Pulm I Practice Questions
Which of the following statements concerning alveolar macrophages is true? (A) They secrete alpa 1-antitrypsin. (B) They secrete elastase. (C) They originate from blood neutrophils. (D) They may play a role in causing hyaline membrane disease. (E) They secrete small amounts of surfactant.
(B) They secrete elastase. -elastase can cause lung damage that leads to obstructive diseases -they arise from monocytes (m -->M) BRS Histology #6
Which one of the following disorders may in some cases be successfully treated with antielastase (alpha 1-antitrypsin}? (A) Asbestosis (B) Asthma (C) Carbon monoxide poisoning (D) Emphysema (E) Hyaline membrane disease
(D) Emphysema -this counteracts the effects of elastase to prevent further damage to alveoli BRS Histology #7
The Po2 (in mm Hg) inside skeletal muscle cells during exercise is closest to: A. 3 B. 10 C. 20 D. 30 E. 40
A. 3 mm Hg West Ch. 6
In the situation described in Question 2, (PO2 is 149 mm Hg, .21 fractional concentration) how much does the inspired O2 concentration (%) have to be raised to return the arterial Po2 to its original level? A. 7 B. 11 C. 15 D. 19 E. 23
A. 7 100 = PIO2 -(80/0.8) PIO2 = 199 mmHg 199/(760-47) = .28 fractional concentration difference would be 28-21= 7% West Ch. 5
A 45-year-old man is admitted with severe right lower lobe pneumonia and is placed on mechanical ventilation. On the 2nd hospital day, his hypoxemia worsens and a repeat chest radiograph shows increased opacities in both lungs. A blood gas reveals a pH of 7.47 and an arterial PO2 of 55 mm Hg while an echocardiogram demonstrates normal left ventricular function and left atrial size but significantly increased systolic pulmonary artery pressure. Which of the following factors likely accounts for the findings on his echocardiogram? A. Decreased alveolar PO2 B. Decreased arterial PO2 C. Decreased sympathetic nervous system activity D. Increased blood pH E. Increased pulmonary venous pressure
A. Decreased alveolar PO2 West Ch. 4
A 58-year-old woman with a long-standing use of ibuprofen for osteoarthritis presents to her doctor because of excessive tiredness. Laboratory studies reveal a hemoglobin concentration of 9 g·dl−1 (normal 13 to 15 g·dl−1). Which of the following abnormalities would you most likely observe? A. Decreased diffusing capacity for carbon monoxide B. Decreased functional residual capacity C. Decreased residual volume D. Increased physiologic dead space E. Increased ventilation to the upper lung zones
A. Decreased diffusing capacity for carbon monoxide -diffusing capacity of CO depends on vol. of blood in pulm capillary/volume of RBCs containing hemoglobin West Ch. 3
A patient with normal lungs but a right-to-left shunt is found at catheterization to have oxygen concentrations in his arterial and mixed venous blood of 18 ml·100 ml−1 and 14 ml·100 ml−1, respectively. If the O2 concentration of the blood leaving the pulmonary capillaries is calculated to be 20 ml·100 ml−1, what is his shunt as a percentage of his cardiac output? A. 23 B. 33 C. 43 D. 53 E. 63
B. 33 (20-18)/(20-14) = 2/6 West Ch. 5
If a climber on the summit of Mt. Everest (barometric pressure 247 mm Hg) maintains an alveolar Po2 of 34 mm Hg and is in a steady state (R ≤ 1), his alveolar Pco2 (in mm Hg) cannot be any higher than: A. 5 B. 8 C. 10 D. 12 E. 15
B. 8 PO2 = 0.21 * (247-47) = 42 mmHg alveolar PO2 = 42 - PCO2/.8 set equal to 0 to remain at 34 PCO2 cannot exceed 34 West Ch. 5
A 66-year-old woman presents with a 9-month history of worsening dyspnea on exertion. Spirometry reveals an FEV 1.0 that is significantly lower than predicted based on her age, height and gender, a lower than predicted FVC, and a decreased FEV1.0/FVC ratio. Which of the following could explain these results? A. Decreased number of pulmonary capillaries B. Decreased lung elastic recoil C. Fibrotic changes in the interstitial space D. Increased cross-sectional area for airflow E. Thickening of the blood-gas barrier
B. Decreased lung elastic recoil -decreased recoil leads to airway obstruction
A 26- year-old man presents to his physician complaining of progressive shortness of breath over the past week. He has had a dry, nonproductive cough. He has smoked one pack of cigarettes per day for 5 years. He was diagnosed recently with testicular cancer and treated with orchiectomy and bleomycin . Fine bilateral crackles are heard on lung auscultation . Pulmonary function is tested. Which of the following measurements (relative to normal) would be consistent with the patient's condition? A. Decreased residual volume and decreased FEV1:FVC B. Decreased residual volume and increased FEV1:FVC C. Decreased total lung capacity and decreased FEV1:FVC D. Increased residual volume and decreased FEV1:FVC E. Increased residual volume and increased FEV1:FVC F. Increased total lung capacity and increased FEV1: FVC
B. Decreased residual volume and increased FEV1:FVC pt presents with interstitial fibrosis, secondary to bleomycin, pt breathes at lower lung volume and decreased Residual volume leads to increased FEV1 USMLERX
If a small airway in a lung is blocked by mucus, the lung distal to this may become atelectatic. Which of the following statements is true? A. Atelectasis occurs faster if the person is breathing air rather than oxygen. B. The sum of the gas partial pressures in mixed venous blood is less than in arterial blood during air breathing. C. The blood flow to the atelectatic lung will rise. D. The absorption of a spontaneous pneumothorax is explained by a different mechanism. E. The elastic properties of the lung strongly resist atelectasis.
B. The sum of the gas partial pressures in mixed venous blood is less than in arterial blood during air breathing. -atelectasis faster when breathing pure oxygen -elastic properties do not help with collapse caused by absorption of gas West Ch. 9
Concerning the extra-alveolar vessels of the lung: A. Tension in the surrounding alveolar walls tends to narrow them. B. Their walls contain smooth muscle and elastic tissue. C. They are exposed to alveolar pressure. D. Their constriction in response to alveolar hypoxia mainly takes place in the veins. E. Their caliber is reduced by lung inflation.
B. Their walls contain smooth muscle and elastic tissue. -tension from alveolar walls tends to pull vessels open -these vessels are not exposed to alveolar pressure West Ch. 4
In a body plethysmograph, as a pt makes an expiratory effort against a closed glottis, what happens to box volume and pressure?
Box volume will increase and pressure will decrease West Ch. 2
In a measurement of FRC by helium dilution, the original and final helium concentrations were 10% and 6%, and the spirometer volume was kept at 5 liters. What was the volume of the FRC in liters? A. 2.5 B. 3.0 C. 3.3 D. 3.8 E. 5.0
C. 3.3 FRC = [(5*.10)/0.06] - 5 = 3.3L West Ch. 2
What is the relationship of the arteries to the airway in a bronchopulmonary segment? A. Arteries run alone in the center of the segments B. Arteries run with the airways at the periphery in the intersegmental space C. Arteries run with the airways in the center of the segments D. Arteries run with the lymphatics at the periphery in the intersegmental space E. Arteries run with the veins in the center of the segments
C. Arteries run with the airways in the center of the segments USMLERx #8
Concerning the diffusing capacity of the lung: A. It is best measured with carbon monoxide because this gas diffuses very slowly across the blood-gas barrier. B. Diffusion limitation of oxygen transfer during exercise is more likely to occur at sea level than at high altitude. C. Breathing oxygen reduces the measured diffusing capacity for carbon monoxide compared with air breathing. D. It is decreased by exercise. E. It is increased in pulmonary fibrosis, which thickens the blood-gas barrier.
C. Breathing oxygen reduces the measured diffusing capacity for carbon monoxide compared with air breathing. - reduces the measured diffusing capacity for CO because O2 competes for hemoglobin West Ch. 3
If a subject inhales several breaths of a gas mixture containing low concentrations of carbon monoxide and nitrous oxide: A. The partial pressures of carbon monoxide in alveolar gas and end-capillary blood will be virtually the same. B. The partial pressures of nitrous oxide in alveolar gas and end-capillary blood will be very different. C. Carbon monoxide is transferred into the blood along the whole length of the capillary. D. Little of the nitrous oxide will be taken up in the early part of the capillary. E. The uptake of nitrous oxide can be used to measure the diffusing capacity of the lung
C. Carbon monoxide is transferred into the blood along the whole length of the capillary. -Carbon monoxide is diffusion limited but is quickly taken up by Hb, therefore dissolved CO remains low ^this is the opposite for nitrous oxide (it is perfusion limited) West Ch. 3
In carbon monoxide poisoning, you would expect: A. Reduced arterial Po2. B. Normal oxygen concentration of arterial blood. C. Reduced oxygen concentration of mixed venous blood. D. O2 dissociation curve is shifted to the right. E. Carbon monoxide has a distinct odor.
C. Reduced oxygen concentration of mixed venous blood. -Concentration will change, not pressure West Ch. 6
A patient with lung disease who is breathing air has an arterial Po2 and Pco2 of 49 and 48 mm Hg, respectively, and a respiratory exchange ratio of 0.8. The approximate alveolar-arterial difference for Po2 (in mm Hg) is: A. 10 B. 20 C. 30 D. 40 E. 50
D. 40 PAO2 = PIO2 - (48/0.8) A-a= 89-49 = 40 West Ch. 5
The presence of hemoglobin in normal arterial blood increases its oxygen concentration approximately how many times? A. 10 B. 30 C. 50 D. 70 E. 90
D. 70 0.003*100 mL = 0.3 West Ch. 6
Pulmonary vascular resistance is reduced by: A. Removal of one lung B. Breathing a 10% oxygen mixture C. Exhaling from functional residual capacity to residual volume D. Acutely increasing pulmonary venous pressure E. Mechanically ventilating the lung with positive pressure
D. Acutely increasing pulmonary venous pressure -this raises capillary pressure and recruits /distends more capillaries, ultimately reducing PVR West Ch. 4
A 56-year-old woman is started on mechanical ventilation after presenting to the emergency department with acute respiratory failure. The ventilator is set to deliver a tidal volume of 750 mL 10 times per minute. After transfer to the ICU, the physician decreases her tidal volume to 500 mL and raises her respiratory rate to 15 breaths per minute. She is heavily sedated and does not initiate any breaths beyond what the ventilator gives to her (in other words, total ventilation is fixed). Which of the following changes would you expect to occur as a result of the physician's intervention? A. Decrease in the volume of the anatomic dead space B. Decrease in airway resistance C. Decrease in PaCO2 D. Increase in the dead space fraction E. Increase in CO2 production
D. Increase in the dead space fraction -dead space ventilation would increase West Ch. 2
Concerning the blood vessels of the human lung: A. The pulmonary veins form a branching pattern that matches that of the airways. B. The average diameter of the capillaries is about 50 μm. C. The bronchial circulation has about the same blood flow as does the pulmonary circulation. D. On average, blood spends about 0.75 s in the capillaries under resting conditions. E. The mean pressure in the pulmonary artery is about 100 mm Hg.
D. On average, blood spends about 0.75 s in the capillaries under resting conditions. E. The mean pressure in the pulmonary artery is about 100 mm Hg. -branching pattern of arteries, not veins, matches the airways -pulm artery pressure ~ 15 mmHg West Ch. 1
The most important stimulus controlling the level of resting ventilation is: A. Po2 on peripheral chemoreceptors B. Pco2 on peripheral chemoreceptors C. pH on peripheral chemoreceptors D. pH of CSF on central chemoreceptors E. Po2 on central chemoreceptors
D. pH of CSF on central chemoreceptors West Ch. 8
A 35 year-old man is found to have a large arteriovenous malformation (fistula) in one of the lowest segments of his right lower lobe. Which of the following changes would you expect to see when the patient changes from the supine to the upright position? A. Decreased alveolar Po2 B. Decreased alveolar-arterial oxygen difference C. Increased arterial Pco2 D. Increased dead-space fraction E. Increased shunt fraction
E. Increased shunt fraction -blood flow increase increases shunt fraction A-a difference will increase, no change in dead space West Ch. 5
How can you find ERV on spirometry graph?
ERV = FRC - RV
Does surgery improve survival for non-metastatic Small Cell Lung cancer?
No
What is the dead space equation?
VD = VT * [(PaCO2-PECO2)/PaCO2]
What is a clear distinguishing factor between CO poisoning and Cyanide poisoning in a pt?
With Cyanide poisoning, supplemental O2 will not help the pt- venous O2 saturation will be increased
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
a. A decrease in airway resistance -this decreases work of breathing Pre-test #204
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. Onehalf 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
a. Alveolar hypoventilation -pt will have chronic hypercapnia Pre-Test #190
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.
a. Cardiac contractility is lower than on the previous admission. - increased pulm. capillary hydrostatic pressure decreases net reabsorption in pulmonary capillaries Pre-Test #189
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.
a. Diffusing capacity of the lungs increases. -exercise increases surface area and diffusion Pretest #223
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: PAO2: 67 mmHg PaCO2: 60 mmHg pH: 7.27 [HCO3-]: 26 mEq/L [Hb]: 15 g% SaO2: 90% PVO2: 30 mmHg SVO2: 55% ValveolarO2: 350 mL./min. CaO2-CVO2: 7 mL O2/100 mL. 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
a. Hypoxic hypoxia (hypoxemia) -something about Cardiac Output difference Pre-test Physiology #178
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
b. Arterial pH -pectus excavatum (sunken sternum) indicates restrictive lung disease -ductus arteriosus remains open for about 48 hours after birth Pre-Test #193
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
b. Carotid body chemoreceptor reflex -signals travel via glossopharyngeal nerve Pre-test Physiology #177
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. V/Q ratio
b. FEV1/FVC ratio -increased recoil force of restrictive lung diseases produces a normal or increased FEV1/FVC ratio
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
b. Lung compliance Pre-test Physiology #179
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 V/Q 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.
b. The alveoli at the base of the lung are more compliant. -gravity makes these alveoli more compliant and intrapleural pressure LESS negative at bottom of the lung Pretest #221
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.
b. The pressure gradient required for airflow will increase. Pre-test Physiology #173
Stratified squamous epithelium line the ___________ but not the lungs.
bronchus
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
c. An increase in the PCO2 of blood flowing through the brain -central chemoreceptors: at or near the ventral surface of the medulla --> depressed by long-term/sever decrease in O2 supply, not stimulated by decreased PaO2 or blood O2 content Pretest #219
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
c. Arterial carbon dioxide tension -decreased metabolism --> decreased CO2 production Pretest #210
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
c. Increased cardiac output -increased CO leads to passive decrease in PVR secondary to distension of perfused vessels and recruitment of more parallel vascular beds -sympathetic nervous system does not normally impact PVR Pretest #214
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
c. Pulmonary blood flow Pre-test Physiology #184
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
d. 5625 mL/min *assumed dead space = 1 mL/lb (500-125) * 15 Pre-test Physiology #169
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
d. 665 mm Hg PAO2 = (1)*(757-47) - (36/0.8) Pre-test Physiology #172
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
d. Dysfunctional central chemoreceptors -obstructive sleep apnea: upper airway obstruction -> hypotonic pharyngeal or genioglossus muscles Pre-test #199
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. V/Q inequality
d. Hypoxemia -result of a restrictive impairment Pretest #213
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
d. Inspired lung volume -equal pressure point moves away from lungs with increased recoil/decreased volume -pressure point moves towards lungs if intrapleural pressure increases Pre-test #197
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: PaO2: 95 mmHg PaCO2: 33 mmHg pH: 7.46 [HCO3-]: 22 mEq/L. [Hb]: 15g% SaO2: 95% 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
d. Right-to-left shunting -O2 does not rise to expected level for 100% O2 administration Pre-test Physiology #180
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
e. An underlying diffusion impairment coupled with a decrease in pulmonary capillary transit time during exercise Pre-test Physiology #168
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
e. Arterial oxygen tension is normal -arterial O2 tension is determined by dissolved O2, which is not impacted by CO poisoning Pretest #217
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 ∆P/∆V. e. It is inversely related to the elastic recoil properties of the lung.
e. It is inversely related to the elastic recoil properties of the lung. Pretest # 218
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
e. Pre-Bötzinger complex in the ventral respiratory group -centers for breathing control are spread throughout the brain Pre-test #194
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
e. Resistive work of breathing -decreased anatomic dead space, no significant effect on lung compliance, therefore doesn't effect elastic work Pretest #220
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 transection 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.
e. The limbic system will no longer be able to exert any control over ventilation. -sites superior to pons would remain intact Pre-test #205
What pathophysiology and diagnostic timeline criteria are associated with chronic bronchitis?
hypertrophy of mucus secreting glands persistent cough for > 3 months for > 2 consecutive years
How does cyanide poisoning lead to hypoxia? How does this effect O2 sat?
impairs oxidative phosphorylation and O2 utilization O2 sat will be normal Pre-Test #191
What occupations are typically associated with silicosis?
mining, foundry work, glass making -small particles in lung
At which point of a flow-volume loop will the airflow remain constant despite increased effort?
slope from expiration to residual volume -only initial expiration is effort dependent
