1. E-D = ERV 160. A healthy 30-year-old woman is referred for a life insurance physical exam. History reveals that she has never smoked and vesicular
... [Show More] breath sounds are heard at the periph- ery of the lung with aus- cultation. In the patient's spirometry tracing below, the expiratory reserve vol- ume (ERV) equals which of the following?
2. .21*380 = 80 mmHg 161. A group of third-year medical students accom- panied a medical mission team to Peru, South Amer- ica. After arriving at the air- port in Bolivia, they hiked to a remote mountain vil- lage in the Andes at an el- evation of 18,000 ft. With a barometric pressure of 380 mm Hg at this altitude, what would be the result- ing PO2 of the dry inspired air?
3. The answer is c
The measured PaO2 will be higher and the
162. A 28-year-old man is admitted to the emer- gency department with
multiple fractures suffered
measured PaCO2 will be lower than the pa- tient's actual blood gas values.
in a car accident. Arterial blood gases are ordered while the patient is breath- ing room air. After the
first-year resident obtains an arterial blood sample from the patient, the glass plunger slides back, draw- ing an air bubble into the syringe before it is handed to the blood gas technician for analysis. How does ex- posure 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 pa- tient'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 mea- sured PaCO2 will be low- er than the patient's actual blood gas values.
d. The measured PaO2 will be lower and the mea- sured PaCO2 will be high- er than the patient's actual blood gas values.
e. The measured values of PaO2 and PaCO2 will ac- curately reflect the actual values.
4. The answer is a.
In pulmonary fibrosis, the diffusing capacity of the lung is decreased due to an increase in the thickness of the diffusional barrier, as predicted by Fick law of diffusion. Pulmonary
fibrosis is characterized by a decrease in lung compliance and an increase in lung elastic recoil ("stiff" lungs), which results in findings typical of a restrictive impairment. Pulmonary function test values characteristic of a restric- tive impairment include a decrease in all lung volumes and capacities and a ratio of the FEV1 to the total FVC that is normal or increased.
Airway radius is decreased, and thus airway
163. A 68-year-old woman with pulmonary fibrosis presents with a com- plaint of increasing dysp- nea while performing ac- tivities of daily living. She is referred for pulmonary function testing to assess the progression of her dis- ease. Which of the follow- ing laboratory values is consistent with her diag- nosis?
a. Decreased diffusing ca-
pacity of the lung
resistance is increased, at lower lung volumes, b. Increased residual vol-
but in restrictive disorders, the airway resis- tance is normal when corrected for lung vol- ume in contrast to obstructive disorders, in which an increased airway resistance is a hall- mark of the functional imp airment .
Decreased lung compliance Increased recoil
Normal resistance when corrected for lung vol- ume
5. The answer is b.
A pulmonary thromboembolism results in ar- eas of the lung that are ventilated, but not perfused, yielding ratios of infinity and an in- crease in alveolar dead space. When the ratio equals , the PAO2 of the affected alveoli will be the same as that in the humidified inspired air because atmospheric air enters the alveoli via the process of ventilation, but no gas ex- change takes place because the alveoli are not perfused. Areas of the lung that are perfused
ume
c. Decreased forced expi- ratory volume exhaled in 1 second (FEV1)/forced vital capacity (FVC)
d. Increased lung compli- ance
e. Increased airway resis- tance corrected for lung volume
164. A 34-year-old woman presents in the emergency department with tachyp- nea and shortness of breath of acute onset. The history reveals that she has been taking oral con- traceptives for 9 years. A lung scan demonstrates
a perfusion defect in the left lower lobe. Which of the following occurs if the
but not ventilated constitute areas of shunting (venous admixture), characterized as a ratio equal to 0, and having PAO2 values that equili- brate with the mixed venous blood.
6. Z - In pulmonary edema, the abnormal accu- mulation of fluid in the lungs causes a restric- tive pulmonary impairment characterized by decreased lung compliance.
X - emphysema
blood flow to alveolar units is totally obstructed by
a pulmonary thromboem- bolism?
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 in- crease in shunting (ve- nous admixture) in the lung.
e. There will be a decrease in alveolar dead space.
166. A hospitalized patient has tachypnea and signifi- cantly labored respirations requiring mechanical ven- tilation. Based on the pres-
The increase in airway resistance in asthma is sure-volume curve of the
not associated with an increase (or decrease) in lung compliance. In emphysema, alveolar septal departitioning causes the destruction of elastic fibers, which decreases the elastic re- coil of the lungs, thereby increasing lung com- pliance (curve X). Emphysematous changes in the lungs also occur in aging. An L/S ratio
e2 indicates normal biochemical maturation of the lung in utero, with normal surfactant pro- duction and lung compliance (normal curve). If the L/S ratio is less than 2, such as may occur in preterm infants, there is an increased inci- dence of respiratory distress syndrome of the
lungs shown as curve Z in the figure below, which of the following is the most likely diagnosis for the pa- tient?
newborn, a restrictive impairment that would be characterized by curve Z.
7. The answer is b
When air enters the pleural space due to in- terruption of the pleural surface through ei- ther the rupture of the lung or a hole in the chest wall, the pressure in the pleural space becomes atmospheric, the lung on the affected side collapses because of the lung's tenden- cy to recoil inward, and the chest wall on the affected side recoils outward. With collapse of the lung, the v/q ratio on the affected side decreases. The trachea shifts toward the af- fected lung in a spontaneous pneumothorax and away from the affected lung in a tension pneumothorax.
167. A 62322 tall, 140-lb,
20-year-old man was watching television when he felt pain in his shoul- der blades, shortness of breath, and fatigue. His father noticed how pale he was and took him
to the emergency depart- ment. The physical exam revealed decreased tac- tile fremitus, hyperreso- nance, and diminished breath sounds. A chest x- ray revealed a 55% pneu- mothorax 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 pneu- mothorax?
a. The chest wall on the af-
fected side recoils inward.
b. The intrapleural pres- sure 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 nor- mal.
8. The answer is d.
VTV = VD + VA
VA = VT-VD = 500 - 125 = 375 mL * 15 = 5625
9. The answer is a.
During exercise, minute ventilation and alve- olar ventilation increase linearly with carbon dioxide production up to a level of about 60% of the maximal workload. Above that level, called the anaerobic threshold, muscle lactate spills into the circulation causing a metabolic acidosis, characterized by a decrease in pH and [HCO3] . The increased [H+] stimulates the peripheral (not central) chemoreceptors to in- crease alveolar ventilation more proportional- ly than the increase in carbon dioxide produc- tion, resulting in a decrease in PaCO2.
10. The answer is c
Because the dead space air does not partici- pate in gas exchange, the entire output of CO2 in the expired gas comes from the alveolar gas. Accordingly, alveolar (and arterial) PCO2
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 hyper- capnic respiratory failure. She requires immediate intubation and is placed on a mechanical ventilator on an FIO2 of 40%, a con- trol rate of 15 breaths per minute, and a tidal volume of 500 mL. Which of the fol- lowing 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 fol- lowing will increase?
a. Alveolar ventilation
b. Arterial pH
c. PaCO2
d. Plasma [HCO-3]
e. Firing of the central chemoreceptors
171. A medical student waiting for her first pa- tient interview at the clin- ical skills center becomes very anxious and increas- es her rate of alveolar ven-
can be expressed in terms of CO2 output and alveolar ventilation according to the following equation:
Thus, an increase in alveolar ventilation at a constant rate of carbon dioxide production will lower PACO2 and PaCO2. Hyperventilation in- creases PAO2 and PaO2, with no change in the alveolar-arterial PO2 difference. The V/q will be normal or increased.
11. The answer is b.
An increased velocity of airflow will increase turbulent airflow, as predicted by an increased Reynolds number. Resistance to turbulent air- flow exceeds that for laminar airflow, and thus the pressure gradient required for airflow in- creases when flow is turbulent. Because the
tilation. If her rate of CO2 production remains con- stant, which of the follow- ing will decrease?
a. pH
b. PaO2
c. PaCO2
d. V/Q per min
e. Alveolar-arterial PO2 difference
173. A 58-year-old woman experiences an acute ex- acerbation of asthma, which causes her breath- ing to become labored and faster. As a result, which of the following changes in airflow is expected?
velocity of airflow is greatest in the trachea and a. Flow in the trachea and
large airways, the predisposition to turbulent airflow is greater in the central than in the pe- ripheral airways. Airway resistance varies in-
upper airways will become more laminar.
b. The pressure gradient
versely with the fourth power of airway radius, required for airflow will in-
according to Poiseuille law.
12. The answer is e.
Alveolar ventilation is the volume of air enter- ing and leaving the alveoli per minute. Alveolar ventilation is less than the minute ventilation
crease.
c. The resistance to airflow will decrease.
d. The resistance to airflow will increase linearly with the decrease in airway ra- dius.
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 con-
(minute volume) because the last part of each inspiration remains in the conducting airways and does not reach the alveoli. The minute ventilation is the product of tidal volume and respiratory rate (14,400 mL/min). Alveolar ven- tilation cannot be measured directly but must be calculated by subtracting dead space ven- tilation from minute ventilation. The ratio of the physiological dead space volume to the tidal volume (VD/VT) can be calculated using the Bohr equation (PaCO2 PECO2/PaCO2), and then multiplied by the VT to yield the dead space volume, which when multiplied by the respiratory rate yields the dead space ventila- tion (5760 mL/min). Thus, alveolar ventilation in this patient is 8640 mL/min. The adequacy of alveolar ventilation is determined by the alve- olar air equation, which states that the PaCO2 is approximately equal to the rate of carbon dioxide production divided by the rate of alve- olar ventilation. At a normal rate of alveolar ventilation, PaCO2 is in the normal range of 35 to 45 mm Hg. Assuming a constant rate
of carbon dioxide production, a decrease in
alveolar ventilation (hypoventilation) causes a higher PaCO2 than normal (ie, >45 mm Hg) and a rate of alveolar ventilation that is greater than normal (hyperventilation) "blows off" exces- sive CO2 causing PaCO2 to decrease below normal (ie, <35 mm Hg). Thus, in this patient, the PaCO2 of 30 mm Hg indicates that she
is hyperventilating. If her increase in alveolar ventilation matched an increased carbon diox- ide production, then PaCO2 would be in the normal range.
13. The answer is c.
Pulmonary surfactant increases lung compli-
cern that she has been breathing faster than usu- al. Lab results revealed the following:
Based on the data, what conclusions can you draw about the level of the patient's alveolar ventila- tion?
a. Alveolar ventilation ex- ceeds her minute ventila- tion.
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 de- velops respiratory dis-
ance by lowering alveolar surface tension. As a result, the pressure gradient needed to in- flate the alveoli decreases, as does the work of breathing. Although surfactant replacement therapy has proven to be beneficial in res- piratory distress syndrome of the newborn, surfactant replacement therapy is not current- ly recommended in acute respiratory distress syndrome based on clinical evidence against efficacy of the therapy.
14. The answer is a
tress syndrome. Mechani- cal ventilation on 100% O2 with 10 cm H2O of pos- itive end-expiratory pres- sure (PEEP) does not pro- vide sufficient oxygena- tion. After porcine sur- factant is instilled via a fiberoptic bronchoscope, the PaCO2, fraction of in- spired oxygen (FIO2), and shunting improve impres- sively. The improvements in respiratory function oc- curred because surfactant increased which of the fol- lowing?
a. Alveolar surface tension
b. Bronchiolar smooth muscle tone
c. Lung compliance
d. The pressure gradient needed to inflate the alve- oli
e. The work of breathing
176. In the maximal expi- ratory flow-volume curves
Cigarette smoking is the major cause of COPD. below, curve A would be
In obstructive lung diseases, the increase in airway resistance causes a decrease in expi- ratory flow rates and "air-trapping," which re- sults in an increased residual volume, and thus total lung capacity. This hyperinflation pushes the diaphragm into a flattened position. As- bestosis and pulmonary fibrosis are restrictive lung diseases, in which curve C would be the typical MEFV curve. Decreased effort would decrease flow rates during the effort-depen-
typical of which of the following clinical presenta- tions?
a. A 75-year-old man who has smoked two packs of cigarettes per day for 60 years. His breath sounds are decreased bilateral- ly and his chest x-ray
dent portion of a MEFV curve, but not during the effort-independent portion.
shows flattening of the di- aphragm.
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 low- er and middle lung fields. The man states that he was exposed to asbestos for approximately 10 years when he worked in a facto- ry in his 30s.
c. A 57-year-old woman
with pulmonary fibrosis who presents to the emer- gency room with short- ness of breath.
d. An 84-year-old woman with a history of myocar- dial infarction who reports shortness of breath that worsens in the recumbent position.
e. A healthy, 22-year-old man getting his army en- listment physical exam. He has never smoked, but is tired that morning, and does not use much effort while exhaling.
15. The answer is b. 177. A 14-year-old adoles- cent girl presents with a
The afferent pathway from the carotid body chemoreceptors is the Hering nerve, a branch of cranial nerve IX, the glossopharyngeal
lump in the neck. Fine nee- dle aspiration biopsy re- veals acinic cell carcino-
nerve. The vagus nerve constitutes the afferent ma of the parotid gland.
pathway from the aortic baroreceptors, the J receptors, the irritant airway receptors, and the rapidly adapting stretch receptors mediating the Hering-Breuer inflation reflex.
16. The answer is a
The answer is a. (Barrett, pp 649-653. Lev- itzky, pp 181-184.) Alveolar hypoventilation (as evidenced by the higher-than-normal value
of PaCO2) is a type of hypoxic hypoxia or hypoxemia (as evidenced by the decreased PaO2). Anemic hypoxia is characterized by a decreased concentration of hemoglobin (ane- mia) or a reduction in the saturation of he- moglobin with oxygen (SaO2) expected for a given PaO2, as would occur in carbon monox- ide poisoning or methemoglobinemia. Stag- nant hypoxia is characterized by a decreased cardiac output; in this patient, cardiac output, calculated as
is 5 L/min, which is normal. In histotoxic hy-
poxia, oxygen extraction is impaired, and thus
During the parotidectomy, there is compression in- jury of the glossopharyn- geal nerve. As a result, which of the following res- piratory reflexes will be im- paired?
a. Aortic baroreceptor re- flex
b. Carotid body chemore- ceptor reflex
c. Hering-Breuer inflation reflex
d. Irritant airway reflex
e. Juxta pulmonary capil- lary (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 ob- tained while the patient was breathing room air:
Which of the following is the most appropriate clas- sification of the patient's hypoxia?
a. Hypoxic hypoxia (hypox- emia)
b. Anemic hypoxia
c. Stagnant (hypoperfu-
CaO2 - CvO2 would be less than normal and SvO2 would be greater than normal.
sion) hypoxia
d. Histotoxic hypoxia
e. Carbon monoxide poi- soning
17. 179. The answer is b. 179. A 63-year-old woman is required to undergo pul- monary function testing as part of a life insur- ance health assessment. The occupational medi- cine physician orders the testing to be done in both the upright and supine po- sitions. In the upright po- sition, which of the follow- ing variables will be lower in the apex compared with the base of the lung?
A. PaCO2
B. Lung compliance
C. Pulmonary vascular re- sistance (PVR)
D. Resting lung volume (functional residual capac- ity [FRC])
E. V/Q min ratio
18. The answer is c. (Le, p 549. Levitzky, pp
90-91.) PVR is calculated as: PVR = (DeltaP/q
- MPAP)-M LAP/ Pulmonary blood flow = 35-15 mmhg / 4 L/min = 5 mmhg/L/min
181. A 67-year-old man who is a candidate for cardiac transplantation un- dergoes cardiac catheteri- zation to assess his hemo- dynamic status. Findings include:
Pulmonary artery pres- sure (PAP) = 35 mm Hg Cardiac output = 4 L/min
19. The answer is b.
Hemoglobin has 240 × greater affinity for car- bon monoxide than for oxygen. Thus, in car- bon monoxide poisoning, the amount of dis- solved oxygen, as reflected by the PaO2, may be normal, but the saturation of hemoglobin with oxygen will be lower than expected for a given PaO2.
In anemia, hemoglobin concentration is re- duced, but the saturation of hemoglobin O2 is normal.
Hypoventilation, v/q mismatch with low v/q units, and right-to-left shunting are all causes of hypoxemia (decreased PaO2).
20. The answer is a.
Reversibility of airway obstruction is assessed by the change in expiratory flow rate before and after administration of a bronchodilator drug, such as a ²2-adrenergic agonist, which increases airway radius, thereby decreasing airway resistance and increasing expiratory airflow as predicted by Poiseuille law. Increas- ing the effort of muscular contraction on exha-
Left atrial pressure (LAP)
= 15 mm Hg
Right atrial pressure = 10 mm Hg
Which of the following val- ues 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 med- ical center. Blood gases re- veal a normal PaO2 but a lower-than- normal arteri- al O2 saturation. Which of the following conditions is most consistent with the findings?
a. Anemia
b. Carbon monoxide poi- soning
c. Hypoventilation
d. Low ratio
e. Right-to-left shunt
183. A 22-year-old male presents with a nonpro- ductive cough, wheezing, and dyspnea. While doing a FVC maneuver, he gen- erated curve 1 in the fig- ure below. After receiving an aerosolized medica- tion, he generated curve 2 while repeating the vi-
lation would increase expiratory airflow on the effort-dependent portion of the MEFV curve, but not the effort-independent portion, as de- lineated in the figure below. Regardless of in- creased effort, flow rates decrease during the effort-independent portion of a maximal ex- piration due to dynamic compression of the airways by the positive intrapleural pressure generated by a forced (active) expiration .
21. The answer is c
In CHF, left ventricular dysfunction increases left ventricular end-diastolic pressure, which raises LAP, pulmonary venous pressure, and pulmonary capillary pressure, which is the hy- drostatic pressure tending to drive fluid move- ment out of the pulmonary capillaries, ac- cording to Starling law. Thus, pulmonary ede- ma, generally limited to the interstitium of the lungs, is a hallmark of CHF. All of the other responses would act to decrease fluid move- ment out of the capillary, in accordance with Starling law.
tal capacity 10 minutes lat- er. Compared to curve 1, the greater flow rates mea- sured 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 con- tracting the expiratory muscles
e. Intrapleural pressure
185. A 62-year-old man with congestive heart fail- ure (CHF) develops in- creasing shortness of breath in the recumbent position. A chest x-ray re- veals cardiomegaly, hor- izontal lines perpendicu- lar to the lateral lung surface indicative of in- creased opacity in the pul- monary septa, and lung consolidation. Pulmonary edema in CHF is promoted by which of the following?
22. The answer is c
Destruction of the alveolar septa in emphy- sema causes a loss of pulmonary capillar- ies, which decreases the surface area avail- able for diffusion, and therefore decreases the rate of diffusion in accordance with Fick law. Alveolar septal departitioning with destruction of pulmonary capillaries results in enlarge- ment of the air spaces distal to the terminal bronchioles and an increase in alveolar dead space, that is, alveoli that are ventilated but not perfused. Elastic fibers are also found in the alveolar septa. In emphysema, the destruction of elastic fibers decreases lung elastic recoil and increases lung compliance. The loss of elastic recoil increases intrapleural pressures, which decreases transmural pressure across the noncartilaginous airways (less radial trac- tion), which decreases airway caliber and in- creases airway resistance in accordance with Poiseuille law. In addition, the loss of elastic recoil impairs the ability to oppose dynamic compression of the airways. As a result, dy- namic compression occurs closer to the alve-
a. Decreased pulmonary capillary permeability
b. Decreased pulmonary interstitial oncotic pres- sure
c. Increased pulmonary capillary hydrostatic pres- sure
d. Increased pulmonary capillary oncotic pressure
e. Increased pulmonary in- terstitial hydrostatic pres- sure
186. A 76-year-old patient with emphysema presents for his annual pulmonary function testing to assess the progression of his dis- ease. As a result of alveo- lar septal departitioning in emphysema, there is a de- crease in which of the fol- lowing?
a. Airway resistance
b. Alveolar dead space
c. Diffusing capacity
d. Lung compliance
e. Total lung capacity
oli during forced expirations, resulting in air trapping and an increase in residual volume and total lung capacity.
23. 189. The answer is a
The elevated LAP, which is normally approxi- mately 5 mm Hg, is indicative of an increase in left ventricular preload. Plotting LAP (pre- load) and cardiac output in the cardiac func- tion curves below demonstrates that cardiac contractility has decreased since the previ- ous admission. PVR, calculated as (mean PAP mean LAP)/cardiac output, is (35 - 20)/3 = 5 mm
189. A person with CHF and progressive short- ness of breath is ad- mitted to the hospital for cardiac transplanta-
tion surgery. Hemodynam- ic recordings made with a Swan-Ganz catheter were as follows:
Mean pulmonary artery
Hg/L/min, which is higher than normal [(15 5pressure (PAP): 35 mm
mm Hg)/5 L/min = 2 mm Hg/L/min]. PAWP mea- sured with a Swan-Ganz catheter is an index of the pulmonary capillary hydrostatic pressure.
Hg
Mean left atrial pressure (LAP): 20 mm Hg
Normal PAWP is d12 mm Hg. An elevated PAWPPulmonary artery wedge
of 25 mm Hg is indicative of an increased pul- monary capillary hydrostatic pressure, which will drive fluid movement out of the pulmonary capillaries according to Starling law, thereby decreasing net fluid reabsorption into the pul- monary capillaries.
pressure (PAWP): 25 mm Hg Cardiac Output: 3 L/min On a previous ad- mission, the patient's LAP was 15 mm Hg and car- diac 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 previ- ous admission.
c. Net fluid absorption into the pulmonary capillaries is increased.
d. Pulmonary capillary hy- drostatic pressure is lower
24. The answer is e.
The alveoli at the apex of the lung are larger than those at the base, so their compliance is less. Because the compliance is reduced, less inspired gas goes to the apex than to
the base. Also, because the apex is above the heart, less blood flows through the apex than through the base. However, the reduction in
than normal.
e. Pulmonary vascular re- sistance is lower than nor- mal at present.
201. A 72-year-old man with CHF, paroxysmal noc- turnal dyspnea, and or- thopnea is referred for pul- monary function test in the supine and upright posi- tions. Which of the follow- ing is higher at the apex of the lung than at the base
airflow is less than the reduction in blood flow, when a person is upright?
so that the ratio at the top of the lung is greater than it is at the bottom. The increased ratio at the apex makes PACO2 lower and PAO2 higher than they are at the base.
25. 202. The answer is a
Lymph flow is proportional to the amount of fluid filtered out of the capillaries. The amount of fluid filtered out of the capillaries depends on the Starling forces and capillary perme- ability. Increasing capillary oncotic pressure directly decreases filtration by increasing the hydrostatic (osmotic) force drawing water into the capillary. Increasing capillary pressure, capillary permeability, and interstitial protein concentration (oncotic pressure) all directly increase lymph flow. When venous pressure is increased, the capillary hydrostatic pressure is increased and, again, capillary filtration is in- creased. Lymph flow is normally approximate- ly 2 to 3 L per day.
a. Blood flow
b. Lung compliance
c. PaCO2
d. Ventilation
e. V/Q ratio
202. A 65-year-old smok- er develops a squamous cell bronchogenic carcino- ma that metastasizes to the tracheobronchial and parasternal lymph nodes. The chest x-ray is consis- tent with accumulation of fluid in the pulmonary in- terstitial space. Flow of flu- id through the lymphatic vessels will be decreased if there is an increase in which of the following?
a. Capillary oncotic pres-
sure
b. Capillary permeability
c. Capillary pressure
26. The answer is A
Respiratory muscles consume oxygen in pro- portion to the work of breathing. The work of breathing is equal to the product of the change in volume for each breath and the change
in pressure necessary to overcome the resis- tive work of breathing and the elastic work
of breathing. Resistive work includes work to overcome tissue as well as airway resistance; thus, a decreased airway resistance will de- crease the work of breathing and the oxygen consumption of the respiratory muscles. A de- creased lung compliance would increase the elastic work of breathing. An increase in respi- ratory rate or tidal volume increases the work of breathing.
27. 206. The answer is c
When the pleura and hence the lung-chest wall system are intact, the inward elastic recoil of the lung opposing the outward elastic recoil of the chest wall results in a subatmospheric (negative) pressure within the pleural space.
When one reaches lung volumes in excess of approximately 70% of the total lung capacity, the chest wall recoil is also inward.
d. V per min/Q per min
e. Central venous pres- sure
f. Interstitial protein con- centration
204. A 57-year-old woman presents with dyspnea on exertion. Pulmonary func- tion studies with plethys- mography demonstrate an increased resting oxygen consumption and work of breathing. Which of the fol- lowing will decrease the oxygen consumption of the respiratory muscles?
a. A decrease in airway re-
sistance
b. A decrease in diffusing capacity of the lung
c. A decrease in lung com- pliance
d. An increase in rate of respiration
e. An increase in tidal vol- ume
206. A 48-year-old coal miner complains of short- ness of breath and a pro- ductive cough. He has smoked one to two packs of cigarettes per day since he was 16 years old. Pul- monary function studies are ordered, including an esophageal balloon study to measure intrapleural
28. 209. The answer is b.
pressures. Normally, in- trapleural pressure is neg- ative throughout a tidal inspiration and expiration because of which of the following?
a. The lungs have the ten- dency 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.
209. Several months after recovering from mononu-
Respiratory muscle paralysis causes an acute, cleosis, a 26-year-old man
uncompensated respiratory acidosis. The pri- mary disturbance is an elevation in arterial PCO2 due to alveolar hypoventilation from the impaired mechanics of breathing. The hyper- capnia lowers the ratio of HCO3 to dissolved CO2 in the plasma, and thus lowers the pH ac- cording to the Henderson-Hasselbalch equa- tion. In acute respiratory acidosis, the plasma HCO3 concentration increases 1 mmol/L for every 10 mm Hg increase in PaCO2 due to in- tracellular buffering. In chronic respiratory aci- dosis (eg, in COPD), the kidneys compensate
develops weakness and tingling in both legs. Three days later, he is hospi- talized when his legs be- come paralyzed. A con- duction block in the pe- ripheral A²,sensory fibers and the finding of autoan- tibodies to Schwann cell gangliosides confirm the diagnosis of Guillain-Bar-
re syndrome. The next day
for the acidosis by increasing the net excre- tion of H+, which increases the plasma HCO3 by 0.4 mmol/L for every mm Hg increase in PaCO2, which helps return the pH back into the normal range (choice c). The interpretation of choice a is metabolic acidosis, in which there is a lower than normal pH due to a primary
the weakness and paral- ysis ascended to his up- per extremities and trunk. Stat arterial blood gas re- sults indicated the need for mechanical ventilation. Which of the following sets
decrease in plasma HCO3, with compensatory of values is consistent with
hyperventilation that decreases arterial PCO2. acute respiratory muscle
Choice d represents acute respiratory alkalo- sis, in which hyperventilation lowers arterial PCO2 and increases arterial pH; plasma HCO3 decreases 0.2 mmol/L for every mm Hg de- crease in PaCO2 due to intracellular buffering. Choice e is compensated metabolic alkalosis.
paralysis?
29. 210. The answer is c. (Le, p 550. Levitzky, pp 23, 210. A 37-year-old woman
171-173. Longo, p 278.) Kyphoscoliosis is a de- formity of the spine involving both lateral dis- placement (scoliosis) and anteroposterior an- gulation (kyphosis), which decrease the com- pliance of the chest wall. Decreased chest wall compliance and respiratory muscle weakness cause inadequate alveolar ventilation, which leads to an accumulation of carbon dioxide and a decrease in arterial pH (respiratory aci- dosis). Restrictive impairments are character- ized by a decrease in all lung volumes and capacities, but a normal or increased ratio of FEV1 to FVC.
is admitted to the hospi- tal with severe kyphoscol- iosis and respiratory mus- cle weakness. Which of the following physiological variables is most likely de- creased in this patient?
a. Airway resistance
b. Alveolar surface tension
c. Arterial carbon dioxide tension
d. Chest wall compliance
e. FEV1/FVC
30. 213. The answer is d (Levitzky, pp 65-67, 73-75, 213. An 83-year-old
171-172.) A decrease in alveolar ventilation results in an increased PaCO2. Alveolar hy- poventilation in this patient is likely due to shallow breathing from abdominal pain or de- pressed respirations secondary to pain med- ication. A decrease in metabolic activity would decrease the rate of production of carbon
woman is found unrespon- sive by her son approxi- mately 3 hours after she returned to her hospital room following gall blad- der surgery. The nurse re- ported that the patient had
dioxide (VCO2), which would decrease PaCO2, asked for her pain medica-
assuming that alveolar ventilation does not change. V/q inequality causes hypoxemia, and thus reflex hyper-ventilation. At a constant tidal volume and respiratory rate, a decrease in the dead space volume would increase alve- olar ventilation, and thus lower the PaCO2.
31. 214. The answer is c. (Levitzky, pp 90-102, 105-107.) Increasing cardiac output causes
PVR to passively decrease due to two mecha- nisms— distention of perfused vessels and re- cruitment of more parallel vascular beds. Car- diac output is often elevated in septic shock, which differentiates it from hypovolemic and cardiogenic shock. Decreasing alveolar PO2 causes hypoxic pulmonary vasoconstriction and a rise in PVR. Increasing alveolar PCO2 or pulmonary artery H+ concentration also caus- es PVR to rise. The sympathetic nervous sys-
tions and said she was go- ing to rest for a while. Arte- rial blood gases reveal hy- percapnia 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 con- dition progresses rapidly to septicemia and sep-
tic shock. He is transport-
tem exerts little effect on PVR under physiolog- ed to the ICU, intubated,
ic conditions, but stimulation of sympathetic nerves will constrict the pulmonary vessels,
and started on mechanical ventilation. A Swan-Ganz
causing increased PVR. At high lung volumes, catheter is inserted to
the pulmonary capillaries ("alveolar" vessels) are stretched and compressed causing an in- creased PVR; this is true with spontaneous respirations and occurs even more so with positive pressure ventilation.
monitor pulmonary hemo- dynamics and lung flu-
id balance. Which of the following conditions will cause a decrease in PVR?
a. Alveolar hypoxia
32. 215. The answer is a.. (Barrett, pp 666-669. Levitzky, pp 228-233). During moderate aerobic exercise, oxygen consumption and CO2 pro- duction increase, and alveolar ventilation in- creases in proportion. Thus, PaCO2 (and PaO2) does not change. Arterial pH and blood lactate concentration are also normal during moder- ate aerobic exercise, but during anaerobic ex- ercise, which is reached at workloads that ex- ceed approximately 60% of the maximal work- load (called the anaerobic threshold), there is increased production of muscle lactic acid, which spills over into the circulation, causing an increase in the concentration of arterial lac- tate and a decrease in the pH of the blood.
33. 216. The answer is d (Levitzky, pp 130-140. Longo, pp 456, 898-900.) The diffusing capacity is the volume of gas transported across the lung per minute per mm Hg partial pressure difference. Diffusing capacity is measured by measuring the transfer of oxygen or carbon monoxide across the alveolar-capillary mem- brane. Because the partial pressure of oxy- gen and carbon monoxide is affected by their chemical reactions with hemoglobin, as well as their transfer through the membrane, the diffusing capacity of the lung is determined
b. Decreased pH in the pul- monary artery
c. Increased cardiac out- put
d. Inflation of the lungs to total lung capacity
e. Sympathetic stimulation of the pulmonary vessels
215. A healthy 32-year-old woman undergoes pul- monary exercise stress testing prior to starting
a training regimen in preparation for her first marathon. Normally, dur- ing moderate aerobic exer- cise, which of the following occurs?
a. Alveolar ventilation in- creases
b. Arterial pH decreases
c. Arterial lactate level in- creases
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. Pul- monary function tests re- veal an increase, rather than a decrease, in the dif- fusing capacity of the lung.
both by the diffusing capacity of the mem- brane itself and by the reaction with hemoglo- bin. Increases in the diffusing capacity can be produced by increasing the concentration of hemoglobin within the blood (polycythemia). The approach to the patient with polycythemia includes determination of not only hematocrit but also red cell mass, erythropoietin lev-
els, arterial oxygen saturation, and hemoglo- bin's affinity for oxygen in order to distinguish among the various causes. The diffusing ca- pacity of the membrane can be calculated by rearranging Fick law of diffusion, and is related to the ratio of the surface area available for diffusion and the thickness of the alveolar-cap- illary interface. The area available for diffusion is decreased by alveolar-septal departitioning in emphysema and by obstruction of the pul- monary vascular bed by pulmonary emboli.
The thickness of the diffusional barrier is in-
creased by interstitial fibrosis and by intersti- tial or alveolar edema found in CHF.
34. 217. The answer is e. (Kaufman, p 272. Lev-
Which of the following con- ditions 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
itzky, pp 153-154, 183.) The decrease in arterial develops headache and
oxygen saturation caused by carbon monox- ide poisoning reduces the oxyhemoglobin and thus total arterial oxygen contents but does not reduce the amount of oxygen dissolved in the plasma, which determines the arterial oxygen tension. Carbon monoxide is odorless and tasteless, and dyspnea and respiratory distress are late signs, which is the reason why it is so important to install carbon monox- ide detectors in homes and businesses. Res- piratory distress becomes manifest with se- vere tissue hypoxia and anaerobic glycolysis, which leads to lactic acidosis. The decrease in arterial pH stimulates ventilation via the pe-
becomes dizzy after work- ing on a tractor in his barn. His wife suspects carbon monoxide poison- ing and brings him to
the emergency depart- ment where he complains of dizziness, lightheaded- ness, headache, and nau- sea. The patient's skin is red, he does not appear to be in respiratory dis- tress, and denies dysp- nea. Blood levels of car-
ripheral chemoreceptors. The resultant hyper- boxyhemoglobin are ele-
ventilation decreases arterial (and CSF) PCO2, vated. Which of the follow-
causing CSF pH to rise. Carboxyhemoglobin has a cherry-red color.
35. 218. The answer is e. (Levitzky, pp 20-28.) Lung compliance is an index of lung distensibility or the ease with which the lungs are expand- ed; thus, compliance is the inverse of elastic recoil. Compliance is defined as the ratio of change of lung volume to the change in pres-
ing best explains the ab- sence of respiratory signs and symptoms associated with carbon monoxide poi- soning?
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 compli-
sure required to inflate the lung ( V/ P). Coma-nce. Which of the fol-
pliance decreases in patients with pulmonary edema or surfactant deficiency and increases when there is a loss of elastic fibers in the lungs, such as occurs in patients with emphy- sema and with aging.
lowing statements best characterizes lung compli- ance?
a. It decreases with ad- vancing age.
b. It increases when there is a deficiency of surfac- tant.
c. It increases in patients with pulmonary edema.
d. It is equivalent to P/ V.
e. It is inversely related to the elastic recoil proper- ties of the lung.
36. 219. The answer is c. (Barrett, pp 661, 665-667. 219. A 36-year-old man
Levitzky, pp 207-209.) The central chemorecep- tors, located at or near the ventral surface of the medulla, are stimulated to increase ventila- tion by a decrease in the pH of their extracellu- lar fluid (ECF). The pH of the ECF is affected by the PCO2 of the blood supply to the medullary chemoreceptor area, as well as by the CO2 and lactic acid production of the surround- ing brain tissue. The central chemoreceptors are not stimulated by decreases in PaO2 or blood oxygen content but rather depressed by long-term or severe decreases in oxygen supply.
37. 220. The answer is e. (Le, pp 233, 544, 564.
Levitzky, pp 32-36, 49-50.) Methacholine is a cholinergic agonist, which causes constric- tion of bronchial smooth muscle. Bronchocon- striction reduces airway radius, which increas- es airway resistance, and thus the resis-
tive work of breathing. Methacholine-induced [Show Less]