Describe how the lungs adjust to extrauterine life
About 30ml of amniotic fluid is forced out of the lungs during the birthing process and the rest is absorbed within the next 12-24 hrs
Air then fills the lungs instead of fluid
Pressures in the lungs change the pressures in the heart, leading to blood going into the pulmonary arteries to be oxygenated
What are the triggers for newborn respiration?
Mechanical stimulus: of being pushed thru the birth canal and compression of the chest
Chemical stimuli: mild hypoxia, hypercapnia, and resp acidosis stimulates the medulla to stimulate respirations
Thermal stimui: drop in temp promotes resp
Sensory stimuli: experiencing light, touch, sound, and gravity for the first time promotes resp
How can you test for surfactant production prior to birth? What do you use if you know the baby is going to be preterm? In what gestational week is surfactant produced and at what week is it sufficient (surge of surfactant)?
L/S ratio during amniocentesis: a ratio of 2:1 denotes matured lungs with reduced risk of RDS
If you know the baby is going to be preterm, mom will be given corticosteroids IM, such as betamethasone, to promote lung maturation and surfactant production
Surfactant begins production from type 2 cells at 24 wks gestation, but it does not surge until 36 wks gestation
What are signs of respiratory distress in the newborn?
Apnea >15 sec
Tachypnea (normal is 30-60 rpm)
What cardiovascular adaptations are made after birth?
Pressures in the resp system are connected to pressure changes in the cardiovascular system
Decreased pulmonary vascular resistance leas to increased pulmonary blood flow
Increased systemic vascular resistance leads to cardiovascular changes (such as the closing of the foramen ovale and the ductus arteriosis)
Foramen venosis functionally closes with the clamping of the umbilical cord
Why is thermoregulation so important in the newborn?
Newborns lose about 4x the amount of heat as an adult, esp thru their head
A balance needs to be made between heat production and heat loss (this is a narrow range of balance)
Baby's have less fat and burn brown fat in the response to cold (babys do not have the shiver reflex)
Requires more 02 and increased metabolic rate in order to thermoregulate
Keeping the baby in a flexed position helps decrease heat loss
How do newborn's lose heat?
Convection: heat loss due to cooler air currents
Evaporation: heat loss as fluid leaves the skin
Radiation: heat transfer to cooler surfaces and objects not in contact with the baby
Conduction: heat transfer to cooler surfaces and objects in contact with the baby
Why are newborns unable to thermoregulate?
Non-shivering thermogenesis uses Brown Adipose Tissue to produce heat