Question 1

Which of the following statements describe truncus arteriosus?

  1. The pulmonary artery arises from the left ventricle, and the aorta stems from the right ventricle.
  2. If PVR increases relative to systemic vascular resistance (SVR), more blood flows to the lungs through the truncus, decreasing systemic cardiac output.
  3. If SVR decreases relative to PVR, blood flow will be shunted from right to left, bypassing the lungs.
  4. A large VSD allows total mixing of blood from the two ventricles.

Truncus arteriosus refers to a rare defect where a single great artery arises from the ventricles of the heart, supplying the systemic, pulmonary, and coronary arteries (see Figure 24-18 in the textbook). A large VSD allows complete mixing of blood in the ventricles. The blood passes through a truncal valve before passing into the common truncus. The cardiac output and systemic oxygen saturations are determined by the balance between PVR and SVR. As PVR drops in the first several days of life, more blood flows to the lungs relative to the body, resulting in decreased systemic perfusion. If SVR decreases, blood will flow more to the body, leading to decreased pulmonary blood flow and hypoxemia.

 

Question 2

What factor is responsible for closure of the foramen ovale?

  1. Increased PaO2
  2. Increased pressure on the left side of the heart
  3. Blood flowing through the lungs
  4. High pulmonary vascular resistance

The increased fetal blood flow that results from the drop in PVR increases pulmonary venous blood return and, therefore, increases the left atrial pressure. At the same time, the RA pressure decreases when the umbilical cord is ligated and no longer provides placental blood flow to the IVC. The result of the higher LA pressures and the lower RA pressures is the closure of the foramen ovale.

 

Question 3

What is the incidence of respiratory distress syndrome (RDS) among infants born at less than 28 weeks of gestation?

  1. 30% to 40%
  2. 40% to 50%
  3. 60% to 80%
  4. >80%

In the United States, respiratory distress syndrome (RDS) has been estimated to occur in 20,000 to 30,000 newborn infants each year and is a complication in about 1% of pregnancies. Its incidence is inversely related to gestational age and birth weight. It occurs in 60% to 80% of infants < 28 wk of gestational age, in 15% to 30% of those between 32 and 36 wk, and rarely in those > 37 wk.

 

Question 4

What radiographic features is the therapist likely to see on a typical chest X-ray of an infant with MAS?

  1. Ground-glass appearance
  2. Complete whiteout
  3. Decreased lung volume
  4. Patchy areas of atelectasis

The typical chest radiograph shows patchy areas of atelectasis due to obstruction, as well as hyperexpansion from air trapping with flattening of the diaphragm sometimes noted on the radiograph.

 

Question 5

The therapist is treating a child with TOF who appears to be having a “tet” spell. What should the therapist suggest to treat this event?

  1. Beta blockers
  2. Knee-chest position to increase SVR
  3. Morphine sulfate
  4. Oxygen

See Box 24-1 in the text (Treatment of “tet” spells). Knee-chest position increases systemic vascular resistance and promotes blood flow from the right ventricle to the pulmonary artery rather than the aorta. Morphine sulfate decreases irritability and may lead to pulmonary artery dilation, which will increase pulmonary blood flow. Oxygen improves oxygenation and decreases pulmonary vascular resistance. Beta blockers (propranolol) may relax RVOT spasms. Systemic vasoconstrictors (phenylephrine) increase systemic vascular resistance to promote pulmonary blood flow. Sodium bicarbonate, administered to treat acidosis, decreases PVR.

 

Question 6

The therapist is setting pulse oximetry to determine the presence of right-to-left shunt in an infant suspected of having a heart defect. Where should the therapist place the pulse ox probe to obtain the most accurate measure of preductal oxygen saturation?

  1. Any finger of the right hand
  2. Any finger of the left hand
  3. Left earlobe
  4. Lower extremities

Pulse oximetry is a fundamental monitoring device in children with congenital heart disease. In addition to measuring systemic oxygenation, it can also be used to measure the degree of right-to-left shunting in lesions where this is a possibility. This is done by measuring preductal and postductal saturations. Preductal saturations are measured by placing the pulse oximeter on the right upper extremity. Postductal saturations are reflected by placing the pulse oximeter on any other extremity, though the lower extremities are preferred as preductal and postductal blood may be incompletely mixed at the left upper extremity. If postductal saturations are 5% to 10% lower than preductal saturations, then right-to-left shunting should be suspected.

 

Question 7

Which of the following physiologic mechanisms need to be in place to ensure adequate systemic perfusion in infants with hypoplastic left heart syndrome (HLHS)?

  1. Presence of an ASD
  2. Presence of a mitral regurgitation
  3. Adequate left atrial function
  4. Presence of a PDA

Adequate systemic perfusion in these infants depends on the presence of a nonrestrictive atrial septal connection, adequate right ventricular function, a patent ductus arteriosus, and a balance between the pulmonary and systemic circulations.

 

Question 8

Blood samples are simultaneously obtained from both the right radial artery and the umbilical artery, and the arterial partial pressure of oxygen (PaO2) value from the right radial artery is 20 mm Hg greater than that analyzed from the umbilical artery sample. On the basis of this finding, which of the following conditions does the neonate likely have?

  1. PPHN
  2. MAS
  3. Neonatal pneumonia
  4. RDS

A PaO2 gradient between a preductal (right radial artery) and a postductal (umbilical artery) site of blood sampling >20 mm Hg suggests right-to-left shunting through the ductus arteriosus, as does an oxygenation saturation gradient >5% between preductal and postductal sites on pulse oximetry.

 

Question 9

What ventilator settings should a therapist select for a newborn with respiratory distress syndrome?

  1. PIP 25-30 cm H2O
  2. PEEP 3-6 cm H2O
  3. VT 5-6 mL/kg
  4. Frequency 60 breaths per minute

Generally, once the infant is stabilized and in the NICU, a pressure-limited ventilator utilizing a sinusoidal flow pattern is used. Peak inspiratory pressures (PIPs) generally begin at 15 to 25 cm H2O, depending on the size of the infant and the severity of the disease, to establish a tidal volume (VT) between 3 and 5 mL/kg. Positive end-expiratory pressure (PEEP) levels of 3 to 6 cm H2O are used to prevent further alveolar collapse, and rates of 20 to 50 breaths per minute are used to treat hypercapnia. Inspiratory times should be initiated at 0.3 to 0.4 second. If a longer inspiratory time is required before surfactant administration, it should be lowered to 0.3 second after surfactant is administered.

 

Question 10

Why does meconium staining occur predominantly in infants older than 36 weeks of gestational age?

  1. Because these infants can generate strong inspiratory efforts
  2. Because infants this age have significant cardiac outputs
  3. Because these infants demonstrate strong peristalsis
  4. Because these newborns have weak anal sphincter tone

Meconium passage into the amniotic fluid requires strong peristalsis and anal sphincter tone, which is not common in preterm infants. Meconium aspiration syndrome rarely occurs in infants born at less than 36 weeks of gestation. The longer a pregnancy is allowed to continue past 42 weeks, the greater the chances are of the passage of meconium.

 

Question 11

Which of the following clinical manifestations is consistent with an atrial septal defect (ASD)?

  1. An ASD often causes congestive heart failure (because of decreased pulmonary blood flow).
  2. The right ventricle may become hypertrophic (right ventricular hypertrophy).
  3. Most patients with an ASD are symptomatic in the neonatal intensive care unit, presenting with right atrial enlargement.
  4. Chest radiographs are usually abnormal.

The pathophysiology of an ASD involves left-to-right shunting, leading to right atrial enlargement, right ventricular volume overload, and increased pulmonary blood flow. Over time this may result in right ventricular hypertrophy, congestive heart failure, and pulmonary vascular disease. Infants with ASDs rarely are symptomatic and may remain so well into adulthood. Only 8% of children with ASDs develop symptoms before 2 years of age. Chest radiographs are typically normal, unless the child has congestive heart failure, which may result in cardiomegaly and prominent pulmonary vascular markings.

 

Question 12

What is the typical type of airway obstruction that occurs with MAS?

  1. Ball valve
  2. Complete
  3. No obstruction
  4. Airway inflammation

If the infant has a large amount of thick meconium within the airways at the time of delivery, complete bronchiole obstruction with subsequent alveolar collapse will result. The more typical picture, however, is that of smaller amounts of meconium within amniotic fluid, causing a ball-valve effect because of partial obstruction of the airways.

 

Question 13

How should the therapist interpret a preductal-to-postductal PaO2 difference of 8 mm Hg in a neonate?

  1. Unreliable data
  2. Absence of ductal shunting
  3. Presence of ductal shunting
  4. Inconclusive data

Clinical signs of a PDA depend on the degree of left-to-right shunting but may include tachypnea and a continuous murmur. In addition to signs on exam, one can detect the presence of shunting by looking for a difference in oxygenation of preductal and postductal blood. A preductal blood gas should be obtained from the right radial or temporal artery, while a postductal gas may be obtained from the umbilical artery or from a peripheral artery in the lower extremity. A difference in PaO2 > 15 mm Hg indicates significant shunting across the PDA.

 

Question 14

Which of the following congenital cardiac anomalies is classified as conotruncal, associated with a “boot-shaped” appearance of the heart?

  1. Tetralogy of Fallot
  2. Transposition of the great vessels
  3. Coarctation of the aorta
  4. Atrioventricular canal defect

Chest radiography of patients with TOF classically reveals a “boot-shaped” appearance of the heart, which is a result of the narrow mediastinum and the effects of right ventricular outflow tract obstruction that leads to right ventricular hypertrophy.

 

Question 15

Which of the following medications should the therapist recommend for an infant with apnea of prematurity experiencing episodes of apnea?

  1. Caffeine
  2. Benzodiazepines
  3. Antibiotics
  4. Doxapram

Caffeine’s proposed mechanisms include stimulation of skeletal and diaphragmatic muscle contraction, increase in the respiratory center’s sensitivity to carbon dioxide, and stimulation of the central respiratory drive. Caffeine appears to be a safer drug, can be given less frequently than aminophylline or theophylline, and is more effective in treating apnea.

 

Question 16

Which of the following therapeutic interventions is generally needed to treat transient tachypnea of the newborn (TTN)?

  1. Endotracheal intubation
  2. 30%-40% oxygen hood
  3. Bronchial hygiene therapy
  4. Bronchodilator therapy

Treatment is largely supportive. The objectives of treatment of TTN are to maintain adequate oxygenation and ventilation. Supplemental oxygen via oxygen hood (usually < 40%) is indicated when signs of respiratory distress are present. CPAP levels of 3 to 5 cm H2O may be needed when higher FiO2 levels are required.

 

Question 17

Which of the following blood gas parameters should the therapist target when managing patients with PPHN?

  1. SaO2 > 95%
  2. PaCO2 35-45 mm Hg
  3. pH 7.35-7.45
  4. PaO2 > 95 mm Hg

Adjust ventilators to maintain adequate oxygenation and mild hyperventilation, until stability is achieved for 12 to 24 hours after initially attempting to keep the oxygen saturation above 95%, arterial carbon dioxide tension (PaCO2) at 35 to 45 mm Hg, and pH at 7.35 to 7.45.

 

Question 18

Eight hours after being born, a baby presents with cyanosis despite administration of adequate ventilation, tachypnea, and retractions. Which of the following conditions should the therapist suspect is affecting this newborn?

  1. RDS
  2. BPD
  3. PPHN
  4. GBS pneumonia

PPHN should be suspected in all term infants who have cyanosis that may occur despite adequate ventilation. The recognition of risk factors for PPHN is one of the major diagnostic tools to differentiate babies with PPHN from those with structural heart disease, keeping in mind that idiopathic PPHN can present without signs of acute perinatal distress. Marked lability in oxygenation is frequently part of the clinical history. The infant with PPHN usually presents within the first 12 hours of life with cyanosis, tachypnea, and hypoxia that are refractory to oxygen therapy, as well as signs of respiratory distress, including retractions, grunting, and nasal flaring.

 

Question 19

Which of the following clinical features characterize a critical aortic stenosis in a neonate?

  1. Chest radiography reveals pleural effusion and pulmonary engorgement.
  2. The neonate often has metabolic alkalosis.
  3. The neonate presents in cardiogenic shock with hypotension.
  4. These infants are rarely symptomatic during the first month of life.

The clinical presentation and natural history of aortic stenosis is determined by the time of presentation and the degree of stenosis. Neonates who present with critical aortic stenosis frequently present in cardiogenic shock with hypotension, poor perfusion, and metabolic acidosis. The chest radiograph frequently includes cardiomegaly and pulmonary edema.

Question 20

When using subambient oxygen therapy, what range of oxygen saturations should the therapist target?

  1. >95% to 95%
  2. 85% to 90%
  3. 75% to 85%
  4. 70% to 80%

When using this setup, special care must be taken in order to avoid inadvertent delivery of low oxygen. A continuous oxygen analyzer must be placed in the line with alarms for high and low levels of oxygen. Another safeguard that may be employed is requiring two clinicians to check the setup before applying it to the patient. Typically clinicians target oxygen saturations of 75% to 85%, utilizing an FiO2 as low as 0.16 to 0.17.

 

Question 21

At birth, what factor causes dilation of the pulmonary vascular bed and a decrease in the pulmonary vascular resistance?

  1. Increased arterial partial pressure of oxygen (PaO2)
  2. Decreased arterial partial pressure of carbon dioxide (PaCO2)
  3. Lung inflation
  4. Circulating indomethacin

With inflation of the lungs and the beginning of their participation in gas exchange, PaO2 increases and PaCO2 decreases, both of which contribute to dilation of the pulmonary vasculature and a resultant reduction in pulmonary vascular resistance (PVR). This leads to reduced right ventricular pressures and increased pulmonary blood flow.

 

Question 22

While reviewing the chest X-ray of a newborn, the therapist observes the following features:

Pulmonary vascular congestion
Prominent perihilar streaking
Fluid in the interlobular fissures
Hyperexpansion
Flat diaphragm

Which of the following conditions does this patient likely have?

  1. RDS
  2. Persistent pulmonary hypertension of the newborn
  3. Transient tachypnea of the newborn
  4. Barotrauma

The chest radiograph shows pulmonary vascular congestion, prominent perihilar streaking, fluid in the interlobular fissures, hyperexpansion, and a flat diaphragm (see Figure 22-4 in the textbook). Mild cardiomegaly and pleural effusions may also be present.

 

Question 23

While reviewing the chest X-ray of a newborn, the therapist observes the following features: continuous diaphragm sign and linear bands of air paralleling the left side of the heart and the descending aorta with extension superiorly along the great vessels into the neck. Which of the following conditions does this patient likely have?

  1. Pneumothorax
  2. Cardiac tamponade
  3. Pneumomediastinum
  4. Pneumopericardium

Typical radiological signs of pneumomediastinum include the continuous diaphragm sign (interposition of air between the pericardium and the diaphragm, which becomes visible in the central mediastinal part) and linear bands of mediastinal air paralleling the left side of the heart and the descending aorta (pleura appears as a fine opaque line) with extension superiorly along the great vessels into the neck.

 

Question 24

How should the therapist interpret a lecithin-to-sphingomyelin (L:S) ratio of 2:1?

  1. The presence of lung maturity
  2. A gestational age of less than 28 weeks
  3. The likelihood of RDS
  4. Laboratory error

Lecithin, also known as dipalmitoyl phosphatidylcholine, is the most abundant phospholipid found in surfactant. RDS is unlikely if the L:S ratio is 2.0 or greater.

 

Question 25

The therapist is treating a child with a congenital heart defect who is unresponsive to oxygen therapy. Although the chest X-ray is relatively normal, the heart is described as “egg-shaped.” Which of the following heart defects is more consistent with this description?

  1. Complete transposition of the great arteries
  2. Coarctation of the aorta
  3. Truncus arteriosus
  4. Tetralogy of Fallot

The main clinical sign of TGA is cyanosis that is not responsive to oxygen therapy. Chest radiography of TGA is frequently normal, though the cardiac silhouette may have the classic “egg on a string” appearance.

 

Question 26

Which of the following strategies can be used to increase pulmonary vascular resistance (PVR) in infants with hypoplastic left heart syndrome (HLHS)?

  1. FiO2 < 0.21
  2. Induce hypocapnia
  3. Administer indomethacin
  4. Close the PDA

A number of interventions may be employed to balance the systemic and pulmonary circulations. As the PVR decreases, minimizing the amount of administered oxygen can decrease pulmonary vasodilation and pulmonary blood flow. Occasionally, subambient oxygen concentrations (FiO2 < 0.21) are used to increase PVR. Target FIO2s are usually in the 0.17 to 0.21 range in order to keep systemic oxygen saturations 70% to 80%. Hypercarbia can also be utilized to elevate PVR.

 

Question 27

Which of the following methods is involved in the management of a PDA?

  1. Increasing the circulating volume
  2. Maintaining/optimizing the hematocrit at the low end of normal hemoglobin level
  3. Administering indomethacin
  4. Administering digoxin

Medical management includes maintaining euvolemia and by optimizing the hemoglobin to ensure adequate oxygen delivery. In mechanically ventilated patients, increasing PEEP may serve to decrease the pulmonary blood flow by increasing PVR. In addition nonsteroidal anti-inflammatory agents such as indomethacin and ibuprofen are often used in the medical management of PDA. Indomethacin may be used prophylactically to prevent PDA and therapeutically to treat a symptomatic PDA. A dose of indomethacin (0.2 mg/kg/dose IV) given in the first 24 hours of life can be effective in preventing a PDA. Therapy later in life is usually given over a 48-hour period. Doses of 0.1 to 0.2 mg/kg/dose IV every 12 to 24 hours are effective. Side effects are uncommon but include oliguria, renal insufficiency, and dilutional hyponatremia. Ibuprofen may also be used, though a recent meta-analysis found that the use of ibuprofen was associated with increased incidence of chronic lung disease when compared to indomethacin.

 

Question 28

For which of the following congenital cardiac defects may spontaneous closure of the ductus arteriosus be catastrophic?

  1. Tetralogy of Fallot with pulmonary atresia
  2. Atrial septal defect
  3. Severe coarctation of the aorta
  4. Hypoplastic left heart syndrome

Shunting is potentially harmful, either due to prolonged cyanosis and decreased end organ oxygen delivery, or to increased PVR over time. However, shunting also has an important compensatory effect in patients with obstructed pulmonary or systemic blood flow. In these lesions, referred to as ductal-dependent lesions, the presence of a PDA provides lifesaving blood flow. Lesions with systemic outflow tract obstruction, such as critical coarctation of the aorta or hypoplastic left heart syndrome, rely on the PDA to provide systemic blood flow via a right-to-left shunt; these lesions have ductal-dependent systemic blood flow. With both right-to-left shunt (cyanotic cardiac defect) and left-to-right shunt (acyanotic cardiac defect), several lesions depend on a patent ductus arteriosus for adequate pulmonary and systemic blood flow. These anomalies are also called ductal-dependent lesions because spontaneous closure of the ductus arteriosus can prove catastrophic. Anomalies included in this group are severe coarctation of the aorta, hypoplastic left heart syndrome, and tetralogy of Fallot with pulmonary atresia.

 

Question 29

The therapist is reviewing the chest radiograph of a newborn, preterm infant and observes diffuse, fine, reticulogranular densities, which provide a ground-glass appearance. On the basis of these radiographic findings, which of the following conditions should the therapist suspect is present?

  1. Persistent pulmonary hypertension of the newborn
  2. Respiratory distress syndrome
  3. Bronchopulmonary dysplasia
  4. Pulmonary interstitial emphysema

The chest radiograph in RDS typically reveals diffuse, fine, granular (reticulogranular) densities, which present a ground-glass appearance. The heart may be slightly enlarged, and the thymus is nearly always visible.

 

Question 30

In addition to Group B Streptococcus, which of the following microorganisms are responsible for nosocomial pneumonia acquired after delivery?

  1. RSV
  2. Escherichia coli
  3. Pseudomona spp.
  4. Haemophilus influenza

Bacteria that should be considered when pneumonia is acquired in utero or in the immediate perinatal period include Escherichia coli, Klebsiella spp., Group D Streptococci, Listeria monocytogenes, andpneumococci acquired via transmission from the mother.

 

Question 31

Which of the following risk factors contribute to the pathogenesis of BPD?

  1. Lung immaturity
  2. Respiratory failure
  3. Oxygen supplementation
  4. Positive-pressure ventilation

Northway and colleagues proposed four major factors in BPD pathogenesis: (1) lung immaturity, (2) respiratory failure, (3) oxygen supplementation, and (4) positive-pressure mechanical ventilation.

 

Question 32

What is the significance of an infant with RDS demonstrating a grunt during each exhalation?

  1. Resolution of the RDS
  2. An effort to maintain its functional residual capacity (FRC)
  3. An attempt to overcome increased airway resistance
  4. Impending death

A characteristic grunt during expiration is an attempt to maintain the FRC.

 

Question 33

The therapist is assessing a newborn on the mechanical ventilator. The neonate shows clear signs of respiratory distress, and lung auscultation reveals shifting of the PMI towards the left and breath sounds decreased on the right. What should the therapist suspect this newborn developed?

  1. Right-sided pneumothorax
  2. Severe right lung atelectasis
  3. Right pleural effusion
  4. Left-sided atelectasis

Neonates with spontaneous pneumothorax are usually asymptomatic or have mild signs of tachypnea with an oxygen requirement. Occasionally, severe respiratory distress (grunting, nasal flaring, and intercostal retractions) may occur. In the ventilated neonate, pneumothorax may lead to a rapid clinical deterioration, resulting in cyanosis, hypotension, hypoxemia, hypercapnia, and respiratory acidosis. In unilateral pneumothorax, the cardiac apex can be shifted away from the affected side and breath sounds decreased over that side.

 

Question 34

When neonatal pneumonia is suspected, how long does an infant generally receive broad-spectrum antibiotics?

  1. 24 hours
  2. 48 hours
  3. 72 hours
  4. 96 hours

Whenever neonatal pneumonia is suspected, broad-spectrum antibiotics are given for at least 72 hours, or until definitive culture results are obtained. If results prove that infection is present, antibiotics are continued for 14 to 21 days.

 

Question 35

Identify the following congenital cardiac anomaly:

  1. Truncus arteriosus
  2. Hypoplastic left ventricle
  3. Transposition of the great vessels
  4. Ventricular septal defect

The cardiac anomaly depicted in this question is truncus arteriosus, which can be viewed in the textbook in Figure 24-16.

 

Question 36

Which of the following medications is the most common preoperative treatment to minimize preductal constriction until surgical correction of coarctation of the aorta can be achieved?

  1. Indomethacin
  2. Prostaglandin E1
  3. Negative inotropes
  4. Diuretics

Treatment of neonates with severe coarctation includes prostaglandin E1 to restore patency of the ductus arteriosus. These patients may also have significant ventricular dysfunction, congestive heart failure, and acidosis, requiring inotropes, diuresis, and ventilatory support.

 

Question 37

When should a therapist consider intubation and mechanical ventilation for a newborn with respiratory distress?

  1. FiO2 > 40% to 70%
  2. SpO2 < 85%
  3. CPAP of 5-10 cm H2O
  4. pH < 7.20

Classic indications for endotracheal intubation and mechanical ventilation are infants with respiratory failure or persistent apnea. Reasonable measures of respiratory failure are: (1) arterial blood pH < 7.20, (2) arterial blood PaCO2 of 60 mm Hg or higher, and (3) oxygen saturation <85% at oxygen concentrations of 40% to 70% and CPAP of 5 to 10 cm H2O.

 

Question 38

When should a therapist consider CPAP for a newborn with respiratory distress?

  1. FiO2 > 40% to 70% and SpO2 < 85%
  2. FiO2 > 90% and SpO2 < 95%
  3. Respiratory rate of 40 breaths per minute
  4. PaO2 50 to 60 mm Hg

If oxygen saturation cannot be kept > 85% at inspired oxygen concentrations of 40% to 70% or greater, continuous positive airway pressure (CPAP) via nasal prongs or nasopharyngeal tube using a continuous-flow ventilator may be instituted.

 

Question 39

A therapist monitoring an infant after a Blalock-Tausig shunt placement notices a significant drop in the end-tidal carbon dioxide (ETCO2) despite no changes in the infant’s respiratory rate. How should the therapist interpret this change?

  1. The infant has dramatically improved ventilation by breathing deeply.
  2. The ETCO2 monitor is not accurate.
  3. Loss of pulmonary blood flow through the shunt
  4. Tricuspid regurgitation

The magnitude of the ETCO2 tracing may be used as a surrogate of efficacy of cardiopulmonary resuscitation (CPR). Finally, in children with a Blalock-Taussig shunt, a precipitous drop in the ETCO2 may indicate a loss of pulmonary blood flow due to shunt thrombosis.

 

Question 40

Which of the following blood flow patterns occurs in complete transposition of the great arteries?

  1. The systemic venous blood passes through the right heart chambers.
  2. The pulmonary venous blood traverses the left side of the heart and then returns to the systemic circulation.
  3. When PVR increases relative to SVR, blood flow increases through the ductus arteriosus.
  4. Systemic venous blood flows to the lungs after leaving the right ventricle.

In TGA the positions of the aorta and the pulmonary artery are reversed, with the aorta arising from the RV and the pulmonary artery arising from the LV (see Figure 24-17 in the textbook). The physiologic result is that the two circulations are in parallel rather than in series with each other. Deoxygenated systemic venous blood passes through the right heart and to the body without flowing through the lungs. Oxygenated pulmonary venous blood passes through the left heart and back to the lungs without flowing to the body. Survival depends on mixing at one or more points in the circulation. The potential sites for mixing of blood are ASDs, VSDs, or the PDA.

 

Question 41

Which of the following clinical pathophysiologic manifestations are consistent with a large ventricular septal defect (VSD)?

  1. The majority of the blood flow is shunted from left right to right left.
  2. Shunting typically occurs during ventricular diastole, which causes left atrial enlargement.
  3. Chest radiography reveals an enlarged cardiac silhouette and increased pulmonary vascular markings, increasing pulmonary blood flow.
  4. Thickening and fibrosing of the pulmonary veins develop, decreasing pulmonary artery pressure.

The pathophysiology of VSDs involves left-to-right shunting, left ventricular volume overload, left atrial enlargement, and increased pulmonary blood flow. The size of the defect and the pulmonary vascular resistance determines the amount of shunting, which usually occurs during systole. Large defects may lead to large shunts, sometimes termed nonrestrictive VSDs, and may result in congestive heart failure and pulmonary hypertension.

 

Question 42

A newborn suspected of having a pneumothorax is rapidly deteriorating. What should the therapist suggest at this time?

  1. Intubation and mechanical ventilation
  2. Mask CPAP
  3. Needle aspiration
  4. Confirm air leak with a chest X-ray and place a chest tube afterwards

Needle aspiration: In a rapidly deteriorating clinical situation, thoracentesis or pericardiocentesis may confirm the diagnosis and be therapeutic in pneumothorax and pneumopericardium, respectively.

 

Question 43

What should the therapist select as target gas exchange parameters after surgical intervention for infants with hypoplastic left ventricular syndrome HLHS?

  1. pH < 7.35
  2. PaO2 of 60 mm Hg and PaCO2 of 60 mm Hg
  3. pH > 7.45
  4. PaO2 of 40 mm Hg and PaCO2 of 40 mm Hg

Goal gas exchange in these infants should follow the “rule of forties,” which targets PaO2 approximately 40 mm Hg and PaCO2 40 mm Hg. Any manipulation of the endotracheal tube in these patients should be conducted with caution.

 

Question 44

How should the therapist interpret the lack of foam appearing during the shake test?

  1. The test needs to be redone.
  2. The unborn infant’s lungs have matured.
  3. The infant’s lungs are immature.
  4. The patient has a 50% chance of developing RDS.

Other tests for lung maturity have been developed; in the foam stability test, amniotic fluid is mixed with different volumes of 95% ethanol. When this mixture is shaken with air, a foam develops that can be seen for several hours at room temperature. If no surfactant is present, the foam will not appear or will appear only briefly, indicating the strong possibility of immature lungs. The shake test is not as specific as a low L:S ratio.

 

Question 45

Which of the following vessels return blood to the right atrium?

  1. Pulmonary vein
  2. Inferior vena cava
  3. Superior vena cava
  4. Coronary sinus

To understand the normal anatomy of the heart, one can trace the path of blood as it travels through the heart. This begins with deoxygenated venous blood that enters the right atrium (RA) from one of three sources. Venous blood from organs superior to the heart drains to the RA by way of the superior vena cava (SVC). Venous blood from organs inferior to the heart enters the RA via the inferior vena cava (IVC). Finally, venous blood from the heart itself drains into the RA by way of the coronary sinus

 

Question 46

Which of the following conditions increase the risk for developing RDS?

  1. Maternal diabetes
  2. Cesarean delivery
  3. Multiple births
  4. Premature rupture of membranes

The risk for development of RDS increases with maternal diabetes, multiple births, cesarean delivery, precipitous delivery (delivery of infant anywhere unintended), asphyxia, cold stress, and a maternal history of previously affected infants.

 

Question 47

Identify the congenital cardiac defect depicted in the following illustration:

  1. Atrial septal defect
  2. Hypoplastic left ventricular syndrome
  3. Hypoplastic right ventricular syndrome
  4. Atrioventricular canal defect

The cardiac anomaly depicted in this question is hypoplastic left ventricular syndrome, which can be viewed in the textbook in Figure 24-8.

 

Question 48

Why must supplemental oxygen be judiciously administered to patients with an atrioventricular canal defect?

  1. To prevent the development of retinopathy of prematurity
  2. To avoid oxygen-induced hypoventilation
  3. To minimize pulmonary vascular dilation
  4. To reduce oxidative stress

Oxygen saturations in these children may be low (75% to 90%) due to venous admixing but are tolerated well by most patients. Supplemental oxygen may be given judiciously, given the potential for oxygen to induce pulmonary vascular dilation and increased pulmonary blood flow.

Question 49

The therapist is contemplating the possibility of intubating and suctioning a nonvigorous newborn with MAS. Which of the following clinical parameters confirms the indication for the procedure?

  1. Good muscle tone
  2. Presence of dark green meconium on the skin
  3. Heart rate < 100 beats per minute
  4. Presence of coarse crackles on auscultation

The guidelines are under continuous review and are revised as new evidence-based research becomes available. The current guidelines are as follows: If the baby is not vigorous (defined as depressed respiratory effort, poor muscle tone, and/or heart rate < 100 beats/min), use direct laryngoscopy, intubate, and suction the trachea immediately after delivery. Suction for no longer than 5 seconds. If no meconium is retrieved, do not repeat intubation and suction. If meconium is retrieved and no bradycardia is present, reintubate and suction. If the heart rate is low, administer positive pressure ventilation and consider suctioning again later.

 

Question 50

A neonate diagnosed with a pneumothorax was treated with a chest tube. After 36 hours, the therapist noticed that bubbling is present in the chest tube system. What should the therapist do at this time?

  1. Suggest removal of the chest tube in 24 hours
  2. Clamp the tube and obtain a CXR
  3. Keep the chest tube until bubbling stops
  4. Remove the chest tube and obtain a follow-up CXR

Suction should be maintained until fluctuation of air in the tube and active bubbling have ceased. At this time the tube should be clamped and removed within 24 hours if there has been no reaccumulation of air in the pleural cavity.