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e76 SECTION XV Pediatric Critical Care Board Review Questions Chapter 50 Asthma 1 An 8 year old with a past medical history of moderate persis tent asthma is brought to the emergency department due to[.]
e76 S E C T I O N XV Pediatric Critical Care: Board Review Questions Chapter 50: Asthma An 8-year-old with a past medical history of moderate persistent asthma is brought to the emergency department due to progressive respiratory distress and wheezing after running out of his albuterol rescue inhaler The patient is in moderate respiratory distress with diffuse inspiratory and expiratory wheezing and moderate subcostal retractions Vital signs are pulse, 148 beats per minute; respiratory rate, 34 breaths per minute; blood pressure, 115/78 mm Hg, oxygen saturation as measured by pulse oximetry (Spo2), 96% The patient is started on the standard asthma acute care protocol After 30 minutes, he is less distressed, with scattered expiratory wheeze and improved work of breathing Subsequent vital signs are heart rate, 164 beats per minute; respiratory rate, 22 breaths per minute; blood pressure, 122/82 mm Hg; Spo2, 88% Which of the following interventions best explains the decrease in Spo2? A Intramuscular ceftriaxone B Intravenous fluid bolus with 0.9% saline C Intravenous magnesium sulfate D Intravenous methylprednisolone E Nebulized albuterol Preferred response: E Rationale A significant adverse effect of b-agonist agents is hypoxia This is related to drug mediated pulmonary vasodilation overcoming local hypoxic vasoconstriction and increasing perfusion to poorly ventilated lung units creating intrapulmonary shunt Intravenous fluids, corticosteroids, magnesium sulfate, and ceftriaxone are all common therapeutic interventions used in the emergency department setting to treat acute severe asthma However none of these interventions would explain hypoxia in this particular patient Which of the following statements regarding the assessment of a child with critical asthma is most accurate? A Lactic acidosis in a child with critical asthma is typically due to tissue hypoxia (type A) and should be treated with fluid administration and vasoactive medications B Less severe pulsus paradoxus (a smaller decrease in blood pressure with inspiration) is typically a sign of a less severe asthma exacerbation C Serial measurements of blood chemistry is indicated in critical asthma to assess for beta-agonist induced hyperkalemia D The degree of wheezing heard upon auscultation correlates well with disease severity, with the sickest patients having the loudest wheezing Preferred response: B Rationale Children with more severe asthma exacerbations have more prominent pulsus paradoxus via multiple mechanisms, including that the increased effort of breathing leads to a more negative intrapleural pressure and therefore a larger increase in left heart afterload Some children with very severe asthma exacerbations have reduced air entry and quieter breath sounds, leading to reduced or even inaudible wheezing Lactic acidosis in children with critical asthma is typically due to excess sympathetic stimulation (type B) from adrenergic medications (e.g., albuterol, terbutaline) Beta-agonist medications can cause hypokalemia, not hyperkalemia Which of the following is the predominant mechanism by which terbutaline causes bronchodilation? A Activating the b-2 receptor, which increases cyclic adenosine monophosphate (cAMP) levels by augmenting its synthesis by adenylate cyclase B Blocking the acetylcholine receptor, reducing the level of cyclic guanosine monophosphate (cGMP) C Blocking the N-methyl-D-aspartate receptors in airway smooth muscle D Inhibiting phosphodiesterase, which increases cAMP levels by preventing its degradation Preferred response: A Rationale An increase in cyclic adenosine monophosphate (cAMP) levels through adenylate cyclase–mediated synthesis is the predominant mechanism by which the b-agonists cause bronchodilation Response B is the mechanism by which anticholinergic medications (e.g., ipratropium bromide) work Response C is one mechanism by which ketamine causes bronchodilation The methylxanthines (e.g., aminophylline) also cause bronchodilation by increasing cAMP However, they work by inhibiting phosphodiesterase and preventing the breakdown of cAMP (response D) Which of the following statements regarding near-fatal asthma is true? A A ventilation strategy of low respiratory rates (,12 breaths/min), moderate-to-high tidal volumes (8–12 mL/kg), and permissive hypercapnia has been proved to be associated with increased mortality and a rate of pneumothorax approaching 100% B Increasing positive end-expiratory pressure (PEEP) in mechanically ventilated asthma patients receiving neuromuscular blockade has been shown to have unfavorable effects on lung volumes, airway pressure, and hemodynamics C Ketamine is contraindicated during intubation due to its slow onset of action and tendency to cause bronchoconstriction D Nearly all subjects have a history of severe persistent asthma with frequent ICU admissions in the year preceding the episode of near-fatal asthma Preferred response: B Rationale Tuxen established in 1989 that increasing PEEP in patients with airway obstruction who are receiving neuromuscular blockade is associated with unfavorable increases in hyperinflation and intrathoracic pressures and frequent decreases in systemic blood pressure and venous oxygen saturation In our practice, we set PEEP to zero in mechanically ventilated asthmatic patients during neuromuscular blockade (barring extenuating circumstances) and use minimal PEEP (less than auto-PEEP and not more than cm H2O) during spontaneous breathing Mortality from near-fatal asthma is approximately 4% in the United States In a study by the Collaborative Pediatric Critical Care Research Network, 11 fatalities were observed out of 261 children with near-fatal asthma (4.2%) Of these 11 children, 10 had suffered a cardiac arrest prior to PICU admission In that same publication the authors reported that 13% of subjects had no prior history of CHAPTER 136 Board Review Questions asthma (response D) and that only 29% of patients had an admission for asthma in the preceding year Similarly, among 51 subjects who died from asthma in Australia, 32% of subjects had never been admitted to the hospital because of asthma prior to their death Ketamine is commonly employed when intubating a child with near-fatal asthma (response C) due to its rapid onset, bronchodilatory effects, and beneficial hemodynamic outcomes As described in the text, we suggest a ventilatory strategy that employs relatively low respiratory rates (6–12 breaths/min), tidal volumes of to 12 mL/kg, and permissive hypercapnia (response A) When a similar strategy was used in 26 subjects, all patients survived, and pneumothorax was uncommon A 10-year-old boy is admitted to the pediatric intensive care unit with status asthmaticus refractory to initial treatment in the emergency department The patient is agitated and exhibits severe intercostal and subcostal retractions with barely audible breath sounds Mechanical ventilation is initiated because of hypoxemia and impending respiratory failure Based on current best standards of care, which of the following ventilation strategies should be used after intubation? A Permissive hypercapnia with the use of low respiratory rates and long expiratory times to avoid dynamic hyperinflation B Pressure-controlled ventilation with a long inspiratory time and a short expiratory time C The application of high levels of positive end-expiratory pressure (10 to 15 cm H2O) to prevent derecruitment and atelectasis in the patient who has undergone neuromuscular blockade D The use of high tidal volumes and rapid respiratory rates to deliver supraphysiologic minute ventilation and correct the respiratory acidosis Preferred response: A Rationale Mechanical ventilation of a child with asthma should follow a strategy based on long expiratory times, slow respiratory rates, and permissive hypercapnia to avoid dynamic hyperinflation Attempts at normalizing arterial blood gases by delivering supraphysiologic minute ventilation increase the risk of air leak, hemodynamic instability, and death Chapter 51: Neonatal Pulmonary Disease The rapid physiologic response to surfactant therapy is: A Decreased lung compliance B Increased functional residual capacity (FRC) C Increased lung resistance D Increased surface tension Preferred response: B Rationale Exogenous surfactant delivery of natural or synthetic surfactant proteins and phospholipids acts to rapidly decrease alveolar surface tension (Laplace’s Law: distending pressure surface tension/alveolar radius) and increase lung compliance (volume/pressure), effectively increasing FRC A direct effect of surfactant on lung resistance is unlikely, which can be seen by Ohm’s Law (resistance pressure/flow), but with the resultant airway opening would act to either decrease or maintain lung resistance e77 What is the stage of lung maturation in a fetus at 28 weeks of gestation? A Alveolar B Embryonic C Pseudoglandular D Saccular Preferred response: D Rationale The progression of human lung development begins with the embryonic stage (,0–5 weeks’ gestation), progressing to the pseudoglandular stage (,5–16 weeks), to canalicular stage (,16–25 weeks), to the terminal sac or saccular stage (,25–36 weeks), and finally entering the early alveolar stage at near term (.36 weeks) Not unexpectedly, human newborns in the late canalicular or saccular stage of lung development may require supplemental oxygen and respiratory support for respiratory insufficiency Premature birth halts the normal intrauterine progression of lung development, believed to contribute to the development of “new” bronchopulmonary dysplasia (BPD) predominantly in infants ,28 weeks’ gestation The consequences of exogenous surfactant therapy for respiratory distress syndrome (RDS) include: A Decreased risk of pulmonary hemorrhage B Enhanced ventilation/perfusion C Increased risk of air leaks D Inhibited endogenous surfactant production Preferred response: B Rationale Exogenous surfactant rapidly improves lung compliance and functional residual capacity (FRC) allowing for enhanced ventilation/perfusion, resulting in improved oxygenation and resolution of hypercarbia Surfactant is also recycled and either catabolized or reutilized and does not decrease endogenous production by the type II alveolar cells In randomized controlled trials (RCTs), surfactant reduced the incidence of air leak syndromes when compared to mechanical ventilation alone for RDS In meta-analyses of RCTs, surfactant did not impact pulmonary hemorrhage and, in fact, a listed complication of exogenous surfactant labelling is pulmonary hemorrhage Rather than a direct effect of surfactant, it is hypothesized that a rapid drop in pulmonary vascular resistance with improved oxygenation results in increased shunting of systemic blood to the lungs across a patent ductus arteriosus, leading to over-circulation and capillary leakage or pulmonary hemorrhage A 36-week-old male infant born by spontaneous vaginal delivery is found to have biphasic stridor when he is agitated His oxygen saturations are 100%, but he shows increased work of breathing when he becomes upset He had mild hypotonia, and brain computed tomography demonstrated a mild subarachnoid hemorrhage Based on these findings, what is the most likely cause of the infant’s stridor? A Laryngomalacia B Tracheomalacia C Unilateral vocal cord paralysis D Vascular ring Preferred response: A e78 S E C T I O N XV Pediatric Critical Care: Board Review Questions Rationale Biphasic stridor is usually the result of laryngeal obstruction It tends to worsen with agitation, and it is the most common type of stridor in the neonatal period Of the various causes of laryngeal obstruction, laryngomalacia is the most common laryngeal anomaly A 3-month-old term baby presents with a history of chronic wheezing that is unresponsive to bronchodilators and difficulty feeding A chest x-ray reveals an abnormally shaped mediastinum Which of the following is most likely? A Gastroesophageal reflux B Laryngomalacia C Tracheoesophageal fistula D Vascular ring Preferred response: D Rationale Vascular compression of the trachea or main stem bronchus can result from improper regression of the embryonic branchial arch arteries during fetal development The most common anomaly is a vascular “ring” consisting of a double aortic arch, in which the vessel completely encircles the trachea and esophagus Other variants include an ectopic aortic arch (passing behind the esophagus) or an aberrant origin of the right brachiocephalic artery Vascular rings cause inspiratory stridor and expiratory wheezing, neither of which change appreciably with the infant’s position Intermittent worsening of symptoms is sometimes seen when the infant is feeding, as boluses passing down the esophagus further compress the trachea Feeding difficulty also may be present because of esophageal compression When a previously undiagnosed child first presents with these symptoms, the child may be misdiagnosed as having tracheomalacia, bronchomalacia, or tracheobronchomalacia until further imaging confirms the cardiovascular abnormality This condition also can be detected antenatally An abnormally shaped mediastinum on a chest film often provides a clue to this diagnosis Endoscopy may identify tracheal or esophageal compression An echocardiogram may define the nature of the vascular anomaly, but cardiac catheterization is sometimes necessary Decisions regarding surgical correction of this defect depend on the relative compromise of the trachea and esophagus; however, the degree of compression may actually worsen as the infant grows A 37-week gestational age infant is born to a diabetic mother The infant is vigorous at birth with a strong cry His extremities are pink, and perfusion is excellent At hours of life, tachypnea and irritability develop, progressing to apnea Oxygen saturation is 93% in room air His lungs are clear on auscultation, and no murmur is present What is the most probable cause for this child’s symptoms? A Apnea of prematurity B Congenital heart disease C Hyperviscosity syndrome D Laryngomalacia Preferred response: C Rationale This child most likely has hyperviscosity syndrome Hyperviscosity syndrome is a result of polycythemia and can occur in several situations, including twin-twin transfusion, maternal-fetal transfusion, delayed cord clamping, home delivery, maternal diabetes, small-for-gestational-age infants, postmature infants, and infants with Down syndrome or Beckwith-Wiedemann syndrome Symptoms generally relate to the degree of hyperviscosity and can range from tachypnea to apnea, listlessness to irritability, and jitteriness to seizures Hyperviscosity syndrome presents in the first few hours of an infant’s life, and the presentation can mimic that in infants with congenital pneumonia, meconium aspiration, persistent pulmonary hypertension, or congenital heart disease This child is a full-term infant, thus discarding the possibility of apnea of prematurity Because this child was born with a strong cry, it is unlikely that he has vocal cord paralysis Unilateral vocal cord paralysis usually presents with a weak or sometimes hoarse cry Bilateral vocal cord paralysis manifests with moderate to severe stridor, and some infants may have near total airway obstruction Infants with tracheomalacia may be mildly or severely affected, depending on the extent of involvement and the ability of surrounding supporting tissues to maintain airway patency Affected infants generally have symptoms in the newborn period, but presentation may be delayed for many days or weeks if the defect is mild In these milder cases, infants may remain symptom free until an intercurrent infection leads to increased airway secretions and increased work of breathing Symptoms include expiratory wheezing and respiratory distress including tachypnea and retractions, and the infant may receive a mistaken diagnosis of reactive airway disease; however, the use of bronchodilators may actually worsen the condition In the neonate, significant congenital heart disease typically presents in one of two ways: (1) cyanosis with minimal or no respiratory distress or (2) cardiorespiratory failure Cyanotic lesions, such as transposition of the great vessels or tetralogy of Fallot, usually present in an infant who is blue but comfortable Characteristically, congenital cyanotic heart disease is suspected in such an infant, even if a murmur is absent, particularly if the infant remains desaturated or hypoxemic in 100% oxygen Less common in the neonate are the conditions that lead to early heart failure, such as an atrioventricular canal defect or a large ventricular septal defect These infants generally are not cyanotic but are pale with marked respiratory distress and often a loud murmur; chest radiographs may show the classic signs of cardiomegaly and pulmonary vascular congestion Chapter 52: Pneumonitis and Interstitial Disease Pulmonary hemorrhage, proteinuria and/or hematuria as well as anti–basement membrane antibody confirms the diagnosis of? A Goodpasture syndrome B Heiner syndrome C Systemic lupus erythematosus D Wegener granulomatosis Preferred response: A Rationale Goodpasture syndrome is associated with auto-antibodies to the alveolar and glomerular basement membrane causing the symptoms of hemoptysis, proteinuria, or hematuria initially Wegener granulomatosis is a primary vasculitis while lupus is related to immune complex deposition Heiner syndrome is a food hypersensitivity pulmonary disease CHAPTER 136 Board Review Questions In which of the following disease processes is direct injury to the mucosal surface the most common mode of pulmonary injury, causing epithelial cells of air passages to become necrotic and desquamate, resulting in marked airway obstruction and bronchospasm? A Fungal infection B Inhalational injury C Interstitial lung disease D Viral pneumonitis Preferred response: B Rationale Injury of the airways in inhalational injury may be manifested as upper airway obstruction resulting in laryngotracheitis, bronchitis, and upper airway edema More peripheral airway obstruction may present with classic findings of asthma and airway edema with hypersecretion In cases of massive exposure, the presenting symptoms may be those associated with acute respiratory distress syndrome, manifested by profound ventilation/perfusion (V/Q) mismatch, cyanosis, dyspnea, and respiratory failure In inhalational injury, the injury is directly to the tissues within the airway; in infectious or interstitial lung diseases, it is infiltration by other cell types that results in significant injury Which of the following is the leading cause of lower respiratory tract infection in infants and children? A Fungus B Staphylococcus aureus C Streptococcus pneumoniae D Viral agents Preferred response: D Rationale Viral agents are the leading cause of lower respiratory tract infection in infants and children Respiratory syncytial virus (RSV) followed by parainfluenza are the most commonly isolated viral agents Streptococcus followed by Staphylococcus aureus are the leading causes of bacterial pneumonia but are far less common than viruses Fungus and atypical pathogens are less common causes of lower respiratory infection in infants and children What is the appropriate order of therapeutic objectives in the management of massive pulmonary hemorrhage? A Bronchoscopy (therapeutic or diagnostic), endotracheal intubation, fluid resuscitation B Endotracheal intubation, increase positive end-expiratory pressure (PEEP), fluid resuscitation, bronchoscopy (therapeutic or diagnostic) C Embolization of bleeding vessel, fluid resuscitation, endotracheal intubation D Fluid resuscitation, endotracheal intubation, embolization of bleeding vessel Preferred response: B Rationale Securing a safe and stable airway is always the primary goal of any resuscitation Increasing the end-expiratory pressure may provide a tamponade to the site of hemorrhage in an effort to prevent further profuse bleeding After establishing an airway, the patient needs to be resuscitated to allow for increased stability for future short-term control of the bleeding These measures could include bronchoscopy or embolization of the bleeding vessel e79 Which of the following is present in the early stage of interstitial lung disease? A Decreased expiratory flow rates B Decreased resting arterial oxygen tension C Diminished carbon monoxide diffusing capacity D Increased carbon dioxide tension Preferred response: C Rationale Changes in lung volumes in pulmonary parenchymal disease depend primarily on the intensity of the alveolitis and the stage of the disease process Acute severe pneumonitis with an intense alveolitis is characterized by moderate to severe reduction in both vital capacity and total lung capacity It also is associated with a reduction in pulmonary compliance In the early stages, patients with chronic interstitial diseases involving the lung parenchyma often have normal vital capacity and total lung capacity There is subsequent reduction in lung volumes and pulmonary compliance as the disease progresses and pulmonary fibrosis ensues Expiratory flow rates usually are preserved in pneumonitis involving the lung parenchyma, and major obstructive defects, although reported, are rare The carbon monoxide diffusing capacity, one of the earliest and most sensitive tests of parenchymal inflammation, is diminished in persons with interstitial lung disease A reduction in carbon monoxide diffusing capacity is not specific and may be found with other parenchymal disorders In early parenchymal disease, resting arterial oxygen tension may be normal, but there is often mild alveolar hyperventilation with a reduction in alveolar carbon dioxide tension and widening of the alveolar-arterial oxygen gradients (Pao2 – Pao2) With exercise, hypoxemia and an increased Pao2 – Pao2 become exaggerated because of ventilation/ perfusion imbalance Ventilation/perfusion mismatch is attributed to regional alterations of flow, altered parenchymal compliance, and increased obstruction to pulmonary airflow Progressive alveolitis and subsequent derangement of gas exchange lead to deterioration of ventilatory efficiency and markedly increased work of breathing Adequate oxygenation may become impossible even with the use of high-flow supplemental oxygen Resting hypercapnia, pulmonary hypertension, and eventual right ventricular dysfunction with heart failure are common sequelae A 15-month-old child is admitted to the pediatric intensive care unit with severe anemia (hemoglobin of g/dL) due to pulmonary hemorrhage The child’s previous medical history is significant for six episodes of otitis media in the previous 12 months The child was born full term with a birth weight of 3.2 kg Currently the child weighs kg Besides pallor, tachycardia, and tachypnea, no other abnormalities are noticed on physical examination Of the following, which is the most likely diagnosis for this child? A Behỗet syndrome B Goodpasture syndrome C Heiner syndrome D Wegener granulomatosis Preferred response: C Rationale Pulmonary hemorrhage (PH) is defined as extravasation of blood into airways or lung parenchyma Massive PH in adults is defined as blood loss of 600 mL or more in 24 hours Loss of 10% of a patient’s circulating blood volume into the lungs regardless of age causes a significant alteration in cardiorespiratory function and should be considered massive The diagnosis of PH following an e80 S E C T I O N XV Pediatric Critical Care: Board Review Questions episode of silent bleeding is established by pulmonary hemosiderosis, which is the abnormal accumulation of iron within lung parenchyma and alveolar macrophages The classic clinical triad of hemoptysis, microcytic hypochromic anemia, and diffuse alveolar-filling opacities on chest radiograph is found in most episodes of diffuse/immune PH Although the lung may be the only organ affected, more frequently multiple organs are involved In patients with PH, establishing which extrapulmonary organs are involved by the disease helps to narrow the differential diagnosis of which of the immune-mediated disorders is most likely present Diffuse parenchymal bleeding without evidence of extrapulmonary involvement occurs in idiopathic pulmonary hemosiderosis, Heiner syndrome, and drug-induced PH Idiopathic pulmonary hemosiderosis, a disease of childhood, is a diagnosis of exclusion Clinically, episodes of PH recur, with 30% to 50% of patients eventually dying of exsanguination or respiratory failure Microscopic examination of the lungs is compatible with nonspecific injury rather than a specific cause such as vasculitis or immune deposits Heiner syndrome, which affects children between the ages of months and years, usually manifests other symptoms, such as chronic rhinitis, recurrent otitis media, and growth retardation Tests for precipitating antibodies to milk proteins are positive Symptoms resolve when milk and milk products are eliminated from the diet In children with PH and either proteinuria, hematuria, or red cell casts, Goodpasture syndrome is the most likely etiology The presence of a linear immunofluorescent staining of immunoglobulin and C3 along glomerular capillary walls and antibasement membrane antibody in the serum confirms the diagnosis of Goodpasture syndrome Fifty percent of patients with Goodpasture syndrome die of asphyxia as a result of massive PH The presence of sinusitis or bilateral, multiple cavitary pulmonary nodules and evidence of glomerulonephritis in patients with PH help distinguish Wegener granulomatosis from the other vasculitides The immune-mediated causes of PH with multisystem organ involvement often have characteristic physical findings to suggest the diagnosis Serositis, arthritis, facial erythema, fever, and glomerulonephritis are present prior to the development of PH in patients with systemic lupus erythematosus (SLE) Ten percent of all cases of immune-mediated PH are associated with SLE The onset of PH in persons with SLE is abrupt Recurrent uveitis, mucocutaneous ulcerations, and genital ulcerations in a patient with PH suggests Behỗet syndrome as the etiology Other clinical features seen with Behỗet syndrome include arthritis, gastrointestinal disease, cardiovascular involvement, and central nervous system disease A necrotizing vasculitis of small- to medium-sized arteries and veins and thromboses of the terminal vascular beds or vena cava confirm the diagnosis Chapter 53: Diseases of the Pulmonary Circulation Pulmonary vasodilators that not cause systemic vasodilation and systemic hypotension are referred to as selective pulmonary vasodilators Which of the following agents is a selective pulmonary vasodilator? A Inhaled nitric oxide B Intravenous milrinone C Intravenous sildenafil D Oral sildenafil Preferred response: A Rationale Inhaled nitric oxide (iNO) is a specific pulmonary vasodilator and does not cause systemic hypotension Although it has some effects on systemic circulation, it typically does not cause systemic hypotension in patients with pulmonary hypertension It is inactivated by combining with hemoglobin to form methemoglobin with minimal effects on systemic vasculature In the management of pulmonary arterial hypertension in children, which statement is most appropriate regarding the use of phosphodiesterase inhibitors? A All patients in the START-1 trial had exercise tolerance performed by bicycle ergometry as the primary end point at 16 weeks B The FDA recommends the use of low-dose sildenafil in the chronic management of PH in children, as it improves exercise ability C In the START-1 trial, the Kaplan-Meier estimates of 3-year survival rates from the start of sildenafil were 94%, 93%, and 88%, respectively, for patients randomized to low-, medium-, and high-dose sildenafil D Tadalafil has a lower affinity for PDE-5 compared with the other PDE inhibitors Preferred response: C Rationale The START-1 (sildenafil in treatment-naïve children aged to 17 years with pulmonary arterial hypertension) pediatric trial was a landmark study, with the primary end point of exercise tolerance using bicycle ergometry testing only in those subjects able to perform (about half of study patients) The controversy arose when the mortality was assessed on the yearly basis in the low-dose (10 mg), medium-dose (10–40 mg), and high-dose (20–80 mg) groups By years, the hazard ratios for mortality were 3.95 (CI: 1.46–10.65) for high- versus low-dose and 1.92 (CI: 0.65–5.65) for mediumversus low-dose sildenafil Kaplan-Meier estimates of 3-year survival rates from the start of sildenafil were 94%, 93%, and 88%, respectively, for patients randomized to low-, medium-, and high-dose sildenafil in the START-1 trial In August 2012, the FDA issued a strong warning against the chronic use of sildenafil for pediatric patients (1–17 years of age) The warning states that (1) children taking a high dose of Revatio had a higher risk of death than children taking a low dose and (2) low doses of Revatio are not effective in improving exercise ability However, future statements clarified that the earlier FDA statement was not intended to suggest that Revatio should never be used in children and can be used in acute critical care settings and in infants with bronchopulmonary dysplasia and pulmonary hypertension One of the advantages of tadalafil is its strong affinity for PDE-5 compared to other PDE inhibitors and hence its longer duration of action ... confirms the cardiovascular abnormality This condition also can be detected antenatally An abnormally shaped mediastinum on a chest film often provides a clue to this diagnosis Endoscopy may identify... most probable cause for this child’s symptoms? A Apnea of prematurity B Congenital heart disease C Hyperviscosity syndrome D Laryngomalacia Preferred response: C Rationale This child most likely... pulmonary hypertension, or congenital heart disease This child is a full-term infant, thus discarding the possibility of apnea of prematurity Because this child was born with a strong cry, it is unlikely