Dialyzer and method for manufacturing the same

#The present invention relates to a dialyzer used in dialysis. More specifically, it relates to an internal filtration accelerating-type dialyzer which can increase an internal filtration rate and an internal backfiltration rate within the dialyzer.

#For therapy of patients whose renal function is impaired, for example, patients whose function of removing waste products or the like in blood is impaired because of renal insufficiency or the like, therapy by blood purification such as hemodialysis or hemodialytic filtration has so far been performed. In this blood purification therapy, urea, creatinine, uric acid, low-molecular proteins, water and the like accumulated in blood are removed by bringing the blood into contact with a dialyzate through semipermeable membranes in a dialyzer.

#In recent years, a substance that causes amyloidosis, which is one of complications in dialysis, has been identified as β2 microglobulin having a molecular weight of 11,800 (F. Gejyo et al., Kidney International, vol.30, pp.385-390, 1986). Since β2 microglobulin having a high molecular weight has a low diffusion rate, removal efficiency is higher by hemofiltration than by hemodialysis. Further, since a substance having a low molecular weight, such as urea, has a high diffusion rate, removal efficiency is higher by hemodialysis than by hemofiltration. Accordingly, a hemodialytic filtration therapy (HDF) being a combination of hemodialysis and hemofiltration has been conceived. In the HDF therapy, filtration of a large amount of fluid is conducted with a dialyzer and a replenisher is supplied in a blood circuit. Therefore, an exclusive device with a complicated structure is required.

#The dialyzer of the present invention is described in detail below by referring to preferable embodiments shown in the appended drawings. However, the present invention is not limited to these embodiments.

#FIG. 1 is a longitudinal sectional view showing an embodiment of the dialyzer of the present invention before use.

#FIG. 2 is a longitudinal sectional view showing another embodiment of the dialyzer of the present invention.

#As shown in FIG. 1, the dialyzer, an example of the present invention, is comprised of a nearly cylindrical case (or container) 1 with both ends open, a hollow fiber bundle 3 made of a plurality of hollow fiber membranes 2 and inserted into the cylindrical case 1 and a cylindrical heat-shrinkable tube 4 provided on an outside of the hollow fiber bundle 3 and at least a part of which can be shrunk by heating.

#The case 1 in the dialyzer of the present invention has a nearly cylindrical case body 11 with both ends open and caps 121 and 122 mounted on both ends of the case body 11. The case body 11 is further provided with a dialyzate inlet 131 and a dialyzate outlet 132. The cap 121 is provided with a blood inlet 141 and the cap 122 is provided with a blood outlet 142.

#The case body 11 and the caps 121 and 122 are made of a hard resin such as, for example, polyethylene, polypropylene, polycarbonate, acrylic resin such as polymethyl methacrylate, hard polyvinyl chloride, styrene-butadiene copolymer or polystyrene. For providing blood visibility inside the dialyzer, the material constituting the case body 11 and the caps 121 and 122 is preferably transparent or semitransparent. For discriminating between the blood inlet 141 and the blood outlet 142, the caps 121 and 122 may be formed of materials colored in different tints.