Fetal Adaptations Flashcards
t/f in utero, fetal core temp is >0.5 C than the mother’s temp
true
how is heat lost in newborns
conduction
convection
evaporation
radiation
how do newborns produce heat
lipolysis of brown adipose tissue
why are pre-term babies more at risk for hypothermia
immature skin
greater surface area to body weight ratio
decreased brown adipose stores`
t/f preterm infants will have smooth skin
f, transparent and thin skin
methods to produce heat
drying the infant, radiant warmers, plastic wrap, kangaroo care
optimal environmental temperature for minimal heat loss nd oxygen consumption
36.5-37 C
t/f the breathing movements fetuses do in utero are for gas exchange
false, these are intermittent and not for gas exchange
factors leading to adequate lung function
airway patency
functional lung development
maturity of respiratory control
during labor, there is an increase in ____ that enhances lung fluid absorption and triggers ___
increase in catecholamines, vasopressin, prolactin, and glucocorticoids
triggers change in epithelia from chloride secretory to sodium resorptive
what does surfactant do
enhances aeration of gas free lungs by reducing surface tension, lowering pressure required to open alveoli
t/f air entry into the lungs displaces the fluid causing an increase in hydrostatic pressure and decrease in pulmonary blood flow
false, decrease in hydrostatic pressure and increase in pulmonary blood flow
how is spontaneous breathing after birth maintained
activation of chemoreceptors
decrease in placental hormones that inhibit respiration
presence of natural environmental stimulation
most critical reason for apnea
acidosis secondary to compromised fetal circulation
others: narcotics, anesthetics, mg
how to manage fetal apnea
- primary apnea: reverse by stimulation
- secondary apnea: assisted ventilation
t/f frc is lowest in immature infants due to decreased alveolar number
true
timeline for surfactant production
20 aog: high conc but not on surface
28-32 w: in amniotic fluid
35 w: mature levels
incidence of rds
60-80% <28 aog
15-30% 32-36 aog
rare at >37 aog
three structures in fetal circulation
ductus venosus = uv to ivc
fo = bypass right to left atrium
da = connects pulmonary artery to aorta
in utero circulation
go to trans
rv to lv ratio and total fetal cardiac output
rv to lv ratio 1.3:1
total fetal cardiac output 450 ml/kg/min
expansion of lungs and incresed arterial po2 leads to
decreased pulmonary vascular resistance and increased systemic vascular resistance
ductus venosus closure
closed by removal of placenta in 1-3 hrs
ductus arteriosus closure
closed by high arterial po2 in 10-15 hrs
foramen ovale closure
closed by increased LA and LV pressure by 3rd month of life
t/f the fall in prostaglandin causes the DA and UA to close
true
t/f newborns at rest have a low oxygen consumption which is associated with high cardiac output
false, high oxygen consumption, high cardiac output, high hr
t/f increased fetal hemoglobin requires increased co
true
average central aortic pressure in neonates
75/50 mmhg
cardiac output changes
350 ml/kg/min -> 150 ml/kg/min in first 2 months
75 ml/kg/min in adult levels
conditions that cause hypoxia
asphyxia
meconium aspiration (postterm)
pneumonia
extreme prematurity
fetal hemoglobin is present until
3 mos
high affinity of hbf means
less oxygen is available for the tissues = clingy to the o2
when is physiologic decrease of hemoglobin noticed
8-12 w in term, 6 w in preterm
t/f the infant brain lacks cerebral autoregulation
true, makes infants predisposed to intraventricular hemorrhage
consequence of weak bbb
medications easliy permeate central venous system = increased sensitivity to lipid soluble drugs
spinal cord and dural sac ends at
spinal cors: l3 (adult l1)
dural sac s4 (adult s2)
t/f there is a surge of tsh immediately after birth and increase in t3/4
true
factors leading to ger
decreased gastric emptying and decreased lower esophageal tone
factors leading to high urine output
unable to concentrate urine due to lack of kidney’s tubular function
physiologic weight loss due to high urine output
10% of baby’s birth weight
