dry cough after heart surgery

My father has  Mitral Valve repair and five bypasses  on Oct 4, 2011. He has chronic dry cough, he cannot sleep last night. Has hardtime breathing when lay down. He got discharged from hospital fifth day of his surgery.
I took him to hospital 2-3 times after surgery they said his lungs sounds ok so there is no need of x-ray. Any insights .

[justin61]

some medications like ace inhibitors can cause a dry cough, it might be a side effect of any medications that he is on

[rosco888]

What meds is your father taking?  I am convinced that Metoprolol following my failed angioplasty caused me to develop COPD.  I couldn't sleep lying down; couldn't walk far without stopping to gasp for air; was leaking urine all the time.  Now I'm on an inhaler for the rest of my life.

[Flycaster305]

It's also possible that his cough is the result of the breathing tube he had in his throat during and after the surgical procedure.