Pathopysiology Of A Preterm Neonate Flashcards
Terminology
Newborns = neonates = newborn infant
0-4 weeks 28 day
A baby must adapt physiologically to extra- uterine life
Neonatal period is a period of transition for both baby and family
The moment of birth
Physical size
Weight
- Average 3.5kg
- May lose 5-10% birth weight in 1st week of life and should regain this by day 10
- Steady gain at 180-210 g per week thereafter
Length
- average 51cm
Head circumference
- 35-36cm
- grows 2cm in first month
- size and speed of head growth is significant
More than 10th or less than 90th centipedes may indicate abnormality
Adaptation
Infants are most vulnerable in fist 24 hours of life
The neonate must achieve physiological changes that are critical to survival
In a healthy neonate, this transition occurs without problems
Organ system failure/ malformation/ disease can delay/ hinder/ prevent the adaptation to extrauterine life
Essential adeption
Respiration
Circulation
Thermoregulation
Nutrition - glucose homestasis
Excretion
Respiration’s
The infant must use their respiratory system for uptake of oxygen, and removal of carbon dioxide
The lungs need to be sufficiently developed for successful gaseous exchange
Lung liquid needs to be removed
Surfactant production is required to reduce surface tension between the walls of the alveoli
Circulatory changes at birth
Lungs expand
Pulmonary vessels dilate
Resistance drops in pulmonary circuit
Blood rushes to fill the pulmonary vessels
Rising o2 causes constriction of ducts artereosus
Pressure rise in the left atrium causing the closure of the foremen ovale
Foetal circulation
Placenta
Umbilical vein
Ductus arteriosus
Foramen ovale
Ductus venosus
Umbilical arteries
Postnatal heart
Ductus arteriosus closed
Right atrium
Forage ovale closed
Inferior vena cava
Right ventricle
Pulmonary trunk
Left atrium
Left ventricle
The APGAR Score
1 min 5 min 10 min
Appearance- blue, pale - body pink, Lima blue, all pink
Pulse- absent, <100, >100
Grimace- none, grimace, cry
Activity- limp, some flexion of limbs, active movement, well flexed limbs
Respiratory effort- none, slow, irregular, god strong cry
APGAR
> 8-10 no intervention
5-7 may need o2, stimulation and reassessment
< 5 will require prolonged/ major intervention
Thermoregulation
Neonates is at high risk of heat loss
. Poor temperature control due to immature hypothalamus
. Inability to spontaneously generate heat by shivering
. High surface area: volume ratio
.low levels of insulation -thin body shell
Normal bodily temperature range 36.5 37.2 °C
Can utilise town fat reserves - brown fat thermogenesis
Limb movement can generate heat
Sweat mechanism is poorly developed
Glucose homeostasis
Blood glucose levels fall for the first two hours after birth, then rise due to mobilsed energy stores
Energy stores are mobilised at birth:
- glygogenolysis ( brakedown of glycogen)
- lypolysis (breakdown of fats)
- gluconeogenesis (production of glucose)
Glycogen reserve depleted after 12 hours - fat then used as energy
Feeding needs to be established
First days
Stabilisation of body temperature
Establishment of feeding
Kidney, bladder and dowel function
Erythrocyte homeostasis and neonatal jaundice
The guy and feeding
Sucking/ swallowing coordinated
Stomach has a 15-30 ml capacity which increase rapidly in first few weeks
Cardiac sphincter is weak - reflux
Meconium passage in 12 - 24 hours
Established stools from day 3
High energy requirements for growth
Low gastric acid and enzymes levels
Gut structure present but physiology immature
Metabolic needs
High metabolic rate
High oxygen and energy needs
Limited nutrient storage
Glycogen stores easily depleted
Less able to mount metabolic response to stress
Immature liver
