Introduction to Neonatology Flashcards
The development of CVS:
Begins to develop toward the end of the _____ week
Heart starts to beat at the beginning of the ______ week
The critical period of heart development is from day 20 to day 50 after fertilization
third
fourth
describe foetal circulation?
- Oxygenated blood via umbilical vein – Ductus Venosus
- Some blood via Foramen Ovale to Left Atrium – Left Ventricle – Aorta (Ao)
- Some of blood to Right Ventricle – Pulmonary Artery (PA) - Patent Ductus Arteriosus (PDA) from PA to Ao
- Saturation SaO2 in foetal body is 60-70%
what is the function of Ductus Arteriosus?
Protects lungs against circulatory overload
Allows the right ventricle to strengthen
Carries low oxygen saturated blood
Ductus Venosus:
- Foetal blood vessel connecting the umbilical vein to the ___
- Blood flow regulated via sphincter
- Carries mostly _________ blood
IVC
oxygenated
what happens after the first breath of a baby is taken?
Fluid leaves lungs
Oxygen most potent vasodilator
Drop of pulmonary pressure
Circulation of heart significantly changes
Duct doesn’t necessary close immediately
what are the Normal vital signs of Full Term newborn?
Breathing/respiratory rate:
- 30-60 /min
- Periodical breathing
Heart rate:
Normal Heart rate - 120-160 b/min
Tachycardia - >160 b/min
Bardycardia - < 100 b/min
how is thermoregulation done in newborns?
Maternal thermoregulation in the womb.
Newborn babies lack shivering thermo genesis thus need a metabolic production of the heat.
Brown fat well innervated by sympathetic neurons.
Cold stress leads to lipolysis and heat production.
how is heat lost in newborns?
Radiation: Heat dissipated to colder objects
Convection: Heat loss by moving air
Evaporation: We are born in the water
Conduction: Heat loss to surface on which baby lies
who gets Physiological jaundice?
Appears on Day of life (DOL) 2-3
Disappears within 7-10 DOL in term infants and up to 21 DOL in premature infants
Up to 60% terms and 80% premature babies develop visible jaundice
6% terms up to 220 mcmol/L
10% breast fed jaundice at 30 DOL
Physiological jaundice:
75% bilirubin comes from haemoglobin
Metabolised, conjugated in liver
Bilirubin is lipid soluble thus crosses haemato-encephalic barrier
At high concentrations it cause an irreversible changes in the brain - what is this called?
how is physiological jaundice treated?
kernicterus
Blue light converts bilirubin to water soluble form and increases oxidation of bilirubin.
what is Fluid balance like in term newborn?
Full term infant is able to maintain fluid / electrolyte balance
Weight loss up to 10% is normal
Loss is due to: Shift of interstitial fluid to intravascular, Diuresis
It is normal not to pass urine for the first 24 hrs!
what is Fluid balance like in premature infants?
Less fat in body composition
Increased loss through kidney: Slower GFR, Reduced Na reabsorption, Decreased ability to concentrate or dilute urine
Increased Insensible Water Loss (IWL): Via immature skin and breathing, Physiological IWL is 20-40 ml/kg/day but could be up to 82 ml/kg/day in 750-1000 g, (IWL can lead to sever dehydration of the babies)
what causes Anaemia of prematurity?
Reduced erythropoesis
Infection
Blood letting – most important cause!
Summary:
Full term newborn is prepared for extra-uterine life
Premature infants require lots of help and support (trying to mimic conditions they have in the womb and not always easy to do)