Ma. Luisa de Villa-Manlapaz, MD, MHPEd February 8, 2011
ASMPH
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Learning Objectives To review the fetal circulation To learn
the changes in the pulmonary and cardiovascular system that occur
during birth To learn the hepatic adaptations in glucose
metabolism, bilirubin metabolism, and vitamin K production To learn
how a newborn achieves thermoregulation
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Fetal Circulation Placenta is responsible for exchange of
gases, nutrients and metabolic waste products Fetus receives blood
from the placenta and returns it to the placenta
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Fetal Circulation Blood flows from the placenta into the
umbilical vein The blood which contains a PO 2 of approx 35 mmHg
passes through the liver and ductus venosus
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Fetal Circulation Blood from ductus venosus drains into the
inferior vena cava foramen ovale left atrium
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Fetal Circulation Superior vena cava drains de-oxygenated blood
from the brain into the right atrium. right ventricle. 90% of blood
from RA shunted through the ductus arteriosus 10% ejected to
pulmonary artery lungs
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Fetal Lungs and Circulation Alveoli filled with lung fluid
Pulmonary arterioles constricted Pulmonary blood flow diminished
1-7 Click on the image to play video
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Neonatal Circulation After birth, umbilical cord is cut
Systemic vascular resistance increases (BP in aorta increases)
Pulmonary vascular resistance decreases ((BP in lungs
decreases)
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Lungs and Circulation After Delivery Lungs expand with air
Fetal lung fluid leaves alveoli 1-9 Click on the image to play
video
Lungs and Circulation Blood oxygen levels rise Ductus
arteriosus constricts Blood flows through lungs to pick up oxygen
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Normal Transition Fluid in alveoli absorbed and replaced by air
Umbilical arteries and vein constrict thus increasing blood
pressure Blood vessels in lungs relax, increasing pulmonary blood
flow 1-12 The following major changes take place within seconds
after birth:
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Baby cries and take first breath which help open alveoli
Surfactant keeps the alveoli from collapsing after they expand
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Metabolic Adaptation In utero, fetus relies primarily on
placental transfer of glucose and nutrients from mother to meet
energy demands
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Metabolic Adaptation Fetus stores glucose in the form of
glycogen in last trimester especially in last month of
trimester
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After Birth Enzymes activate breakdown of glycogen back into
glucose molecules Glucose released into bloodstream to maintain
blood sugar Normal glucose utilization rate in fasting healthy term
infant is 4-6 mg/kg/min
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Factors which influence glucose levels Glycogen stores Insulin
levels Glucose utilization Premature baby Infant of diabetic mother
Sick infant
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Thermoregulation In utero, the fetus is in a warm and dark
environment Temperature is controlled
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At birth, newborn has to produce as much heat as much as is
lost THERMOREGULATION
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Normal Response to Cold Stress Vasoconstriction in arms and
legs Increased movement and flexion of extremities Brown fat
metabolism
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Brown Fat Metabolism
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Heat loss Occurs on a gradient from warmer to cooler Babys warm
body to cooler air or surface Heat loss accentuated by: Wet skin
Cool air temperature Drafts
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Kangaroo mother care Mother provides warmth to the baby by skin
to skin contact. Provides easy access to the breasts, promoting
breastfeeding
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Hepatic adaptation Minor role of fetal liver portal circulation
shunted through the ductus venosus Majority of bilirubin pigment
transferred unaltered across the placenta to the maternal
circulation Fetus has a high percentage of circulating red blood
cells to utilize all available oxygen in a low oxygen
environment
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PHYSIOLOGIC JAUDICE Increased bilirubin load on liver cell
Increased erythrocyte volume Decreased erythrocyte survival
Increased enterohepatic circulation of bilirubin Immature liver
function
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Hepatic Adaptation Liver manufactures clotting factors needed
for blood coagulation Several factors need Vitamin K for their
production Bacteria that produce Vitamin K are normally found in
the gastrointestinal tract
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However, the gastrointestinal tract of the newborn is sterile
Therefore newborn cannot manufacture vitamin K which is needed to
produce some clotting factors Newborns are given Vitamin K either
intramuscularly or orally at birth to prevent bleeding
disorders
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Learning Objectives To review the fetal circulation To learn
the changes in the pulmonary and cardiovascular system that occur
during birth To learn the hepatic adaptations in glucose
metabolism, bilirubin metabolism, and vitamin K production To learn
how a newborn achieves thermoregulation
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Brazeltons States of Reactivity 1. Deep sleep: quiet,
non-restless sleep state 2. Light sleep: eyes closed but more
activity is noted; newborn moves actively; may show sucking
behaviour 3. Drowsy: eyes open and close and eyelids look heavy;
body activity is present with episodes of fussiness
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4. Quiet alert: quiet state with little body movement, but the
newborns eyes are open and she is attentive to people and things
that are near her 5. Active alert: eyes are open and active body
movements are present; newborn responds to stimuli actively 6.
Crying: eyes may be tightly closed, thrashing movements are made
together with active crying