There is definite pressure loss, since the air (not just oxygen) is leaking out of the ship. I read on Wiki that humans can only survive complete depressurization for about 90 seconds, after which death may be unavoidable.
I have three variables as the air leaks out: time until they become unconscious, time until they die, and time until they can no longer be resuscitated. I'm hoping to keep the three to about ten minutes total. I have complete freedom for the first, which is based on the size of the leak.
I used a seatback to slow the air loss enough to set the three numbers above to 6, 9, and 11 minutes, although I pulled those three figures out of my hat. Since there is potentially significant loss of air until they slow the leak, the first number (time to unconsciousness) can be as short as I want (e.g., 2 minutes), leaving plenty of time for the other two variables.
I don`t want someone using their body to block the opening, since their pain/swelling then becomes the focus of the scene, which makes it unusable.
Finally, I'd like Apollo to be able to walk out unaided, since there are hundreds of his military arrayed on the deck of the flagship, and he doesn't want to be carried out in front of them. He can still show signs of decompression sickness, which can be treated in a hyperbaric chamber after the scene ends.
Given all that, are there any candidate figures for my three variables better than 6, 9, and 11? Perhaps 4, 9, and 11, to allow time for the heart to stop after 5 minutes of unconsciousness (9 - 4)?
Thanks.