Perinatal Adaptation

Question 1

What are the 3 shunts in the fetal circulation?

Answer 1

ductus venosus; foramen ovale; ductus arteriosus

Question 2

What is the function of the ductus venosus?

Answer 2

shunts blood from the umbilical vein to the IVC to bypass the liver

Question 3

What is the function of the foramen ovale?

Answer 3

shunts blood from the right atrium to the left atrium- bypassing the lungs

Question 4

What is the function of the ductus arteriosus?

Answer 4

connects the proximal pulmonary artery to the descending aorta, allowing blood in the right ventricle to bypass the lungs

Question 5

What hormones are increased in the fetus at the onset of labour?

Answer 5

increased catecholamines/amines stopping synthessis of lung fluid

Question 6

What occurs with the circulatory transition in newborns?

Answer 6

pulmonary vascular resistance drops; whilst systemic vascular resistance rises; oxygen tension risese; prostaglandins drop; ductus arteriosus and foramen ovale close

Question 7

What causes the baby to take their first breath?

Answer 7

their CNS reacting to the change of environment and temperature

Question 8

What causes the umbilical arteries to constrict and increase the resistance of the placenta?

Answer 8

oxygenated blood

Question 9

What causes closure of formaen ovale?

Answer 9

increase in pulmonary venous return results in higher left atrial pressure than right

Question 10

What causes closure of hte ducutus arteriosus?

Answer 10

increased oxygenation; decreased flow through the duct and decreased prostaglandins

Question 11

What does the ductus venosus become?

Answer 11

ligamentum teres

Question 12

What does the ductus arteriosus form?

Answer 12

ligamentum arteriosus

Question 13

What happens in persistent pulmonary hypertension of hte newborn?

Answer 13

persistance of the fetal circulation in the newborn (PFO and PDA) due to pulmonary vascular resistance not reducing as it should, so right-left shunting still occurs resulting in poorly oxygenated blood in the systemic circulation

Question 14

How is PPHN diagnosed?

Answer 14

pre- and post-ductal oxygen saturations- difference of >10% suggests hypertension

Question 15

What is the managemtn of PPHN?

Answer 15

ventilation; oxygen; nitric oxide; sedation; inotropes; ECLS

Question 16

What causes PPHN in term babies?

Answer 16

acidosis and alveolar hypoxia are potent pulmonary vasocontrictors eg sepsis or asphyxia

Question 17

What is the most common cause of respiratory distressi n newborns?

Answer 17

transient tachypnoea of the newborn

Question 18

What causes transient tachypnoea of the newborn?

Answer 18

incomplete absorption of the fetal lung fluid after birth

Question 19

What happens to fetal lung fluid during labour?

Answer 19

progressivley absorbed into the interstital spaces and lympathatics so that lungs can fill with air once born

Question 20

What is the normal course of transient tachypnoea of the newborn?

Answer 20

fluid is reabsorbed after birth and signs of resp distress improve within 24-48 hours

Question 21

What is seen on CXR with transient tachypnoea of the newborn?

Answer 21

streaky parenchymal lung opacities and small pleural effusions

Question 22

What are the 4 methods of heat loss inthe new born?

Answer 22

radiation; convection; evaporation; conduction

Question 23

What is the main source of heat production in the newborn?

Answer 23

non-shivering thermogenesis

Question 24

What is non-shivering thermogenesis?

Answer 24

heat produced by breakdown of stored brown adipose tissue in response to catecholamines

Question 25

Why are neonates are high risk of hypothermia?

Answer 25

large surface area-to-body mass ratio; decreased subcut fat; immature skin- evaporative loss; greater water content; poorly developed mechanisms (no shivering); altered skin flow (peripheral cyanosis )

Question 26

What is the greatest loss of heat after birth for the neonate?

Answer 26

evaporation of amniotic fluid

Question 27

What is conduction?

Answer 27

When baby is placed on cold table etc. and heat transfer occurs

Question 28

Waht is radiation?

Answer 28

When newborn is near cool objects, transfer of heat between surfaces that arent touching

Question 29

What is convection?

Answer 29

When newborn is exposed to cool surrounding air

Question 30

Why are SGA and preterm babies at higher risk of hypothermia?

Answer 30

low stores of brown fat; little subcut fat and larger surface area:volume

Question 31

How is hypothermia avoided in neonates?

Answer 31

get baby dry; hat; skin-to-skin; blanket/clothes; heated matress; incubator

Question 32

How do neonates compensate for loss of placental glucose infusion?

Answer 32

mobilisation of hepatic glycogen stores for gluocneogenesis and use ketones as brain fuel

Question 33

What are the reasons for babies developing hypoglycaemia?

Answer 33

increased energy demands; low glycogen stores; inappropriate insluin/glucagon ratio; some drugs

Question 34

What may cause a baby to have increased energy demands?

Answer 34

unwell or hypothermia

Question 35

What may cause a baby to have low glycogen stores?

Answer 35

small; premature

Question 36

Waht is the role of oxytocin in breastfeeding?

Answer 36

milk ejection

Question 37

What is the difference between colostrum and mature breast milk?

Answer 37

thick, yellowish secretion that is higher in immunoglobulins (IgA) phospholipids; cholesterol and protein and lower in lactose and fact

Question 38

What causes physiological jaundice?

Answer 38

breakdown of fetal haemoglobin; conjugating pathways are immature resulting in a rise in circulating unconjugated bilirubin