Perinatal Adaptation Flashcards
What are some placental functions?
Fetal homeostasis Gas exchange Nutrient transport to fetus Waste product transport from fetus Acid base balance Hormone production Transport of IgG
What are the 3 fetal shunts?
Ductus venosus
Foramen ovale
Ductus arteriosus
How does the fetus prepare for birth in the 3T?
Surfactant production
Accumulation of glycogen-liver, muscle, heart
Accumulation of brown fat- between scapulae and around internal organs
Accumulation of subcut fat
Swallowing amniotic fluid
How does the fetus prepare for birth during labour and delivery?
Onset of labour- increased catecholamines/cortisol
Synthesis of lung fluid stops
In vaginal delivery- squeezes lungs
What circulatory transition occurs at birth?
Pulmonary vascular resistance drops Systemic vascular resistance rises Oxygen tension rises Circulating prostaglandins drop Duct constricts Foramen ovale closes
What happens to the foramen ovale after birth?
Closes or persists as PFO (10%)
What happens to the ductus arteriosus after birth?
Becomes ligamentum arteriosus
Persistent ductus arteriosus (causing persistent pulmonary HT)
What happens to the ductus venosus after birth?
Becomes ligamentum teres
How is PPHN managed?
Ventilation Oxygen Nitric oxide Sedation Inotropes ECLS
By what methods does heat loss occur?
Radiation
Convection
Evaporation
Conduction
How is a baby adapted for thermoregulation?
Large SA
Wet when born
What is the main source of heat production in the newborn?
Non shivering thermogenesis- heat produced by breakdown of stored brown adipose tissue in response to catecholamines, not efficient in first 12 hours
What other methods of thermoregulation exist in the newborn?
Peripheral vasoconstriction
Babies need help to maintain temp
Why may small for dates/PT babies suffer from hypothermia?
Low stores of brown fat
Little subcut fat
Larger SA:V
How can hypothermia be avoided in the newborn?
Dry Hat Skin to skin Blanket/clothes Heated mattress Incubator
Describe glucose homeostasis in the newborn
Interruption of glucose supply from placenta
Very little oral intake of milk
Drop in insulin, increase in glycogen
Mobilisation of hepatic glycogen stores for gluconeogenesis
Ability to use ketones as brain fuel
How does hypoglycaemia occur in the newborn?
Increased energy demands-unwell, hypothermia
Low glycogen stores- small, premature
Inappropriate insulin/glucagon ratio- maternal diabetes, hyperinsulinism
Some drugs
What happens to fetal haemoglobin in the newborn?
Becomes disadvantageous
Increase in 2,3 DPG shifts curve to right
Where does haematopoiesis move to in the newborn?
Bone marrow
What can result from adult Hb being synthesised more slowly than fetal Hb breakdown?
Physiological anaemia
Nadir at 8-10 wks
Why does physiological jaundice occur in the newborn?
Breakdown of fetal haemoglobin
Conjugating pathways immature
Rise in circulating unconjugated bilirubin
Generally not harmful unless very high levels
What are some RFs for adaptation problems?
Hypoxia / asphyxia during delivery Particularly small or large babies Premature babies Some maternal illnesses and medications Ill babies – sepsis, congenital anomalies
