What Treatment Is Suggested Post Transverebral Transposition?

My father is 63 years old and recently had a transvertebral transposition due to 100% occlusion (they grafted onto his carotid). He had a stroke a little over a year ago, and then recently had another episode of dizziness, loss of balance, and nausea which is what prompted this surgery. He s 5 days s/p surgery, and his voice is still very hoarse. He s also struggling with mucous and constantly coughing or clearing his throat which is making him almost lose his voice completely. Do you have any idea what the problem might be and if these problems will subside? I m concerned about a possibly respiratory infection and/or issues with his vocal cords. Thank you.