How does a sick person make up for missed prayers while staying in the hospital for surgery? And is expiation (kaffarah) obligatory upon him?

If the father lost consciousness during the operation, there is a difference of opinion among scholars regarding the obligation of making up the prayers. The Hanbalis obligated making them up absolutely. The Malikis and Shafi'is did not obligate it. The Hanafis obligated it if it did not exceed five prayers. Although the view that there is no obligation to make up prayers for someone who lost consciousness is strong, making them up is more cautious.

However, if he did not lose consciousness, then it was obligatory for him to perform the prayers at their prescribed times according to his ability: standing, or sitting, or on his side, or by gesturing with his head, or by blinking. Since he did not do so, he must immediately make up those prayers in their proper order. There is no expiation for him other than seeking forgiveness, regretting it, and resolving not to return to such an act.