Where Does The Edema Go When Using A Compression Pump?

Where does the edema go when using a compression pump? If it goes into the body, does the same edema return the next day? I am 86 y.o., a survivor of Intravascular Lymphoma with chemo-therapy treatment from 2007- 2011. Biopsy was done on the L. leg for diagnosis. Weight is 147# & H, is 5'. I have no extra fat/fluid anywhere but on my legs. Lasix 40mg. only as I have no fluid retention but on the legs.I have had by-pass surgery 2012 & use O2 night time only for sleep apnea.