Paraquat poisoning: new aspects of therapy.

Clinical, laboratory, and pulmonary physiologic features of three fatal cases of paraquat poisoning are presented. Experimental investigations and clinical experience would suggest several possible means of modifying paraquat toxicity. The following specific therapeutic interventions, several of which had previously been applied only in experimental circumstances, were used: (1) inhibition of absorption of paraquat with Fuller's Earth and catharsis by magnesium sulfate, (2) elimination of absorbed paraquat by hemodialysis with ultrafiltration and forced diuresis, (3) competition by d-propranolol for tissue binding sites, (4) modification of direct pulmonary tissue effects of paraquat by hypoxic breathing mixtures, superoxide dismutase, and corticosteroids. Treatment was unsuccessful. However, our clinical experience and data concerning paraquat concentration in body and dialysis fluids suggest a therapeutic approach aimed at preventing early and progressive tissue damage. A combination of Fuller's Earth and magnesium sulphate should be used immediately and in frequently repeated doses to prevent absorption. Diuresis and haemodialysis should be instituted as soon as possible to increase excretion. Hypoxic atomspheres should be created urgently to produce a PaO2 of 40-45 mmHg, and the use of superoxide dismutase be further investigated. It is hoped that the high mortality of paraquat poisoning will be modified by this combined approach of early and intensive treatment.