Newborn Adaptations to Extrauterine Life Flashcards
The initiation of respirations in the neonate is the result of:
a combination of factors
- chemical
- mechanical
- thermal
- sensory
Describe the chemical processes associated with fetal respiratory adaptation:
1) Chemoreceptors in carotid arteries and aorta= hypoxia with labor
2) Contractions cause decrease in uterine blood flow= fetal hypoxia and hypercarbia
3) Cumulative effect on fetus= drop in PO2, increase PCO2, low blood pH
4) This STIMULATE THE RESPIRATORY CENTER IN MEDULLA
Clamp in cord can also cause prostaglandin to drop (prostaglandin INHIBITS respirations)= this drop promotes breathing
Describe the mechanical factors associated with fetal adaptation to repiratory function:
1 -intrathoracic pressure resulting from compression of the chest during vaginal birth.
2 -With birth this pressure on the chest is released, and the negative intrathoracic pressure helps to draw air into the lungs.
3 -Crying increases the distribution of air in the lungs and promotes expansion of the alveoli.
4 -The positive pressure created by crying helps to keep the alveoli open
Describe thermal factors associated with newborn adaptation to respiratory function:
- With birth the newborn enters the extrauterine environment in which the temperature is significantly lower.
- The profound change in environmental temperature stimulates receptors in the skin, resulting in STIMULATION OF THE RESPIRATORY CENTER
Describe sensory factors associated with newborn adaptation to respiratory function:
- handling by the obstetric health care provider
- suctioning the mouth and nose
- drying by the nurses
- Environmental factors (lights, sounds, smells)
THESE ALL STIMULATE THE RESPIRATORY CENTER
What is an abnormal amount of time for the newborn to not breath?
Apneic periods longer than 20 seconds are abnormal and should be evaluated
The reflex response to nasal obstruction is to open the mouth to maintain an airway. This response is not present in most infants until 3 weeks after birth; therefore:
cyanosis or asphyxia can occur with nasal blockage
In most newborns, auscultation of the chest reveals:
- loud, clear breath sounds that seem very near because little chest tissue intervenes
- clear and equal bilaterally
- fine rales for the first few hours are not unusual
Signs of respiratory distress can include:
- nasal flaring
- intercostal or subcostal retractions (in-drawing of tissue between the ribs or below the rib cage)
- grunting with respirations
Suprasternal or sub-clavicular retractions with stridor or gasping most often represent:
an upper airway obstruction
What are seesaw or paradoxic respirations?
Seesaw or paradoxic respirations (exaggerated rise in abdomen with respiration as the chest falls) instead of abdominal respirations are abnormal and should be reported.
What is the normal respiratory rate for the newborn?
A respiratory rate of less than 30 or greater than 60 breaths/ min with the infant at rest must be evaluated.
Describe the normal and abnormal findings regarding the color of the newborn (blue vs. pink):
- Acrocyanosis, the bluish discoloration of hands and feet, is a normal finding in the first 24 hours after birth
- Transient periods of duskiness while crying are common immediately after birth
- central cyanosis is abnormal and signifies hypoxemia. (the lips and mucous membranes are bluish) (circumoral cyanosis)
- central cyanosis is a late sign of distress, newborns usually have significant hypoxemia when cyanosis appears
When does the ductus arteriosus close? What causes this closure?
- In term infants, it functionally closes within the first 24 hours after birth; permanent (anatomic) closure usually occurs within 2 to 3 months, and the ductus arteriosus becomes a ligament.
- After birth, when the PO 2 level in the arterial blood approximates 50 mm Hg, the ductus arteriosus constricts in response to increased oxygenation.
- Circulating prostaglandin E2 (PGE2) levels also have an important role in closing the ductus arteriosus.
Can the ductus arteriosus reopen?
YES> The ductus arteriosus can reopen in response to low oxygen levels in association with hypoxia, asphyxia, prolonged crying, or pathologic problems.
What would an open ductus arteriosus resemble?
With auscultation of the chest, a patent ductus arteriosus can be detected as a heart murmur
When and how should the nurse respond to heart rate changes in the newborn?
A heart rate that is either high (more than 160 beats/ min) or low (fewer than 100 beats/ min) should be reevaluated within 30 minutes to 1 hour or when the activity of the infant changes.
Where does the nurse know to place her stethoscope when she is listening to the apical impulse/PMI of a newborn?
- fourth intercostal space and to the left of the midclavicular line
- The PMI is often visible and easily palpable because of the thin chest wall; this is also called precordial activity
When should the newborn be evaluated for sinus dysrhythmias?
Irregular heart rate or sinus dysrhythmia is COMMON IN THE FIRST FEW HOURS but thereafter may need to be evaluated
Heart sounds during the neonatal period:
- higher pitch, shorter duration, and greater intensity than adults
- (S1) is typically louder and duller than the second sound (S2), which is sharp
- third and fourth heart sounds are not audible in newborns
Are heart murmurs an ominous sigh in the newborn?
Not really > Most heart murmurs heard during the neonatal period have no pathologic significance, and more than one-half of the murmurs disappear by 6 months of age
When should heart murmurs be evaluated?
the presence of a murmur and accompanying signs such as poor feeding, apnea, cyanosis, or pallor is considered abnormal and should be investigated
What should the nurse expect in the newborn concerning MAP?
The mean arterial pressure (MAP) should be nearly equivalent to the weeks of gestation. For example, an infant born at 40 weeks of gestation should have a MAP of at least 40.
A drop in systolic BP (approximately 15 mm Hg) in the first hour of life is common.
Expected values for BP (systolic/ diastolic) in a term infant are:
- At birth: 75– 95/ 37– 55
- 12 hours: 50– 70/ 25– 45
- 96 hours: 60– 90/ 20– 60
What is a normal range of blood volume for the term and the preterm infant?
- term newborn ranges from 80 to 100 mL/ kg of body weight
- preterm infant, the range is 90 to 105 mL/ kg
The preterm infant has a relatively greater blood volume than the term newborn. Why does this occur?
the preterm infant has a PROPORTIONATLY greater plasma volume
(not a greater red blood cell mass)
Delayed clamping of the umbilical cord (DCC):
changes the circulatory dynamics of the newborn
DCC has been associated with:
- increased blood volume and BP
- reduced risk for intraventricular hemorrhage and necrotizing enterocolitis
- These benefits are most important for preterm infants.
Persistent tachycardia (more than 160 beats/ min) can be associated with:
- anemia
- hypovolemia
- hyperthermia
- sepsis
Persistent bradycardia (less than 80 beats/ min) can be a sign of:
- congenital heart block
- hypoxemia
Unequal or absent pulses, bounding pulses, and decreased or elevated BP can indicate:
-cardiovascular problems
The newborn’s skin color can reflect cardiovascular problems. Describe findings and meanings for each:
- Pallor = anemia or marked peripheral vasoconstriction as a result of intrapartum asphyxia or sepsis
- Cyanosis other than in the hands or feet, with or without increased work of breathing= respiratory and/ or cardiac problems.
- jaundice = ABO or Rh factor incompatibility problems
What factors may increase the risk for neonatal cardiac defects?
- rubella
- diabetes
- maternal drugs
Heat loss must be controlled to protect the infant who is at risk for hypothermia. What interventions are implemented at birth to prevent excessive heat loss?
- Drying the infant quickly after birth
- The naked newborn is placed on the mother’s bare chest and covered with a warm blanket
- a cap may be placed on the infant’s head
- Or… the neonate is placed under a radiant warmer
How do newborns produce heat (thermogenesis)?
NONSHIVERING THERMOGENESIS:
- metabolism of brown fat, which is unique to the newborn
- increased metabolic activity in the brain, heart, and liver
Describe the etiology of Cold Stress in the newborn using 8 steps:
1) DROP IN TEMPERATURE=VASOCONSTRICTION= pale and mottled; the skin feels cool, especially on the extremities.
2) IF UNCORRECTED> COLD STRESS
3) RESPIRATORY RATE INCREACES (oxygen consumption and energy are diverted from maintaining normal brain and cardiac function and growth to thermogenesis for survival)
4) If the infant cannot maintain an adequate oxygen tension, vasoconstriction follows and jeopardizes pulmonary perfusion.
5) PO2 DECREASES AND PH DROPS
6) Surfactant synthesis can be altered
7) THIS CAUSES> transient respiratory distress or aggravate existing RDS
8) DUCTUS ARTERIOSUS CAN REOPEN
Although less frequently than hypothermia, hyperthermia can occur and must be corrected. When is the nurse alerted to a need for intervention concerning newborn temperature?
A body temperature greater than 37.5 ° C (99.5 ° F) is considered to be abnormally high and is typically caused by excess heat production related to sepsis or a decrease in heat loss.
Hyperthermia can result from:
the inappropriate use of external heat sources such as radiant warmers, phototherapy, sunlight, increased environmental temperature, and the use of excessive clothing or blankets.
