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Pre term delivery
Less than 38 weeks
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Post term delivery
More than 42 weeks
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What are the three things that are needed for gas exchange?
- Alveoli
- Blood vessels (pulmonary blood flow
- Surfanctant
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Embryonal stage of development!
- Day 26 to day 52
- Developement of trachea and major bronchi
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Pseudoglandular stage of development!
- Day 52 to week 16
- Development of remaining conducting airways
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Canalicular stage of development!
- Week 17 to week 26
- Development of vascular bed and framework of respiratory acini
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Saccular stage of development!
- Week 26 to week 36
- Increased complexity of saccules
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Alveolar stage of development!
- Week 36 to term
- Development of alveoli
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What time frame is gas exchange possible and in what pgase?
- 22 to 24 weeks
- canalicular stage
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Two phases of surfactant production!
- Methylation pathway
- Cholination pathway
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Methylation pathway
- Produces a surfactant that has equal amounts of lecithin and sphingomyelin. (L/S ratio of 1:1)
- The surfactant is unstable with a short half life
- This pathway starts at 18 weeks gestation and continues until the baby reaches 34-26 weeks of age.
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Cholination pathway
- Produces a surfanctant that is more stable with twice as much lecithin as sphingomylein. (L/S ratio of 2:1)
- THis pathway starts around 34-36 weeks gestation and continues throught life.
- Babies born at this time should have very little diffcuilt with breathing
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What does the PG level indicate?
determination of fetal lung maturity
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If there is insufficient surfactant, what does this mean for the baby?
- Increase in alveolar surface tension
- Increase in work of breathing
- Atelectasis
- Development of hypoxemia
- Respiratory acisosis
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Conditions that delay surfactant production!
- Acidosis
- Hypoxia
- Shock
- Ovrinflation
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Conditions that accelerate surfactant production!
- Maternal heroin addiction
- Maternal hypertension
- Maternal infection
- PROM
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Factors that affect lung growth!
- Hypoxia
- Starvation
- Hyperoxia
- Cigarrette smoke
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Alveolar growth after birth!
- After birth the alveoli develop in increasing numbers until the age of 8 years and increase in size until growth of the chest wall is finished
- Lung volumes will increase 23 fold, alveolar number will increase 6 fold, and surface area will increase 21 fold
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Fetal lung liquid
- Gives shape to the alveolus or else the walls of the alveoli will grow together
- Also helps with cleaning alveoli of damanged cells
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The intial lung bud emerges from the...
Pharynx 26 days after conception
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Type I pneumocytes
- Flat cells serving as a thin, gas permeable membrane for the diffusion of gases and as a barrier against water and solute leakage
- Account for more than 97% of surface area
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Type II pneumocyte
The principle structure involved in surfactant production, storage, secretion, and reuse
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What is the lung developement stage formerly thought to be the last stage before birth, and characterized by relatively smooth walled, cylindrical structures subdivided by ridges known as secondary crest?
Saccular stage
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formation of Fetal circulation
- Aortic arch IV grows into aortic arc
- Aortic arch VI grows into pulmonary artery
- Aortci arch III becomes carotid
- Takes 2 month for heart to form
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What is the purpose of the shunts?
Increase O2 to brain
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Where is the highest PaO2?
Umblical vein
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Where is the lowest PaO2?
Right ventricle
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Why is the a difference between the ascending aorta and the descending aorta?
Ductus arteriosus
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What direction does the DA and the FO shunt?
- Right to left
- Cause of high pulmonary vascular resistance and least resistance
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Fetal circulation
- 10 to 15% of cardiac output goes to lung
- Place of gas exchange is in Placenta
- Make sure the highest PaO2 goes to the brain
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Foramen Ovale
A hole between the right and left atrium
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Maternal Diabetes mellitus and how it affects the fetus!
- Influence lung naturation
- increase insulin levels
- inhibit the synthesis of the phospholipid part of surfactant
- jaundice
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Placental abruption and how it affects the fetus!
- baby at risk of hemorage, hypoxecimia, and anemia, asphyxia
- Premature labor
- Associated with cocain use
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Premature rupture of membranes and how it affects the fetus!
- Responsible for nearly 50% of preterm births in the US.
- Increased likehood of fetal infection
- Occurs more in premies
- This is when there is prolonged labor after rupture
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Oligohydramnios and how it affects the fetus!
- Too little amniotic fluid
- When occurs early in gestation, it can cause lung hypoplasis and limb deformities
- Pulmonary or renal problems
- Small lungs
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The five events that must occure for extra uterine life to occure!
- Establish breathing
- Get rid of fetal lung liquid
- Establish FRC
- Increase pulmonary flow
- Close our shunts
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A baby established breathing by...
- Loud craying
- Noise, touch, light, loudness, cold air
- External and internal factors
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A baby gets rid of fetal lung liquid in three ways!
- Vaginal squeeze
- Lymphatic system- labor
- Pulmonary circulation- breathing
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A baby establishes FRC by...
Air trapping
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A baby increases pulmonary flow by...
- Increasing alveolar PO2
- Decreasing vascular resistance
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A baby closes his shunts by...
- An increase in PaO2 closes ductus arteriosis
- Increase in PAO2 opens capalliles
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What are the stimuli for the onset of respirations?
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What happens to the work of breathing as the number of breaths taken increases!
The FRC increases and compliance increases, therefore the WOB decreases
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What factors increase pulmonary blood flow?
- First breath
- Air entry
- Increase in Alveolar PO2
- Decrease pulmonar vascular resistance
- Thus reversing hypoxic vasoconstriction
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What closes the Foramen ovale?
- The flap closes due to an increase in SVR
- The RA pressure drops due to a decrease in volume
- The L heart pressure increases due to a back up of the blood that previously went to the placenta
- L heart pressure also rises because increased PBF results in a larger return of pulmonary blood to the LA
- loss of umblicanl circulation
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What are the factors that close the ductus arteriosus?
- Decrease PVR allows increased PBF, so there is less flow through the shunt
- As SVR gets higher than PVR, flow is reversed from the aorta to the pulmonary artery (L to R)
- As the PO2 increases, the DA will constrict
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Explain the relationship between the number of breaths, the work of breathing, and the establishment of FRC!
The WOB breathing gradually decreases with an increase of FRC and an increase in compliance cause of air trapping
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APGAR scoring
- Heart rate
- Respiratory rate
- Skin color
- Reflex irritability
- Muscle tone
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What is the most common cause of bradycardia?
hypocemia
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What is the rate of PPV in resuscitation?
40 to 60 breaths/min
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What is the compression/ventilation ratio?
3:1 ratio
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Do you have to use 100% oxygen to resuscutate? and why is this a problem in premature babies?
- No
- Premature babies are more vernerable to hyperoxia
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Immediately after delivery the first step in stabilizing the infant is...
to place the infant on a preheated radiant warmer before any other interactions.
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Infants who are vigorous at birth (strong respiratory effort, heart rate >100 beats/min, good muscle tone) should
not receive tracheal suctioning.
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Infants who are not vigorous (no or poor respiratory effort, heart rate <100 beats/min, poor muscle tone)
may receive direct laryngotracheal suctioning.
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The ideal heart rate for a newborn is
120 to 140 beats per minute
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If the heart rate is 60 beats/minute or less and adequate ventilation is being provided,
chest compressions should be initiated immediately.
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The self inflating bag is ideal for neonatal resuscitaion because it...
Requries the least experience and training for the individual using it
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The one procedure that should always be carried out immediately after the birth of an infant known or suspected to have a diaphragmatic hernia is...
placement of a nasogastric tube hooked to suction
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Providing adequate ventilation is the...
primary factor in the effective resuscitation of a neonate.
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The perferred way to administer epinephrine during neonatal resuscitation is by...
The intravenous route
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After 10 minutes of continuous and adequate resuscitative efforts...
discontinuation of resuscitation may be justified if there are no signs of life
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placental abruption
- early seperation from the uterine wall
- Bleeding from both mom and baby
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Maternal diabetes mellitus
Risk to the infant include prematurity, stillbirth, birth injury due to size
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Placenta previa and how it affects the fetus!
- Can cause premature labor and fetal hypoxeia
- asphyxia
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Severe maternal diabetes can...
Increase surfactant production
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Mild maternal diabetes can
Decrease surfactant production
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Mild Pregnancy induced hypertension!
Will increase surfactant production
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Severe pregnancy induced hypertension!
Will decrease surfactant production
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Pregnancy induced hypertension!
- Preclampsia
- Can be caused by an abnormally developed placenta
- Blood supply to baby is decreased and can cause asphyxia
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What is placenta previa?
Abnormal implantation of the placenta in the lower wall
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What is placental abruption?
Abnormal seperation of a normally implanted placenta
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Multiple gestation
- Perinatal mortality is increased with twins
- Most common problem is prematurity
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Rh incompatability!
- not a problem in first pregnancy
- Mom (Rh-) will make antibodies to Rh+. If the baby is Rh+ the antibodies will attack the baby RBC's and a severly anemic, jaundice baby will be born.
- Treat with Rhogram after delivery of first baby to stop the developement of antibodies
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Premature labor
- Delivery before week 37, lower gestation = higher mortality rate
- RDS
- Poor immunity
- poor tissue oxygentaion
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How does pulmonary vascular resistance decrease?
- FLL is removed from the alveoli, so there is less pressure on the pulmonary capillaries
- The expanded alveoli will straighten pulmonary vessels
- Spontaneous breathing increases PAO2 thus reversing hypoxic vasoconstriction
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Describe the importance of oxygentation in making a complete and uncompilcated transition from fetus to baby!
- Oxygenation is needed to closes the ductus arteriosus by an increase n arterial O2
- Oxygenation helps with decreasing right atrial pressure, so that the foramen ovale can close
- Oxygenation increases pulmonary blood flow because of pulmonary vasodilation
- Adequate oxygenation maintains breathing, lung expansion, and gets rid of fetal lung liquid
- Adequate oxygenation keep you breathing which establishes FRC
- Oxygen is important to keep an adequate heart rate
- Oxygentation decreases WOB
- Oxygen maintains a normal breathing pattern
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What size tube for a 1000g baby and how far should it be inserted?
2.5 and 7 cm
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What size tube for a 2000g baby and how far should it be inserted?
3.0 and 8cm
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What size tube for a 3000g baby and how far should it be inserted?
3.5 and 9 cm
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What size tube for a 4000g baby and how far should it be inserted?
4.0 and 10
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What factors increase Systemic vascular resistance?
clamping the cord
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Infants who are not vigorous (no or poor respiratory effort, heart rate<100 beats, poor muscle tone)...
- may receive direct laryngotracheal suctioning
- For direct laryngotracheal suctioning, intubate the infant and apply suction directly to the endotracheal tube with the help of a meconium aspirator
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What are the five fetal heart rate patterns?
- Early deceleration--- normal
- Late deceleration--- very bad
- variable deceleration--- not good
- Fetal bradycardia--- abnormal
- beat to beat variablity--- normal
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What does APGAR stand for?
- Apperance
- Pulse
- Grimise
- Activity
- Respirations
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What is the common APGAR?
- Pink with blue hands and blue feet
- Acrocyanosis
- 9 is the most common
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Targeted pulse-ox SPO2 after birth!
- 1 minute ----- 60 to 65%
- 2 minutes ---- 65 to 70%
- 3 minutes ---- 70 to 75%
- 4 minutes ---- 75 to 80%
- 5 minutes ---- 80 to 85%
- 10 minutes ---- 85 to 95%
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What are the two categories of meds given to treat preterm labor?
- Tocolytics and corticosteriods
- To try and accelerate surfactant production
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Smoking during pregnancy and complications for the fetus!
- Low birth weight
- Risk of sudden infant death syndrome
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Cocaine use during pregnancy and complication for the fetus!
- Congential malformations
- Withdrawl symptons
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Alcohol during pregnancy and complications for the fetus!
- Mental retardation
- prenatal and postnatal growth restriction
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Polyhydramnios is frequently associated with fetal malformations including...
anencephaly, esophageal atresia, and tracheoesophageal fistula; it is also associated with hydrops fetalis, twin gestation, and maternal diabetes
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Poor beat-to-beat variability, late decelerations, and bradycardia during labor may be...
signs of fetal compromise due to placental insufficiency.
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Loss of deep tendon reflexes is usually...
the first sign of toxicity
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All women between 24 and 34 weeks of gestation with preterm labor and intact membranes are candidates for...
antenatal corticosteroid therapy
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Patients with preterm labor and ruptured membranes may benefit from corticosteroid therapy
between 24 and 32 weeks of gestation.
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How is most of the fetal blood entering the main pulmonary artery shunted to the aorta?
Through the ductus arteriosus
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What set of actions causes the systemic circulation to transition from a low resistance system to a high resistance system?
Clamping the umblical cord, thus preventing blood from the placenta
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Anatomic closure of the ductus arteriosus begins in the last trimester...
as endothelial tissue begins to proliferate into the lumen of the ductus, forming bulges
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The respiratory function of the blood!
- Fetal O2 dissociation curve is to the left of an adult
- Fetal hemoglobin has a higher affinity for oxygen than does adult hemoglobin
- Fetal hemoglobin has a greater O2 unloading capacity at pO2 of 15-28
- 2-3 DPG does not facilitate O2 release from fetal hemoglobin
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Preclampsia
- Proteins in the urine
- Edema
- Increased blood pressure
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Oxygenation!
- Oxygenation is needed to close the DA by an increase n arterial O2
- Oxygenation is needed to supply energy to the muscles of respiration to establish a constant breathing pattern
- With the increase in arterial O2, this will help elimante bradycardia ans apnea
- O2 in the alveoli is needed to cause vasodilation of the pulmonary vessels to decrease PAP, this also allows for pulmonary blood flow to increase
- Once PAP is decreased this will make RAP higher, If the LAP is higher than RAP then the FO closes
- O2 keeps baby breathing and facilitates lung expansion and will rid the lungs of FLL
- O2 is needed to establish FRC
- If the baby is Hypoxemic the DA will saty open
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