My husband fell and broke his knee. They found blood clots in his lungs and can't operate until we deal with the clots.

Please check they’re not over-drugging him. That can also cause mental confusion. But if they are over-drugging, they’re unlikely to ever admit it.

Your wrote in your profile that your husband "is 73 years old, living at home with age-related decline, alzheimer's / dementia, and mobility problems."

Cwillie suggested to check for stroke (which might have caused his fall and may be connected to the clots in his lungs) and I agree.

Does he have a medical diagnosis of dementia?

Have they ruled out a UTI (was he catheterized)? I'm assuming they discounted pneumonia, so he's getting enough oxygen presumably. Also discount dehydration (is someone with him to make sure he is drinking and eating enough)? Does he have an IV in, can he keep one in? Could it be any meds he has been given that he's having a reaction to? Sometimes certain antibiotics don't play well with seniors. You will need to push the staff to work through possible other causes for his delirium. I wish you success in getting an accurate diagnosis and best care for him. Also, take care of yourself!

Start by getting him tested for a Urinary Tract Infection --these can cause all kinds of psychiatric-looking symptoms.

You might consider having him re-admitted to the hospital to find out what else might be going on-stroke is one possibility.

Has he had a CT scan to rule out stroke?