Neonatal A&P 2 Flashcards
During an inhalation induction, a neonate begins to desaturate shortly after the removal of the facemask. Which statement BEST explains why the neonate desaturated so quickly?
a. decreased tidal volume to dead space ratio
b. oxygen consumption is 3 mL/kg/min
c. increased alveolar ventilation to FRC ratio
d. the patient is experiencing malignant hyperthermia
c. increased alveolar ventilation to FRC ratio
What is the oxygen consumption of neonates compared to adults?
higher to support metabolic demand (6 mL/kg/min)
What is the FRC of the neonate?
slightly decreased than the adult which reflects a reduced oxygen reserve
Compared to adults, neonates have an _________________ to increase oxygen supply
increased alveolar ventilation
During hypoventilation or apnea, the neonate’s relatively higher oxygen consumption will
quickly exhaust the oxygen reserve contained in the FRC leading to rapid desaturation
Describe the speed of inhalation inductions for neonates.
faster b/c faster turnover of the FRC allows for speedier development of anesthetic partial pressure inside the alveoli
It is metabolically more efficient for the neonate to increase ___________ rather than ___________
respiratory rate; tidal volume
Alveolar ventilation of the neonate is
130 mL/kg/min
Tidal volume of the neonate is
6 mL/kg
When compared to the adult, select the true statements regarding the pulmonary system in the newborn. (select 2)
a. the diaphragm has more type 1 than type 2 muscle fibers
b. the diaphragm has more type 2 than type 1 muscle fibers
c. the newborn has a higher tidal volume on a per weight basis
d. neonates have the same amount of dead space on a per weight basis
b. the diaphragm has more type 2 than type 1 muscle fibers
d. neonates have the same amount of dead space on a per weight basis
__________ is the primary muscle of inspiration
The diaphragm
Neonates have a lower amount of _____________ muscle fibers which increases the neonate’s risk for
type 1 slow-twitch endurance; respiratory fatigue and developing respiratory failure
Neonates are at risk of _______ following surgery and anesthesia
apnea
______________________ should be admitted for 24 hour observation with an apnea monitor
Patients less than 60 weeks post-conceptual age
The risk of apnea is inversely related to
gestational and post-conceptual age
_______________ may reduce the risk of postoperative apnea after general anesthesia but it does NOT take the place of postoperative admission with apnea monitoring
Prophylactic caffeine (10 mg/kg IV)
______________ is an alternative to caffeine but it carries a higher risk of toxicity
theophylline
________________ have a greater risk of postoperative apnea than infants >44 weeks PCA
Former pre-term infants < 44 weeks PCA
In the neonate, what percentage of respiratory muscles are type-1 fibers?
25% (compared to 55% in adults)
When compared to the adult, which statement presents the MSOT accurate understanding of neonatal pulmonary mechanics? (select 2)
a. airflow resistance during tidal breathing is decreased
b. residual volume is decreased
c. closing capacity is increased
d. chest wall compliance is increased
c. closing capacity is increased
d. chest wall compliance is increased
Compared to the adult, the newborn has _______ lung compliance and __________ chest wall compliance
lower lung compliance and higher chest wall compliance
The lower lung compliance and higher chest wall compliance of the newborn favors
chest wall collapse during inspiration (paradoxical breathing) and reduced lung volumes at expiration
What is the neonates residual volume compared to adults?
higher
What is the neonates closing capacity compared to adults?
higher
What is the FRC of the neonate compared to adults
lower
What is the vital capacity and total lung capacity of the neonate compared to adults?
lower
When the neonate inspires, it must overcome the
resistance to airflow as well as the elastic properties of the chest wall and lungs
Minor reductions in airway diameter of the newborn can
significantly increase the work of breathing
The newborn is predisposed to hypoxemia because
the closing capacity overlaps with tidal volume during normal breathing leading to V/Q mismatch and increased A-a gradient
How does the newborn dynamically increase FRC?
sustained tonic activity of inspiratory muscles
narrowing of glottis during expiration
shorter expiratory time with a faster RR creates end-expiratory pressure
Select the data set that MOST accurately depicts a normal umbilical artery blood gas.
a. pH= 7.20 PaO2= 50 PaCO2= 50
b. pH= 7.30 PaO2= 20 PaCO2=50
c. pH= 7.35 PaO2= 30 PaCO2= 40
d. pH= 7.40 PaO2= 90 PaCO2=30
b. pH= 7.30
PaO2= 20
PaCO2= 50
Describe the fetal circulation (umbilical vein & artery)
umbilical vein supplies oxygen to the fetus
umbilical arteries (2) return Co2-rich blood to the placenta
Clamping the umbilical cord stimulates the newborn to
breathe rhythmically
________________ promotes continuous breathing——– _______ causes apnea
an acute rise in PaO2; hypoxemia
The arterial pH of the newborn stabilizes at
1 hour after delivery
Respiratory control doesn’t mature until
42-44 weeks post-conceptual age
What is the blood gas of the umbilical vein?
pH: 7.35
PaO2: 30
PaCO2: 40
What is the blood gas of the umbilical arteries?
pH: 7.30
PaO2: 20
PaCO2: 50
What is the blood gas of the newborn 10 minutes after delivery?
7.20
PaO2: 50
PaCO2: 50
What is the blood gas of the newborn 1 hour after delivery?
pH 7.35
PaO2: 60
PaCO2: 30
The newborn comes into the world
hypoxic
acidotic
retaining CO2
After maturation of respiratory control, hypoxemia
stimulates ventilation
Which statement regarding fetal hemoglobin is TRUE?
a. it has a higher P50 than the adult
b. it is replaced by hemoglobin A at 9 months of age
c. it has an increased affinity for 2,3 DPG
d. erythrocytes containing hemoglobin F have a shorter lifespan
d. erythrocytes containing hemoglobin F have a shorter lifespan
Fetal hemoglobin shifts the curve to the
left
The P50 of fetal hemoglobin is
19.5 mmHg
Why is a leftward hemoglobin shift beneficial for the fetus?
it creates an oxygen partial pressure gradient across the uteroplacental membrane that facilitates the pass of O2 from the mother to the fetus
Hemoglobin A begins to replace hemoglobin F at _________ and this is complete by ___________
2 months of life; 6 months of life
The adult P50 is
26.5 mmHg
What is the makeup of fetal hemoglobin versus adult hemoglobin?
fetal hemoglobin- two alpha & two gamma chains
adult hemoglobin- two alpha and two beta chains
The binding site for 2,3 DPG is only on
the beta chain so fetal hemoglobin cannot bind to 2,3 DPG
What happens to the infants hemoglobin at 2-3 months of age?
physiologic anemia Hgb declines to 10 g/dL as Hgb A starts replacing Hgb F
