a. C

b. D

c. E

d. C + D

e. E – D

161. A group of third-year medical students accompanied a medical mission team to Peru, South America. After arriving at the airport in Bolivia, they hiked to a remote mountain village in the Andes at an elevation of 18,000 ft. With a barometric pressure of 380 mm Hg at this altitude, what would be the resulting PO₂ of the dry inspired air?

a. 160 mm Hg

b. 100 mm Hg

c. 80 mm Hg

d. 70 mm Hg

e. 38 mm Hg

162. A 28-year-old man is admitted to the emergency department with multiple fractures suffered in a car accident. Arterial blood gases are ordered while the patient is breathing room air. After the first-year resident obtains an arterial blood sample from the patient, the glass plunger slides back, drawing an air bubble into the syringe before it is handed to the blood gas technician for analysis. How does exposure to room air affect the measured values of PO₂ and PCO₂ in arterial blood?

a. The measured values of both PaO₂ and PaCO₂ will be higher than the patient’s actual values.

b. The measured values of both PaO₂ and PaCO₂ will be lower than the patient’s actual values.

c. The measured PaO₂ will be higher and the measured PaCO₂ will be lower than the patient’s actual blood gas values.

d. The measured PaO₂ will be lower and the measured PaCO₂ will be higher than the patient’s actual blood gas values.

e. The measured values of PaO₂ and PaCO₂ will accurately reflect the actual values.

163. A 68-year-old woman with pulmonary fibrosis presents with a complaint of increasing dyspnea while performing activities of daily living. She is referred for pulmonary function testing to assess the progression of her disease. Which of the following laboratory values is consistent with her diagnosis?

a. Decreased diffusing capacity of the lung

b. Increased residual volume

c. Decreased forced expiratory volume exhaled in 1 second (FEV₁)/forced vital capacity (FVC)

d. Increased lung compliance

e. Increased airway resistance corrected for lung volume

164. A 34-year-old woman presents in the emergency department with tachypnea and shortness of breath of acute onset. The history reveals that she has been taking oral contraceptives for 9 years. A lung scan demonstrates a perfusion defect in the left lower lobe. Which of the following occurs if the blood flow to alveolar units is totally obstructed by a pulmonary thromboembolism?

a. The ratio of the alveolus equals zero.

b. The PO₂ of the alveolus will be equal to that in the inspired air.

c. The PO₂ of the alveolus will be equal to the mixed venous PO₂.

d. There will be an increase in shunting (venous admixture) in the lung.

e. There will be a decrease in alveolar dead space.

165. A 150-lb patient scheduled for abdominal surgery is sent for preoperative evaluation and testing. His chest x-ray is normal, and pulmonary function results on room air show the following:

Tidal volume = 600 mL

Respiratory rate = 12/min

Vital capacity = 5000 mL

PaO₂ = 90 mm Hg

PaCO₂ = 40 mm Hg

P_ECO₂ = 28 mm Hg

The volume of the patient’s physiological dead space, determined by applying the Bohr equation, equals which of the following?

a. 0.3 mL

b. 150 mL

c. 180 mL

d. 420 mL

e. 7200 mL

166. A hospitalized patient has tachypnea and significantly labored respirations requiring mechanical ventilation. Based on the pressure–volume curve of the lungs shown as curve Z in the figure below, which of the following is the most likely diagnosis for the patient?

a. Asthma

b. Emphysema

c. Dyspnea with aging

d. Newborn with lecithin to sphingomyelin (L/S) ratio greater than 2

e. Pulmonary edema

167. A 6′3″ tall, 140-lb, 20-year-old man was watching television when he felt pain in his shoulder blades, shortness of breath, and fatigue. His father noticed how pale he was and took him to the emergency department. The physical exam revealed decreased tactile fremitus, hyperresonance, and diminished breath sounds. A chest x-ray revealed a 55% pneumothorax of the right lung, which was attributed to rupture of a bleb on the surface of the lung. What changes in lung function occur as a result of a pneumothorax?

a. The chest wall on the affected side recoils inward.

b. The intrapleural pressure in the affected area equals to atmospheric pressure.

c. The trachea deviates away from the affected lung.

d. There is hyperinflation of the affected lung.

e. The ratio on the affected side increases above normal.

168. An insulation worker presents with a chief complaint of dyspnea on exertion. Pulmonary function test is consistent with a restrictive impairment. His arterial PO₂ is normal at rest but hypoxemic during exercise stress testing. Which of the following is the most likely explanation for the decline in the patient’s PaO₂ during exercise compared with rest?

a. A decreased partial pressure gradient for O₂ diffusion during exercise

b. A decreased surface area for diffusion during exercise

c. An increase in hemoglobin’s affinity for O₂ during exercise resulting in more oxygen being transported as oxyhemoglobin and less in the dissolved state

d. An increased uptake of oxygen from the blood by exercising skeletal muscles

e. An underlying diffusion impairment coupled with a decrease in pulmonary capillary transit time during exercise

169. A 125-lb, 40-year-old woman with a history of nasal polyps and aspirin sensitivity since childhood presents to the emergency department with status asthmaticus and hypercapnic respiratory failure. She requires immediate intubation and is placed on a mechanical ventilator on an FIO₂ of 40%, a control rate of 15 breaths per minute, and a tidal volume of 500 mL. Which of the following is her approximate alveolar ventilation?

a. 375 mL/min

b. 3500 mL/min

c. 5250 mL/min

d. 5625 mL/min

e. 7500 mL/min

170. A 26-year-old man training for a marathon reaches a workload that exceeds his anaerobic threshold. If he continues running at or above this workload, which of the following will increase?

a. Alveolar ventilation

b. Arterial pH

c. PaCO₂

d. Plasma

e. Firing of the central chemoreceptors

171. A medical student waiting for her first patient interview at the clinical skills center becomes very anxious and increases her rate of alveolar ventilation. If her rate of CO₂ production remains constant, which of the following will decrease?

a. pH

b. PaO₂

c. PaCO₂

d.

e. Alveolar–arterial PO₂ difference

172. A 36-year-old man with a history of AIDS and Pneumocystis infection presents to the emergency department with severe respiratory distress. The patient is placed on a ventilator at a rate of 16, tidal volume of 600 mL, and FIO₂ of 1.0. An arterial blood sample taken 20 minutes later reveals a PO₂ of 350 mm Hg, a PCO₂ of 36 mm Hg, and a pH of 7.32. At a barometric pressure of 757 mm Hg, and assuming a normal respiratory exchange ratio (R) of 0.8, the patient’s alveolar oxygen tension is approximately which of the following?

a. 105 mm Hg

b. 355 mm Hg

c. 576 mm Hg

d. 665 mm Hg

e. 712 mm Hg

173. A 58-year-old woman experiences an acute exacerbation of asthma, which causes her breathing to become labored and faster. As a result, which of the following changes in airflow is expected?

a. Flow in the trachea and upper airways will become more laminar.

b. The pressure gradient required for airflow will increase.

c. The resistance to airflow will decrease.

d. The resistance to airflow will increase linearly with the decrease in airway radius.

e. Reynolds number will decrease.

174. A 27-year-old woman at 30 weeks of gestation goes to the obstetrician for a prenatal visit. During the visit, she expresses concern that she has been breathing faster than usual. Lab results revealed the following:

Based on the data, what conclusions can you draw about the level of the patient’s alveolar ventilation?

a. Alveolar ventilation exceeds her minute ventilation.

b. Alveolar ventilation is inadequate due to rapid, shallow breathing.

c. Alveolar ventilation is less than her dead space ventilation.

d. Alveolar ventilation matches the increased CO₂ production during pregnancy.

e. Alveolar ventilation is greater than normal.

175. A newborn of 28 weeks of gestation develops respiratory distress syndrome. Mechanical ventilation on 100% O₂ with 10 cm H₂O of positive end-expiratory pressure (PEEP) does not provide sufficient oxygenation. After porcine surfactant is instilled via a fiberoptic bronchoscope, the PaCO₂, fraction of inspired oxygen (FIO₂), and shunting improve impressively. The improvements in respiratory function occurred because surfactant increased which of the following?

a. Alveolar surface tension

b. Bronchiolar smooth muscle tone

c. Lung compliance

d. The pressure gradient needed to inflate the alveoli

e. The work of breathing

176. In the maximal expiratory flow–volume curves below, curve A would be typical of which of the following clinical presentations?

a. A 75-year-old man who has smoked two packs of cigarettes per day for 60 years. His breath sounds are decreased bilaterally and his chest x-ray shows flattening of the diaphragm.

b. A 68-year-old man who presents with a dry cough that has persisted for 3 months. His chest x-ray shows opacities in the lower and middle lung fields. The man states that he was exposed to asbestos for approximately 10 years when he worked in a factory in his 30s.

c. A 57-year-old woman with pulmonary fibrosis who presents to the emergency room with shortness of breath.

d. An 84-year-old woman with a history of myocardial infarction who reports shortness of breath that worsens in the recumbent position.

e. A healthy, 22-year-old man getting his army enlistment physical exam. He has never smoked, but is tired that morning, and does not use much effort while exhaling.

177. A 14-year-old adolescent girl presents with a lump in the neck. Fine needle aspiration biopsy reveals acinic cell carcinoma of the parotid gland. During the parotidectomy, there is compression injury of the glossopharyngeal nerve. As a result, which of the following respiratory reflexes will be impaired?

a. Aortic baroreceptor reflex

b. Carotid body chemoreceptor reflex

c. Hering–Breuer inflation reflex

d. Irritant airway reflex

e. Juxta pulmonary capillary (J) receptor reflex

178. A 30-year-old woman is admitted to the emergency department with dyspnea, tachycardia, confusion, and other signs of hypoxia. The following laboratory data were obtained while the patient was breathing room air:

Which of the following is the most appropriate classification of the patient’s hypoxia?

a. Hypoxic hypoxia (hypoxemia)

b. Anemic hypoxia

c. Stagnant (hypoperfusion) hypoxia

d. Histotoxic hypoxia

e. Carbon monoxide poisoning

179. A 63-year-old woman is required to undergo pulmonary function testing as part of a life insurance health assessment. The occupational medicine physician orders the testing to be done in both the upright and supine positions. In the upright position, which of the following variables will be lower in the apex compared with the base of the lung?

a. PaCO₂

b. Lung compliance

c. Pulmonary vascular resistance (PVR)

d. Resting lung volume (functional residual capacity [FRC])

e. ratio

180. A 68-year-old woman convalescing from surgery developed fever, hypoxemia, and shortness of breath. She was given 100% O₂ for 30 minutes, and the laboratory results were as follows:

The response to 100% O₂ reveals that the patient has which of the following?

a. Alveolar hypoventilation

b. Diffusion impairment

c. inequality with low units

d. Right-to-left shunting

e. Carbon monoxide poisoning

181. A 67-year-old man who is a candidate for cardiac transplantation undergoes cardiac catheterization to assess his hemodynamic status. Findings include:

Pulmonary artery pressure (PAP) = 35 mm Hg

Cardiac output = 4 L/min

Left atrial pressure (LAP) = 15 mm Hg

Right atrial pressure = 10 mm Hg

Which of the following values is his PVR?

a. 0.16 L/min/mm Hg

b. 0.2 L/min/mm Hg

c. 5 mm Hg/L/min

d. 6.25 mm Hg/L/min

182. A 36-year-old woman is found comatose at her home and is life-flighted to the nearest regional medical center. Blood gases reveal a normal PaO₂ but a lower-than-normal arterial O₂ saturation. Which of the following conditions is most consistent with the findings?

a. Anemia

b. Carbon monoxide poisoning

c. Hypoventilation

d. Low ratio

e. Right-to-left shunt

183. A 22-year-old male presents with a nonproductive cough, wheezing, and dyspnea. While doing a FVC maneuver, he generated curve 1 in the figure below. After receiving an aerosolized medication, he generated curve 2 while repeating the vital capacity 10 minutes later. Compared to curve 1, the greater flow rates measured after exhaling 3 L on curve 2 can be attributed to an increase in which of the following?

a. Airway radius

b. Airway resistance

c. Dynamic compression of the airways

d. Effort exerted in contracting the expiratory muscles

e. Intrapleural pressure

184. Noninvasive color Doppler ultrasound studies are ordered on a term infant and a preterm infant of 28 weeks gestation. Which of the following is likely to have a lower value in the preterm infant compared with the term infant?

a. Blood flow from the pulmonary artery through the ductus arteriosus

b. Pulmonary artery pressure

c. Pulmonary blood flow

d. Pulmonary capillary hydrostatic pressure

e. Pulmonary vascular resistance

185. A 62-year-old man with congestive heart failure (CHF) develops increasing shortness of breath in the recumbent position. A chest x-ray reveals cardiomegaly, horizontal lines perpendicular to the lateral lung surface indicative of increased opacity in the pulmonary septa, and lung consolidation. Pulmonary edema in CHF is promoted by which of the following?

a. Decreased pulmonary capillary permeability

b. Decreased pulmonary interstitial oncotic pressure

c. Increased pulmonary capillary hydrostatic pressure

d. Increased pulmonary capillary oncotic pressure

e. Increased pulmonary interstitial hydrostatic pressure

186. A 76-year-old patient with emphysema presents for his annual pulmonary function testing to assess the progression of his disease. As a result of alveolar septal departitioning in emphysema, there is a decrease in which of the following?

a. Airway resistance

b. Alveolar dead space

c. Diffusing capacity

d. Lung compliance

e. Total lung capacity

187. A 54-year-old man with severe asbestosis reports worsening of his dyspnea. Pulmonary function tests are ordered and the patient is instructed to take in a maximal inspiration and then to exhale as hard and fast as he can to generate a maximal expiratory flow–volume (MEFV) curve. As a result, the patient generates curve C shown below:

The patient’s MEFV curve is consistent with which of the following sets of values?

188. A 35-year-old woman with gestational diabetes develops hypertension and preeclampsia, requiring the preterm delivery of her fetus of 30 weeks of gestation. The woman is given two doses of betamethasone, 12 mg, intramuscularly, 24 hours apart. Which of the following is the purpose of prenatal steroid therapy?

a. Increase blood flow from the right atrium into the left atrium across the foramen ovale

b. Increase blood flow to the fetal lungs

c. Increase fetal PO₂

d. Shift the fetal oxyhemoglobin dissociation curve to the right

e. Increase the lecithin/sphingomyelin ratio in the amniotic fluid

189. A person with CHF and progressive shortness of breath is admitted to the hospital for cardiac transplantation surgery. Hemodynamic recordings made with a Swan–Ganz catheter were as follows:

Mean pulmonary artery pressure (PAP): 35 mm Hg

Mean left atrial pressure (LAP): 20 mm Hg

Pulmonary artery wedge pressure (PAWP): 25 mm Hg

Cardiac Output: 3 L/min

On a previous admission, the patient’s LAP was 15 mm Hg and cardiac output was 4 L/min. What can be deduced from these data?

a. Cardiac contractility is lower than on the previous admission.

b. Left ventricular preload is lower than on his previous admission.

c. Net fluid absorption into the pulmonary capillaries is increased.

d. Pulmonary capillary hydrostatic pressure is lower than normal.

e. Pulmonary vascular resistance is lower than normal at present.

190. A 68-year-old man with chronic obstructive pulmonary disease (COPD) entered the emergency department complaining of shortness of breath. His respirations were 35 per minute and labored. He had a productive cough and rales were heard over all lung fields. The patient had a rather ashen complexion and his nail beds gave clear evidence of cyanosis. An arterial blood sample was obtained and a chest x-ray was ordered. The patient was then placed on an O₂ mask delivering 40% O₂. One-half hour later, the physician was called to the bedside by the nurse who found the patient unresponsive. The patient’s complexion had changed to a flushed pink with no trace of cyanosis. His respirations were quiet at a rate of 6 per minute and a tidal volume of 300 mL. Repeat arterial blood gases showed that his arterial PCO₂ had increased from 55 to 70 mm Hg, and his PaO₂ increased from 55 to 70 mm Hg. Oxygen therapy most likely resulted in which of the following?

a. Alveolar hypoventilation

b. Elimination of the hypercapnic drive

c. Hypoxic pulmonary vasoconstriction

d. Increased firing of carotid body chemoreceptors

e. Oxygen toxicity

191. A scientist doing experiments with sodium cyanide started experiencing headache, dizziness, clumsiness, decreased visual acuity, and nausea. The medical student doing research in the laboratory was not certain if this was unusual behavior for the professor, but thought it was best to take him to the emergency department to be evaluated for possible hypoxia. Blood values obtained from the professor while he was breathing room air were as follows:

The professor’s hypoxia is most likely the result of which of the following?

a. Hypoxemia

b. Impaired diffusion across the alveolar–capillary membrane

c. Impaired hemoglobin oxygen transport

d. Impaired oxygen delivery

e. Impaired oxygen utilization

192. A 42-week gestation infant is delivered by cesarean section. Which of the following occurs with the baby’s first diaphragmatic respiration?

a. All of the fetal vascular channels functionally close.

b. PaO₂ increases.

c. Pulmonary capillary hydrostatic pressure increases.

d. Pulmonary vascular resistance increases.

e. Systemic vascular resistance decreases.

193. A 29-year-old woman is admitted to the hospital because of increasing dyspnea and swelling of both feet. An examination of her chest shows a severe pectus excavatum with only 2 cm of space between the vertebral bodies and the sternum. Pulmonary function tests show FVC and FEV₁/FVC values that were 15% and 100%, respectively, of predicted. Which of the following laboratory measurements will most likely be below normal in this patient?

a. Arterial PCO₂

b. Arterial pH

c. Elastic recoil of the chest wall

d. Hemoglobin concentration

e. Plasma bicarbonate concentration

194. An 18-year-old male college freshman living in a dormitory contracts meningitis, which causes a centrally mediated increase in his respiratory rate. The pacemaker neurons responsible for respiratory rhythmogenesis are located in which of the following regions of the brain?

a. Apneustic center in the pons

b. Central chemoreceptors in the medulla

c. Inspiratory neurons in the dorsal respiratory group

d. Pontine respiratory groups

e. Pre-Bötzinger complex in the ventral respiratory group

195. A 56-year-old man presents to the emergency department with severe abdominal pain and a temperature of 103°F. The patient is in severe respiratory distress. Moderate amounts of pulmonary edema fluid are aspirated during suctioning. The patient is placed on a ventilator with an FIO₂ of 0.5 and an arterial blood gas sample reveals a PO₂ of 160 mm Hg and a PCO₂ of 40 mm Hg. His alveolar oxygen tension, at a barometric pressure of 747 mm Hg and a respiratory exchange ratio (R) of 0.8, is approximately what?

a. 100 mm Hg

b. 200 mm Hg

c. 300 mm Hg

d. 400 mm Hg

e. 500 mm Hg

196. A 68-year-old man who has COPD presents to his pulmonologist with fatigue, dyspnea at rest, and peripheral edema. His blood gases on room air are PaO₂ = 60 mm Hg, PaCO₂ = 60 mm Hg, and pH = 7.36. His alveolar–arterial (A–a) O₂ gradient, at a barometric pressure of 760 mm Hg and a respiratory exchange ratio (R) of 0.8, is approximately what?

a. 5 mm Hg

b. 10 mm Hg

c. 15 mm Hg

d. 20 mm Hg

e. 25 mm Hg

197. A 45-year-old man presents with severe back pain that he attributes to an injury from operating a jackhammer for his job as a cement worker. An MRI of the spine confirms a herniated disk. The patient reports that he has smoked one to two packs of cigarettes a day for 30 years, so the neurosurgeon requests pulmonary function studies prior to the patient’s back surgery. During a forced expiration, the patient generates an intrapleural pressure of 20 mm Hg. The patient’s equal pressure point will move closer to the mouth and forced expiratory volume will increase if there is an increase in which of the following?

a. Airway resistance

b. Airway smooth muscle tone

c. Expiratory effort

d. Inspired lung volume

e. Lung compliance

198. A healthy, 24-year-old man is prescribed sustained-release bupropion (Zyban) for smoking cessation. Three weeks later, he presents to his family physician with intermittent fever and a generalized rash, at which time the bupropion is discontinued. A month later, he develops a dry, intermittent cough and dyspnea. Which of the following pulmonary function results is consistent with allergic bronchospasm?

a. A decreased FEV₁/FVC

b. A decreased residual volume

c. An increased diffusing capacity

d. An increased FVC

e. An increased lung compliance

199. A 5-month-old infant is admitted to the hospital for evaluation because of repeated episodes of sleep apnea. During a ventilatory response test, his ventilation did not increase when PaCO₂ was increased, but decreased during hyperoxia. Which of the following is the most likely cause of this infant’s apnea?

a. Bronchospasm

b. Decreased irritant receptor sensitivity

c. Diaphragmatic fatigue

d. Dysfunctional central chemoreceptors

e. Peripheral chemoreceptor hypersensitivity

200. A 66-year-old woman presents with a chief complaint of shortness of breath accompanying alternating chills and spiking fever. She has an increase in heart rate and respiratory rate. The right lower lobe is dull to percussion and increased vocal fremitus and bronchovesicular breathing are auscultated over this region. Ventilation–perfusion () abnormalities occurring in a patient with lobar pneumonia will generally cause a decrease in which of the following?

a. Alveolar ventilation

b. Anion gap

c. Arterial pH

d. Arterial PO₂

e. A–a gradient for oxygen

201. A 72-year-old man with CHF, paroxysmal nocturnal dyspnea, and orthopnea is referred for pulmonary function test in the supine and upright positions. Which of the following is higher at the apex of the lung than at the base when a person is upright?

a. Blood flow

b. Lung compliance

c. PaCO₂

d. Ventilation

e. ratio

202. A 65-year-old smoker develops a squamous cell bronchogenic carcinoma that metastasizes to the tracheobronchial and parasternal lymph nodes. The chest x-ray is consistent with accumulation of fluid in the pulmonary interstitial space. Flow of fluid through the lymphatic vessels will be decreased if there is an increase in which of the following?

a. Capillary oncotic pressure

b. Capillary permeability

c. Capillary pressure

d. Central venous pressure

e. Interstitial protein concentration

203. A 24-year-old presents with a chief complaint of fatigue and daytime somnolence. His wife has noticed that he stops breathing for periods of 30 to 60 seconds while he is sleeping and that this happens many times throughout the night. His physician orders pulmonary function testing including ventilatory response curves and polysomnography. The tests confirm apneic episodes during sleep. During a ventilatory responsiveness test, his alveolar ventilation increased as predicted in response to breathing 5% CO₂, but his ventilatory response to breathing 16% O₂ was depressed. Which of the following conditions are consistent with these findings?

a. Central hypoventilation syndrome (Ondine curse)

b. Decreased central chemoreceptor sensitivity

c. Decreased peripheral chemoreceptor sensitivity

d. Obstructive sleep apnea

e. Spinal cord injury affecting the fourth cervical vertebra

204. A 57-year-old woman presents with dyspnea on exertion. Pulmonary function studies with plethysmography demonstrate an increased resting oxygen consumption and work of breathing. Which of the following will decrease the oxygen consumption of the respiratory muscles?

a. A decrease in airway resistance

b. A decrease in diffusing capacity of the lung

c. A decrease in lung compliance

d. An increase in rate of respiration

e. An increase in tidal volume

205. An 18-year-old man is life-flighted to a Level 1 trauma center after being thrown from his motorcycle. It is determined that he has a brain tran-section above the pons. How will this lesion affect the control of breathing in this patient?

a. All breathing movements will cease.

b. The central chemoreceptors will no longer be able to exert any control over ventilation.

c. The peripheral chemoreceptors will no longer be able to exert any control over ventilation.

d. The Hering–Breuer reflex will be abolished.

e. The limbic system will no longer be able to exert any control over ventilation.

206. A 48-year-old coal miner complains of shortness of breath and a productive cough. He has smoked one to two packs of cigarettes per day since he was 16 years old. Pulmonary function studies are ordered, including an esophageal balloon study to measure intrapleural pressures. Normally, intrapleural pressure is negative throughout a tidal inspiration and expiration because of which of the following?

a. The lungs have the tendency to recoil outward throughout a tidal breath.

b. The chest wall has the tendency to recoil inward throughout a tidal breath.

c. The lungs and chest wall recoil away from each other throughout a tidal breath.

d. The lungs and chest wall recoil in the same direction throughout a tidal breath.

e. A small volume of air leaves the pleural space during a tidal breath.

207. A 47-year-old man presents with a 7-day history of fever, productive cough, and shortness of breath. A chest x-ray reveals consolidation in the right lower lobe and culture of the sputum is positive for Klebsiella pneumoniae. Blood gases reveal hypoxemia but not carbon dioxide retention. Which of the following would be increased in this patient?

a. Alveolar–arterial PO₂ difference

b. Diffusing capacity of the lung

c. Lung compliance

d. Physiological dead space

e.

208. A 57-year-old man undergoes total knee replacement for severe degenerative joint disease. Four days after surgery, he develops an acute onset of shortness of breath and right-sided pleuritic chest pain. He is now in moderate distress with a respiratory rate of 28 breaths per minute, tidal volume of 450 mL, heart rate of 120 bpm, and blood pressure of 125/85 mm Hg. Arterial blood gases on room air at a barometric pressure of 760 mm Hg and R of 0.8 were PaO₂ = 60 mm Hg, SaO₂ = 90%, PaCO₂ = 30 mm Hg, pH = 7.50, = 22 mEq/L, and P_ECO₂ = 10 mm Hg. The right lower extremity is healing well, but is red, tender, warm to touch, and has 2+ pitting edema. The most likely cause of these postoperative findings is:

a. Atelectasis

b. Pneumonia

c. Pneumothorax

d. Pulmonary embolism

e. Sepsis

209. Several months after recovering from mononucleosis, a 26-year-old man develops weakness and tingling in both legs. Three days later, he is hospitalized when his legs become paralyzed. A conduction block in the peripheral Aβ, sensory fibers and the finding of autoantibodies to Schwann cell gangliosides confirm the diagnosis of Guillain–Barré syndrome. The next day the weakness and paralysis ascended to his upper extremities and trunk. Stat arterial blood gas results indicated the need for mechanical ventilation. Which of the following sets of values is consistent with acute respiratory muscle paralysis?

210. A 37-year-old woman is admitted to the hospital with severe kyphoscoliosis and respiratory muscle weakness. Which of the following physiological variables is most likely decreased in this patient?

a. Airway resistance

b. Alveolar surface tension

c. Arterial carbon dioxide tension

d. Chest wall compliance

e. FEV₁/FVC

For Questions 211 and 212, refer to the following case.

A 32-year-old man is hospitalized with severe respiratory disease following aspiration pneumonia. Inhaled nitric oxide is administered and he is placed in a prone position to improve oxygenation. Values obtained after the administration of nitric oxide are as follows:

Mean pulmonary capillary oxygen content = 19 mL/dL

Arterial oxygen content = 18 mL/dL

Mixed venous oxygen content = 14 mL/dL

Cardiac output = 6 L/min

211. Which of the following is the patient’s shunt fraction (the ratio of shunted to total pulmonary blood flow)?

a. 10%

b. 20%

c. 30%

d. 40%

e. 50%

212. What is the patient’s oxygen consumption?

a. 200 mL/min

b. 210 mL/min

c. 220 mL/min

d. 230 mL/min

e. 240 mL/min

213. An 83-year-old woman is found unresponsive by her son approximately 3 hours after she returned to her hospital room following gall bladder surgery. The nurse reported that the patient had asked for her pain medications and said she was going to rest for a while. Arterial blood gases reveal hypercapnia and hypoxemia. Which of the following is the most likely cause of the high arterial PCO₂ ?

a. Decreased alveolar dead space

b. Decreased metabolic activity

c. Hypoventilation

d. Hypoxemia

e. inequality

214. A 29-year-old man with AIDS presents with a painful, red, swollen area on top of his shin, which is warm to the touch. He has a fever, tachypnea, and tachycardia, and is hospitalized and started on IV antibiotics. His condition progresses rapidly to septicemia and septic shock. He is transported to the ICU, intubated, and started on mechanical ventilation. A Swan-Ganz catheter is inserted to monitor pulmonary hemodynamics and lung fluid balance. Which of the following conditions will cause a decrease in PVR?

a. Alveolar hypoxia

b. Decreased pH in the pulmonary artery

c. Increased cardiac output

d. Inflation of the lungs to total lung capacity

e. Sympathetic stimulation of the pulmonary vessels

215. A healthy 32-year-old woman undergoes pulmonary exercise stress testing prior to starting a training regimen in preparation for her first marathon. Normally, during moderate aerobic exercise, which of the following occurs?

a. Alveolar ventilation increases

b. Arterial pH decreases

c. Arterial lactate level increases

d. PaCO₂ decreases

e. PaO₂ increases

216. A 56-year-old woman presents to her physician complaining of fatigue, headaches, and dyspnea on exertion. She states that she sometimes gets blue lips and fingers when she tries to exercise. Pulmonary function tests reveal an increase, rather than a decrease, in the diffusing capacity of the lung. Which of the following conditions best accounts for an increase in the diffusing capacity?

a. CHF

b. COPD

c. Fibrotic lung disease

d. Polycythemia

e. Pulmonary embolism

217. A 49-year-old farmer develops headache and becomes dizzy after working on a tractor in his barn. His wife suspects carbon monoxide poisoning and brings him to the emergency department where he complains of dizziness, lightheadedness, headache, and nausea. The patient’s skin is red, he does not appear to be in respiratory distress, and denies dyspnea. Blood levels of carboxyhemoglobin are elevated. Which of the following best explains the absence of respiratory signs and symptoms associated with carbon monoxide poisoning?

a. Blood flow to the carotid body is decreased

b. Arterial oxygen content is normal

c. Cerebrospinal fluid (CSF) pH is normal

d. Central chemoreceptors are depressed

e. Arterial oxygen tension is normal

218. A 68-year-old patient with shortness of breath is referred for pulmonary function testing, including lung volumes, flow–volume curves, and lung compliance. Which of the following statements best characterizes lung compliance?

a. It decreases with advancing age.

b. It increases when there is a deficiency of surfactant.

c. It increases in patients with pulmonary edema.

d. It is equivalent to ΔP/ΔV.

e. It is inversely related to the elastic recoil properties of the lung.

219. A 36-year-old man visits his doctor because his wife has long complained of his snoring, but recently observed that his breathing stops for a couple of minutes at a time while he is sleeping. He undergoes polysomnography and ventilatory response testing to ascertain the extent and cause of his sleep apnea. The activity of the central chemoreceptors is stimulated by which of the following?

a. A decrease in the metabolic rate of the surrounding brain tissue

b. A decrease in the PO₂ of blood flowing through the brain

c. An increase in the PCO₂ of blood flowing through the brain

d. An increase in the pH of the CSF

e. Hypoxemia, hypercapnia, and metabolic acidosis

220. A patient complains of paroxysmal episodes of not being able to catch her breath. When no abnormalities are detected with conventional pulmonary function screening, the pulmonologist orders a methacholine challenge test. Which of the following will increase as a result of stimulating cholinergic receptors on the bronchial smooth muscle?

a. Airway diameter

b. Anatomic dead space

c. Compliance of the lungs

d. Elastic work of breathing

e. Resistive work of breathing

221. A 28-year-old woman on oral contraceptives develops tachypnea and reports dyspnea. A ventilation/perfusion scan is ordered to check for pulmonary thromboemboli. Which of the following best explains why, as she takes in a normal inspiration, more air goes to the alveoli at the base of the lung than to the alveoli at the apex of the lung?

a. The alveoli at the base of the lung have more surfactant.

b. The alveoli at the base of the lung are more compliant.

c. The alveoli at the base of the lung have higher ratios.

d. There is a more negative intrapleural pressure at the base of the lung.

e. There is more blood flow to the base of the lung.

222. A 21-year-old woman presents with cough and shortness of breath. The physician conducts a pulmonary function screening test in his office, and the patient generates the maximum flow–volume curve shown to the right of the normal curve in the diagram below. These findings are consistent with which of the following conditions?

a. Asthma

b. Chronic bronchitis

c. Cystic fibrosis

d. Decreased effort

e. Sarcoidosis

223. A 56-year-old man presents for his annual physical examination. His BMI has increased from 28 to 33 over the past year and the fat deposition is mainly around the abdomen. His blood pressure has increased from 125/85 to 140/95 mm Hg since the last visit. Other physical findings are unremarkable and he and his spouse state that he does not snore. Past medical history and social history are insignificant except for his sedentary lifestyle. Exercise stress testing is ordered prior to placing the patient on a regular exercise regimen. Aerobic exercise causes which of the following changes in pulmonary physiology?

a. Diffusing capacity of the lungs increases.

b. Mean PAP decreases.

c. Overall ratio of the lungs decreases.

d. Pulmonary blood flow decreases.

e. PVR increases.

224. A 43-year-old woman develops shortness of breath following a cholecystectomy. Bronchial breath sounds and crackles are heard over all lung fields and the lungs are dull on percussion. A chest x-ray demonstrates a pattern of diffuse opacification characteristic of atelectasis. Intrapulmonary shunting will cause which of the following changes in arterial blood gas values?

a. A

b. B

c. C

d. D

225. A 49-year-old coal miner presents with dyspnea, a nonproductive cough, and decreased exercise tolerance. Lung function tests reveal the following: total lung capacity = 3.34 L (56% of predicted), residual volume = 0.88 L (54% of predicted), and FVC = 1.38 L (30% of predicted). His arterial PO₂ is 68 mm Hg. Which of the following values will be approximately normal?

a. Diffusing capacity

b. FEV₁/FVC ratio

c. FRC

d. Lung compliance

e. ratio

226. A 43-year-old woman with a history of asthma presents to the emergency department with an acute asthma attack after her bronchodilator inhaler ran out the day before. Airway resistance is greater at which of the following?

a. At low lung volumes compared with high lung volumes

b. At lower values for Reynolds number

c. During inspiration compared with expiration

d. In the total cross-section of the small airways compared with the total cross-section of the central airways

e. With laminar flow than with turbulent flow

227. A 78-year-old woman presents to her family physician’s office with a chief complaint of fatigue and shortness of breath. The doctor indicates that he wants her to go to the hospital to get some pulmonary function tests, but there is one who is able to do in the office. A spirometer can be used to directly measure which of the following?

a. FRC

b. Peak flow rate

c. Residual volume

d. Total lung capacity

e. Vital capacity

228. A patient with Wegener’s glomerulonephritis presents with sinusitis and hemoptysis. His chest radiograph shows several large cavitary pulmonary nodules, consistent with ventilation–perfusion imbalance with low units. Which of the following will be greater than normal in a patient with a low ratio?

a. A–a gradient for O₂

b. PaCO₂

c. PaO₂

d. Oxygen dissolved in blood

e. Oxygen combined with hemoglobin

229. An 18-year-old woman presents to her primary care physician with an increased frequency of asthma exacerbations over the previous year. At the time of her visit, her physical examination and flow–volume loop are normal. At which point on the flow–volume loop shown below will airflow remain constant despite an increased respiratory effort?

a. A

b. B

c. C

d. D

e. E

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