Newborn Physiologic Adjustments (Cardiovascular System) Flashcards
What causes a functional closure of the foramen ovale?
Increased pulmonary blood flow from the left side of the heart increases pressure in the left atrium.
During the first few days of life, what may crying do to the foramen ovale?
May temporarily reverse the flow through the foramen ovale and lead to mild cyanosis.
What is an important role for circulating hormone prostaglandin E (PGE2)?
Closure of the ductus arteriosus.
When does the closure of the ductus arteriosus occur in term infants?
Functionally class within the first hours after birth; permanent closure usually occurs within 3 to 4 wks.
What happens to the ductus arteriosus after permanent closure?
Becomes ligaments
Upon auscultation of the chest, ductus arteries can be detected as a…
Heart murmur.
What can the ductus arteriosus open in response to?
Low O2 levels in association with hypoxia, asphyxia, or prematurity.
Why do the umbilical vein and arteries constrict rapidly within the first 2 minutes after birth?
Exposure of the cord to the cooler extrauterine environment and to increased oxygenation as the infant begins to breathe.
What happens to the umbilical arteries, vein and ductus venosus when the cord is clamped or severed?
They are functionally closed and convert to ligaments within 2 to 3 months.
What is the normal HR range for a term newborn?
110 to 160 beats/min
What is the normal HR range for a sleep term newborn?
85 to 100 beats/min
What is the normal HR range for a crying term newborn?
Can increase to 180 beats/min or higher
A HR that is either >160 or <100 should be?
Reevaluated within 30 mins to 1 hr or when the activity of the infant changes.
When can the HR be palpated using the umbilical cord?
Immediately after birth
Where is the apical impulse (point of maximal impulse [PMI]) located on a newborn?
At the 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 known as…
Precordial activity
How long should a nurse auscultate an infants heart rhythm and for how long?
Apical pulse rates should be determined in all infants for 1 whole min. Preferable when the infant is asleep.
When is a abnormal HR not uncommon for an infant?
First few hours of life.
Heart sounds during the neonatal period are of…
Higher Pitch
Shorter Duration
Greater intensity than during adult life.
Are the 3rd and 4th heart sounds auscultated in a normal newborn?
No.
When do half the murmurs of newborns disappear?
After 6 months.
A murmur combined with what characteristics should be investigated?
Presence of a murmur and accompanying signs such as poor feeding, apnea, cyanosis, or pallor are considered abnormal.
What is the average term newborn’s systolic BP?
60 to 80
What is the average term newborn’s diastolic BP?
40 to 50
What should the mean arterial pressure (MAP) be equivalent to?
Equivalent to the wks of gestation.
Example: 40 wks of gestation should have a MAP of at least 40.
The drop of how many systolic mm Hg is common in the first hour of life?
15
What device accomplishes the best infant BP reading and when is it best to use it?
Oscilometirnic device and when the infant is sleeping.
When the systolic BP is ____ mm Hg higher in the upper extremities than in the lower, further diagnostic test may be needed.
10 mm Hg
What does the blood volume range in term newborns?
80 to 100 mL/kg of body weight
Why do preterm infants have a higher blood volume than term infants?
This occurs b/c the preterm infant has a proportionately greater plasma volume, not a greater RBC mass.
What has an effect on the changes of the newborn’s circulatory dynamics?
Early or delayed clamping of the umbilical cord.
Delayed clamping expands the blood volume from the so-called?
Placental transfusion of blood to the newborn.
What are the benefits of delaying cord clamping for > or = 2 minutes after birth?
Reported to be beneficial in improving hematocrit and iron status and decreasing anemia; such benefits can last up to 6 months.
Is polycythemia occurring due to delayed cord clamping harmful to infants and what might it cause?
Usually not harmful
Can cause increased risk of jaundice that requires phototherapy.
Persistent tachycardia (more than 160 beats/min) can be associated with…
- Anemia
- Hypovolemia
- Hyperthermia
- Sepsis
Persistent bradycardia (less than 100 beats/min) can be a sign of…
- Congenital heart block
2. Hypoxemia
What can reflect a newborns cardiovascular problems?
Newborn’s skin color.
Pallor in the immediate post birth period is often symptomatic of underling problems such as…
Anemia or marked peripheral vasoconstriction as a result of intrapartum asphyxia or sepsis.
What can the presence of jaundice indicate?
ABO or Rh factor incompatibility problems
What are the most common type of congenital malformations?
Congenital heart defects
What can provide the most information regarding the risk of congenital heart defects?
Prenatal Hx.
What are associated with an increased risk of cardiac defects?
- Maternal illness (such as rubella)
- Metabolic disease (diabetes)
- Drug ingestion
