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A 34-year-old woman presents in the emergency department with tachypnea and shortness of breath of acute onset.. Which of the following occurs if the blood flow to alveolar units istotal

Respiratory Physiology

Questions

160 A healthy 30-year-old woman is referred for a life insurance physical exam History reveals that she has never smoked and vesicular breath sounds are heard at

the periphery of the lung with auscultation In the patient’s spirometry tracing below, the expiratory reserve volume (ERV) equals which of the following?

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?

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 syringebefore 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 istotally 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:

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 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

x-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 duringexercise 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 15breaths per minute, and a tidal volume of 500 mL Which of the following is her approximate alveolar ventilation?

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?

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 oxygentension is approximately which of the following?

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 M echanical ventilation on 100% O2 with 10 cm H2O of positive end-expiratorypressure (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?

(M odified from Levitzky M G Pulmonary Physiology 7th ed New York, NY: M cGraw-Hill; 2007:46.)

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 ofthe 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 manstates 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 thebase 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?

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 ispromoted 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 (M EFV) curve As a result, the patient generates curve

C shown below:

(M odified from Levitzky M G Pulmonary Physiology 7th ed New York, NY: M cGraw-Hill; 2007:46.)

The patient’s M EFV 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:

M ean pulmonary artery pressure (PAP): 35 mm Hg

M ean 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 gaveclear 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 hadincreased 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 beevaluated 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% and100%, 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.

M oderate 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 samplereveals 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,

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) of0.8, is approximately what?

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 M RI 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 pulmonaryfunction 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 equalpressure point will move closer to the mouth and forced expiratory volume will increase if there is an increase in which of the following?

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 thefollowing 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?

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 inwhich 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 curvesand polysomnography The tests confirm apneic episodes during sleep During a ventilatory responsiveness test, his alveolar ventilation increased as predicted inresponse 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 negativethroughout 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?

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 PECO2 = 10 mm Hg The right lower extremity is healing well, but is red, tender, warm to touch, and has2+ pitting edema The most likely cause of these postoperative findings is:

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 formechanical 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 proneposition to improve oxygenation Values obtained after the administration of nitric oxide are as follows:

M ean pulmonary capillary oxygen content = 19 mL/dL

Arterial oxygen content = 18 mL/dL

M ixed 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)?

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 thefollowing 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 followingconditions best accounts for an increase in the diffusing capacity?

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 andsymptoms 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 thecentral 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 bronchialsmooth 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 atthe 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