Effects of dialysis technique on the acute hypotension: a model-based study

The patient's tendency to develop acute hemodialysis-induced hypotension can be influenced by the choice of hemodialysis technique (dialysate composition, filter, convection/diffusion ratio, etc.). We examined the hypothesis that the dialysis technique affects the pressure behavior during the sessions complicated by hypotension by altering the short-term compensatory reflexes to hemodialysis-induced hypovolemia. Hypotension-prone subjects were studied both during sessions of conventional bicarbonate dialysis (BD) and during sessions of acetate-free biofiltration (AFB) complicated by hypotension (8 BD vs 8 AFB). (a) During BD hypotension occurred, on average, about 70 min earlier than in AFB treatments (hypotension time: 120 ± 66 min in BD vs 193 ± 26 min in AFB, p < 0.01), and (b) patients exhibited a major susceptibility to blood volume reduction (blood volume reduction at hypotension time: −7.17 ± 3.26% in BD vs −10.88 ± 2.46% in AFB, p < 0.05). A mathematical model was used to analyze the efficacy of reflex compensatory mechanisms during hemodialysis sessions. Data analysis using the model indicated that during BD sessions all the compensatory mechanisms were almost inoperative, whereas during the AFB sessions residual compensatory reflexes were active. Model simulation demonstrated that hypotension occurred later in AFB because the residual compensatory capacity in AFB was able to maintain arterial pressure for higher blood volume reductions.