Husband has been immobile on the couch for six days without getting up and is drinking alcohol. will the alcohol help prevent a blood clot?

I'm sorry about him: It's impossible to stop someone from drinking, but this may be something else -- anything from thyroid disease to depression to the onset of major mental illness / catatonia. Blood clots in the legs aren't the principal concern. Ask his physician about whether he might be admitted for evaluation. Be strong and I will be thinking of you in the days ahead.