Garak is desperately trying to get Tain's subspace transmitter to connect with the runabout's transporter to rescue himself & his fellow prisoners.
But the space in the bulkhead is too small. Barely enough room to move, barely enough room to breath.
He starts talking to himself as a distraction; bad jokes, half-forgotten prayers, dirty limericks, anything he can think of.
It seems to be working. Then the lights go out.