Sun21November1151AM 8

A 41-year-old man presents with generalised weakness, starting in the feet and hands, spreading up the limbs and now making swallowing difficult. He had an episode of food poisoning last week which has now resolved.

Which of the following results is most likely to predict the imminent need for invasive ventilation?

(Please select 1 option)

CSF protein count of 500 mg/dL

Positive anti-GD3 titre

Forced vital capacity of 1.4 L Correct

Nerve conduction studies consistent with Guillain-Barré syndrome

Peak expiratory flow rate of less than 50% predicted

Explanation

Guillain-Barré syndrome (GBS) is an acute peripheral ascending polyneuropathy. It often follows an infective trigger, commonly Cytomegalovirus, Campylobacter or influenza. Critical care support is often needed if there is respiratory muscle involvement, which presents with a restrictive-type pattern on spirometry.

The ratio of FEV1/FVC is normally well maintained and therefore measures of maximal expiratory effort (for example, peak flow) may give a falsely high reassuring reading. FVC is a more sensitive indicator of respiratory muscle dysfunction and a better indication of the need for ventilation.

Autonomic dysfunction is another potentially severe complication of GBS.

Although a raised protein CSF, nerve conduction studies consistent with Guillain-Barré syndrome and positive anti-GD3 titre are all investigations that support the diagnosis, they do not correlate with severity.

Answer Statistics

1

1%

2

2%

3

75%

4

4%

5

19%

Times answered: 308