Uses of therapeutic plasma exchange
Immune-mediated hemolytic anemia (IMHA)
>40KDa MW, <0.5L/kg Vd
Immune-mediated thrombocytopenia (ITP)
Systemic lupus erythematosus
Therapeutic plasma exchange
Therapeutic plasma exchange is done by passing the blood through a membrane to separate the red blood cells from plasma. Then, a mixture of donor plasma, colloids, and crystalloid fluids are replaced to the patient. The plasma is the location that stores drugs that are bound to albumin (protein) and antibodies that have been produced by the body.
Use of TPE in IMHA
A study performed in dogs with refractory IMHA did not show a statistical difference in survival between the patients treated with TPE and the ones that did not receive TPE treatments. However, TPE was only performed in patients that failed medical therapy for 7 days and these patients had been on 2 immunosuppressants. The KM curve of survival also showed a sharper decline in initial survival, which also supports the use of TPE. The purpose of TPE in IMHA is to remove the excess number of antibodies from circulation while giving time for the immunosuppressive medications to start acting and preventing more antibody formation. It also seems that dogs undergoing TPE are less transfusion dependent as well.