question: dear sir,  I  am DR. Vasanta. my dad had undergone CABG 3 weeks back.post operatively he  developed pulmonary  edema and treated for the same . he is on lasix now. his lungs are clear. he has developed cough which is more in the night. cough followed by tachypnea.[episodic] he responds to linctus codeine.sometimes we sedate him with lorazepam and he is able to sleep. throught the day he is much comfortable. occassionally coughs.  post op his Xray, ECG, ECHO are normal. is this a broncho constriction ? what treatment should we give?   he is on  T. IVABRADINE, T.LASIX, T.SPIRINOLACCTONE, T.ATORVASTATIN,T.SORBITRATE, T.CLAVIX  Kindly giveyour opinion sir