My mother has pneumonia and her lungs are also traumatized by a recent colonscopy, her po2 is 61. her oxygen saturation drops to 49 every now and then it comes back to 80,s and 90,s. she also had a cardiac arrest 2 days ago due to hypoxia. what to do?

It sounds as though your mother needs to be in a hospital, perhaps even in intensive care unit, to be sure that she is getting enough oxygen to her organs. Future plans will depend on how she is doing after she gets out of the hospital. Good luck.

Make sure you connect with her medical team as she might have suffered hypoxic brain damage. These are cases where a palliative care team may explain better what to expect and if a meaningful recovery is still possible. Hope for the best, prepare for all possibilities.