THE EFFICACY OF CHELATION-THERAPY AND FACTORS INFLUENCING MORTALITY IN LEAD INTOXICATED PETROL SNIFFERS

Background: The use of chelating agents to treat patients with petrol sniffing encephalopathy has been controversial, since alkyllead additives in petrol are not chelatable. A high mortality has also been reported in hospitalised petrol sniffers. Aims: (i) Evaluate the efficacy of chelating agents in mobilising lead for excretion and lowering blood lead; (ii) Review factors contributing to mortality in hospitalised petrol sniffers. Methods: All males chelated between 1992-1993 were studied (n = 20). Blood and urinary lead were measured daily before and during chelation then twice weekly until discharge. Parenteral calcium disodium edetate (EDTA) and dimercaprol (BAL) were administered together, every six hours for five days, seven patients subsequently received oral D-penicillamine until discharge. Clinical details were reviewed for eight patients with petrol sniffing encephalopathy who died between 1990-1994. Results: Urinary lead excretion substantially increased during parenteral chelation (median excretion = 113 mu M/5 days, compared with pre-chelation excretion = 1.1 mu M/day). Median blood lead concentration fell from 4.83 mu M/L (pre-chelation) to 1.91 mu M/L (post-chelation). D-Penicillamine did not appear to increase urinary lead excretion appreciably. All eight deaths followed sepsis; five from complications of aspiration pneumonia. Conclusions: Airway maintenance and management are crucial for survival in these patients. In the short-term, parenteral chelation was effective in mobilising lead for excretion and reducing blood lead in encephalopathic petrol sniffers and was comparable to cases of inorganic lead intoxication. However, as in the treatment of inorganic lead intoxication, the long-term efficacy of chelation for petrol sniffers remains controversial. Prevention strategies against petrol sniffing at a community level are recommended.