Physiology of the Newborn I Flashcards
(29 cards)
define the neonatal period
first 28 days of life, most vulnerable time of postnatal period w most dramatic physiological changes that will ever occur in life
What is the most immediate change at birth?
baby needs to use its own lungs for gas exchange and circ system has to start functioning like adult
what factors trigger transition to fetal lung use and normal circ?
blood flow from umbilical cord stops, lungs expand, temp drops, tactile touch
compare fetal Hb to adult Hb
fetal: 2 alpha and 2 gamma chains make the protein which makes it better at taking up oxygen but worse at depositing it
adult: 2 alpha and 2 beta chains make the protein, allows easy process for fetal blood cells to take O2 via O2 gradient
outline change is SpO2 after first breath
from 50 to 95%
what is RBC production mainly influenced by?
erythropoietin which is stimulated by low O2 in blood
how does rise is sats at birth affect EPO?
reduces EPO which lowers RBC formation until about 6 weeks old, can lead to anaemia since not making adult RBCs
what is main function of ductus venosus?
shunts blood away from liver to inferior vena cava
main function ductus arteriosus
shunts blood away fromk pulm trunk/artery to aorta and into circ
describe chain of events relating to CV system after the removal of the placenta
first breath -> lungs full of O2 and RBCs collecting it, resistance in lungs decreases allowing blood to flow easier from R) ventricle to L) atrium
what factors are needed for baby to breathe effectively?
fluid clearance, changes to vasc flow, surfactant secretion, alveolar distention
how do changes in umbilical cord relate to first breath?
cord is compressed in labour -> increased CO2 and decreased O2 which is exaggerated once the cord is cut -> shift stimulates change in resp centre of brain to cause first breath
what structure help reabsorb fluid from lungs and when?
epithelial sodium channels (ENaC), start reabsorbing a few days before natural delivery
what drives ENaC reabsorption of lung fluid?
increase in cortisol and other hormones -> stimulation of adrenaline -> increase in ENaC activity and reabsorption
how does lung fluid clearance happen during labour and after birth?
labour: chest wall compression
post birth: lymphatic and vascular drainage
what occurs if fluid not cleared well?
transient tachypnoea of the newborn (TTN) -> CPAP
describe pros and cons of delayed cord clamping
pros: more iron and RBCs transferred
cons: assoc with jaundice since fetal RBCs are transferring which are less effective in extrauterine life
what causes RDS?
insuff surfactant -> increased surface tension and alveolar collapse
what can be given in prep for preterm birth to help increase surfactant?
betamethasone/steroids
what disease is diagnosed if resp support req >36K
chronic lung disease or bronchopulmonary dysplasia (BPD)
what can cause neonatal pneumothorax and how is it treated?
increased WOB, surfactant defic, damage from mech vent, prem/IUGR, mec asp
treated with drain/needle asp
describe apnoea of newborn and possible causes
gaps in breathing -> reduction in O2 tension, assoc SIDS, can be caused by infection, Fe issues, exposure to drugs, prem
What occurs during process of replacing FRBCs with ARBCs?
bilirubin formed as a byproduct
what are the effects of high levels bilirubin?
brain damage (kernicterus), bilirubin enceph/neuropathy
