Chapter 19: Normal Newborn Processes of Adaptation Flashcards
Neonatal Resuscitation
- ABCs
- thermoregulation
- glucose metabolism
development of fetal lungs
- during fetal life, the alveoli produce fetal lung fluid that expands the alveoli and is essential for lung development
- as fetus nears term, the amount of fluid produced decreases in preparation for birth when the fluid must be cleared for the infant to breathe
- average size baby makes 400 mL/day
fetal lung fluid
- decreases in amount near end of the pregnancy
- during labor, the fluid begins to move into the interstitial spaces, where it is absorbed
- absorption is accelerated by secretion of fetal epinephrine and corticosteroids but may be delayed by C/S w/o labor
- removal of fluid helps reduce pulmonary resistance to blood flow that is present before birth and enhances the advent of air breathing
pulmonary surfactant
- this is a combination of lipoproteins that is detectable by 24-25 weeks of gestation
- lines the inside of alveoli and reduces surface tension w/in alveoli which allows them to remain partially open when the infant breathes
- w/o surfactant, alveoli collapse when infant exhales and must re-expand w/ each breath which inc WOB
- by 34-36 weeks, sufficient surfactant is produced to prevent RDS
- surfactant secretion inc during labor and immediately after birth to enhance transition to neonatal life
steroids and pulmonary surfactant
- steriods are given to a woman in preterm labor to help inc surfactant production and speed maturation of the lungs
which conditions can cause accelerated lung maturation?
- intrauterine growth restrictions
- stress from conditions like maternal HTN, heroin addiction, pre-E, or infection
- placental insufficiency
- PROM greater than 48 hours
which condition slows fetal lung maturity?
maternal GDM
what happens at birth to allow the infant to breathe?
- at birth, the infant’s first breath must force remaining fetal lung fluid out of the alveoli and into the interstitial spaces around the alveoli to allow air to enter the lungs
what are chemical factors that initiate breathing?
- chemoreceptors in the carotid arteries and aorta respond to hypoxia in the blood that occurs w/ birth
- a dec in O2 and pH and an inc in CO2 stimulates the respiratory center
- occlusion of vessels in the cord ends the flow of placental substances that inhibit respirations
- if prolonged hypoxia caused CNS depression, then stimulation of the respiratory center will not occur
what are mechanical factors that initiate breathing?
- during a vaginal birth, the fetal chest is compressed by narrow birth canal
- 1/3 of lung fluid is forced out of lungs into upper airway passages and is suctioned out
- when pressure against chest is released at birth, recoil of chest draws a small amount of air into the lungs and helps remove some of the fluid
- complete absorption of fluid may take 24 hours
what are thermal factors that initiate breathing?
- temp changes that occurs w/ birth stimulates respirations
- at birth, the infant moves from a warm, fluid filled uterus to a coller temp
- sensors in the skin respond to the change and send impulses to the medulla to stimulate breathing
- at birth, the infant moves from a warm, fluid filled uterus to a coller temp
what are sensory factors that initiate respirations?
- tactile, visual, auditory, and olfactory stimuli occur
- nurses hold, dry, place infants skin to skin, and wrap them in blankets to provide more stimuli
continuation of respirations
- as alveoli expand, surfactant allows them to remain partially open b/w breaths
- some air from first breaths remain in the lungs to become residual capacity, so then subsequent breaths require less effort
- as infant cries, pressure in lungs inc and push remaining fetal lung fluid into interstitial spaces where it is absorbed into circulatory and lymphatic systems
- why lungs may be moist sounding at first
interference w/ lung expansion
- lack of thoracic squeeze
- occurs w/ small babies and C/S
- respiratory depression
- aspiration of amniotic fluid or meconium
periodic/episodic breathing
- occurs in some full term, but more common in preterm
- count respiratory rate for 1 min to make up for this
- this is pauses of 5-15 sec w/o changes in skin color/HR followed by rapid respirations for 10-15 sec
signs of respiratory distress
- tachypnea (RR > 60)
- see saw respirations/paradoxical respirations
- nasal flaring
- expiratory grunting or sighing
- intercostal/xiphoid retractions
- central cyanosis
what are the goals for a nursing diagnosis of ineffective airway clearance?
what are the interventions?
- goals:
- maintain patent airway
- maintain RR of 30-60
- no signs of respiratory distress
- interventions:
- positioning
- suctioning
assessment of newborn respiratory system
- rate:
- 30-60, easily altered by stimuli
- normal is an irregular respiratory rate
- may be up to 60-70 for 1st-2 hours
- 30-60, easily altered by stimuli
- characteristics: abdominal breathing and obligatory nose breathers
- breath sounds should be present in all lung fields
- assess for grunting, flaring, retractions
what are 3 shunts in fetal circulation and what is there purpose?
- ductus venosus
- foramen ovale
- ductus arteriosus
- allows the most highly oxygenated blood to be sent to the brain and heart
fetal circulatory circuit involving the 3 shunts
- oxygenated blood from placenta goes thru the umbilical V to the fetus–>about 2/3 go to the liver (by term) and the rest goes straight to the IVC by the ductus venosus
- blood enters RA and joins with deoxygenated blood from lower body/head–>blood goes thru the foramen ovale to the LA–>LV–>aorta–>body
- a small amt of blood from the RV is sent to the lungs to nourish that tissue, then the rest of the blood from the RV goes the ductus arteriosus to the aorta
what are the changes in blood circulation of the baby after birth?
- as infant breathes and the lungs expand, blood flow to the lungs increases, pressure in the right side of the heart falls, and foramen ovale closes
- ductus arteriosus constricts as arterial O2 levels rise
- ductus venosus constricts when blood flow from the umbilical cord stops
- after birth, the ductus venosus and umbilical As and V become ligaments
heart murmurs in infants
- common
- 90% are not associated with anomalies
newborn characteristics that lead to heat loss
- skin is thin
- blood vessels are close to the surface
- little subcutaneous fat is present
- they also have 3x more body surface area which provides more area for heat loss
how do full term infants reduce the amount of skin exposed to surrounding temps and dec heat loss?
- they remain in a position of flexion
- sick/preterm infants have decreased muscle tone and are unable to maintain a flexed position, so at inc risk for cold stress
normal infant axillary temp
36.5-37.5 deg C (97.7-99.4 F)
what are the 4 methods of heat loss?
- conduction: movement of heat away from body occurs when newborns have direct contact with objects that are cooler than skin
- convection: transfer of heat from infant to cooler surrounding air
- occurs when drafts come in
- radiation: transfer of heat to cooler objects that are not in direct contact with infant
- heat loss from infant’s body to sides of crib
- evaporation: conversion of liquid to vapor
- air drying of the skin that results in cooling
- reason we dry off infant ASAP, to prevent evaporation
nonshivering thermogenesis (NST)
- this is the primary method of heat production in infants
- it is the metabolism of brown fat to produce heat
- begins when thermal receptors in the skin detect a skin temp of 35-36 deg C (95-96.8 deg F)–>thermal receptor stimulation is transmitted to hypothalamus–>norepinephrine is released is released in brown fat–>metabolism starts
- occurs even before core body temp drops