Question 1

What appears to be the benefit of administering prophylactic surfactant replacement therapy to preterm infants?
I) Decreased risk of mortality
II) Reduced threat of pneumothorax
III) Decreased incidence of diaphragmatic hernia
IV) Reduced risk of developing pulmonary interstitial emphysema

A) I and II only
B) II and IV only
C) I, II, and IV only
D) II, III, and IV only

Accepted Answer

Prophylactic surfactant is administered after initial stabilization in the first 15 minutes after birth, compared with 1.5 to 7.4 hours in rescue strategies. Initial studies comparing prophylactic to rescue surfactant favored the former, with noted decrease in mortality, pneumothorax, and pulmonary interstitial emphysema.

Question 2

The respiratory therapist administering surfactant to a premature newborn notices a significant deterioration in vital signs. What should be done at this time?&#10;A) Pause the procedure and administer PPV until vital signs are stable.&#10;B) Rapidly infuse the rest of the dose and reconnect the patient to the mechanical ventilator.&#10;C) Extubate the patient and administer nasal CPAP until stable.&#10;D) Continue administration of the surfactant while administering PPV.

Accepted Answer

Surfactant delivery should be paused until vital signs recover and ETT clears of visible surfactant. Infant may need to be repositioned prone and positive-pressure ventilation increased for lung inflation.

Question 3

What is the role of SP-D in human pulmonary surfactant?
I) Suppresses proinflammatory responses
II) Enhances phagocytosis
III) Enhances killing of microbes
IV) Functions as an opsonin for bacteria

A) II and III only
B) III and IV only
C) I, II, and III only
D) I, III, and IV only

Accepted Answer

SP-D is also a collectin and enhances binding, phagocytosis, and killing of microbes by alveolar macrophages. In addition, SP-D has a role in the suppression of proinflammatory responses. Lack of SP-D in transgenic mice leads to emphysema, macrophage activation, accumulation of oxygen-reactive species, and increased surfactant alveolar pools. SP-D also plays a key role in surfactant homeostasis.

Question 4

Which of the following physiologic consequences would develop if the liquid-gas interface were without surfactant?&#10;A) Large alveoli would empty into smaller ones at the end of exhalation.&#10;B) Every exhalation would demand ventilatory muscle activity.&#10;C) Every breath would require a considerable amount of pressure to expand the lung with each inspiration.&#10;D) Some alveoli would collapse during exhalation.

Accepted Answer

The lung can be thought of as a large number of interconnected bubbles that form the interface between the gaseous environment and the wet alveolar surface. If this interface were devoid of surfactant, two consequences would ensue: (1) every breath would take a considerable amount of pressure to expand the lung, comparable to the 80 to 90 cm H₂O of pressure required for a newborn's first breath and (2) the lung would rapidly collapse during exhalation.

Question 5

Which of the following clinical conditions should be suspected in a neonate unresponsive to surfactant due to its inactivation?&#10;A) Pulmonary hypertension&#10;B) Pulmonary hemorrhage&#10;C) Pneumonia&#10;D) Methemoglobinemia

Accepted Answer

Blood is a strong inactivator of surfactant, with several of its components such as hemoglobin, fibrin, fibrinogen, red blood cell membrane lipids, immunoglobulins, and plasma proteins contributing to this process. Inactivation can occur as a result of pulmonary hemorrhage, hemorrhagic edema, or blood aspiration during birth or trauma.

Question 6

Which of the following physiologic conditions results from the presence of normal amounts of pulmonary surfactant in the lung?&#10;A) Pulmonary compliance decreases.&#10;B) Uniform gas distribution during expiration occurs.&#10;C) The functional residual capacity is maintained.&#10;D) Pulmonary perfusion matches alveolar ventilation.

Accepted Answer

Functionally, surfactant increases lung compliance, promotes homogeneous gas distribution during inhalation, and allows a residual volume of gas to be evenly distributed throughout the lung during exhalation-that is, it maintains functional residual capacity. In the absence of surfactant, distribution of ventilation becomes uneven, the lungs become stiff, and atelectasis ensues during exhalation. The result is increased work of breathing, hypoxia, and respiratory failure, the clinical picture exemplified by preterm infants with respiratory distress syndrome (RDS). Surfactant functions are summarized in Box 14-1 in the textbook.

Question 7

A pregnant woman believed to be at 26 weeks gestation has been admitted for premature labor. What should be administered to this woman to decrease the risk of RDS if the infant is delivered prematurely?

A) Magnesium sulfate
B) Terbutaline
C) Systemic corticosteroids
D) Lecithin

Accepted Answer

Antenatal steroids have been extensively studied and have been shown to decrease RDS in infants between 24 and 34 weeks of gestation. There is no increased infection risk with rupture of membranes including prolonged rupture of membranes or chorioamnionitis. A single course of corticosteroids is currently recommended by the American College of Obstetricians and Gynecologists (ACOG) for pregnant women between 24 and 34 weeks of gestation who are at risk of preterm delivery within 7 days. This course may consist of betamethasone (2 doses, 24 hours apart) or dexamethasone (4 doses, 12 hours apart). A single rescue course may be considered if the first course was given more than 2 weeks prior in women less than 32 6/7 weeks of gestation who are likely to deliver within the next week. Additional repeat courses have not demonstrated any benefit, may be associated with poorer outcomes, and are not recommended.

Question 8

How do synthetic surfactants compare with bovine surfactants?&#10;A) Synthetic surfactants contain exclusively SP-A, SP-B, SP-C, and SP-D.&#10;B) Synthetic surfactants contain only SP-A.&#10;C) Bovine surfactants contain SP-B and SP-C, and synthetic surfactants contain SP-A and SP-D.&#10;D) Bovine surfactants contain SP-A and SP-D, and synthetic surfactants contain SP-B and SP-C.

Accepted Answer

The bovine surfactants contain SP-B and SP-C, but not SP-A. Infasurf contains much more SP-B and SP-C than does Survanta. The synthetic surfactants contain no proteins.

Question 9

A full-term infant received surfactant as rescue therapy for RDS. Despite redosing, the infant has not been able to be extubated during the first 2 weeks of life. What should this neonate be evaluated for?

A)

\alpha

1-Antitrypsin deficiency
B) Vitamin B deficiency
C) SP-A deficiency
D) SP-D deficiency.

Accepted Answer

Full-term infants with RDS, surfactant nonresponders, and infants who cannot be extubated in the first weeks of life because of a respiratory condition should be evaluated for SP-B deficiency, alveolar capillary dysplasia, and $\alpha$1-antitrypsin deficiency.

Question 10

Which of the following is(are) considered the most important component(s) of pulmonary surfactant?
I) Dipalmitoyl phosphatidylcholine
II) Phosphatidylglycerine
III) Phosphatidylinositol
IV) Sphingomyelin

A) I only
B) I and IV only
C) I, II, and IV only
D) II, III, and IV only

Accepted Answer

Surfactant composition is fairly constant among mammalian species. Surfactant is composed of approximately 90% lipids (of which 80% to 85% are phospholipids) and approximately 10% proteins (see Table 14-1 in the textbook). Phosphatidylcholine (PC) is the most abundant phospholipid (75% to 80%) and is mostly saturated (40% to 55%) in the form of dipalmitoyl phosphatidylcholine (DPPC). DPPC is the most important surfactant component in reducing surface tension; it consists of two molecules of palmitic acid and one molecule of phosphatidylcholine attached to a glycerol backbone. DPPC has a hydrophobic end (fatty acids) and a hydrophilic end (nitrogenous base) and aligns itself in the air-liquid interface with the hydrophobic end toward the gas phase and the hydrophilic end toward the liquid phase.

Question 11

Which of the following relationships is correct regarding the analysis of amniotic fluid to determine fetal lung maturity?&#10;A) Phosphatidylglycerol (PG) and phosphatidylcholine (lecithin) increase while sphingomyelin decreases during gestation.&#10;B) PG increases and lecithin and sphingomyelin decrease during gestation.&#10;C) PG and lecithin decrease while sphingomyelin increases during gestation.&#10;D) PG and lecithin increase while sphingomyelin decreases during gestation.

Accepted Answer

The answer of Which of the following relationships is correct...

Question 12

Which of the following is the most common form of surfactant abnormality associated with acute lung injury?&#10;A) Inactivation by proteins&#10;B) Altered surfactant metabolism&#10;C) Altered surfactant pool&#10;D) Altered surfactant composition

Accepted Answer

The answer of Which of the following is the most...

Question 13

According to Laplace's law the pressure required to open an alveoli in the lung is:&#10;A) directly proportional to the radius.&#10;B) inversely proportional to the length of the airway.&#10;C) directly proportional to the surface tension.&#10;D) indirectly proportional to the viscosity of the gas in the airway.

Accepted Answer

The answer of According to Laplace's law the pressure required...

Question 14

A term baby with meconium aspiration syndrome is receiving mechanical ventilation per protocol. On the third day, the therapist observes that the FiO₂ requirement is increasing and both lung compliance and oxygenation index are worsening. What should be suggested at this time?

A) Switch to a pressure-limited mode
B) High-frequency chest oscillation
C) ECMO
D) Administer surfactant

Accepted Answer

The answer of A term baby with meconium aspiration syndrome...

Deck 14: Surfactant Replacement Therapy