Hypothermia. You use far less oxygen if your metabolism has essentially ground to a halt.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4530563/

https://www.ncbi.nlm.nih.gov/pubmed/24837800

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4322114/

Part (or much? it's not clear) of that time, rescuers were performing CPR on her, working her heart and lungs for her, so she didn't go that entire span entirely without oxygen.