Thanks for all of your responses, everyone. I went to see my primary care doctor today and he said that although my voice is gone, it seems like this cold sounds worse than it is. He said he doesn't hear any congestion in my chest and doesn't see nasal congestion, so he said it should be fine for tomorrow. He was more worried that my pre-admissions blood tests showed that I have low potassium! So, he prescribed some potassium to boost my levels before surgery tomorrow, and recommended rest and Mucinex. I'm already feeling better this evening, and my cough seems to have died down. Fingers crossed that everything goes well tomorrow morning!!!