monolayer at the air liquid interface
Sufactant is 90% _______ and 10% _____phospholipid; protein
Stability of lungs is determined bywhich pathway produced the surfactant available
Describe the Methyltransferase enzyme system@22-24 weeks, very unstable, Sphingomyelin is predominiant, causes hypoxia and acidosis
Describe the Phosphocholine transferase enzyme systemstable at 35 weeks, lecithin is more stable
around 35 weeks the L/S ratio becomesmore stable 2:1
What is the main phospholipid and when more pevalent indicates stable lunglecithin
What is Phosphyytidyl Glycerol?phospholipid that appears at 35-36 weeks indicates lung maturity
4 effects of a lack of surfactantdecreased lung compliance, decreased FRC, Increased WOB, Increased O2 consumption
PaO2 of uterine arteries=100 mmHg
PaO2 of umbilical vein is__ which is __% saturated29mmHg; 80%
PaO2 of umbilical arteries=17mmHg
2 reasons for the PaO2 difference b/w uterine arteries and umbilical veinO2 consumption in placenta and uneven distribution of maternal blood flow(shunts)
2 reasons saturation is highhigher Hgb concentration in fetal blood increases o2 carry capacity (quadrupled) and FeHb has an increased affinity for O2 and facilitates transfer of O2 across placenta
FeHb shifts the O2 dissociation curve to the ___ causing a higher sat with a lower PaO2left
Fetal circulation pathway
Fetal Circulation pathwayMother-Placenta-umbilical vein-ductus venosus-IVC-RA-foramen ovale-LA-LV-aorta-brain, myocardium, umbilical arteries-placenta
Desaturated venous return flows from the SVC toRA-RV-pulmonary artery, ductus arteriosus-abdominal aorta-placenta
A small amount of pulmonary flow enters the lungs and returns to the LA via the ____ ____pulmonary veins
In fetal circulation the umbilical vein carries _____ blood and the umbilical arteries carry ______ bloodoxygenated; deoxygenated
Fetal circulation has ___ systemic vascular resistance and ___ pulmonary vascular resistancelow; high
3 Large Rt to Lt shunts and their locationsDuctus venosus(liver), Foramen ovale(RA-LA), Ductus Arteriosus(lung-aorta)
Highest O2 content is found hereumbilical vein
Lowest O2 content found hereumbilical artery
At birth __% of total Hgb is Fetal Hgb77%
2 changes in pulmonary vascular anatomy at birthincreases smooth muscle layer and layer thins
Increase Po2-Oxygenation at birth causespulmonary vasodilation causes increase blood flow and constricts ductus arteriosus
Clamping the cord at birth causes whatincreased SVR (sytemic BP), less blood flow to RA, Umbilical vein and arteries constrict
1/3 of fetal lung fluid is__ ____squeezed out
2/3 of fetal lung fluid isabsorberd by lymphatics and capillary bed
After several breaths, fetal lung fluid is moved into ______ _______interstitial spaces
How long does it take for fetal lung fluid to be removed by lymphatics and capillaries?several hours
2 factors influencing initial respirations with exampleschemical stimulation(hypoxia, hypercapnea, acidosis)and sensory stimulation (light, noise, cooling, tactile)
__-__ cmH2o negative pressures are generated with first breath60-80 cmH2o
Path to initial respirationvaginal squeeze compresses thoracic cage, chest recoils passively creating neg pressure, resp muscles stimulated and expand thoracic volume
Changing from fetal circulation to adult circulation can occur __ hours to __ weeks after birth24 hours to 2 weeks
What causes the Ductus venosus and Foramen Ovale to closeclamping the cord which increases SVR
What causes the Ductus Arteriosus to close?increased PO2 and increased blood flow and decreased production on Prostaglandin E
What are some signs that the Ductus Arteriosus has not closed?low PO2 (d/t art and ven blood mix), with BP up and down
What happens to the umbilical vein and arteries when changes from fetal to adult circulation?change into ligaments
What is the number one cause for a high risk birthno prenatal care
Age of mother <__ or >__ is high risk<16, >40
A pregnant woman with diabetes (IDM) has a __-__% chance of having a baby with RDS23-27%
Babies born with acquired infections usually develop what after birthpneumonia
There is a 30% chance of a mother passing ____, and a 90% chance of passing ____ to her babyhiv 30%, Hep B 90%
2 possible with post mature birthsmeconium aspiration and asphyxiation
Polyhydramnios could be caused byneuro problems
What is chorioamnionitisinfection of amniotic fluid
8 high risk situations during labor and birthprecipitous labor (fast), prolonged (>24 hrs), use of gen anesth, narcotics within 4 hrs of birth, meconium stained fluid, prolapsed cord, abruptio placenta, placenta previa
what is a prolapsed cord?cord comes out before baby
What is the most important non invasive tool and what does it tell youultrasound; dates pregnancy, size/growth/position/number of babies, placental placement, assess amnio fluid, rules out anomalies
What is an example of a fetal anomaly that an ultrasound can see?diaphragmatic hernia
Why do an amniocentesisfluid contains fetal epithelial cells and can look for sex, chromosomal defects, presence of meconium, and fetal lung maturity
Describe the shake testfor lung maturity; 1:1 amniotic fluid/95% ethanol alcohol shaken for 15 sec, bubbles positive for surfactant
Where is fetal blood pH taken from and what doe it indicatetaken from fetal scalp, 7.20-7.25 is pre-acidotic, low pH indicates need for c-section
Why is a stress test or non stress test performedto see if the baby will tolerate labor or a c-section needed