The Newborn Infant Flashcards
what structure allows foetal bood to bypass the liver, and what vessel does it join into
the ductus venosus
joints into the IVC - drains into RA of heart
what structures in the heart allow the blood to bypass the lungs
- the foramen ovale between the RA and LA allows blood to flow straight from RA to LA, then LV and out aorta
- if any blood escapes the FO and flows into RV and then out pulmonary artery, the patent ductus arteriosus will allow it to enter the aorta
by which gestational age does the foetus have lungs that function well enough (dont need steroids if delivered)
36 weeks
when does the baby start producing surfactant, and what does this do
from around 24 weeks, it reduces alveolar surface tension stopping the smaller alveoli from collapsing
how does vaginal delivery help lung preparation for the outside world
it squeezes the fluid out of the lungs
if eg C section, there will be delayed clearance of lung fluid and transient tachypnoea/resp distress
what are O2 sats expected to be when thebaby is born
they will intially be around 70% and will increase to around 90% over teh first 10 minutes
hwat colour is the baby when born
blue, turns pink as oxygenated
what changes happen in the lungs after birth
the lungs before were a very high pressure system (unfavourable.). PVR drops and SVR rises, driving blood through lungs
FO and DA close
what causes closure of teh FO, and what is left behind
the pressure in LA > RA - forcing FO shut
fossa ovalis remains
what kept the DA open in utero, and what now causes it to shut
it was kept open by the placental PG
after birth, there are no more PG and high O2 tension causes the smooth muscle in it’s walls to constrict
what is the closed DA called in children/adults
ligamentum arteriosum
what murmur would a PDA cause
machine like murmur below the left clavicle
how do you manage a PDA
IV NSAIDs - indomethacin or ibuprofen (anti COX action inhibits PG production and causes closure).
what does the ducuts venosus become
the ligamentum teres (round ligament) in the liver
why are neonates particularly prone to rapid heat loss
- covered in fluid when born
- have a high surface area : volume ratio
what are the 4 mechanisms by which neonate can lose heat
- radiation
- evaporation of fluid
- conductive - contact with cold surface
- convection - air flow
how do babies warm themselves up? they cant shiver
- non shivering thermogenesis
- stored brown fat breaks down in response to catecholamines - heat is generated through ATP
where is the brown fat found in babies
between scapula, around organs, sternum
does NST work immediately from birth?
no, takes around 12 hours
what are the negative consequences of hypothermia, and NST
it increases metabolic rate
- so uses a lot of O2 = resp rate increases to get more O2 = cant meet demands = anaerobic metabolism and hypoxia
- uses lots of glucose - depletes glycogen stores and results in hypoglycaemia
- hyopglycaemia leads to decreased surfactant proudction and pulmonary vasoconstriction - resp distress
- = HYPOXIA
what necessary precuations must be taken to keep baby warm
good delivery room temperature, dry baby immediately, swaddle (hat), skin to skin contact
what extra precuations must be taken for premature babies or to rewarm hypothermic babies
- put in polyethene bag
- blankets/clothes, heated mattress, prewarmed incubator
what is the normal weight range for a newborn baby
2.5-4kg
neonatal vital signs
- Resp rate: 40-60, signs of work of breathing may be attributable to circulatory adaptation
- HR: 120-140
- Cap refill: 2-3 seconds
- Colour: Pink/blue/white
- SaO2: Around 65-70% when born, increase to 90% in first 10 minutes
what benefit does crying hav on lung developmen
it helps to push fluid out of the lungs
what are the benefits of delayed cord clamping
better outcome for baby = higher haematocrit, Hb levels, better blood flow to vital organs
avoids anaemia and hypovolaemia
when shoudl the cord be cut (delaeyd cord clamping)
when it stops pulsating - 30-60 seconds
what is a normal Apgar score
8/8
outline Apgar score
why is skin to skin recommended s highly
it is assoicated with improved bonding and higher breast feeding rates
it keeps the baby warm
mother is worried because baby is not feeding much, 18 hours old?
wont feed much for first
24 hours - reassure
what extra precuations are taken if mother is known to be at high risk of hep B infection
baby is given an immediate vaccination instead of waiting for routine one at 2 months
what extra precuations are taken if mother is known to have HIV
post exposure prophylaxis - drug infusion started within 4 hours of delviery and continued for 4 weeks
combination drug if DVL, monotherapy if UVL
what ART drug is used for HIV in babies
zidovudine (NRTI)
what extra vaccines does the mother during prengancy get to protect the baby
pertussis vaccine from 16 weeks gestation and influenza vaccine
what NHS intiative has been put in place to keep babies warm and healthy
newborn snuggle bundle
within what time frame should the newborn physical examination be carried out
72 hours
what resp rate and heart rate would you expect on examination
resp 30-60
heart 100-150
if a baby is at high risk of hip problems, what is done
US of hips
eg breech birth
what 4 things does the heel prick test test for
sickle cell
cystic fibrosis
inherited metabolic diseases
congenital hypothyroidism
which sleeping position is recommended for baby
on back
what is the greatest risk factor for neonatal death
prematurity
does previous preterm births put you at risk of more
yes, increases risk a lot
LOW ADMISSION TEMPERATURE IS AN INDEPENDENT RISK FACTOR FOR NEONATAL DEATH
- low BMI, minimual muscle activity
- less brown fat
- les subcutaenous fat
- large surface area : volume ratio
the premature baby has an increased risk of nutritional compromise, how is this managed?
parenteral nutrition initially
what is hypoxic ischaemic encephalopathy
brain and organ damage that occurs due to hypoxia, range in severity
how will the baby with HIE present
signs of hypoxia and low Apgar score at birth
later in lfie it will have developmental delay, epilepsy, cognitive issues etc
management of HIE
active resuscitation
cooling treatment - this changes chemical processes in the brain so that less damage is done. can use cooling mat
what glucose concentrations are considered to be hypoglycaemia in term and preterm infants
<2.2 and <1.7 respectively
what commonyl causes transient hypoglycaemia in babies
LBW/premature - dont have enough glycogen stores.
which drug that is used in obstetric management can cause transienet hypoglycaemia in baby
labetalol
why will the baby of a diabetic mother be hypoglycameia
in order to adapt to high blood glucose levels from mother baby pancreas beta cells undergo hyperplasia - hyperinsulinaemia
how does a hypoglycaemic baby present
many asymptomatic
sweating, tachycardia, lethargy, neurological signs
management of hypoglycaemic baby
IV/gel dextrose
what is the cause of most early onset neonatal ifnections
tend to be acquired intrapartum - most are group B strep
what are TORCH infections
ones that are known to produce congenital defects
toxoplasmoa, others, rubella, CMV, herpes/hepatitis
when would you screen for GBS?
no screening even on maternal request
managment of GBS
benzylpenicillin ABx
