hi, shelley~five, and welcome to allnurses!
is edema the only symptom you have to work with? or does this patient have others? are you to create a concept map of the pathophysiology of edema or a concept map of a care plan for a patient with edema? you didn't make this clear. there can be generalized edema (due to burns, angioedema, renal disorders, heart failure and certain drugs), edema of the arm (due to trauma, superior vena cava syndrome, thrombophlebitis, bites or stings or infiltration of iv fluids), edema of the face (due to an allergic reaction, trauma, malnutrition, eye conditions, dental conditions, renal disorders, sinusitis, preeclampsia, and superior vena cava syndrome), and edema of the lower extremities/legs (due to burns, trauma, heart failure, renal disease, osteomyelitis, thrombophlebitis, chronic venous insufficiency, bites or stings, cellulitis, or rupture of a popliteal cyst).
if you are working on a care plan, you must list out all of the patient symptoms. this would be all the abnormal assessment data you obtained during your assessment activity (review of the medical record, interview of the patient and physical exam of the patient). if this is a case study of a hypothetical patient, then you need to take the medical information that you are given about the patient and look up information about it and list all the signs and symptoms of the medical conditions because they will become the signs and symptoms you need to determine your nursing problems (nursing diagnoses), goals and nursing interventions.
there is information on how to do concept maps along with links to several examples of concept maps (care maps) on this sticky thread:
there is information on writing care plans
and determining nursing diagnoses on these threads:
if you still have questions, please ask.