Perinatal Adaptation Flashcards
List functions of the placenta
Fetal homeostasis Gas exhanges Nutrient transport to fetus Waste products from fetus Acid base balance Hormone production Transport of IgG
What are the 3 shunts present in the foetal circulation?
Ductus venosus (eft umbilical vein blood flow to IVC) Foramen ovale (oxygenated blood from RA to LA) Ductus arteriosus (blood from RV to bypass lungs)
Which foetal shunt allows oxygenated blood from the placenta to bypass the liver?
Ductus venosus
List the stages of embryological development of the fetal lungs
Embryonic Pseudoglandular Cannalicular Saccular Alveolar
From what point in gestation, do babies start to produce surfactant?
24 weeks
Which vessel carries oxygenated blood from the placenta to the foetus?
Umbilical vein via ductus venosus (liver) and IVC
Once oxygenated blood reaches the right atrium, where can it go?
To right ventricle and pulmonary artery
To left atrium via foramen ovale (majority)
Once oxygenated blood reaches the pulmonary artery, where can it go?
To lungs (7%) To aorta via ductus arteriosus
List ways a foetus prepares for birth
Surfactant production Accumulation of glycogen Accumulation of brown fat Accumulation of subcutaneous fat Swallowing amniotic fluid
List physiological adaptions to the fetus during labour
Increase catecholamines/ cortisol
Synthesis of lung fluid stops
Vaginal delivery squeezes lungs
Oxygen is a potent vasoconstrictor/ vasodilator of the lungs and is a potent vasoconstrictor/ vasodilator of vascular smooth muscle
Vasodilator
Vasoconstrictor
List circulatory changes that occur in the fetus at birth
Pulmonary vascular resistance drops
Systemic vascular resistance increases
Why do ducts constrict at birth?
Oxygen tension increases
Circulating prostaglandins reduce
What does the ductus venosus become in circulatory transition?
Ligamentum teres
What does the ductus arteriosus become in circulatory transition?
Ligamentum arteriosus
Persistant ductus arteriosus
What does the foramen ovale become in circulatory transition?
Physiological closing
Patent foramen ovale (10%)
List some causes of failed cardiorespiratory adaptation in a newborn
Cold stress
Prematurity
Meconium aspiration
Hypoxia
What is persistent pulmonary hypertension of the newborn?
Resistance to lung blood flow remains high and foramen ovale persists, causing deoxygenated blood to flow to systemic circulation
Outline management of persistent pulmonary hypertension of the newborn
Ventilation Oxygen Nitric oxide (lung vasodilator) Sedation Ionotropes Extra-corporeal life support (ECLS)
Why do babies lose heat quickly when they are born?
Large surface area
Wet when born
List the four main methods of heat loss that can occur in the fetus
Evaporation
Conduction
Convection
Radiation
What is the main source of heat production in the newborn baby?
Non-shivering thermogenesis
Mobilise brown fat stores in response to catecholamines
State another way that babies thermoregulate
Peripheral vasoconstriction
Why are small for dates or preterm babies more predisposed to hypothermia?
Low stores of brown fat
Little subcutaneous fat
Larger surface area: volume ratio
How does glucose homeostasis change at birth?
Interruption of glucose supply from placenta leading to reduced insulin, increased glycogen for gluconeogenesis
Why are small for dates or preterm babies more predisposed to hyperinsulinaemia?
Low glycogen stores leading to an inappropriate ratio of glycogen to insulin
Give an example of a drug that increases the risk of neonatal hypoglycaemia
Labetalol for maternal hypertension
What reflex helps the baby during breastfeeding?
Rooting and sucking reflex
What harmone stimulates milk ejection from the breast following sucking? Where is it released from?
Oxytocin
Posterior pituitary
What harmone stimulates milk production from the breast following sucking? Where is it released from?
Prolactin
Anterior pituitary
What is colostrum?
Yellowish breastmilk that is produced in the first few days after baby’s birth that is rich in nutrients and antibodies
What is foremilk?
Milk which is first drawn during feeding, generally thin and lower in fat
What is hindmilk?
Milk which follows foremilk during feeding, richer in fat content and is high in calories
In what direction does the haemoglobin dissociation curve shift from fetal to adult haemoglobin?
To the right
Increase in 2,3 DPG (increase oxygen affinity)
Fetal haemoglobin is made in the liver before birth. Where does production of haemoglobin shift to after birth?
Bone marrow
When is the lowest levels of haemoglobin in the fetus? What is the fetus at risk of?
8-10 weeks
Physiological anaemia
When is jaundice in a newborn physiological?
When it occurs from 2 days to 2 weeks
Anything before or after this is pathological
Why does physiological jaundice occur?
Liver enzyme pathways are present but immature
List risk factors for adaptation problems
Hypoxia/ asphyxia during delivery Small or large babies Premature babies Some maternal illness and medications Ill babies e.g. sepsis, congenital anomalies
