MODULE 1: PRE-TEST (PULMONARY)

A neonate born at 28 weeks gestational age has approximately what percentage of fetal hemoglobin? A. 100% B. 70% C. 30%

A. 100% The correct answer is - 100%. All neonates generally have mostly fetal hemoglobin. Babies born at <30 weeks' gestation have nearly 100% fetal hemoglobin. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 80-82.

Apnea of prematurity, when not accompanied by oxygen desaturation and bradycardia, is traditionally defined as cessation of breathing for more than: A. 15-20 seconds B. 25-30 seconds C. 10 seconds

A. 15-20 seconds The correct answer is - 15-20 seconds. Apnea has traditionally been defined as the cessation of breathing for greater than 15 to 20 seconds. Shorter events (<15 seconds) may also be identified as apnea if accompanied by oxygen desaturation and bradycardia. Martin, Fanaroff & Walsh, 2015, pg. 1140

A neonate born at 28 weeks who has not had a blood transfusion and is now 12 weeks postnatal age should have approximately what percentage of fetal hemoglobin? A. 70% B. 100% C. 30%

A. 70% The correct answer is - 70%. The ratio of fetal to adult hemoglobin gradually diminishes so that by 40 weeks' gestation, fetal hemoglobin accounts for approximately 70% of all hemoglobin species, with adult hemoglobin accounting for the remaining 30%. This shift to producing adult hemoglobin and away from producing fetal hemoglobin is related to postmenstrual age and not to chronological age. Therefore, premature delivery does not affect the rate of transitioning away from fetal hemoglobin production. A baby born at 28 weeks with nearly 100% fetal hemoglobin would be expected to have approximately 70% fetal hemoglobin at 12 weeks of age (40 weeks' corrected gestational age), similar to a baby born at 40 weeks' gestation, although the ratio will change more quickly following transfusion with adult blood. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 80-82

It has been shown that successful extubation is accomplished more often in infants coming immediately off intermittent mandatory ventilation (IMV) than after a pre-extubation trial of endotracheal (ET) continuous positive airway pressure (CPAP). This is an example of which of the following physiologic principles: A. Airway resistance B. Functional residual capacity C. Lung compliance

A. Airway resistance Consistent with the physiologic principles of resistance, the preponderance of evidence indicates that the application of PEEP and CPAP decreases airway resistance. However, ETT resistance is of considerable clinical importance. It has been shown that successful extubation is accomplished more often in infants coming directly off intermittent mandatory ventilation than after a 6-hour pre-extubation trial of endotracheal CPAP. Goldsmith, Karotkin, Keszler & Suresh (2017), pp.16-17.

Which of the following components increases pulmonary blood flow? A. Alkalosis B. Acidosis C. Hypercarbia

A. Alkalosis The correct answer is - Alkalosis. Alkalosis shifts the oxyhemoglobin dissociation curve to the left and improves pulmonary blood flow. By modifying hemoglobin oxygen affinity, carbon dioxide facilitates respiratory gas exchange in the lungs. At the lungs, carbon dioxide is given up by red blood cells into the alveoli. Carbon dioxide concentration falls, thereby shifting the oxyhemoglobin dissociation curve to the left; the increase in hemoglobin oxygen affinity enhances uptake of oxygen from the alveoli and enhances pulmonary flow. Polin, Fox & Abman, 2011, p. 973; Goldsmith, Karotkin, Keszler & Suresh (2017), pp. 21-30.

An arterial blood gas contaminated by air bubbles can potentially: A. Alter the PaO2 measurement B. Increase the PaCO2 C. Increase the base deficit

A. Alter the PaO2 measurement The correct answer is - Alter the PaO2 measurement. Even small air bubbles in a blood gas sample can cause significant errors. The air bubbles contain room air, which has four main components: nitrogen (78%), oxygen (21%), argon (1%), and carbon dioxide (0.04%). Room air has a Paco2 that is nearly zero and a PAo2 of approximately 150 mm Hg. If air bubbles contaminate a blood gas sample, they lower the Paco2 and can either raise or lower the Pao2, depending on whether the Pao2 is below or above 150 mm Hg. The amount of air that comes in contact with arterial blood drawn through a butterfly (scalp vein) infusion set is enough to alter the Pao2 measurement. Therefore it is very important to expel air bubbles from the blood sample before placing it in the blood gas analyzer. Goldsmith, Karotkin, Keszler & Suresh (2017), pp. 95-96.

An important clinical sign that best evaluates tissue perfusion is: A. Capillary refill time B. Mean pulse pressure C. Systolic blood pressure

A. Capillary refill time The correct answer is - Capillary refill time (CRT). CRT has been a reliable and time-honored observation. CRT of >3 seconds in term infants is suspect for decreased intravascular volume whereas a CRT of bare 3 seconds in a preterm infant should be equally suspected. Gomella, Cunningham & Eyal, 2013, pg. 819

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) supports: A. Cardiac and pulmonary function B. Cardiac function C. Pulmonary function

A. Cardiac and pulmonary function The correct answer is - Cardiac and pulmonary function. ECMO can be accomplished with a double cannula venoarterial (VA) or a single cannula (double lumen) venovenous (VV) approach. A combination of techniques may also be used. Goldsmith, Karotkin, Keszler & Suresh (2017) pp. 440-441.

End-tidal carbon dioxide (CO2) monitors measure the pCO2 of: A. Exhaled gas at end expiration B. Gas mid-respiratory cycle C. Inspired gas

A. Exhaled gas at end expiration The correct answer is - Exhaled gas at end expiration. End-tidal CO2 monitoring measures expired breath by infrared spectroscopy for CO2 content and provides a close correlation to PaCO2. It gives rapid information about changes in CO2, unlike the slow response time of tcPCO2. Gomella, Cunningham & Eyal, 2013, p. 72-73, 88.

Which one of the following would NOT satisfy generally accepted eligibility criteria for extracorporeal membrane oxygenation (ECMO)? A. Grade II intraventricular hemorrhage (IVH) B. Oxygenation Index (OI) of 45 C. Gestational age of 35 weeks

A. Grade II intraventricular hemorrhage (IVH) The correct answer is - Grade II intraventricular hemorrhage (IVH). The patient selection criteria for ECMO include: Gestational age of 34 weeks or older, normal cranial ultrasound (grade I intraventricular hemorrhage is a relative contraindication), weight greater than 200 grams, OI of greater than 40. There absence of complex congenital heart disease, fewer than 10 to 14 days of assisted ventilation, reversible lung disease, including congenital diaphragmatic hernia, and failure of maximum medical therapy. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 438; Martin, Fanaroff & Walsh, 2015, pp. 1172-1173.

Which of the following modes of mechanical ventilation have proven most successful with respect to the incidence and treatment of air leak syndromes? A. High frequency jet ventilation (HFJV) B. High frequency oscillatory ventilation (HFOV) C. Conventional mechanical ventilation (CMV)

A. High frequency jet ventilation (HFJV) The correct answer is - High frequency jet ventilation (HFJV). Of all forms of high frequency ventilation (HFV), HFJV has been the most successful with respect to the incidence and treatment of air-leak syndromes. An air leak will persist when gas is delivered at a pressure that opens the injured tissue, creating a low-resistance path for flow. The leak will continue during an inspiration for as long as the pressure exceeds that needed to stent the leak open. During CMV or HFOV, because of both the inspiratory time and the characteristics of gas flow, a leak may persist, whereas during HFJV, it may rapidly close. Goldsmith, Karotkin, Keszler & Suresh (2017), pp. 221-222.

During surfactant administration the infant suddenly becomes cyanotic, bradycardic and oxygen saturation is 75%. Which is the most appropriate response? A. Increase FiO2 and slow the rate of surfactant administration B. Administer surfactant more quickly and increase rate of positive pressure ventilation C. Stop administering surfactant and administer at a later time when infant has fully recovered

A. Increase FiO2 and slow the rate of surfactant administration The correct answer is - Increase FiO2 and slow the rate of surfactant administration. Transient hypoxia and bradycardia can occur as a result of acute airway obstruction immediately after surfactant instillation. Other acute adverse effects of surfactant administration include reflux of surfactant into the pharynx from the endotracheal tube, increase in transcutaneous carbon dioxide tension, tachycardia, gagging, and mucous plugging of the endotracheal tube. These complications of surfactant administration generally respond to a slower rate of surfactant administration or to an increase in the airway pressure or FiO2 during administration. ? Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 346.

Which ventilator move is most appropriate when trying to improve ventilation during high frequency oscillatory ventilation (HFOV)? A. Increase the delta p (amplitude) B. Increase the hertz (Hz) C. Increase the mean airway pressure

A. Increase the delta p (amplitude) The correct answer is - Increase the delta p (amplitude). The general principles of conventional mechanical ventilation also apply to the oscillator with amplitude being analogous to PIP. Ventilation is accomplished by adjusting the amplitude, which in turn regulates gas delivery during inspiration and gas removal during expiration. Gomella, Cunningham & Eyal, 2013, pg. 87; Martin, Fanaroff & Walsh, 2015, pg. 1100-1101.

Which ventilator change is most appropriate when trying to improve oxygenation during high-frequency oscillatory ventilation (HFOV)? A. Increase the mean airway pressure (Mean Paw) B. Increase the hertz (Hz) C. Increase the delta p (amplitude)

A. Increase the mean airway pressure (Mean Paw) The correct answer is - Increase the mean airway pressure (Mean Paw). The general principles of conventional mechanical ventilation also apply to the oscillator. Mean Paw is used to inflate the lung and recruit alveoli for oxygenation. This may be thought of as continuous distending pressure, because the lung remains inflated throughout the respiratory cycle. Gomella, Cunningham & Eyal, 2013, pg.87; Martin, Fanaroff & Walsh, 2015, pg. 1100-1101.

Clinical findings present in an infant diagnosed with pulmonary hypertension include: A. Increased pulmonary vascular contractility B. Increased pulmonary blood flow C. Left to right shunting

A. Increased pulmonary vascular contractility The correct answer is - Increased pulmonary vascular contractility. The neonatal pulmonary vasculature is sensitive to changes in PaO2, and pH and, during stress, can become even hyperreactive and constrict to cause increased pressure against which the neonatal heart cannot force blood flow to the lungs. If pulmonary artery pressure is higher than systemic, blood flows through the path of least resistance, away from the lungs through the foramen ovale and the ductus arteriosus. The infant becomes progressively hypoxemic and acidemic, and the cycle perpetuates. Martin, Fanaroff & Walsh, 1205, pg. 1205.

Mechanisms of action of methylxanthines, used in the treatment of apnea of prematurity, include: A. Increases minute ventilation B. Decreases diaphragmatic activity C. Decreases CO2 sensitivity

A. Increases minute ventilation The correct answer is - Increases minute ventilation. Xanthines have been used in the management of apnea of prematurity for more than 30 years. Both theophylline and caffeine are used in neonatal management. Effects seen with xanthine therapy include increased minute ventilation, improved CO2 sensitivity, decreased hypoxic depression of breathing, enhanced diaphragmatic activity and decreased periodic breathing. Martin, Fanaroff & Walsh, 2015, pg. 1144.

On a conventional ventilator, which of the following changes will have the greatest impact on increasing the mean airway pressure? A. Increasing the peak end expiratory pressure (PEEP) B. Increasing the peak inspiratory pressure (PIP) C. Increasing frequency (rate)

A. Increasing the peak end expiratory pressure (PEEP) The correct answer is - Increasing the peak end expiratory pressure (PEEP). The most direct impact on mean airway pressure (mean Paw) comes from positive end expiratory pressure (PEEP) because it is applied throughout the respiratory cycle. PEEP is the baseline pressure, the lowest level to which airway pressure falls. It is used to take advantage of Laplace's law, by maintaining some degree of alveolar inflation during expiration, thus reducing the pressure necessary to further inflate the alveolus during inspiration. There is a 1:1 relationship between PEEP and mean Paw; for every 1-cm H2O increase in PEEP, there is a 1-cm H2O increase in mean Paw. Martin, Fanaroff & Walsh, 2015, pp. 1090-1091.

Which of the following appears to play a major role in the pathogenesis of bronchopulmonary dysplasia (BPD)? A. Inflammatory response B. Non-invasive respiratory support modalities C. Permissive hypercapnia

A. Inflammatory response The correct answer is - Inflammatory response. Although volutrauma and oxygen toxicity directly injure the neonatal lung, these effects are in part mediated and potentiated by the recruitment and activation of inflammatory cells and the release of potent inflammatory products. Inflammation appears to be triggered by factors such as oxygen, positive-pressure ventilation, PDA, and prenatal or postnatal infections. Increased concentration of inflammatory mediators may contribute to the bronchoconstriction and vasoconstriction and the increased vascular permeability characteristic of these infants. The inflammatory reaction might also be responsible for the decreased alveolarization characteristic of infants with BPD. Martin, Fanaroff & Walsh, 2015, pg. 1160-1162.

In time-cycled synchronized intermittent mandatory ventilation (SIMV), synchrony between mechanical and spontaneous breath occurs during: A. Inspiration only B. Expiration only C. Inspiration and expiration?

A. Inspiration only The correct answer is - Inspiration only. In time-cycled SIMV, synchrony between mechanical and spontaneous breath occurs only during inspiration, because the inspiratory time for both mechanical and spontaneous breaths may be different. This discrepancy can be offset by using flow cycling, wherein synchrony occurs during both inspiration and expiration. Martin, Fanaroff & Walsh, 2015, p. 1093.

Therapeutic hypothermia results in a shift of the oxygen dissociation curve to the: A. Left B. No shift C. Right

A. Left The correct answer is - Left. Conditions such as respiratory alkalosis or therapeutic hypothermia will shift the dissociation curve to the left. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 80-82.

Conditions that causes a shift of the oxygen dissociation curve (ODC) to the right will result in which of the following? A. Lower oxygen saturation for a given Pao2 B. Stable oxygen saturation for a given Pao2 C. Higher oxygen saturation for a given Pao2

A. Lower oxygen saturation for a given Pao2 The correct answer is - Lower oxygen saturation for a given PaO2. Oxygen that is bound to hemoglobin is not readily available to tissues until it has been released and can dissolve in plasma. As the curve shifts to the right, hemoglobin has less binding affinity for oxygen at a given Pao2 and releases oxygen more easily to the tissues, thus a lower hemoglobin oxygen saturation for a given PaO2. When dissociation curve is shifted to the left, oxygen is bound more tightly to hemoglobin thereby releasing oxygen less easily to the tissues and there is a higher oxygen saturation at a given Pao2. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 80-82.

During conventional mechanical ventilation, oxygenation is most often improved by increasing the: A. Mean airway pressure B. Ventilator rate C. Inspiratory time

A. Mean airway pressure The correct answer is - Mean airway pressure. The two major factors that are responsible for oxygenating the blood are the fraction of inspired oxygen and the pressure to which the lung is exposed. Oxygenation is proportional to mean airway pressure, which is the average pressure applied to the lungs during the respiratory cycle. Inflation of the lung exposes more of the pulmonary surface area to alveolar gas. Thus, those factors that increase mean airway pressure will, up to a certain point, improve oxygenation. Martin, Fanaroff & Walsh, 2015, pg. 1090.

In which of the following respiratory disorders does the chest acquire an overinflated appearance? A. Meconium aspiration syndrome (MAS) B. Respiratory Distress Syndrome (RDS) C. Transient Tachypnea of the Newborn (TTN)

A. Meconium aspiration syndrome (MAS) The correct answer is - Meconium aspiration syndrome (MAS). Characteristically, the chest acquires an overinflated appearance, and rales can be audible on auscultation. The chest radiograph shows coarse, irregular pulmonary densities with areas of diminished aeration or consolidation. Hyperinflation of the chest and flattening of the diaphragm secondary to air trapping are sometimes noted on chest radiograph. Cardiomegaly might be observed as a manifestation of the underlying perinatal hypoxia. Martin, Fanaroff & Walsh, 2015, pp. 1123-1124.

Monitoring an infant on inhaled nitric oxide (iNo) therapy includes measurement of: A. Methemoglobin levels B. Liver function values C. Ventilation-perfusion disturbances (V/Q)

A. Methemoglobin levels The correct answer is - Methemoglobin levels. When nitric oxide (NO) combines with hemoglobin it forms methemoglobin which has the potential of becoming toxic. Although this is not a frequent complication, blood methemoglobin concentrations should be monitored because of the potential problem. iNO can decrease pulmonary vascular resistance and improve pulmonary blood flow without compromising systemic blood pressure or worsening V/Q mismatch. Gomella, Cunningham & Eyal, 2013, pg. 819; Martin, Fanaroff & Walsh, 2015, pp. 1181.

During conventional mechanical ventilation, carbon dioxide elimination is most often improved by increasing: A. Minute ventilation B. Positive end expiratory pressure C. Tidal volume

A. Minute ventilation The correct answer is - Minute ventilation. During conventional ventilation carbon dioxide removal is the product of tidal volume (TV) and frequency (rate). Tidal volume is determined by the amplitude of the mechanical breath, or the difference between the peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP). Clinically, the product of tidal volume and frequency is expressed as minute ventilation or minute volume (the volume of gas moved per minute). Martin, Fanaroff & Walsh, 2015, pg. 1091.

The best way to maintain lung expansion using a conventional ventilator is to increase the: A. Peak inspiratory pressure (PIP) B. Positive end-expiratory pressure (PEEP) C. Inspiratory time

A. Peak inspiratory pressure (PIP) The correct answer is - Peak inspiratory pressure (PIP). Conventional ventilation with distending pressure is used to recruit atelectatic alveoli. Alternative therapies of high frequency ventilation and with nasal continuing positive airway pressure have also used. Martin, Fanaroff & Walsh, 2015, pg. 1078; Gomella, Cunningham & Eyal, 2013, pg. 83.

The oxygen dissociation curve (OCD) describes the: A. Percent of hemoglobin saturated with oxygen at a given PaO2 B. Concentration of red blood cell diphosphoglycerate (DPG) in the blood C. Ratio of adult hemoglobin (A) to fetal hemoglobin (F)

A. Percent of hemoglobin saturated with oxygen at a given PaO2 The correct answer is - Percent of hemoglobin saturated with oxygen at a given PaO2. The relationship between the Pao2 and the hemoglobin saturation is sigmoidal over the physiologic range. Hemoglobin is almost fully saturated at a Pao2 of 80 to 100 mm Hg. This sigmoidal oxyhemoglobin dissociation curve (ODC) describes the percent of hemoglobin saturated with oxygen at a given Pao2. Modifications of hemoglobin function that increase oxygen affinity shift the curve to the left, whereas those that decrease oxygen affinity shift the curve to the right. Goldsmith, Karotkin, Keszler & Suresh (2017), pp. 80-82.

The most common cause of mortality from congenital lung malformations is: A. Persistent pulmonary hypertension B. Pulmonary air leak C. Meconium aspiration syndrome

A. Persistent pulmonary hypertension The correct answer is - Persistent pulmonary hypertension. Several lung malformations, can lead to pulmonary hypoplasia, thereby putting the neonate at risk for concomitant persistent pulmonary hypertension of the newborn (PPHN). Among these malformations are congenital diaphragmatic hernia and congenital cystic adenomatoid malformation. Martin, Fanaroff & Walsh, 2015, pp. 1201-1204.

Studies indicate that sildenafil (Viagra) may be useful in the management of persistent pulmonary hypertension of the newborn. What is the mechanism of action? A. Phosphodiesterase (PDE5) inhibitor B. Nitric oxide antagonist C. Selective pulmonary vasodilator

A. Phosphodiesterase (PDE5) inhibitor The correct answer is - Phosphodiesterase (PDE5) inhibitor. PDE5 activity is elevated in PPHN, leading to interest in a role for PDE5 inhibitors as primary or adjunctive therapeutic agents. The use of enteral sildenafil was reported in a small, randomized, controlled trial that showed a dramatic improvement in oxygenation and survival. A subsequent open-label pilot trial of intravenous sildenafil demonstrated improved oxygenation in infants with PPHN, with low mortality and utilization of ECMO. Sildenafil causes vasodilation in the pulmonary vasculature and, to a lesser extent, in systemic circulation. Systemic hypotension was the most commonly reported adverse effect, although it can be avoided by delivering the loading dose over a longer 3-hour period. Martin, Fanaroff & Walsh, 2015, pg. 1206; Gomella, Cunningham & Eyal, 2009, pg. 996.

Which of the following equations describes work of breathing? A. Pressure (force) X Volume (displacement) B. Change in pressure/Change in flow C. Tidal volume X Frequency

A. Pressure (force) X Volume (displacement) The correct answer is - Pressure (force) X Volume (displacement). Work of breathing is the force generated to overcome the frictional resistance and static elastic forces that oppose lung expansion and gas flow into and out of the lungs. The workload depends on the elastic properties of the lung and chest wall, airway resistance, tidal volume, and respiratory rate. Approximately two-thirds of the work of spontaneous breathing is the effort to overcome the static elastic forces of the lungs and thorax (tissue elasticity and compliance). Approximately one-third of the total work is applied to overcoming the frictional resistance produced by the movement of gas and tissue components (airflow and viscous). Goldsmith, Karotkin, Keszler & Suresh (2017), pp.16-17.

A common side effect of nitric oxide (NO) is: A. Production of nitrogen dioxide (NO2) B. Improved oxygenation C. Formation of free-oxygen radicals

A. Production of nitrogen dioxide (NO2) The correct answer is - Production of nitrogen dioxide (NO2). Nitric oxide reacts with oxygen to form other oxides of nitrogen and in particular nitrogen dioxide. This may produce toxic effects and must therefore be removed from the respiratory circuit. Gomella, Cunningham & Eyal, 2013, pg. 819; Martin, Fanaroff & Walsh, 2015, pp. 1181.

Persistent pulmonary hypertension of the newborn (PPHN) presents with: A. Pulmonary artery pressure higher than systemic pressure B. Pulmonary artery pressure lower than systemic pressure C. No differences in pulmonary and systemic pressure

A. Pulmonary artery pressure higher than systemic pressure The correct answer is - Pulmonary artery pressure higher than systemic pressure. Successful transition from intrauterine to extrauterine life requires that the pulmonary vascular resistance decrease precipitously at birth. In infants with PPHN, this decrease does not occur. Pulmonary arterial pressure remains elevated, and blood continues to shunt right to left across the ductus arteriosus and the foramen ovale, resulting in significant hypoxemia. High pulmonary vascular resistance causes pulmonary and right ventricular hypertension. Goldsmith, Karotkin, Keszler & Suresh (2017) pp. 125.

Venovenous (VV) extracorporeal membrane oxygenation (ECMO) supports: A. Pulmonary function B. Cardiac and pulmonary function C. Cardiac function

A. Pulmonary function The correct answer is - pulmonary function. Venovenous (VV) ECMO is a modality used to provide adequate oxygen delivery for infants in respiratory failure but with adequate cardiac function. VV ECMO precludes the need for arterial access and the process in infants has been improved by the development of a double lumen catheter that allows bypass support with cannulation of the right atrium alone. Advantages of VV bypass include avoidance of carotid artery cannulation and maintenance of pulmonary blood flow. The major disadvantage is that, unlike VA bypass, VV ECMO does not provide cardiac support. Infants undergoing VV ECMO can also be more difficult to manage and may have to be converted to VA ECMO if cardiac failure ensues. Thus this modality is often best used in those infants who come early to ECMO, are in the more stable category, and require help primarily with gas exchange. . Goldsmith, Karotkin, Keszler & Suresh (2017) pp. 440-441.

There is an increase in the risk of which of the following with surfactant therapy? A. Pulmonary hemorrhage B. Adverse immunologic responses C. Intraventricular hemorrhage

A. Pulmonary hemorrhage The correct answer is - Pulmonary hemorrhage. There is a well-described increase in the risk of pulmonary hemorrhage with surfactant therapy. Although trials in which animal-derived surfactants were used reported a higher incidence of pulmonary hemorrhage than trials of synthetic surfactant, direct comparison of the two types of surfactants demonstrates no difference in the risk of pulmonary hemorrhage. The overall incidence of pulmonary hemorrhage was low, and the absolute magnitude of the increased risk is small. However, moderate and severe pulmonary hemorrhage is associated with an increased risk of death and short-term morbidity. It is not associated with increased long-term morbidity. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 346.

Which of the following choices represents the most correct interpretation of the following blood gas: pH - 7.13 PaCO2 - 78 PaO2 - 156 Bicarb (HCO3) 20. A. Respiratory acidosis B. Respiratory alkalosis C. Metabolic acidosis

A. Respiratory acidosis

Central apnea can best be defined as total cessation of: A. Respiratory effort B. Respiratory volume C. Respiratory airflow

A. Respiratory effort The correct answer is - Respiratory effort. Central apnea is the complete absence of respiratory effort with no evidence of obstruction. Martin, Fanaroff & Walsh, 2015, pg. 1140.

Acidosis results in a shift of the oxygen dissociation curve (ODC) to the: A. Right B. Left C. No shift

A. Right The correct answer is - Right. The position of the ODC is described by the P50, which represents the Pao2 at an oxygen saturation of 50%. The position of the ODC, and hence the P50, is dependent on several factors. An increase in body temperature, pH, Paco2, 2, 3-DPG, or adult hemoglobin concentration will each independently shift the ODC to the right, whereas a decrease in any of these factors will shift the curve to the left. Goldsmith, Karotkin, Keszler & Suresh (2017), pp. 80-82.

Increasing postnatal age will progressively shift the oxygen dissociation curve (ODC) to the: A. Right B. No shift C. Left

A. Right The correct answer is - Right. The concentration of red blood cell diphosphoglycerate (DPG) and the ratio of adult hemoglobin (A) to fetal hemoglobin (F) shifts the position of the oxygen dissociation curve (ODC). With increasing postnatal age, the concentration of DPG and the proportion of hemoglobin A increase, thus progressively shifting the curve to the right. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 80-82.

The shunt pathway that exists in infants who have been diagnosed with persistent pulmonary hypertension of the newborn (PPHN) is: A. Right-to-left B. Left-to-right C. Bidirectional

A. Right-to-left The correct answer is - Right-to-left. Suprasystemic pulmonary arterial pressure results in right ventricular hypertrophy and deviation of the intraventricular septum to the left. This reduces the left ventricular volume and decreases systemic output. Extrapulmonary right-to-left shunting occurs at the level of the foramen ovale from the right atrium to the left atrium and at the level of the ductus arteriosus from the pulmonary artery to the aorta. Martin, Fanaroff & Walsh, 2015, p. 1199-1203. .

Which of the following drugs, when given to a pregnant woman 24 to 48 hours prior to delivery of her baby, will decrease the incidence and severity of respiratory distress syndrome (RDS)? A. Steroids B. Tocolytics C. Antibiotics

A. Steroids The correct answer is - Steroids. Steroids, when given to the mother at least 24 to 48 hours prior to delivery, decrease both the incidence and severity of respiratory distress syndrome (RDS). Accelerated lung maturation occurs with physiologic stress levels of corticosteroids, via receptor-mediated induction of specific developmentally regulated proteins. Martin, Fanaroff & Walsh, 2015 p. 1077.

Match the condition, "Resistance X Compliance," with the variable: A. Time constant B. Dynamic compliance C. Work of breathing

A. Time constant The correct answer is - Time constant. The time constant of an infant's respiratory system is a measure of how quickly the lungs can inflate or deflate, that is, how long it takes for alveolar and proximal airway pressures to equilibrate. Passive exhalation depends on the elastic recoil of the lungs and chest wall. Because the major force opposing exhalation is airway resistance, the expiratory time constant of the respiratory system is directly related to both lung compliance, which is the inverse of elastic recoil, and airway resistance. Goldsmith, Karotkin, Keszler & Suresh (2017), pg. 17.

Functional residual capacity (FRC) is the: A. Volume of gas in the lungs that is in direct communication with the airways at the end of expiration B. Total volume of gas in the thorax at the end of expiration C. Total volume of gas in the lungs and airways

A. Volume of gas in the lungs that is in direct communication with the airways at the end of expiration The correct answer is - Volume of gas in the lungs that is in direct communication with the airways at the end of expiration. The volume of gas in the FRC serves as an oxygen storage compartment in the body and a buffer so that large changes in alveolar gas tension are reduced. Martin, Fanaroff & Walsh, 2015, pg. 1065-1066.

You are caring for a 7 hour old, 37 week gestation infant on conventional mechanical ventilation. Her preductal oxygen saturation is reading 92% and the post-ductal saturation is 80%. Her arterial blood gas reads: pH 7.0 - pCO2 55 - pO2 - 38 - Bicarb (HCO3) 13. Which of the following is the most correct interpretation of the infant's blood gas? A. uncompensated mixed acidosis B. uncompensated metabolic acidosis C. uncompensated respiratory acidosis

A. uncompensated mixed acidosis The correct answer is - uncompensated mixed acidosis. This is an uncompensated mixed acidosis (low pH, high pCO2, and low HCO3), pO2 is also decreased. This is most likely due to a right-to-left shunt as interpreted by 12% difference in pre and post ductal oxygen saturations. Martin, Fanaroff & Walsh, 2015, pp. 677-681.

In respiratory distress syndrome, the expiratory grunt is the infant's attempt to: A.Maintain a normal functional residual capacity B. Decrease upper airway resistance C. Conserve energy

A.Maintain a normal functional residual capacity The correct answer is - maintain a normal functional residual capacity. Grunting is thought to result from partial closure of the glottis during expiration which acts to trap alveolar air and maintain functional residual capacity (FRC). Martin, Fanaroff, & Walsh, 2015, pg. 1077.