What are the three things that are needed for gas exchange?
Blood vessels (pulmonary blood flow
Embryonal stage of development!
Day 26 to day 52
Developement of trachea and major bronchi
Pseudoglandular stage of development!
Day 52 to week 16
Development of remaining conducting airways
Canalicular stage of development!
Week 17 to week 26
Development of vascular bed and framework of respiratory acini
Saccular stage of development!
Week 26 to week 36
Increased complexity of saccules
Alveolar stage of development!
Week 36 to term
Development of alveoli
What time frame is gas exchange possible and in what pgase?
22 to 24 weeks
Two phases of surfactant production!
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.
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
What does the PG level indicate?
determination of fetal lung maturity
If there is insufficient surfactant, what does this mean for the baby?
Increase in alveolar surface tension
Increase in work of breathing
Development of hypoxemia
Conditions that delay surfactant production!
Conditions that accelerate surfactant production!
Maternal heroin addiction
Factors that affect lung growth!
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
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
The intial lung bud emerges from the...
Pharynx 26 days after conception
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
Type II pneumocyte
The principle structure involved in surfactant production, storage, secretion, and reuse
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?
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
What is the purpose of the shunts?
Increase O2 to brain
Where is the highest PaO2?
Where is the lowest PaO2?
Why is the a difference between the ascending aorta and the descending aorta?
What direction does the DA and the FO shunt?
Right to left
Cause of high pulmonary vascular resistance and least resistance
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
A hole between the right and left atrium
Maternal Diabetes mellitus and how it affects the fetus!
Influence lung naturation
increase insulin levels
inhibit the synthesis of the phospholipid part of surfactant
Placental abruption and how it affects the fetus!
baby at risk of hemorage, hypoxecimia, and anemia, asphyxia
Associated with cocain use
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
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
The five events that must occure for extra uterine life to occure!
Get rid of fetal lung liquid
Increase pulmonary flow
Close our shunts
A baby established breathing by...
Noise, touch, light, loudness, cold air
External and internal factors
A baby gets rid of fetal lung liquid in three ways!
Lymphatic system- labor
Pulmonary circulation- breathing
A baby establishes FRC by...
A baby increases pulmonary flow by...
Increasing alveolar PO2
Decreasing vascular resistance
A baby closes his shunts by...
An increase in PaO2 closes ductus arteriosis
Increase in PAO2 opens capalliles
What are the stimuli for the onset of respirations?
What happens to the work of breathing as the number of breaths taken increases!
The FRC increases and compliance increases, therefore the WOB decreases
What factors increase pulmonary blood flow?
Increase in Alveolar PO2
Decrease pulmonar vascular resistance
Thus reversing hypoxic vasoconstriction
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
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
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
What is the most common cause of bradycardia?
What is the rate of PPV in resuscitation?
40 to 60 breaths/min
What is the compression/ventilation ratio?
Do you have to use 100% oxygen to resuscutate? and why is this a problem in premature babies?
Premature babies are more vernerable to hyperoxia
Immediately after delivery the first step in stabilizing the infant is...
to place the infant on a preheated radiant warmer before any other interactions.
Infants who are vigorous at birth (strong respiratory effort, heart rate >100 beats/min, good muscle tone) should
not receive tracheal suctioning.
Infants who are not vigorous (no or poor respiratory effort, heart rate <100 beats/min, poor muscle tone)
may receive direct laryngotracheal suctioning.
The ideal heart rate for a newborn is
120 to 140 beats per minute
If the heart rate is 60 beats/minute or less and adequate ventilation is being provided,
chest compressions should be initiated immediately.
The self inflating bag is ideal for neonatal resuscitaion because it...
Requries the least experience and training for the individual using it
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
Providing adequate ventilation is the...
primary factor in the effective resuscitation of a neonate.
The perferred way to administer epinephrine during neonatal resuscitation is by...
The intravenous route
After 10 minutes of continuous and adequate resuscitative efforts...
discontinuation of resuscitation may be justified if there are no signs of life
early seperation from the uterine wall
Bleeding from both mom and baby
Maternal diabetes mellitus
Risk to the infant include prematurity, stillbirth, birth injury due to size
Placenta previa and how it affects the fetus!
Can cause premature labor and fetal hypoxeia
Severe maternal diabetes can...
Increase surfactant production
Mild maternal diabetes can
Decrease surfactant production
Mild Pregnancy induced hypertension!
Will increase surfactant production
Severe pregnancy induced hypertension!
Will decrease surfactant production
Pregnancy induced hypertension!
Can be caused by an abnormally developed placenta
Blood supply to baby is decreased and can cause asphyxia
What is placenta previa?
Abnormal implantation of the placenta in the lower wall
What is placental abruption?
Abnormal seperation of a normally implanted placenta
Perinatal mortality is increased with twins
Most common problem is prematurity
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
Delivery before week 37, lower gestation = higher mortality rate
poor tissue oxygentaion
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