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Peds 1.1
Fetal Circulation
| Question | Answer |
|---|---|
| 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 as | 23-24 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 larger | canalicular |
| 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 birth | 20-30; 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 by | which 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 system | stable at 35 weeks, lecithin is more stable |
| around 35 weeks the L/S ratio becomes | more stable 2:1 |
| What is the main phospholipid and when more pevalent indicates stable lung | lecithin |
| What is Phosphyytidyl Glycerol? | phospholipid that appears at 35-36 weeks indicates lung maturity |
| 4 effects of a lack of surfactant | decreased lung compliance, decreased FRC, Increased WOB, Increased O2 consumption |
| PaO2 of uterine arteries= | 100 mmHg |
| PaO2 of umbilical vein is__ which is __% saturated | 29mmHg; 80% |
| PaO2 of umbilical arteries= | 17mmHg |
| 2 reasons for the PaO2 difference b/w uterine arteries and umbilical vein | O2 consumption in placenta and uneven distribution of maternal blood flow(shunts) |
| 2 reasons saturation is high | higher 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 PaO2 | left |
| Fetal circulation pathway | |
| Fetal Circulation pathway | Mother-Placenta-umbilical vein-ductus venosus-IVC-RA-foramen ovale-LA-LV-aorta-brain, myocardium, umbilical arteries-placenta |
| Desaturated venous return flows from the SVC to | RA-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 ______ blood | oxygenated; deoxygenated |
| Fetal circulation has ___ systemic vascular resistance and ___ pulmonary vascular resistance | low; high |
| 3 Large Rt to Lt shunts and their locations | Ductus venosus(liver), Foramen ovale(RA-LA), Ductus Arteriosus(lung-aorta) |
| Highest O2 content is found here | umbilical vein |
| Lowest O2 content found here | umbilical artery |
| At birth __% of total Hgb is Fetal Hgb | 77% |
| 2 changes in pulmonary vascular anatomy at birth | increases smooth muscle layer and layer thins |
| Increase Po2-Oxygenation at birth causes | pulmonary vasodilation causes increase blood flow and constricts ductus arteriosus |
| Clamping the cord at birth causes what | increased 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 is | absorberd 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 examples | chemical stimulation(hypoxia, hypercapnea, acidosis)and sensory stimulation (light, noise, cooling, tactile) |
| __-__ cmH2o negative pressures are generated with first breath | 60-80 cmH2o |
| Path to initial respiration | vaginal 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 birth | 24 hours to 2 weeks |
| What causes the Ductus venosus and Foramen Ovale to close | clamping 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 birth | no 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 RDS | 23-27% |
| Babies born with acquired infections usually develop what after birth | pneumonia |
| There is a 30% chance of a mother passing ____, and a 90% chance of passing ____ to her baby | hiv 30%, Hep B 90% |
| 2 possible with post mature births | meconium aspiration and asphyxiation |
| Polyhydramnios could be caused by | neuro problems |
| What is chorioamnionitis | infection of amniotic fluid |
| 8 high risk situations during labor and birth | precipitous 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 you | ultrasound; 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 amniocentesis | fluid contains fetal epithelial cells and can look for sex, chromosomal defects, presence of meconium, and fetal lung maturity |
| Describe the shake test | for 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 indicate | taken 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 performed | to see if the baby will tolerate labor or a c-section needed |
Created by:
Dabi2
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