Question about localized peripheral edema?

[andreabenetrn]

Hello,
this is my first post ever, so please correct me if I am doing anything wrong. My patient is 11 years old, he has Lennox-Gastaut Syndrome (a rare form of epilepsy), chronic lung disease, and he is mentally and physically disabled. He is completely dependent for ADL's, can't walk, talk,etc.. My question is this.. He has developed swelling in his left arm from his wrist to his shoulder. Lungs and heart sounds are clear. NO pitting, the arm is not warm , and the color is the same as the other arm. Could there be a blockage Blood or lymphedema perhaps? I am stumped by the cause of this swelling. I am a new nurse with little experience, and would be very grateful if you could give me some ideas of what could be happening here. This is the second time this has happened to him in the past two weeks, and before this it has never occurred according to his parents. please give me some insights.?? Thank you.