Perinatal Adaptation Flashcards
Purpose of ductus venosus
Allows oxygenated blood to bypass the liver into IVC
Purpose of foramen ovale
Allows blood to pass from the right to left atrium to bypass lungs
Purpose of ductus arteriosus
Connects pulmonary artery to aorta to allow blood to flow back into the placenta after perfusing foetal organs
What is surfactant
Produced by type II pneumocytes to reduce surface tension of the lungs
Explain the circulatory transition at birth
Lungs fill with oxygen, pulmonary vascular resistance decreases below SVR due to cord clamping, blood flow through shunts decreases and decrease prostaglandin circulation from the placenta and oxygen acting as a vasoconstrictor closes the ductus arteriosus
What do the ductus arteriosus and ductus venosus become after birth
Ductus arteriosus= ligamentum arteriosus
Ductus venosus= ligamentum teres
What is PPHN
Persistent pulmonary hypertension, PVR does not decrease below SVR causing mixing of oxygenated and deoxygenated blood via the foramen oval and ductus arteriosus
Causes of PPHN
Sepsis, Hypoxic/ischaemic insult, meconium aspiration
Diagnosis of PPHN
Pre/postductal sats (right arm + left leg) > 3%= PPHN
Treatment of PPHN
Ventilation, oxygen, nitric oxide (vasodilator)
What is transient tachypnoea
Failure of lung fluid to be absorbed, diagnosis of exclusion
What babies are affected by transient tachypnoea
Babies born by C-section
Pathogenesis of transient tachypnoea
No squeezing of the lungs during birth, the babies take longer to absorb the lung fluid
Symptoms of transient tachypnoea
Difficulty breathing/grunting
Treatment of transient tachypnoea
Self-limiting, can require respiratory support
In what ways is heat lost in newborns
Radiation, evaporation, conduction, convection
How is heat produced in newborns
Non-shivering thermogenesis
Explain glucose homeostasis in newborns
Glucose supply from placenta is lost and mother’s milk supply takes time so physiological drop in insulin
What illnesses can precede hypoglycaemia in newborns and why
Septic, hypoxic, acidotic babies, due to high metabolic states putting increased energy demands on their glucose store
Explain glucose problems in premature babies
They haven’t got a large enough glycogen supply and I immature hepatic enzymes for glycogenolysis and gluconeogenesis
Explain the differences between foetal haemoglobin and adult haemoglobin
Foetal haemoglobin has a higher affinity for oxygen allowing it to be removed from the mother’s bloodstream and transported to the organs + tissues of the foetus.
Describe the changes in haemoglobin after birth
Adult haemoglobin releases oxygen far better than foetal haemoglobin, it is produced in the bone marrow and increased 2,3-BPG increases post-nasally which shifts the curve to the right helping the development of adult haemoglobin
Explain physiological anaemia in newborns
The breakdown of foetal haemoglobin occurs at a rate faster than adult haemoglobin being produced
Explain physiological jaundice
The large breakdown of foetal haemoglobin producing bilirubin and the conjugating pathway is still immature, occurs between 3rd and 8th days of life
Explain Pathological jaundice
Jaundice in first 24 hours, jaundice lasting >24 hours, persistent high levels of unconjugated bilirubin, can cross the BBB and settle in basal ganglia causing neurological consequences e.g. cerebral palsy
Treatment of jaundice
Blue light therapy (phototherapy or blanket + light cables)
What babies are at increased risk of jaundice
HIE, large/small babies, premature babies, maternal illness, medications, sepsis
Explain APGAR scoring
A= Appearance P= Pulse G=Grimace A=Activity R=Respiration Taken in first 1,5, 10 minutes after birth, normal >8, score of 10 is rare as most babies are born with some degree of acrocyanosis
What is hydrops foetalis
Fluid build up in baby’s tissues due to heart failure from baby’s heart having to pump a larger blood volume t achieve the same level of oxygenation, caused by anaemia from rhesus disease or chromosomal problems
