Master the board step 3

Pulmonology
··
If pleurodesis fails, decortication is performed. Decortication is the stripping
off of the pleura from the lung so it will stick to the interior chest wall.
This is an operative procedure.
Sleep Apnea
Look for an obese patient complaining of daytime somnolence. The patient’s
sleep partner will report severe snoring. In addition, there will be hypertension,
headache, erectile dysfunction, and a fat neck.
The majority (95 percent) of cases are obstructive sleep apnea from fatty tissues of
the neck blocking breathing. A small number of patients will have central sleep
apnea, which is decreased respiratory drive from the central nervous system.
Diagnostic Testing
Sleep apnea is diagnosed with a sleep study, polysomnography. The patient is
observed for periods of apnea lasting > 10 seconds each. The patient’s oxygen
saturation is also monitored. Mild sleep apnea is defined as 5–20 apneic periods
an hour. Severe sleep apnea is defined as > 30 periods an hour.
Treatment
Obstructive Disease
··
Treat with weight loss and continuous positive airway pressure (CPAP) or
BiPAP.
··
If this is not effective, surgical resection of the uvula, palate, and pharynx
can be performed.
Central Sleep Apnea
··
Central sleep apnea is managed by avoiding alcohol and sedatives.
··
It may respond to acetazolamide, which causes a metabolic acidosis. This
may help drive respiration.
··
Some patients respond to medroxyprogesterone, which is also a central
respiratory stimulant.
Basic Science Correlate
Mechanism of Acetazolamide
Acetazolamide is an inhibitor of carbonic anhydrase. This enzyme is needed
for reabsorption of bicarbonate that has been filtered at the glomerulus. In
the absence of carbonic anhydrase, the bicarbonate is urinated off and the
body becomes acidotic. Acidosis acts as a stimulant to the medulla to drive
respiration.
127