A 57-Year-Old Woman with Known Myasthenia Gravis Is Brought to the Emergency

question 195

Multiple Choice

A 57-year-old woman with known myasthenia gravis is brought to the emergency department after 2 weeks of progressively worsening weakness in her arms and legs, fatigue, and intermittent shortness of breath.  She could not eat breakfast today due to difficulty swallowing.  Her only other medical problem is hypertension, and her medications include pyridostigmine, olmesartan, and chlorthalidone.
The patient's blood pressure is 122/72 mm Hg, pulse is 78/min, respirations are 14/min, and oxygen saturation is 98% on room air.  Physical examination shows clear lung fields and normal first and second heart sounds.  There is no nasal flaring or usage of accessory respiratory muscles.  There is mild proximal weakness (4/5) in the arms and legs.  Pinprick and light touch sensations are intact.
Her vital capacity is 25 mL/kg.  Laboratory results include serum potassium of 3.8 mEq/L and serum creatinine of 0.8 mg/dL.  Her chest x-ray is clear.
Which of the following is the most appropriate way to monitor this patient's respiratory status?

• A)Arterial PCO₂
• B)Maximal inspiratory force
• C)Oxygen saturation
• D)Peak expiratory flow rate
• E)Respiratory rate

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Definitions:

Passing

The ability of an individual to be regarded as a member of an identity group or category different from their own, which can include racial identity, gender, or social class.

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