Problems after on-pump byp surgery ?

5 days ago my grandpa(67) had on-pump byp surgury and the doctor has said that he has been progressing a little slow post surgury. Last night he tryed to get out of bed to go home and today he was yelling at my grandma and the nurses saying they we stealing his electronics and slapped the nurses arms and kept asking my cousin whos dog was running in his room but there was no dog and was throwing away trash that wasnt there..They determined that he has had multiple strokes and they said that this is the reason for his abnormal behavior...I was just wanting to know if this behavior and low mental capacity I should come to expect or if its more likely they are short term effects from the surgury and Stokes