血液透析時,超過濾程序負責除去病人血液中多餘的血漿水,超過濾速率係由超過濾係數(Kuf)與膜上壓(TMP)決定。Kuf為透析器薄膜固有的重要質傳特性。血液透析治療時,如果透析器薄膜對白蛋白具有高通過率,則病人血液中蛋白質類會穿過薄膜而大量流失。因此,透析器對白蛋白的篩出係數應儘可能低至安全範圍,以確保透析器對血液中必要物質有甚低的通過率。本研究依據ISO 8637之要求:「超過濾與篩出係數之測定,測試流體應採用含抗凝血劑及蛋白質含量60±5g/L之牛血漿,或採用含抗凝血劑全血(血球比容32±3%及蛋白質含量60±5g/L)。超過濾係數測定應涵蓋TMP範圍與血液流量範圍。篩出係數測定應包含白蛋白、葡萄糖與肌紅蛋白或β2-Microglobulin,涵蓋超過濾速率範圍。我們應用實驗數據資料來計算得到透析器160與180之超過濾速率(KUF)分別為65.7±3.4 mL/hr/mmHg及74.0±3.3mL/hr/mmHg;篩出係數(Sc)平均為Inulin=1、β2-MG=0.78、 Albumin=0.006;透析膜阻力分別為184.37 cm/min及200.19 cm/min;血液腔質傳阻力分別為13.98 cm/min及4.73 cm/min;β2-MG反射係數σ為0.576及0.548;利用這些數據來計算得到透析膜膜孔半徑為4.29 nm及4.47 nm。
Ultrafiltration is mainly responsible for the removal of excess plasma water from patient′s blood during hemodialysis. The ultrafiltration rate is determined by ultrafiltration coefficient of the dialyzer (Kuf) and transmembrane pressure (TMP). Kuf is a natural and important mass transfer characteristic of the membrane of the dialyzer. A high albumin permeability of a hollow-fiber membrane may lead to protein losses for the patient during hemodialysis. Therefore, the goal is to manufacture a dialyzer with the lowest possible sieving coefficient for albumin to ensure the dialyzer has low permeability of essential substances. This study conforms to the requirements of ISO 8637, “ when test the ultrafiltration and sieving coefficients, the tested fluid should be bovine plasma containing anticoagulant and protein of 60±5g/L or whole blood containing anticoagulant (The hematocrit level is 32±3% and the protein content is 60±5g/L), the test of ultrafiltration coefficient should covers TMP and blood flow volume.” The test of sieving coefficient should include albumin, glucose, myoglobin or β2-Microglobulin, covering the range of ultrafiltraion rate. Utilizing the experimental data to calculate, then the KUF of model 160 and 180 were 65.7±3.4 mL/hr/mmHg and 74.0±3.3 mL/hr/mmHg respectively; the average sieving coefficients (Sc) were: Inulin=1、β2-MG=0.78、 Albumin=0.006; the dialysis membrane resistance were 184.37 cm/min and 200.19 cm/min respectively; the Solute mass-transfer resistance of the blood compartment boundary layer were 13.98 cm/min and 4.73 cm/min respectively the reflection coefficient σ of β2-MG was 0.576 and 0.548 ; The above data was used to calculate the pore radius of the dialysis membrane and in 4.29 nm and 4.47 nm respectively.