Yes, it’s common during and after surgery as patient under went Anesthetic drugs and to support the metabolic activity in the body and support the respiration, it’s essential

Yes it’s common for patient to feel less energetic after open umbilical hernia surgery,.as the incision is done little above umbilical might cause little difficulties in breathing especially elderly patients also because of pain patient tends to breathe shallow and many more reasons,.so as precautionary oxygen required post op..

Yes, it's common