Development and clinical effectiveness of intermittent infusion hemodiafiltration (I-HDF) as a new HDF therapy

Background factors for a marked improvement in the efficacy of dialysis may include the development of devices such as high-performance dialyzers and hemodiafiltration (HDF) filters, a therapeutic mode allowing full realization of their performance, and the development of optimal treatment conditions. When appropriate solute removal for individual patients is taken into consideration, however, the influence of the internal environment of the patient may also be regarded as an important factor. Excessive water removal, which is performed within the limited time allotted for dialysis, often induces hypotension and muscle spasm, thereby leading to peripheral circulatory failure. We devised a new HDF therapy, Intermittent Infusion Hemodiafiltration : I-HDF, which may transiently improve the peripheral circulation by repeated intermittent infusion. This modality is intended to : (1) correct the blood flow conditions, (2) enhance water transfer from the extravascular to intravascular compartment, and (3) improve the efficacy of solute removal from the intracellular compartment. In conventional HDF, the substitution fluid is continuously infused into the blood circuit on the venous side, while I-HDF includes maneuvers to perform intermittent infusion (rapid infusion at a rate of 400-600 mL per infusion ; 3-4 times per hour) and the amplitude of the patient's circulatory blood flow volume is maintained within a range of approximately 5%. Seven chronic dialysis patients underwent I-HDF and conventional HDF in a crossover manner, and the clear space of each solute was compared between I-HDF and conventional HDF. The amount of substitution fluid was the same in each treatment session. As a result, the subjects were divided into a group with an increased clear space and a group with an unchanged clear space. The clear space was re-evaluated by laser flowmeter for determination of the microcirculation on the skin surface in 4 patients whose peripheral circulation was improved after intermittent infusion. The clear space showed a high value in patients treated by I-HDF, and there were significant differences particularly in creatinine, uric acid and β₂-MG between I-HDF and conventional HDF. All 4 of these patients maintained stable conditions under chronic dialysis, while the 3 patients who showed no response to intermittent infusion were (1) elderly (74 years old), (2) complicated by obstructive arteriosclerosis or (3) mitral regurgitation. Based on these observations and results, we speculate that various patient background factors induce differences in the effects of intermittent infusion. A therapeutic method taking into consideration the patient's peripheral circulation in addition to the procedure for solute removal, which depends on conventional extracorporeal devices, should be further developed in the future.