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51 Cards in this Set

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Placenta

The nutrient, gas exchange and waste removal organ of the fetus


6 to 8 inches in diameter


Occupies 1/3 of intrauterine surface

Placenta

Moms arterial blood O2, diffuses into umbilical vein


Fetal blood picks up O2


Blood goes to through fetal circulation


Fetal blood, high in CO2, returns back to the placenta via umbilical arteries


CO2 diffuses into moms venous system and it is exhaled

Closer look at placenta

The embryo implants into the uterus by finger like projections (chorionic villi)


:These contain fetal vessels



As these continus to grow, the endometrium erodes, creating pockets (intervillous spaces)


:These contain maternal blood



Cotyledon: grouping of 15 to 28 villi and intervillous spaces

Closer look at placenta

Gas exchange takes place between fetal and maternal blood


No contact between either blood source



Placenta to attack and build the upper 1/3 of the baby cavity, it stays away from the cervical opeing, so birth is not obstructed in any way.

Umbilical cord

lifeline between fetus and mother


Mean length 55 cm (22 inches)


3 vessels surrounded by whartons jelly


:2 umbilical arteries/ 1 umbilical cord



AMNION: sack that surrounds the fetus and amniotic fluid

Amniotic fluid

1t 40 weeks, 1 liter of fluid


produced at 7 days


Made of maternal and amniotic membrane fluid


gIt is always being replenished and reabsorbed


24 to 26 weeks the fetal skin is permeable

Amniotic fluid

Skin starts to harden after 26 weeks, so skin is impermeable to the fluid (keratinization)



Absorption is now done by fetal swalling (500 ml/day) and



Fluid in the amniotic sack is replenished by fetal urination and lung fluids (500 ml/day)


Purpose of amniotic fluid

Allows for fetal movement



Protects from shock or maternal movement



Thermoregulation



Helps metabolism by giving fluids to fetus

Polyhydramnios

Abnormally high amounts of fluid


:Greater than 2000 ml



Indicates a "swallowing problem of fetus


:May also indicate abnormalities such as


::anencephaly


::Esophageal atresia


::TE fistula



Complication from this


:PROM (premature rupture of membrane)


:Lead to prolapse of cord


:A premature delivery

Oligohydraminos

Decreased amount of amniotic fluid less than 500 ml


Caused by:


:Urinary tract defect


:Post term preganacy



Coplications


:adhesion of body parts


:compression of the umbilical cord leading to asphyxia


:lung hypoplasia (failure of lung to deelop_


:limb deformaties


:Potters syndrome (worse case scenario, this is always fatal)


Fetal blood

Higher affinity for oxygen due to higher hemoglobin content


Lower levels of 2,3 DPG so the OXYGEN DISSOCIATION CURVE SHIFTS TO THE LEFT


P50= 7.8 mmHg lower than the adult P50 of 27 mmHg


Highest PaO2 is in the umbilical vein (29 mmHG) SaO2= 80%

Chemoreceptors

Not present (or non functional) in fetus due to immaturity of carotid sinus



Located in carotid arteries and aorta



Sensitive to PaO2, PaCO2, pH



Regulation of ventilation and the baby's first breath



Cental chemo receptors are located in the brain steam, they are the primary chemoreceptors (depedant on CO2)


Fetal to neonatal circulation

Foramen ovale closes


Ductus arteriosus closes


Ductus venosus closed


Decreased PVR for circulation to the lung

Decreased PVR/ lung circulation

umbilical cord clamped


Less blood returns to the right side of heart, so pressures decrease


Left heart pressures increase because it is no longer pumping blood back to the low resistant placenta, it is now pumping to the systemic system



Lung fluid expelled, relieving pressure on the pulmonary vessels

Decrease LVR/ lung circulation

Pulmonary vessels can now expand, hold more blood, decreasing PVR



Breathing starts and PAO2 increases causing vasodilation



With better pulmonary perfusion more blood is circulated to left atrium so left heart/system pressures increase


Ductus venosus closes

Remains open but not blood flow, function stops right away



Automatically closes within 3 to 7 days


:functional closure happens when cord is cut



Due to lack of blood flow

Foramen ovale closes

Closes via a flap valve when left pressures exceed right heart pressures



Happens immdiately



If right heart pressures exceed left, the foramen ovale can reopen allowing for shunting


Ductus arteriosus closes

Constricts and closes due to an increase in O2 tension



Decreased PVR allows right ventricle to pump blood easier into the lung and onto left heart, so there is less blood flow through the ductus arteriosus



DA DOES NOT CLOSE IMMEDIATELY



can take 24 hours to functionally close and up to 3 weeks to to structurally close

ductus arteriosus closes (most problems, and most connection with

first hours: remains open but blood flow will be from the left to right because pressures are higher in left than right



Several hours later: constrictus due to higher PaO2



Functional closure 12 to 18 hours after birth



Total closed by 3 weeks



PROSTAGLANDINS keeps DA open in utero but are prohibited by high PaO2, causing constriction



INDOMETHICIN: GIven to hypoxic premature infants following delivery to help close DA (CLOSES DA)



Depending on CHD, need to keep open or to close

Factors responsible for 1st breath

TRANSIENT FETAL ASPHYXIA: fetal circulation is cut off. Hypoxia and hypercapnia arise. Chemoreceptors stimulated



THORAX COMPRESSED ON delivery, lung fluid removed, then reexpands for air entry



ENVIRONMENTAL STIMULATION


First breath

-60 to -100 cmH20, but decrease on subsequent breaths



VT= 40 cc initially, but only 20 cc exhaled



Establishing FRC, within a few hours after birth



Surfactant is present to decrease surface tension



If not can lead to RDS (respiratory distress syndrome)

Prenatal history

Risk factors Persings, Chapter 13

High Risk moms

Younger than 16, older than 40



History of previous births



Previous caesarian section, miscarriages, pre and postmature delivers, fetal/neonatal deaths



Smoking, drug use, alcohol abuse, diseases


High Risk Labors

Prolonged



Delayed birth after PROM (premature rupture of membrane)



Placental dislocation



Meconium stained amniotic fluid



Maternal medications

Maternal disorders

Toxemia



Pre eclampsia , increased blood pressure



Eclampsia: increased blood pressure with convulsions

Uteroplacental insufficiency (UPI)


Causes: pre and post maturity; maternal heart and pulmonary disease



Results of UPI:


:Lack of growth (IUGR) intrauterine growth retardation


:Death


:chronic fetal asphyxia


:Meconium stained amniotic fluid

Diabetic mom (page 22)

Complicates: 4% of US pregnancies



Mild form (controlled by diet): large infants (LGA) with no other problems. Infants have delayed lung maturation INFANTS HAVE DELAYED LUNG MATURATION



Insulin dependant: normal or small (SGA) babies with higher risk for hypoglycemia. Infants have increased lung maturation HYPOGLYCEMIA, INFANTS HAVE INCREASED LUNG MATURATION

diabetic complications

Mom has it, mom at risk for


chronic hypertension and pre: exlampsia



Mom has it and baby has problems with


Prematurity



Large infants with possible birth injury: shoulder displacement



Hyperinsulinemia: infant at risk for hypoglycemia after birth



UPI due to maternal hypertension, leading to hypoxia

Infants of diabetic moms (IDM)

Classic presentation: fat, large infant



If UPI present, there will be a decrease in fetal growth


Smoking

CO interferes with O2 supply with fetus



Nicotine crosses placenta (greater than 15 % higher than maternal levels)



Causes developmental delays



Danger of premature delivery


Alcohol

Freely crosses placental barrier


O.5- 2 per 1000 births


:1 in 9 women report binge drinking during pregnancy


:1 in 5 women report drinking during pregnancy


Most problematic in 1st tirmester



FETAL ALCHOHOL SYNDROME



the lifetime cost for one individual with FAS in 2016 was estimated to be 2.5 million $

Drugs as a risk factor

Sedatives: depress respirations. Poor muscle tone, trouble breathing/feeding after delivery



Narcotics: tremors, dyspnea, seizures, death from withdrawal, baby born addicted



Cocaine, causes placenta to detach too sooon. Causes bleeding, preterm birth and fetal death

Torch syndrome materanl infections page 24

Toxoplasmosis


Others


Rubella


Cytomegalovirus


Herpes



ALl have similiar clinical manifestattions, so all grouped together

Toxoplasmosis (cat litter disesase)

Protozoa found in cat feces or eating raw meat



Mother may be asymptomatic or fluish



Can cause congenital defects



Diagnosis with antibodies in blood serum

RUbella

Preventable if mom is vaccinated before conception


Highly contagious viral illness


Characterized by rash, swollen glands and join pain


May be asymptomatic



Affects fetus in first 5 months


Low body weight

cytomegalovirus (CMV)

member of herpes family


pregnant healthcare personnel should NOT treat infants with CMV


Spread by person to person contact


mom may be aymptomatic

Herpes simplex type 2

secually transmitted


acquired by fetus during birth via contact with genital secretions or following rupture of the membrane



c section preferred (if active)


Can affect CNS, skin, and has a high mortality if disseminated in the lung


HIV infection

Neonatal HIV is more commonly from infected mom



Risk factors for prenatal infections


:Mom is IV drug user


:Infant exposure to infected blood products or breast milk

Transmission of HIV

during delivery by coming in contact with moms blood


breast feeding


transufsion with infected blood


trasnplacental transfer (not all hiv moms pass the virus)


Zidovudine (AZT) antiretroviral drug, given prior too delivery to mom, then for 6 weeks to infant to reduce incidence of HIV coplications

Manifestations of HIV

failure to thrive (FTT)


Developmental delay


Infection risks


Treat with AZT, pentamidine (antimicrobial) to prevent and treat pneumocystis, steroids)

Group B streptococcus

Risk of death if premature delivery or PROM



Vaginal cultures at 35 to 37 weeks



Penicillin/ ampicillin

Multiple gestations

2 or more

Complications of multiple gestation

Premature labor and delivery


IUGR (intrauterine growth retardation): if identical twins, one twin will have a smaller placenta


Breech/ abnormal presentations during delivery (head up butt down)



Twin transufation syndrome (one twin bigger than other twin

Twin transfusion syndrome

One twin (larger)


Polycythemia,, CHF, hyperbilirubinemia



Second twin (smaller)


Anemic, shock from blood loss


Placental problems

Placental previa (to low in the uterus)


Rather than being attached to the upper wall of the uterus, the placenta lies low in the uterus, partially or completely covering the cervix

Placenta previa: complications for baby and mom

Associated with blood loss


IUGR due to poor placental perfusion


Fetal asphyxia



Life threatening hemorrhage


Cesarean delivery may be required

Abruption placenta

Tearing of the placenta away from the uterine wall prior to delivery



Mom can fall, or rear ended in a car accident, potential to rip placenta away from uterine wall

Abruption placenta

Normally attached placenta separates prematurely causing labor to begin


Maternal mortality up to 10 %, infant mortality up to 50%



Can be partial or complete


BLeeding can be visible or concealed



Risk if severe hypoxia and blood loss

Abruption Placenta

Maternal hypertension



Trauma



Shortened umbilical cord



Uterine abnormalities



Excessive number of previous pregnancies

Abruption placenta risks for baby

prematurity


Hypoxia


Hemorrhage


Abruption placenta treatment

Replaced blood volume to mother


Mother positioned on lateral position to allow maximum placental circulation


Intensive monitoring


Emergency C section delivery in cases of maternal shock or fetal distress