pulmo 6 - darkhorse

[ArchivalUser]

A 54-year-old male presents to your clinic complaining of dyspnea on exertion. The patient notes that he
previously was quite active despite having had poliomyelitis at age 14. He was left with no chronic motor
impairments, although he remembers being confined to an "iron lung" for 6 months. One year ago the
patient played tennis three time weekly and jogged 3 miles a day; now he cannot jog a mile. He also
notes that he is unable to sleep flat at night because of dyspnea. On physical examination, the patient
appears well developed and has no obvious difficulty with speech. When the patient lies flat, paradoxical
abdominal motion is seen. On chest examination there are no crackles, wheezes, or rhonchi. However,
usual thoracic expansion with inspiration is not seen and diaphragmatic excursion is not appreciated.
Which of the following statements about the patient's condition is true?

A. An elevation in the alveolar-arterial (A-a) gradient is expected.
B. The patient's baseline PaCO2 while awake is invariably elevated.
C. A cuirass is a form of positive-pressure ventilation that may be used to assist the patient with
nocturnal ventilation.
D. The patient's maximal voluntary ventilation is normal.
E. The presence of respiratory muscle dysfunction during the original presentation of polio increases the
likelihood that the patient will develop chronic respiratory difficulties with postpolio syndrome

[ArchivalUser]

A----

[ArchivalUser]

C or E ?
E.

[ArchivalUser]

e.

[ArchivalUser]

The answer is E.



Patients who develop postpolio syndrome tend to have affliction of the same muscle groups that were
affected in the original presentation. This patient presents with symptoms of diaphragmatic muscle
weakness 40 years after the initial presentation with poliomyelitis. The initial presentation was
complicated by respiratory muscle weakness as evidenced by his need for negative-pressure ventilation
in an "iron lung." Diaphragmatic muscle weakness can present insidiously with dyspnea on exertion and
orthopnea as primary complaints as a result of the actions of accessory muscles. Physical examination
may reveal accessory muscle use, paradoxical abdominal motion, and lack of diaphragmatic excursion
with inspiration. The diagnosis can be confirmed by electromyography of the diaphragm with nerve
conduction studies of the phrenic nerve, measurement of maximum inspiratory and expiratory pressures,
fluoroscopy of the diaphragm during sniff maneuver, or measurement of transdiaphragmatic pressure
with esophageal and gastric balloons. Maximum voluntary ventilation shows early fatigability. Early in the
process, symptoms are most pronounced at night because the accessory muscles contract with less vigor
during sleep. PaCO2 usually rises nocturnally but may normalize during the daytime hours early in the
disease. The ability for gas exchange is not affected, and the alveolar-arterial oxygen gradient should be
normal although hypoxemia may be present if significant hypoventilation occurs. Lung mechanics are
altered, and there is decreased vital capacity and lung compliance. Most patients with postpolio
syndrome ultimately become dependent on ventilation at least nocturnally, although some require
continuous mechanical ventilatory support. A cuirass is a form of negative-pressure ventilation that is
used infrequently. More commonly patients receive positive-pressure support ventilation through a nasal
mask or tracheostomy.

[ArchivalUser]

I agree its E