How do you deal with angry patients (at hospital institute)?

You need to be calm, patience, and try to understand the patient needs.

From all above before listen to him , we MUST read his / her report before meeting , in order to know everything about the person who talking with and the feelings or Pains which he / she going through and be ready for any Questions or needs.

try to listen to them to the end, be collaborative as much as you can, without any interference, because anything that you would say at that time will not be taken into consideration, on the contrary, they will become more angry. When they calm down, you can tell them everything in a smooth and a calm way, so they don't feel they are offended

Only listen his all the point of concern untill or unless he/she not finished. If you have answer request him to give your word to patients and motivate him soon all will be fine..