How can I repair my O2 Generator in an oxygen deprived ship?

If my ship has 0% oxygen in it, how can I repair my O₂ generator if my crew wont live long enough to do so?

Note that I've already tried, and because of this I have 2 crew members stuck in my medbay holding even at 10% health each.

If I upgrade my medbay, it will heal my crew faster than the O₂ depletion hurts them, allowing me to take 2 crew members and send them to the O₂ generator and repair it fast enough to get back to the medbay and safety while my ship equalizes pressure.

Edit Advanced Edition: It's also worth noting that if you have Engi-Med Bot Dispersal and Emergency-Respirators you can last a HECK OF A LONG TIME in full vacuum.

If you expect to get into this sort of situation, repair bots are very useful as they don't require any oxygen. Similarly, in the Advanced Edition, you can also use repair bombs.

Another (more desperate) approach - acquire more crew!

If your engines are still online and fully charged, and you can get a crew member to the helm for long enough to click on Jump, and there happens to be a store in an adjacent system, you might be able to purchase a crew member, who'll join your ship at full health and may be able to repair your Oxygen system before asphyxiating.

Even if there isn't a store within range, it's possible that there's a 'free crew' event - (Advanced Edition - even better if you're in an abandoned sector and the new crew member happens to be Lanius). If you have the necessary scrap, see if you can upgrade any of your systems that would qualify for relevant blue options.