According to the latest update on Sarah Palin's Facebook page, Todd Palin is on a respirator. So that means he was not able to maintain satisfactory oxygenation levels with just the one lung inflated.
Sarah, who I doubt knows the implications of what she is writing, also states that "the chest tube is working overtime to drain his lung". And that they have decided not to perform several other surgeries - the shoulder blade fracture and the ACL in his knee.
If the shoulder blade is not displaced or not too badly displaced, they can delay for a while. The ACL repair, well that can happen later. I'd think they will want to see less drainage from the chest cavity prior to further surgery. They've already done the life-saving surgeries.
I feel really bad for him. He is still in a serious condition, that's for sure. And yes, there are things that can go wrong - such as blood clots and infections. It sounds like he is receiving excellent medical care. Serious chest injuries like this are very painful. And being on a respirator, while a life-saving device in this situation, comes with known dangers of its own.
When it was my loved one I know there were times that I wished I just did NOT even know as much as I did. Even though I do not agree with Sarah Palin's politics, I wish them both the best.