MedCosmos Surgery
Surgery Lecture Notes, Books, MCQ and Good Articles
Saturday, September 6, 2008
Thoracic Surgery MCQ
1. The bronchial circulation:
A. Is the blood supply to the conducting airways.
B. Drains into a peribronchial venous network that may expand
considerably with conditions such as bronchiectasis and chronic
obstructive pulmonary disease.
C. Is an especially important consideration in pulmonary
transplantation.
D. All of the above.
Answer: D
DISCUSSION: The bronchial circulation is the primary blood supply for
the conducting airways, pulmonary vessels, lymphoid tissue, and
squamous cell carcinomas. In conditions such as mitral stenosis,
bronchiectasis, or chronic obstructive pulmonary disease, the rich
peribronchial venous network that drains the bronchial circulation
may expand considerably, creating significant left-to-right shunts.
Whenever the pulmonary artery circulation is obstructed, there is a
tendency for bronchial circulation to increase; thus, the bronchial
circulation is an important consideration during lung transplantation
as well as in the surgical treatment of cyanotic congenital heart
disease and chronic pulmonary embolism.
2. Clearance of mucus produced in the tracheobronchial tree in
chronic bronchitis secondary to smoking may:
A. Be hampered by the fact that the amount of mucus is increased by
the number of mucus-producing cells at the expense of ciliated cells.
B. Be slowed if patients have decreased lung volume and are
therefore unable to generate a vigorous cough that would cause an
inflammatory process.
C. Cause a decrease in diffusion capacity and associated hypoxemia.
D. All of the above.
Answer: A
,DISCUSSION: Chronic bronchitis may have an acute component, and
in these patients therapy with antibiotics and bronchodilators may
improve the flow rate as measured by pulmonary function tests
within 3 or 4 days of the cessation of smoking and treatment of the
acute condition. However, the chronic bronchitic will continue to
produce large amounts of mucus, most evident in the morning, even
after the acute process has been resolved. Clearance of these
secretions is hampered by the inability to cough, perhaps secondary
to the pain of thoracotomy or abdominal surgery or by a decrease in
the number of ciliary cells that help move mucus up the
tracheobronchial tree. This causes plugging of small airways and
atelectasis, which may progress to pneumonia. For this reason,
cessation of smoking for 3 to 5 days before surgery is very beneficial
in preventing pulmonary complications during the postoperative
period.
3. The pulmonary circulation:
A. Is the only vascular system in which the veins do not have the same
course as the arteries.
B. Has a direct connection of vein to adjacent lung tissue by
connective tissue fibers, making the diameter of the tissue fibers
dependent upon lung volume.
C. Supplies the metabolic needs of the alveoli.
D. All of the above.
Answer: C
DISCUSSION: Pulmonary artery circulation transports oxygenated
blood to the alveoli level where gas exchange occurs, and it is here
that the matching of ventilation and perfusion is so important during
the postoperative period. The loss of lung volume that generally
occurs after all surgical procedures does not return to baseline for 5
to 7 days and may play an important role in the ventilation-perfusion
ratio. Improving or returning lung volume to normal is performed by
manipulating functional residual capacity (FRC) and preventing
atelectasis, which in turn maintains circulation to the alveolus and
optimizes the ventilation-perfusion ratio.
4. Which of the following screening tests are important for
preoperative evaluation of pulmonary function?
A. History and physical examination.
B. Room air arterial blood gases.
C. Chest film.
D. Vital capacity and forced expiratory volume in 1 second (FEV 1).
E. Cardiopulmonary exercise testing.
Answer: ABCDE
,DISCUSSION: The most important clues to impairment of respiratory
function are found in the history and physical examination. A negative
history and physical examination in combination with a relatively
normal room air arterial blood gas and normal chest film are
sufficient to screen patients to support the clinical impression that
there is minimal pulmonary disease. Patients with symptoms, positive
physical findings, and/or abnormalities in the arterial blood gases or
chest film can be screened most effectively with an additional
evaluation of the vital capacity and FEV 1. More elaborate tests such
as cardiopulmonary exercise testing are reserved for patients with
obvious and marked impairment of pulmonary function who are
being evaluated for the feasibility of surgical intervention.
5. Carbon monoxide diffusion capacity (DLCO) has been shown to
correlate with:
A. The thickness of the alveolar lining membrane.
B. The permeability of the erythrocyte to carbon dioxide.
C. Pulmonary emboli.
D. Total alveolar-capillary capacity.
Answer: ABCD
DISCUSSION: The single-breath DLCO is a screening test that has been
shown to be decreased in all of the above examples. It is an estimate
of the total capacity of the functional alveolar microarchitecture and
has been demonstrated to be an independent measure of physiologic
capability apart from the FEV 1 and forced ventilatory capacity.
6. The closing volume is:
A. The volume remaining in the lung at the end of expiration below
which alveolar collapse begins to occur, resulting in physiologic
shunting.
B. Higher in young persons.
C. Not changed during surgery.
D. Relative to the oxygen content of mixed venous blood.
Answer: AC
DISCUSSION: The closing volume is conceptually the remaining lung
volume at the end of expiration below which alveolar collapse begins
to occur, causing intrapulmonary right-to-left shunting and thus
desaturation of blood in the left atrium. In a normal young person this
closing volume is well below the functional residual capacity (FRC);
thus, such physiologic shunting does not occur until there is a
decrease in the elastic properties of the lung. Although FRC gradually
increases with age, so does the effective closing volume. Eventually
, some alveoli are being underventilated (at end-expiration), allowing
physiologic right-to-left shunting to occur. Closing volume is
unchanged, but FRC decreases during surgery (i.e., shunting occurs).
Closing volume has no direct relationship to the oxygen content of the
mixed venous blood.
7. The effect of high positive end-expiratory pressures (PEEP) on
cardiac output is:
A. None.
B. Increased cardiac output.
C. Decreased cardiac output because of increased afterload to the left
ventricle.
D. Decreased cardiac output because of decreased effective preload
to the left ventricle.
Answer: D
DISCUSSION: Higher levels of PEEP can be associated with decreases
in cardiac output as a consequence of an effective decrease in the
preload to the left ventricle owing to impaired left ventricular filling.
8. Weaning patients from maximum ventilator support usually
involves:
A. Weaning PEEP first, tidal volume second, and the fraction of
inspired oxygen (FIO 2) third.
B. Weaning FIO 2 first, ventilator rate second, and PEEP third.
C. Weaning FIO2 first, PEEP second, and tidal volume third.
D. Weaning FIO 2 first, PEEP second, and ventilator rate third.
Answer: D
DISCUSSION: When the inspired oxygen concentration is greater than
60% for more than 24 to 28 hours, the risk of oxygen toxicity
increases. PEEP is usually weaned to physiologic levels (i.e., 5 to 7 cm.
H 2O) before weaning either rate or tidal volumes. Generally, the
optimal tidal volume to achieve alveolar recruitment is selected and
usually is not decreased unless peak airway pressures increase. If
decreases in ventilatory rate are not tolerated, airway pressure
support can be added.
9. Which of the following statements about bronchoscopy is false?
A. The morbidity and mortality are approximately 0.2% and 0.08%,
respectively.
B. The most common complications of bronchoscopy are related to
premedication of patients.
C. Adjunctive cancer therapy such as laser treatment and
Surgery Lecture Notes, Books, MCQ and Good Articles
Saturday, September 6, 2008
Thoracic Surgery MCQ
1. The bronchial circulation:
A. Is the blood supply to the conducting airways.
B. Drains into a peribronchial venous network that may expand
considerably with conditions such as bronchiectasis and chronic
obstructive pulmonary disease.
C. Is an especially important consideration in pulmonary
transplantation.
D. All of the above.
Answer: D
DISCUSSION: The bronchial circulation is the primary blood supply for
the conducting airways, pulmonary vessels, lymphoid tissue, and
squamous cell carcinomas. In conditions such as mitral stenosis,
bronchiectasis, or chronic obstructive pulmonary disease, the rich
peribronchial venous network that drains the bronchial circulation
may expand considerably, creating significant left-to-right shunts.
Whenever the pulmonary artery circulation is obstructed, there is a
tendency for bronchial circulation to increase; thus, the bronchial
circulation is an important consideration during lung transplantation
as well as in the surgical treatment of cyanotic congenital heart
disease and chronic pulmonary embolism.
2. Clearance of mucus produced in the tracheobronchial tree in
chronic bronchitis secondary to smoking may:
A. Be hampered by the fact that the amount of mucus is increased by
the number of mucus-producing cells at the expense of ciliated cells.
B. Be slowed if patients have decreased lung volume and are
therefore unable to generate a vigorous cough that would cause an
inflammatory process.
C. Cause a decrease in diffusion capacity and associated hypoxemia.
D. All of the above.
Answer: A
,DISCUSSION: Chronic bronchitis may have an acute component, and
in these patients therapy with antibiotics and bronchodilators may
improve the flow rate as measured by pulmonary function tests
within 3 or 4 days of the cessation of smoking and treatment of the
acute condition. However, the chronic bronchitic will continue to
produce large amounts of mucus, most evident in the morning, even
after the acute process has been resolved. Clearance of these
secretions is hampered by the inability to cough, perhaps secondary
to the pain of thoracotomy or abdominal surgery or by a decrease in
the number of ciliary cells that help move mucus up the
tracheobronchial tree. This causes plugging of small airways and
atelectasis, which may progress to pneumonia. For this reason,
cessation of smoking for 3 to 5 days before surgery is very beneficial
in preventing pulmonary complications during the postoperative
period.
3. The pulmonary circulation:
A. Is the only vascular system in which the veins do not have the same
course as the arteries.
B. Has a direct connection of vein to adjacent lung tissue by
connective tissue fibers, making the diameter of the tissue fibers
dependent upon lung volume.
C. Supplies the metabolic needs of the alveoli.
D. All of the above.
Answer: C
DISCUSSION: Pulmonary artery circulation transports oxygenated
blood to the alveoli level where gas exchange occurs, and it is here
that the matching of ventilation and perfusion is so important during
the postoperative period. The loss of lung volume that generally
occurs after all surgical procedures does not return to baseline for 5
to 7 days and may play an important role in the ventilation-perfusion
ratio. Improving or returning lung volume to normal is performed by
manipulating functional residual capacity (FRC) and preventing
atelectasis, which in turn maintains circulation to the alveolus and
optimizes the ventilation-perfusion ratio.
4. Which of the following screening tests are important for
preoperative evaluation of pulmonary function?
A. History and physical examination.
B. Room air arterial blood gases.
C. Chest film.
D. Vital capacity and forced expiratory volume in 1 second (FEV 1).
E. Cardiopulmonary exercise testing.
Answer: ABCDE
,DISCUSSION: The most important clues to impairment of respiratory
function are found in the history and physical examination. A negative
history and physical examination in combination with a relatively
normal room air arterial blood gas and normal chest film are
sufficient to screen patients to support the clinical impression that
there is minimal pulmonary disease. Patients with symptoms, positive
physical findings, and/or abnormalities in the arterial blood gases or
chest film can be screened most effectively with an additional
evaluation of the vital capacity and FEV 1. More elaborate tests such
as cardiopulmonary exercise testing are reserved for patients with
obvious and marked impairment of pulmonary function who are
being evaluated for the feasibility of surgical intervention.
5. Carbon monoxide diffusion capacity (DLCO) has been shown to
correlate with:
A. The thickness of the alveolar lining membrane.
B. The permeability of the erythrocyte to carbon dioxide.
C. Pulmonary emboli.
D. Total alveolar-capillary capacity.
Answer: ABCD
DISCUSSION: The single-breath DLCO is a screening test that has been
shown to be decreased in all of the above examples. It is an estimate
of the total capacity of the functional alveolar microarchitecture and
has been demonstrated to be an independent measure of physiologic
capability apart from the FEV 1 and forced ventilatory capacity.
6. The closing volume is:
A. The volume remaining in the lung at the end of expiration below
which alveolar collapse begins to occur, resulting in physiologic
shunting.
B. Higher in young persons.
C. Not changed during surgery.
D. Relative to the oxygen content of mixed venous blood.
Answer: AC
DISCUSSION: The closing volume is conceptually the remaining lung
volume at the end of expiration below which alveolar collapse begins
to occur, causing intrapulmonary right-to-left shunting and thus
desaturation of blood in the left atrium. In a normal young person this
closing volume is well below the functional residual capacity (FRC);
thus, such physiologic shunting does not occur until there is a
decrease in the elastic properties of the lung. Although FRC gradually
increases with age, so does the effective closing volume. Eventually
, some alveoli are being underventilated (at end-expiration), allowing
physiologic right-to-left shunting to occur. Closing volume is
unchanged, but FRC decreases during surgery (i.e., shunting occurs).
Closing volume has no direct relationship to the oxygen content of the
mixed venous blood.
7. The effect of high positive end-expiratory pressures (PEEP) on
cardiac output is:
A. None.
B. Increased cardiac output.
C. Decreased cardiac output because of increased afterload to the left
ventricle.
D. Decreased cardiac output because of decreased effective preload
to the left ventricle.
Answer: D
DISCUSSION: Higher levels of PEEP can be associated with decreases
in cardiac output as a consequence of an effective decrease in the
preload to the left ventricle owing to impaired left ventricular filling.
8. Weaning patients from maximum ventilator support usually
involves:
A. Weaning PEEP first, tidal volume second, and the fraction of
inspired oxygen (FIO 2) third.
B. Weaning FIO 2 first, ventilator rate second, and PEEP third.
C. Weaning FIO2 first, PEEP second, and tidal volume third.
D. Weaning FIO 2 first, PEEP second, and ventilator rate third.
Answer: D
DISCUSSION: When the inspired oxygen concentration is greater than
60% for more than 24 to 28 hours, the risk of oxygen toxicity
increases. PEEP is usually weaned to physiologic levels (i.e., 5 to 7 cm.
H 2O) before weaning either rate or tidal volumes. Generally, the
optimal tidal volume to achieve alveolar recruitment is selected and
usually is not decreased unless peak airway pressures increase. If
decreases in ventilatory rate are not tolerated, airway pressure
support can be added.
9. Which of the following statements about bronchoscopy is false?
A. The morbidity and mortality are approximately 0.2% and 0.08%,
respectively.
B. The most common complications of bronchoscopy are related to
premedication of patients.
C. Adjunctive cancer therapy such as laser treatment and
