What Is The Life Expectancy In A Person With Medically Induced Coma?

My father in law has been in a medically induced coma for 7 days ... He had surgery to amputate his leg a few weeks ago and then found out he had some heart problems during the surgery ... Now he just had open heart surgery 8 days ago and has been in a medically induced coma ever since ... What are the chances of his survival? He also has diabetes and he is 58 yrs old