ob

exam 3

neonatal period

birth to first 28 days of life

fetal breathing-like movements (FBI) are practiced in utero by \____ weeks gestation

17

why are fetal breathing movements necessary in utero?

for cell kinetic regulation (cell proliferation and death) via the expression of growth factors like insulin and thyroid transcription factor

lack of fetal breathing movements can cause __1__, because __2__

1. pulmonary hypoplasia

2. although type II pneumocytes can synthesize surfactant proteins, they can't store and release surfactant - this renders type I pneumocytes useless bc they can't flatten to allow gas exchange

fetus obtains O2 from __1\__ via the __2\__ with a pressure gradient difference of __3\__ mmHg partial pressure of O2 in maternal blood and __4\__ mmHg in fetal blood

1. maternal circulation

2. placenta

3. 50

4. 30

fetal hemoglobin carries up to __1\__ more O2 than adult and makes up __2\__ of circulating hemoglobin in fetus and newborn

1. 30%

2. 70-90%

highest concentration of circulating O2 goes where in the fetus?

brain and heart

2 important facts about fetal hemoglobin

1. it has a higher affinity for oxygen and improves oxygen intake from mother

2. it decreases the unloading of oxygen at the tissue level (to overcome this and expedite oxygen release at tissue level, oxygen release is increased by fetal acidosis)

normal fetal pH

-7.25-7.35

-lower than adult pH to expedite oxygen release at the tissue level

respiratory preparation for birth

-FBM and lung fluid production decrease 24-36 hours prior to onset of true birth

-surfactant peaks at 28-32 weeks gestation

-administration of steroids can stress surfactant production and increase oxygenation in preterm lungs (only between 24-34 weeks)

-steroid admin. can help decrease bleeding in ventricles of the brain

compression and recoil of thorax

a mechanical stimulus to initiate newborn respirations

crying partially closes __1\__ and increases __2__

1. glottis

2. positive intrathoracic pressure

-mechanical stimulus to initiate newborn respirations

movement of __1\__ down/flat increases __2__, which causes what?

1. diaphragm

2. negative intrathoracic pressure

-causes passive fluid absorption

-mechanical stimulus to initiate newborn respirations

alveoli in lungs __1__,which increases...

1. expand and are more permeable

-increases O2 concentration

-mechanical stimulus to initiate newborn respirations

increase in what two things mechanically stimulate initiation of respirations in newborns?

-increase in functional residual capacity (FRC) of newborn lungs

-increased absorption of lung fluid via the capillaries and lymphatic system

what facilitates cessation of placental circulation?

umbilical cord clamping

chemical stimuli that initiates respirations in newborns

-increase in CO2

-decrease in O2 and pH

-decrease in pulmonary vascular resistance increases gas exchange

-dilation of pulmonary vessels increases pulmonary blood flow

sensory stimuli that initiates respirations in newborns

-warm, dry, and stimulate

-lights, temperature changes, noise

cord clamping increases \____ in cardiovascular adaptation transition

systemic vascular resistance

ductus arteriosus

-protects lungs against circulatory overload

-blood flows across ductus and into the descending aorta

-high pulm. vascular resistance, low pulm. blood flow

-allows R ventricle to strengthen

-allows for both ventricles to perfuse lower extremities

-carries medium oxygenated blood

foramen ovale

shunts highly oxygenated blood from the R atrium to L atrium

ductus venosus

-fetal blood vessel connecting umbilical vein to inferior vena cava

-blood flow regulated via sphincter

-carries highly oxygenated blood

know fetal circulation pathway

!

what causes the functional closure (collapse) of ductus venosus?

-cessation of umbilical vein circulation by cord clamping

-causes an increase in systemic vascular pressure

what causes the functional closure of ductus arteriosus?

-pulmonary artery pressure decreases and causes increased aortic pressure

-increased O2 helps with vasodilation and loss of PGE from placenta leads to ductus constriction

newborn HR at birth can be as high as what? why?

-180 bpm

-due to epinephrine and norepinephrine release

normal HR range at birth

-110-160

-lower with sleep

murmurs

-caused by turbulent blood flow

-90% are transient

-r/t incomplete closing of foramen ovale and/or ductus arteriosus

newborn BP is highest when?

-right after birth

-decreases at about 3 hours

normal newborn blood volume

-80-85 mL/kg

-affected by timing of cord clamping, gestational age, pre-perinatal hemorrhage, and site of blood sample

newborn Hgb range

14-20 g/dL

newborn Hct range

43-55%

newborn WBC range

10,000-30,000/mm3

newborn platelet range

150,000-350,000/mm3

erythropoesis production

temporarily suspended after birth due to higher levels of oxygenation

why does fetal hemoglobin rise a few hours after birth?

due to movement of fluids from intravascular space to extravascular tissue

fetal hemoglobin drop progession

-3% per week until 6-12 weeks due to decreased RBC mass (physiologic anemia)

-continues 3% drop per week until 6 months when about 92% is adult hemoglobin

cardiovascular signs of abnormality

-tachycardia (\>160 at rest)

-bradycardia (

-circumoral or central cyanosis

-persistent, loud murmurs

-extra heart sounds

-absent pulses

-poor capillary refill

-abnormal BP

tx for cardiac abnormalities

-O2 for circumoral and central cyanosis

-cardiac monitor, pulse ox, echocardiogram

-BP x 4 extremities

-transfer to NICU and notify doctor

normal newborn temperature range

97.7-99.5 F

what causes greater heat loss in post-mature and preemies?

less SQ fat

convection

heat loss due to air currents moving around the baby

radiation

-heat travels to cooler surfaces that are not in direct contact with the baby

-walls, surrounding air

evaporation

heat loss due to water vapor conversion

conduction

-heat loss through direct contact with skin and cold surfaces

-mattress, cold scale

where is the best place for a stable baby?

-skin-to-skin with mom

-mom's temp increases and decreases according to the baby

how does baby keep itself warm? (thermogenesis)

-increase basal metabolic rate by increasing O2 and glucose consumption

-increase muscular activity or flexion

can babies shiver?

no