观察在线密闭式双向回血法在血液透析滤过治疗结束时的应用效果。 方法  采用便利抽样法，选取2020年5月1日～2020年8月1日在上海交通大学医学院附属仁济医院南院区血液净化中心行规律血液透析治疗的43例患者，分别采用开放式回血、密闭式双向回血、在线密闭式双向回血3种回血方法，每人进行8次回血，比较3种方法的回血时间。 结果  在线密闭式双向回血时间最短(197.19±3.55)s，开放式回血时间次之(198.85±4.41)s，密闭式双向回血法回血时间最长(213.74±7.99)s，3组比较差异有统计学意义(F=2.898，P=0.009)。 结论  在线密闭式双向回血法操作简单，能缩短回血时间；置换液作为完成回血的主要液体可减少经济成本，值得临床推广。

Objective  To observe the effects of online closed two-way blood re-infusion at the end of hemodiafiltration therapy.  Methods   A total of 43 patients who received regular hemodialysis treatment in the Blood Purification Center of South Renji Hospital affiliated to Shanghai Jiaotong University School of Medicine from May 1 to August 1 2020 were selected. Three methods of open blood return, closed two-way blood return and online closed two-way blood return were used respectively. Every patient received 8 times of blood return, and the blood return time of the three methods was compared.  Results  The shortest time of blood return was online closed two-way blood return (197.19±3.55)s, followed by open two-way blood return (198.85±4.41)s, and closed two-way blood return (213.74±7.99)s; the difference was statistically significant (F=2.898, P=0.009).  Conclusion   The online closed two-way blood return method is simple and can shorten the blood return time. As the main liquid for blood return, the replacement fluid is reduced to save medical expenses. This method is worthy of clinical promotion.