BRS: Pulmonary
7. Which volume remains in the lungs after a tidal volume (VT) is expired? (A) Tidal volume (VT) (B) Vital capacity (VC) (C) Expiratory reserve volume (ERV) (D) Residual volume (RV) (E) Functional residual capacity (FRC) (F) Inspiratory capacity (G) Total lung capacity
The answer is E During normal breathing, the volume inspired and then expired is a tidal volume (VT). The volume remaining in the lungs after expiration of a VT is the functional residual capacity (FRC).
6. Which of the following is true during inspiration? (A) Intrapleural pressure is positive (B) The volume in the lungs is less than the functional residual capacity (FRC) (C) Alveolar pressure equals atmospheric pressure (D) Alveolar pressure is higher than atmospheric pressure (E) Intrapleural pressure is more negative than it is during expiration
The answer is E During inspiration, intrapleural pressure becomes more negative than it is at rest or during expiration (when it returns to its less negative resting value). During inspiration, air flows into the lungs when alveolar pressure becomes lower (due to contraction of the diaphragm) than atmospheric pressure; if alveolar pressure were not lower than atmospheric pressure, air would not flow inward. The volume in the lungs during inspiration is the functional residual capacity (FRC) plus one tidal volume (VT).
19. Hypoxemia produces hyperventilation by a direct effect on the (A) phrenic nerve (B) J receptors (C) lung stretch receptors (D) medullary chemoreceptors (E) carotid and aortic body chemoreceptors
The answer is E Hypoxemia stimulates breathing by a direct effect on the peripheral chemoreceptors in the carotid and aortic bodies. Central (medullary) chemoreceptors are stimulated by CO2 (or H+). The J receptors and lung stretch receptors are not chemoreceptors. The phrenic nerve innervates the diaphragm, and its activity is determined by the output of the brain stem breathing center.
1) Which of the following lung volumes or capacities can be measured by spirometry? (A) Functional residual capacity (FRC) (B) Physiologic dead space (C) Residual volume (RV) (D) Total lung capacity (TLC) (E) Vital capacity (VC)
The answer is E Residual volume (RV) cannot be measured by spirometry. Therefore, any lung volume or capacity that includes the RV cannot be measured by spirometry. Measurements that include RV are functional residual capacity (FRC) and total lung capacity (TLC). Vital capacity (VC) does not include RV and is, therefore, measurable by spirometry. Physiologic dead space is not measurable by spirometry and requires sampling of arterial PCO2 and expired CO2.
12. A 60-year-old man presents with dyspnea on exertion and a nonproductive cough. He has never smoked, but he worked as a shipbuilder, with known asbestos exposure approximately 20 years ago. To which of the following conditions is this patient especially predisposed? (A) Acute respiratory distress syndrome (B) Goodpasture syndrome (C) Idiopathic pulmonary fibrosis (D) Idiopathic pulmonary hemosiderosis (E) Malignant mesothelioma of the pleura
The answer is E. Asbestosis is caused by inhalation of asbestos fibers, characterized by yellow-brown, rod-shaped ferruginous bodies with clubbed ends that stain positively with Prussian blue. Asbestosis results in a marked predisposition to malignant mesothelioma of the pleura or peritoneum. Exposure to asbestos is also a risk factor for primary lung carcinoma, as well as for carcinoma of the oropharynx, esophagus, and colon. The risk of primary lung carcinoma is greatly increased in cigarette smokers with exposure to asbestos.
11. A 25-year-old African-American woman presents with fatigue, dyspnea, nonproductive cough, and chest pain. She does not smoke. A chest radiograph reveals prominent bilateral hilar lymphadenopathy ("potato nodules") and diffuse reticular densities in the interstitium of the lung. Laboratory studies reveal polyclonal hyper- gammaglobulinemia, hypercalcemia, and increased serum angiotensin-converting enzyme. Which of the following is the most likely diagnosis? (A) Acute respiratory distress syndrome (B) Adenocarcinoma of the lung (C) Eosinophilic granuloma (D) Idiopathic pulmonary fibrosis (E) Sarcoidosis
The answer is E. Sarcoidosis most often presents as a restrictive pulmonary disease that is characterized morphologically by noncaseating granulomas and can involve any organ system. Diagnostic features of note include highest incidence in persons of African lineage, somewhat higher incidence in women, bilateral interstitial pulmonary involvement, prominent hilar lymphadenopathy, polyclonal hypergammaglobulinemia, and hypercalcemia. *Increased serum angiotensin-converting enzyme activity is a nonspecific indicator of granulomatous inflammation.*
1. A 3-year-old girl presents to the emergency department with fever, hoarseness, a "seal bark-like" cough, and inspiratory stridor. Her father states that she has had a cold for the past few days, with runny nose, nasal congestion, sore throat, and cough. He is now concerned because her cough has become loud, harsh, and brassy. Which of the following is the most likely cause of her ailment? (A) Fungus (B) Gram-negative bacteria (C) Gram-positive bacteria (D) Parasite (E) Virus
The answer is E. This is a classic case of acute laryngotracheobronchitis (croup), an acute inflammation of the larynx, trachea, and epiglottis. The most common cause of croup is a viral (parainfluenza virus type I) infection.
17. A 45-year-old woman with no smoking history presents with new onset of cough, shortness of breath, and weight loss. Imaging reveals a peripherally located lung mass with no evidence of primary tumor elsewhere in the body. On light microscopy, the tumor is comprised of poorly formed glands. Which of the following is most likely to be true of this tumor? (A) Positive for synaptophysin immunostaining (B) Associated squamous dysplasia at the periphery of the tumor (C) Most likely already metastatic, therefore surgery is not recommended (D) Driven by tobacco-associated carcino- gens (E) Positive for mutation in EGFR
The answer is E. This woman has an adenocarcinoma. These are the most likely lung cancers to arise in never-smokers and are more common in women. They have been associated with EGFR mutations, and EGFR mutation testing is rapidly becoming the standard-of-care for lung adenocarcinomas in order to direct chemotherapy (EGFR- mutated cases may respond to targeted tyrosine kinase inhibitors). Adenocarcinomas may be preceded by or associated with atypical adenomatous hyperplasia, not squamous dysplasia. Unlike small cell carcinomas, they do not show neuroendocrine features such as synaptophysin staining and metastasis at the time of presentation is not the rule.
22. In the transport of CO2 from the tissues to the lungs, which of the following occurs in venous blood? (A) Conversion of CO2 and H2O to H+ and HCO3− in the red blood cells (RBCs) (B) Buffering of H+ by oxyhemoglobin (C) Shifting of HCO3− into the RBCs from plasma in exchange for Cl− (D) Binding of HCO3− to hemoglobin (E) Alkalinization of the RBCs
The answer is A CO2 generated in the tissues is hydrated to form H+ and HCO3− in red blood cells (RBCs). H+ is buffered inside the RBCs by deoxyhemoglobin, which acidifies the RBCs. HCO3− leaves the RBCs in exchange for Cl− and is carried to the lungs in the plasma. A small amount of CO2 (not HCO3−) binds directly to hemoglobin (carbaminohemoglobin).
20. Which of the following changes occurs during strenuous exercise? (A) Ventilation rate and O2 consumption increase to the same extent (B) Systemic arterial PO2 decreases to about 70 mm Hg (C) Systemic arterial PCO2 increases to about 60 mm Hg (D) Systemic venous PCO2 decreases to about 20 mm Hg (E) Pulmonary blood flow decreases at the expense of systemic blood flow
The answer is A During exercise, the ventilation rate increases to match the increased O2 consumption and CO2 production. This matching is accomplished without a change in mean arterial PO2 or PCO2. Venous PCO2 increases because extra CO2 is being produced by the exercising muscle. Because this CO2 will be blown off by the hyperventilating lungs, it does not increase the arterial PCO2. Pulmonary blood flow (cardiac output) increases manifold during strenuous exercise.
29. Which person would be expected to have the largest A-a gradient? (A) Person with pulmonary fibrosis (B) Person who is hypoventilating due to morphine overdose (C) Person at 12,000 feet above sea level (D) Person with normal lungs breathing 50% O2 (E) Person with normal lungs breathing
The answer is A. *Increased A-a gradient signifies lack of O2 equilibration between alveolar gas (A) and systemic arterial blood* (a). In pulmonary fibrosis, there is thickening of the alveolar/pulmonary capillary barrier and increased diffusion distance for O2, which results in lack of equilibration of O2, hypoxemia, and increased A-a gradient. Hypoventilation and ascent to 12,000 feet also cause hypoxemia, because systemic arterial blood is equilibrated with a lower alveolar PO2 (normal A-a gradient). Persons breathing 50% or 100% O2 will have elevated alveolar PO2, and their arterial PO2 will equilibrate with this higher value (normal A-a gradient).
6. An 80-year-old woman, a retirement home resident, has multiple bouts of pneumonia caused by Streptococcus pneumoniae. In an attempt to prevent such infections, polyvalent vaccines directed at multiple serotypes of the organism have been administered but have not elicited long-acting immunity. Which of the following is the probable explanation for this phenomenon? (A) Memory T lymphocytes respond poorly to polysaccharide antigens. (B) S. pneumoniae evades host immune response by forming capsular coatings composed of host proteins and recognized as "self" antigens. (C) The bacterial capsule binds C3b, facilitating activation of the alternative complement pathway, inducing complement-mediated lysis, and preventing immunization. (D) The capsular polysaccharides of S. pneumoniae have limited hapten potential. (E) The surface carbohydrate capsule on the surface of the organism acts as an opsonin, facilitating phagocytosis by neutrophils, thus preventing immunization.
The answer is A. Antibody responses to the more than 80 differing carbohydrate capsular antigens of the various strains of S. pneumoniae are generally T-cell-independent, and antibody formation is entirely B-cell-mediated. Because of this, memory cells are not formed, and long-lasting immunity is not achieved.
7. A 50-year-old man dies of a respiratory illness that had been characterized by dyspnea, cough, and wheezing expiration of many years' duration. Initially episodic, his "attacks" had increased in frequency and at the time of death had become continuous and intractable. At autopsy, which of the following is the most likely histologic finding in the lungs? (A) Bronchial smooth muscle hypertrophy with proliferation of eosinophils (B) Diffuse alveolar damage with leakage of protein-rich fluid into alveolar spaces (C) Dilation of air spaces with destruction of alveolar walls (D) Hyperplasia of bronchial mucus- secreting submucosal glands (E) Permanent bronchial dilation caused by chronic infection, with bronchi filled with mucus and neutrophils
The answer is A. Bronchial asthma, or hyperreactive airway disease, is a type of COPD caused by narrowing of airways. Asthma manifests morphologically by bronchial smooth muscle hypertrophy, hyperplasia of bronchial submucosal glands and goblet cells, and airways plugged by mucus-containing Curschmann spirals (whorl-like accumulations of epithelial cells), eosinophils, and Charcot-Leyden crystals (crystalloids of eosinophil-derived proteins)
21. If an area of the lung is not ventilated because of bronchial obstruction, the pulmonary capillary blood serving that area will have a PO2 that is (A) equal to atmospheric PO2 (B) equal to mixed venous PO2 (C) equal to normal systemic arterial PO2 (D) higher than inspired PO2 (E) lower than mixed venous PO2
The answer is B If an area of lung is not ventilated, there can be no gas exchange in that region. The pulmonary capillary blood serving that region will not equilibrate with alveolar PO2 but will have a PO2 equal to that of mixed venous blood.
16. Compared with the systemic circulation, the pulmonary circulation has a (A) higher blood flow (B) lower resistance (C) higher arterial pressure (D) higher capillary pressure (E) higher cardiac output
The answer is B Blood flow (or cardiac output) in the systemic and pulmonary circulations is nearly equal; pulmonary flow is slightly less than systemic flow because about 2% of the systemic cardiac output bypasses the lungs. *The pulmonary circulation is characterized by both lower pressure and lower resistance than the systemic circulation*, so flows through the two circulations are approximately equal (flow = pressure/resistance).
23. Which of the following causes of hypoxia is characterized by a decreased arterial PO2 and an increased A-a gradient? (A) Hypoventilation (B) Right-to-left cardiac shunt (C) Anemia (D) Carbon monoxide poisoning (E) Ascent to high altitude
The answer is B Hypoxia is defined as decreased O2 delivery to the tissues. It occurs as a result of decreased blood flow or decreased O2 content of the blood. Decreased O2 content of the blood is caused by decreased hemoglobin concentration (anemia), decreased O2-binding capacity of hemoglobin (carbon monoxide poisoning), or decreased arterial PO2 (hypoxemia). Hypoventilation, right-to-left cardiac shunt, and ascent to high altitude all cause hypoxia by decreasing arterial PO2. Of these, only right-to-left cardiac shunt is associated with an *increased A-a gradient, reflecting a lack of O2 equilibration between alveolar gas and systemic arterial blood*. In right-to-left shunt, a portion of the right heart output, or pulmonary blood flow, is not oxygenated in the lungs and thereby "dilutes" the PO2 of the normally oxygenated blood. With hypoventilation and ascent to high altitude, both alveolar and arterial PO2 are decreased, but the A-a gradient is normal.
2) An infant born prematurely in gestational week 25 has neonatal respiratory distress syndrome. Which of the following would be expected in this infant? (A) Arterial PO2 of 100 mm Hg (B) Collapse of the small alveoli (C) Increased lung compliance (D) Normal breathing rate (E) Lecithin:sphingomyelin ratio of greater than 2:1 in amniotic fluid
The answer is B Neonatal respiratory distress syndrome is caused by lack of adequate surfactant in the immature lung. Surfactant appears between the 24th and the 35th gestational week. In the absence of surfactant, the surface tension of the small alveoli is too high. When the pressure on the small alveoli is too high (P = 2T/r), the small alveoli collapse into larger alveoli. There is decreased gas exchange with the larger, collapsed alveoli, and ventilation/perfusion (V/Q) mismatch, hypoxemia, and cyanosis occur. *The lack of surfactant also decreases lung compliance, making it harder to inflate the lungs, increasing the work of breathing, and producing dyspnea (shortness of breath). Generally, lecithin:sphingomyelin ratios greater than 2:1 signify mature levels of surfactant.
27. In a maximal expiration, the total volume expired is (A) tidal volume (VT) (B) vital capacity (VC) (C) expiratory reserve volume (ERV) (D) residual volume (RV) (E) functional residual capacity (FRC) (F) inspiratory capacity (G) total lung capacity
The answer is B The volume expired in a forced maximal expiration is forced vital capacity, or vital capacity (VC).
18. Compared with the apex of the lung, the base of the lung has (A) a higher pulmonary capillary PO2 (B) a higher pulmonary capillary PCO2 (C) a higher ventilation/perfusion (V/Q) ratio (D) the same V/Q ratio
The answer is B [VII C; Figure 4.10; Table 4.5]. Ventilation and perfusion of the lung are not distributed uniformly. Both are lowest at the apex and highest at the base. However, the differences for ventilation are not as great as for perfusion, making the ventilation/ perfusion (V/Q) ratios higher at the apex and lower at the base. As a result, gas exchange is more efficient at the apex and less efficient at the base. Therefore, blood leaving the apex will have a higher PO2 and a lower PCO2.
3). In which vascular bed does hypoxia cause vasoconstriction? (A) Coronary (B) Pulmonary (C) Cerebral (D) Muscle (E) Skin
The answer is B. Pulmonary blood flow is controlled locally by the PO2 of alveolar air. Hypoxia causes pulmonary vasoconstriction and thereby shunts blood away from unventilated areas of the lung, where it would be wasted. In the coronary circulation, hypoxemia causes vasodilation. The cerebral, muscle, and skin circulations are not controlled directly by PO2.
9. A 49-year-old man with a 15-year history of 2-pack a day smoking come to your office complaining of difficulty in breathing. You immediately notice a wheezing when he breathes. Following pulmonary function tests and lung diffusion studies, you and a pulmonologist colleague diagnose his condition as chronic obstructive pulmonary disease (COPD) and prescribe inhaled tiopropium twice a day. He returns 6 months later, pleased that he has quit smoking, but complaining he is having about 1 episode of serious shortness of breath per day. Which of the following might you add to his treatment? (A) Oral dexamethasone (B) Roflumilast (C) Inhaled beclomethasone (D) Zileuton
The answer is B. *Roflumilast is a fairly specific PDE4 inhibitor*, useful to decrease exacerbations in patients with chronic obstructive pulmonary disease (COPD). Oral glucocorticoids such as dexamethasone pose serious risks when used chronically and inhaled glucocorticoids are not recommended in early-stage COPD although they might be of benefit in patients with severe disease. Zileuton is ineffective in COPD.
8. Zileuton is useful in the treatment of asthma because it (A) Inhibits prostaglandin biosynthesis (B) Inhibits leukotriene synthesis (C) Inhibits leukotriene receptors (D) Inhibits 12-lipoxygenase
The answer is B. By inhibiting 5-lipoxygenase, zileuton reduces leukotriene biosynthesis; it does not inhibit (and in fact it might increase) prostaglandin synthesis.
7. Which of the following statements about the mechanism of action of ipratropium is correct? (A) It acts centrally to decrease vagal acetylcholine (ACh) release (B) It inhibits pulmonary ACh receptors (C) It decreases mast cell release of histamine (D) It blocks the action of histamine at H1 receptors
The answer is B. Ipratropium is an acetylcholine (ACh) muscarinic receptor antagonist; it is poorly absorbed, so most of its effect is in the lung. It does not cross the blood-brain barrier and does not block mediator release or H1-receptors.
4. Which of the following statements regarding the pharmacokinetics of theophylline is correct? (A) It is primarily metabolized by the kidney (B) Its metabolism depends on age (C) It is poorly absorbed after oral administration (D) It has a wide therapeutic index
The answer is B. The metabolism of theophylline depends on age; the half-life of the drug in children is much shorter than in adults. The methylxanthines are all well absorbed and are metabolized in the liver.
5. Which of the following statements correctly describes the action of theophylline? (A) It stimulates cyclic adenosine mono- phosphate (AMP) phosphodiesterase (B) It is an adenosine-receptor antagonist (C) It does not cross the blood-brain barrier (D) It blocks the release of acetylcholine (ACh) in the bronchial tree
The answer is B. Theophylline may have several mechanisms of action, but its adenosine-receptor antagonist activity and the inhibition of phosphodiesterase are the best understood.
2. A woman who has asthma and is recovering from a myocardial infarction is on several medications including a baby aspirin a day. She complains of large bruises on her arms and legs and some fatigue. A standard blood panel reveals markedly elevated alanine aminotransferase (ALT). Which of the following is most likely responsible for the increase in liver enzymes? (A) Heparin (B) Zileuton (C) Zafirlukast (D) Albuterol (E) Aspirin
The answer is B. Zileuton is a leukotriene synthesis inhibitor that can cause increases in hepatic enzymes and altered liver function. It decreases the rate of heparin metabolism, leaving patients prone to easy bruising. Zafirlukast and albuterol are antiasthmatic agents but do not alter liver enzymes. Aspirin might cause bleeding disorders, but the low dose this patient is taking is unlikely to be responsible for the liver enzyme abnormalities.
A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial PO2 is 60 mm Hg and his PCO2 is 30 mm Hg. 5. To treat this patient, the physician should administer (A) an α1-adrenergic antagonist (B) a β1-adrenergic antagonist (C) a β2-adrenergic agonist (D) a muscarinic agonist (E) a nicotinic agonist
The answer is C A cause of airway obstruction in asthma is bronchiolar constriction. β2-adrenergic stimulation (β2-adrenergic agonists) produces relaxation of the bronchioles.
11. Which of the following is the site of highest airway resistance? (A) Trachea (B) Largest bronchi (C) Medium-sized bronchi (D) Smallest bronchi (E) Alveoli
The answer is C The medium-sized bronchi actually constitute the site of highest resistance along the bronchial tree. Although the small radii of the alveoli might predict that they would have the highest resistance, they do not because of their parallel arrangement. In fact, early changes in resistance in the small airways may be "silent" and go undetected because of their small overall contribution to resistance.
9. When a person is standing, blood flow in the lungs is (A) equal at the apex and the base (B) highest at the apex owing to the effects of gravity on arterial pressure (C) highest at the base because that is where the difference between arterial and venous pressure is greatest (D) lowest at the base because that is where alveolar pressure is greater than arterial pressure
The answer is C [VI B]. The distribution of blood flow in the lungs is affected by gravitational effects on arterial hydrostatic pressure. Thus, blood flow is highest at the base, where arterial hydrostatic pressure is greatest and the difference between arterial and venous pressure is also greatest. This pressure difference drives the blood flow.
15. The chest radiograph of a 23-year-old medical student reveals a calcified cavitary pulmonary lesion. The tuberculin test is positive, but sputum smears and cultures are negative for Mycobacterium tuberculosis. A presumptive diagnosis of secondary tuberculosis is made. If further studies, including a biopsy, were performed, which of the following findings would justify the diagnosis of secondary tuberculosis, as contrasted to primary tuberculosis? (A) Calcification (B) Caseating granulomas (C) Cavitation (D) Langhans giant cells (E) Positive tuberculin test result
The answer is C. Cavitation occurs only in secondary tuberculosis. Both primary and secondary tuberculosis are characterized by caseating granulomas, often with Langhans giant cells, which heal by scarring and calcification. The skin test result for tuberculin sensitivity is positive in both forms.
2. A 60-year-old man, a heavy smoker, presents for advice to stop smoking. On physical examination, he is thin and has a ruddy complexion. He has a productive cough and a barrel-shaped chest. He sits leaning forward with his lips pursed to facilitate his breathing. A diagnosis of emphysema is made. Which of the following is the most likely histologic finding in the lungs? (A) Bronchial smooth muscle hypertrophy with proliferation of eosinophils (B) Diffuse alveolar damage with leakage of protein-rich fluid into alveolar spaces (C) Dilation of air spaces with destruction of alveolar walls (D) Hyperplasia of bronchial mucus-secreting submucosal glands (E) Permanent bronchial dilation caused by chronic infection, with bronchi filled with mucus and neutrophils
The answer is C. Emphysema is an example of COPD. Due to the destruction of alveolar walls, a lack of elastic recoil causes air to become trapped in alveoli, and, thus, airflow obstruction occurs on expiration. In COPD, FEV1 is decreased, whereas FVC is normal or increased; therefore, patients with COPD have a decreased FEV1:FVC ratio.
8. A 25-year-old man presents with a progressive illness of several days' duration characterized by nonproductive cough, fever, and malaise. A lateral view chest radiograph reveals platelike atelectasis. Elevated titers of cold agglutinins are detected. Which of the following is the most likely type of pneumonia in this patient? (A) Bacterial pneumonia, most likely caused by S. pneumoniae (B) Hospital-acquired pneumonia, most likely caused by P. aeruginosa (C) Interstitial pneumonia, most likely caused by M. pneumoniae (D) P. jiroveci (carinii) pneumonia, most likely related to an immunocompromised state (E) Viral pneumonia, most likely caused by influenza virus
The answer is C. Interstitial (primary atypical) pneumonia is most commonly caused by M. pneumoniae or viruses. Interstitial pneumonia is characterized by diffuse, patchy inflammation localized to the interstitial areas of alveolar walls, with no exudate in alveolar spaces, and intra-alveolar hyaline membranes. *M. pneumoniae infection is associated with the presence of cold agglutinins, which are IgM antibodies that react nonspecifically with all human red blood cells.* P. jiroveci (carinii) pneumonia is the most common opportunistic infection in patients with acquired immunodeficiency syndrome or other immunodeficiency disorders. Viral pneumonias are the most common type of pneumonia in childhood, caused most commonly by the influenza virus.
13. A female infant is born prematurely at 28 weeks' gestation. Shortly after birth, she shows signs of dyspnea, cyanosis, and tachypnea. She is placed on a ventilator for assisted breathing, and a diagnosis of neonatal respiratory distress syndrome (hyaline membrane disease) is made. Which of the following is the cause of this syndrome? (A) Bronchopulmonary dysplasia (B) Intraventricular brain hemorrhage (C) Lack of fetal pulmonary maturity and deficiency of surfactant (D) Necrotizing enterocolitis (E) Patent ductus arteriosus
The answer is C. Neonatal respiratory distress syndrome (hyaline membrane disease) is the most common cause of respiratory failure in newborns and results from a deficiency of surfactant and immature development of the lungs. Surfactant reduces surface tension within the lung, facilitating expansion by inspiration and thus preventing atelectasis during expiration. The classically referenced indicator of fetal pulmonary maturity is a lecithin:sphingomyelin ratio of approximately 2:1 in the amniotic fluid, although techniques like lamellar body counts and the fluorescence polarization assay are now more commonly used to evaluate fetal lung maturity. Predisposing factors include prematurity, maternal diabetes mellitus, and birth by cesarean section. Known complications of this condition include bronchopulmonary dysplasia, patent ductus arteriosus, intraventricular brain hemorrhage, and necrotizing enterocolitis.
14. A 50-year-old woman has been immobilized in bed for several days after a motor vehicle accident. She had been improving, but this morning she suffered the sudden onset of pleuritic chest pain, hemoptysis, tachypnea, tachycardia, and dyspnea. What is the likely basis of this set of findings? (A) Arterial thrombus originating in pulmonary blood vessels (B) Arterial thrombus originating in the lower extremities with migration to pulmonary veins (C) Deep venous thrombus of the lower extremities with embolization to branches of the pulmonary artery (D) Mural thrombus originating in the left heart with migration to pulmonary blood vessels (E) Venous thrombus originating in pulmonary blood vessels
The answer is C. Pulmonary embolism most often originates from venous thrombosis in the lower extremities or pelvis. An embolus migrates through the venous circulation to the right heart and gets trapped in branches of the pulmonary artery. Pulmonary embolism occurs in clinical settings of venous stasis, such as primary venous disease, congestive heart failure, prolonged bed rest or immobilization, or prolonged sitting while traveling.
3. A 20-year-old college student participates in several intramural athletic programs but is complaining that his asthma, which you have been treating with inhaled glucocorticoids for 5 years, is getting worse. In the last month, he has used his albuterol inhaler at least 20 times following baseball practice, but he has not been waking much at night. You elect to change his treatment regimen. Which of the following would be the best change in treatment for this patient? (A) Oral triamcinolone (B) Zileuton (C) Salmeterol (D) Etanercept
The answer is C. The patient's asthma is worsening, especially in response to exercise or increased allergen exposure, and the excess of short-acting β2-agonists requires a change in medication. The best choice would be a long-acting β2-agonist like salmeterol. Oral glucocorticoids have many adverse effects, and zileuton is unlikely to be sufficiently efficacious in the worsening asthma. Etanercept is an anti-inflammatory used in rheumatoid arthritis.
A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial PO2 is 60 mm Hg and his PCO2 is 30 mm Hg. 4. Which of the following statements about this patient is most likely to be true? (A) Forced expiratory volume1/forced vital capacity (FEV1/FVC) is increased (B) Ventilation/perfusion (V/Q) ratio is increased in the affected areas of his lungs (C) His arterial PCO2 is higher than normal because of inadequate gas exchange (D) His arterial PCO2 is lower than normal because hypoxemia is causing him to hyperventilate (E) His residual volume (RV) is decreased
The answer is D The patient's arterial PCO2 is lower than the normal value of 40 mm Hg because hypoxemia has stimulated peripheral chemoreceptors to increase his breathing rate; hyperventilation causes the patient to blow off extra CO2 and results in respiratory alkalosis. In an obstructive disease, such as asthma, both forced expiratory volume (FEV1) and forced vital capacity (FVC) are decreased, with the larger decrease occurring in FEV1. Therefore, the FEV1/FVC ratio is decreased. Poor ventilation of the affected areas decreases the ventilation/perfusion (V/Q) ratio and causes hypoxemia. *The patient's residual volume (RV) is increased because he is breathing at a higher lung volume to offset the increased resistance of his airways.*
24. A 42-year-old woman with severe pulmonary fibrosis is evaluated by her physician and has the following arterial blood gases: pH = 7.48, PaO2 = 55 mm Hg, and PaCO2 = 32 mm Hg. Which statement best explains the observed value of PaCO2 ? (A) The increased pH stimulates breathing via peripheral chemoreceptors (B) The increased pH stimulates breathing via central chemoreceptors (C) The decreased PaO2 inhibits breathing via peripheral chemoreceptors (D) The decreased PaO2 stimulates breathing via peripheral chemoreceptors (E) The decreased PaO2 stimulates breathing via central chemoreceptors
The answer is D The patient's arterial blood gases show increased pH, decreased PaO2, and decreased PaCO2. The decreased PaO2 causes hyperventilation (stimulates breathing) via the peripheral chemoreceptors, but not via the central chemoreceptors. The decreased PaCO2 results from hyperventilation (increased breathing) and causes increased pH, which inhibits breathing via the peripheral and central chemoreceptors.
12. A 49-year-old man has a pulmonary embolism that completely blocks blood flow to his left lung. As a result, which of the following will occur? (A) Ventilation/perfusion (V/Q) ratio in the left lung will be zero (B) Systemic arterial PO2 will be elevated (C) V/Q ratio in the left lung will be lower than in the right lung (D) Alveolar PO2 in the left lung will be approximately equal to the PO2 in inspired air (E) Alveolar PO2 in the right lung will be approximately equal to the PO2 in venous blood
The answer is D Alveolar PO2 in the left lung will equal the PO2 in inspired air. Because there is no blood flow to the left lung, there can be no gas exchange between the alveolar air and the pulmonary capillary blood. Consequently, O2 is not added to the capillary blood. The ventilation/perfusion (V/Q) ratio in the left lung will be infinite (not zero or lower than that in the normal right lung) because Q (the denominator) is zero. Systemic arterial PO2 will, of course, be decreased because the left lung has no gas exchange. Alveolar PO2 in the right lung is unaffected.
25. A 38-year-old woman moves with her family from New York City (sea level) to Leadville Colorado (10,200 feet above sea level). Which of the following will occur as a result of residing at high altitude? (A) Hypoventilation (B) Arterial PO2 greater than 100 mm Hg (C) Decreased 2,3-diphosphoglycerate (DPG) concentration (D) Shift to the right of the hemoglobin-O2 dissociation curve (E) Pulmonary vasodilation (F) Hypertrophy of the left ventricle (G) Respiratory acidosis
The answer is D At high altitudes, the PO2 of alveolar air is decreased because barometric pressure is decreased. As a result, arterial PO2 is decreased (<100 mm Hg), and hypoxemia occurs and causes hyperventilation by an effect on peripheral chemoreceptors. Hyperventilation leads to respiratory alkalosis. 2,3-Diphosphoglycerate (DPG) levels increase adaptively; 2,3-DPG binds to hemoglobin and causes the hemoglobin- O2 dissociation curve to shift to the right to improve unloading of O2 in the tissues. The pulmonary vasculature vasoconstricts in response to alveolar hypoxia, resulting in increased pulmonary arterial pressure and hypertrophy of the right ventricle (not the left ventricle).
15. Which volume remains in the lungs after a maximal expiration? (A) Tidal volume (VT) (B) Vital capacity (VC) (C) Expiratory reserve volume (ERV) (D) Residual volume (RV) (E) Functional residual capacity (FRC) (F) Inspiratory capacity (G) Total lung capacity
The answer is D During a forced maximal expiration, the volume expired is a tidal volume (VT) plus the expiratory reserve volume (ERV). The volume remaining in the lungs is the residual volume (RV).
26. The pH of venous blood is only slightly more acidic than the pH of arterial blood because (A) CO2 is a weak base (B) there is no carbonic anhydrase in venous blood (C) the H+ generated from CO2 and H2O is buffered by HCO3- in venous blood (D) the H+ generated from CO2 and H2O is buffered by deoxyhemoglobin in venous blood (E) oxyhemoglobin is a better buffer for H+ than is deoxyhemoglobin
The answer is D In venous blood, CO2 combines with H2O and produces the weak acid H2CO3, catalyzed by carbonic anhydrase. The resulting H+ is buffered by deoxyhemoglobin, which is such an effective buffer for H+ (meaning that the pK is within 1.0 unit of the pH of blood) that the pH of venous blood is only slightly more acid than the pH of arterial blood. *Oxyhemoglobin is a less effective buffer than is deoxyhemoglobin.*
28. A person with a ventilation/perfusion (V/Q) defect has hypoxemia and is treated with supplemental O2. The supplemental O2 will be most helpful if the person's predominant V/Q defect is (A) dead space (B) shunt (C) high V/Q (D) low V/Q (E) V/Q=0 (F) V/Q=∞
The answer is D Supplemental O2 (breathing inspired air with a high PO2) is most helpful in treating hypoxemia associated with a ventilation/perfusion (V/Q) defect if the predominant defect is low V/Q. Regions of low V/Q have the highest blood flow. Thus, breathing high PO2 air will raise the PO2 of a large volume of blood and have the greatest influence on the total blood flow leaving the lungs (which becomes systemic arterial blood). Dead space (i.e., V/Q = ∞) has no blood flow, so supplemental O2 has no effect on these regions. Shunt (i.e., V/Q = 0) has no ventilation, so supplemental O2 has no effect. Regions of high V/Q have little blood flow, thus raising the PO2 of a small volume of blood will have little overall effect on systemic arterial blood.
3. A 60-year-old woman with a heavy smoking history presents with chronic productive cough that has been present for three consecutive months over the past two consecutive years. On physical examination, her skin has a bluish tinge, and she is overweight. The patient is diagnosed with chronic bronchitis. Which of the following is the most likely histologic finding in this patient's lungs? (A) Bronchial smooth muscle hypertrophy with proliferation of eosinophils (B) Diffuse alveolar damage with leakage of protein-rich fluid into alveolar spaces (C) Dilation of air spaces with destruction of alveolar walls (D) Hyperplasia of bronchial mucus-secreting submucosal glands (E) Permanent bronchial dilation caused by chronic infection, with bronchi filled with mucus and neutrophils
The answer is D. Chronic bronchitis is an example of COPD. The pathologic hallmark of chronic bronchitis is marked hyperplasia of bronchial submucosal glands and bronchial smooth muscle hypertrophy, which can be quantified by the Reid index, a ratio of glandular layer thickness to bronchial wall thickness.
4. A 65-year-old woman with a significant smoking history presents with cough and shortness of breath. Computed tomography of the chest reveals a central mass near the left mainstem bronchus. Biopsy of the mass is performed. Histologic examination reveals small round blue cells, and a diagnosis of small cell carcinoma is made. Which of the following is a frequent characteristic of this form of lung cancer? (A) Generally amenable to surgical cure at time of diagnosis (B) More common in women, and a less clear relation to smoking than other forms of lung cancer (C) Secretes a parathyroid-like hormone (D) Secretes either corticotrophin or antidiuretic hormone (E) Usually in a peripheral rather than in a central location
The answer is D. Small cell carcinoma of the lung is the most aggressive type of bronchogenic carcinoma. The location of this cancer is usually central. This is an undifferentiated tumor with small round blue cells and is least likely to be cured by surgery because it is usually already metastatic at diagnosis. Associated paraneoplastic syndromes include secretion of adrenocorticotropic hormone and antidiuretic hormone.
9. A 60-year-old man presents with fever and chills, productive cough with rusty sputum, pleuritic pain, and shortness of breath for the past several days. A complete blood count reveals neutrophilia and an increase in band neutrophils. A chest radiograph reveals consolidation involving the entire left lower lobe. Which of the following microorganisms is the most likely etiologic agent? (A) Hemophilus influenzae (B) Klebsiella pneumoniae (C) Staphylococcus aureus (D) Streptococcus pneumoniae (E) Streptococcus pyogenes
The answer is D. The most common cause of lobar pneumonia is S. pneumoniae. The organism is also known as the pneumococcus, and the disease entity is often referred to as pneumococcal pneumonia.
1. A 17-year-old patient is brought to your allergy practice complaining of chronic cough that gets quite severe at times. The condition occurs about twice a week and is beginning to interfere with his studies. Which of the following would be the most appropriate treatment for this patient? (A) Oral prednisone (B) Omalizumab (C) Diphenhydramine (D) Inhaled budesonide (E) Theophylline
The answer is D. This is a fairly classical presentation of asthma, which should be confirmed with further pulmonary testing. Mild persistent asthma can be treated in several ways (Table 9.1), but inhaled glucocorticoids are very effective. Oral prednisone has many side effects, especially in a young person. Omalizumab is for patients who are refractory to other treatments and those with allergies. Antihistamines such as diphenhydramine are poorly effective in asthma, and theophylline is only moderately effective.
16. A 50-year-old female presents with restrictive lung disease. She describes an aggressive clinical course with rapidly progressive shortness of breath over the last year. A lung biopsy reveals a patchy process characterized by temporally heterogeneous areas of fibrosis. Which of the following is most likely of her expected clinical course? (A) Symptoms should abate with smoking cessation and steroid treatment (B) Prognosis is relatively good with the majority of patients surviving at 10 years (C) Excellent prognosis following removal of environmental stimulus (D) Poor prognosis with development of honeycomb lung and death within 5 years (E) Symptoms should improve with antibiotic therapy
The answer is D. This patient has *UIP*, which carries a dismal prognosis characterized by refractoriness to steroids and development of honeycomb lung resulting in death, often within 5 years of diagnosis. The key histologic feature is temporal heterogeneity in the fibrotic changes, whereas LIP shows chronologically uniform, diffuse fibrosis. In contrast to DIP, UIP is not related to smoking. It is not attributed to any environmental stimulus or pathogen.
6. Which of the following statements regarding opiate action is correct? (A) It triggers a vagal reflex to suppress cough (B) It can cause diarrhea (C) Its expectorant action is caused by stimulation of mucus production (D) It acts centrally to suppress the medullary cough center
The answer is D. Opioids such as *codeine act centrally to decrease the sensitivity of the cough center*; they also *decrease propulsion in the bowel (causes constipation)*.
10. A 46-year-old woman presents with fever, hemoptysis, weight loss, and night sweats. She has never smoked. She recently returned from a month-long trip to Asia. A chest radiograph reveals apical lesions with cavitation in the left lung. A purified protein derivative (PPD) test is placed, and 48 hours later an 18-mm wheal develops. Sputum cul- tures reveal numerous acid-fast organisms. This patient is put on contact precautions, and a regimen for tuberculosis is started. Which of the following disorders does this patient most likely have? (A) Acquired immunodeficiency syndrome (B) Congenital immunodeficiency (C) Miliary tuberculosis, with seeding of distal organs with innumerable small millet seed-like lesions (D) Primary tuberculosis, characterized by the Ghon complex (E) Secondary tuberculosis, resulting from activation of a prior Ghon complex, with spread to a new pulmonary site
The answer is E. Tuberculosis, at one time a frequent hazard in the United States, is now relatively uncommon except in immunocompromised individuals and persons returning from parts of the world where the disease remains a common problem. Primary tuberculosis is the initial infection by M. tuberculosis, and is restricted to the primary, or Ghon, complex, a combination of a peripheral subpleural parenchymal lesion and involved hilar lymph nodes. Cavitation and selective localization to the pulmonary apices are characteristics of secondary tuberculosis. *Secondary tuberculosis may spread* through the lymphatics and blood to other organs, *resulting in military tuberculosis*.
8. A 35-year-old man has a vital capacity (VC) of 5 L, a tidal volume (VT) of 0.5 L, an inspiratory capacity of 3.5 L, and a functional residual capacity (FRC) of 2.5 L. What is his expiratory reserve volume (ERV)? (A) 4.5 L (B) 3.9 L (C) 3.6 L (D) 3.0 L (E) 2.5 L (F) 2.0 L (G) 1.5 L
The answer is G Expiratory reserve volume (ERV) equals vital capacity (VC) minus inspiratory capacity [Inspiratory capacity includes tidal volume (VT) and inspiratory reserve volume (IRV)].
17. A healthy 65-year-old man with a tidal volume (VT) of 0.45 L has a breathing frequency of 16 breaths/min. His arterial PCO2 is 41 mm Hg, and the PCO2 of his expired air is 35 mm Hg. What is his alveolar ventilation? (A) 0.066 L/min (B) 0.38 L/min (C) 5.0 L/min (D) 6.14 L/min (E) 8.25 L/min
The answers D . Alveolar ventilation is the difference between tidal volume(VT) and dead space multiplied by breathing frequency. VT and breathing frequency are given, but dead space must be calculated. Dead space is VT multiplied by the difference between arterial
