Thẩm phân máu có thể áp dụng cho bênh nhân [[nội trú]] lẫn [[ngoại trú]]. Routine thẩm phân máu được tiến hành là thẩm phân máu ngoại trú facility, either a purpose built room in a [[hospital]] or a dedicated, stand alone clinic. Less frequently hemodialysis is done at [[home hemodialysis|home]]. Điều trị thẩm phân máu tại bệnh viện do nhân viên có chuyên môn như là y tá, chuyên viên kĩ thuật thực hiện; điều trị thẩm phân máu tại nhà có thể là các thành viên trong gia đình được tự đào tạo và hỗ trợ của các nhân viên huấn luyện.<ref>National Kidney and Urologic Diseases Information Clearinghouse guidance ''[http://kidney.niddk.nih.gov/Kudiseases/pubs/choosingtreatment/index.htm Kidney Failure: Choosing a Treatment That's Right for You]''</ref>
Nguyên tắc thẩm phân máu is the same as other methods of [[dialysis]]; it involves [[diffusion]] of solutes across a semipermeable membrane. Hemodialysis utilizes [[Counter-current exchange|counter current flow]], where the dialysate is flowing in the opposite direction to [[blood flow]] in the [[extracorporeal]] circuit. Counter-current flow maintains the concentration gradient across the membrane at a maximum and increases the efficiency of the dialysis.
Fluid removal ([[ultrafiltration (renal)|ultrafiltration]]) is achieved by altering the [[hydrostatic pressure]] of the dialysate compartment, causing free water and some dissolved solutes to move across the membrane along a created pressure gradient.
The dialysis solution that is used may be a sterilized solution of mineral ions or comply with [[British Pharmacopoeia]]. [[Urea]] and other waste products, [[potassium]], and [[phosphate]] diffuse into the dialysis solution. However, concentrations of [[sodium]] and chloride are similar to those of normal [[Blood plasma|plasma]] to prevent loss. [[Sodium bicarbonate]] is added in a higher concentration than plasma to correct blood acidity. A small amount of glucose is also commonly used.
Note that this is a different process to the related technique of [[hemofiltration]].
