The application describes an insert (100) for a set (200) of blood pipes, containing at least the following parts: a first junction (101) for attaching to the insert (100) a section (205a) of the first tube from a set (200) of blood pipes ； a second junction (103) for connecting to the insert (100) a portion (205b) of a second tube from a set (200) of blood pipes； a third connection point (105) for connecting to the insert (100) a portion (209) of a third tube from a set (200) of blood tubes； a first main line (107a) for passing through the insert (100) a first fluid, preferably blood, the first main line (107a) communicating with the first junction (101) and with the second junction (103)； a second main line (107b) for passing through the insert (100) a first liquid, preferably blood, the second main line (107b) communicating with the first junction (101) and with the second junction (103)； a secondary line (111) for injecting a second fluid, preferably an infusion solution, into at least one of the following: a first main line (107a), a second main line (107b) and a connecting portion (109) connecting both main lines (107a, 107b ) with each other or with the second connection point (103)； wherein the secondary line (111) communicates with the third junction (105), the first junction (101) has a flow-through with a first cross-sectional area, the second junction (103) has a flow-through with a second cross-sectional area, and the first main line ( 107a) and / or the second main line (107b) has a flow lumen with a third cross-sectional area.В заявке описана вставка (100) для комплекта (200) кровопроводящих трубок, содержащая, по меньшей мере, следующие части: первое место соединения (101) для присоединения к вставке (100) участка (205a) первой трубки из комплекта (200) кровопроводящих трубок； второе место соединения (103) для присоединения к вставке (100) участка (205b) второй трубки из комплекта (200) кровопроводящих трубок； третье место соединения (105) для присое
