LITHIUM POISONING TREATED BY HIGH-PERFORMANCE CONTINUOUS ARTERIOVENOUS AND VENOVENOUS HEMODIAFILTRATION

Intermittent hemodialysis is considered the modality of choice when en hanced lithium removal is indicated. However, postdialysis rebound in serum lithium concentration is frequently observed after hemodialysis sessions and results from incomplete intracellular removal. Continuous renal replacement therapy could provide a more gradual and complete l ithium removal since it is performed over longer time periods, thus av oiding rebound following therapy. Seven patients presenting with sympt omatic lithium intoxication were treated by continuous renal replaceme nt therapy (continuous arteriovenous and venovenous hemodiafiltration [CAVHDF and CVVHDF]). For CAVHDF, the dialysate flow rate was increase d to 4 L/hr to optimize solute clearances. Five intoxicated patients ( four acute and one chronic) were treated by high dialysate flow rate ( HDFR) (4 L/hr) CAVHDF and two patients with chronic poisoning were tre ated by CWHDF, one with a dialysate flow rate of 1 L/hr and one with a dialysate flow rate of 2 L/hr. Serum lithium concentrations for the f our acute poisoning cases were 4.0, 4.6, 4.4, and 3.2 mEq/L at initiat ion of HDFR CAVHDF, and decreased respectively to 1.2, 0.8, 1.2, and 1 .1 mEq/L after 15, 19, 35, and 21 hours of treatment. No lithium rebou nd was observed over 24 to 36 hours following CAVHDF. For the three ch ronic intoxication cases, serum lithium concentrations dropped from 1. 7, 2.2, and 3.8 mEq/L to 0.7, 0.17, and 0.4 mEq/L, respectively, after 18, 42, 44 hours of HDFR CAVHDF or CVVHDF. The chronic case treated f or only 18 hours presented a slight rebound in lithium level (0.3 mEq/ L), whereas no significant rebound was observed for the two other case s treated for longer periods. Mean +/- SEM dialyzer urea, lithium, and creatinine clearances during HDFR CAVHDF were 50.5 +/- 5.0, 41.4 +/- 4.6, and 37.6 +/- 3.7 mL/min, respectively (number of measurements = 4 1). Dialyzer lithium clearance during CWHDF was 48.4 +/- 1.4 mL/min (n = 10) and 61.9 +/- 2.3 mL/min (n = 7), with dialysate flow rates of 1 and 2 L/hr, respectively. Mean dialyzer lithium removal for the seven cases was 106.4 mEq, while mean renal lithium removal was 21.5 mEq du ring the same period. We conclude that HDFR CAVHDF and CWHDF are effec tive alternatives to intermittent hemodialysis for the treatment of li thium poisoning. They provide excellent lithium clearances (60 to 85 L /d); in addition, because of their continuous nature, they prevent pos ttherapy lithium rebound by allowing a more gradual and complete remov al from intracellular compartments, and they may be particularly usefu l in chronic poisoning in which intracellular lithium accumulation is more extensive. (C) 1996 by the National Kidney Foundation, Inc.