7th February 2024

A 43-year-old female presents to the acute medical unit with bilateral ptosis and diplopia.

A 43-year-old female presents to the acute medical unit with bilateral ptosis and diplopia. She also demonstrates a reduction in strength in both arms with repeated movements. Anti-ACh receptor antibodies are detected. The consultant is concerned about her respiratory function due to shortness of breath and increased accessory muscle use. 

Derangement in which of the following lung capacity values is vital to determine the management of this patient?