My father is a hemodialysis patient. he is experiencing shortness of breath. what could be the causes? should he seek emergency medical treatment?

Perhaps : He maybe suffering from volume overload from inadequate fluid removal during HD ... If his shortness of breath is significant you need to proceed to ER and contacting his nephrologist right away ...

Likely yes: When was his last hemodialysis? If he is experiencing shortness of breath, esp if this is new or changed, yes, he should seek immediate care. Good luck!

DYSPNEA: A hemodialysis patient experiencing shortness of breath should more often than not be seen probably in an emergency department. There are many possibilities that could explain the symptoms, but all of them require an appropriate medical evaluation in a timely fashion