An extracorporeal complexing hemodialysis system for the treatment of methylmercury poisoning. III. Clinical applications

Observations on experimental animals have established that extracorporeal complexing hemodialysis was a highly effective and safe procedure for removing methylmercury from the body. The procedure makes use of a commercially available artificial kidney (Travenol RSP 145 twin coil hemodialyzer) in which arterial blood is allowed to equilibrate across a semipermeable membrane with physiological saline. A small molecular weight complexing agent (L-cysteine) is infused into the arterial blood entering the dialyzer to convert methylmercury into a diffusible form. Within the coil, both free cysteine and the methylmercury-cysteine complex formed in the blood diffuse across the membrane into the dialysate according to their chemical potentials. The blood returning to the patient carries reduced concentrations of both methylmercury and free complexing agent. This report describes the application of this procedure to 2 patients having elevated blood concentrations of methylmercury. The clinical picture in the 2 patients before treatment showed progressively worsening signs of methylmercury poisoning. Treatment of the patients with this procedure resulted in a reduction of concentrations of mercury in blood. Calculations of methylmercury removal from the blood compartment during treatment indicated that removal of methylmercury from extravascular body compartments had occurred. The clinical status of 1 patient followed over a 2-year period after treatment revealed considerable improvement. It was difficult to tell what degree of improvement was a result of the treatment procedure which was enacted rather late after the onset of poisoning. No adverse effects of the treatment procedure were encountered.