Introduction to Neonatology

Question 1

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

—

Answer 1

third

fourth

Question 2

describe foetal circulation?

Answer 2

• 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%

Question 3

what is the function of Ductus Arteriosus?

Answer 3

Protects lungs against circulatory overload

Allows the right ventricle to strengthen

Carries low oxygen saturated blood

Question 4

Ductus Venosus:

• Foetal blood vessel connecting the umbilical vein to the ___
• Blood flow regulated via sphincter
• Carries mostly _________ blood

Answer 4

IVC

oxygenated

Question 5

what happens after the first breath of a baby is taken?

Answer 5

Fluid leaves lungs

Oxygen most potent vasodilator

Drop of pulmonary pressure

Circulation of heart significantly changes

Duct doesn’t necessary close immediately

Question 6

what are the Normal vital signs of Full Term newborn?

Answer 6

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

Question 7

how is thermoregulation done in newborns?

Answer 7

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.

Question 8

how is heat lost in newborns?

Answer 8

—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

Question 9

who gets Physiological jaundice?

Answer 9

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

Question 10

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?

Answer 10

kernicterus

Blue light converts bilirubin to water soluble form and increases oxidation of bilirubin.

Question 11

what is Fluid balance like in term newborn?

Answer 11

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!

Question 12

what is Fluid balance like in premature infants?

Answer 12

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)

Question 13

what causes Anaemia of prematurity?

Answer 13

Reduced erythropoesis

Infection

Blood letting – most important cause!

Question 14

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)