Radiotherapy for the treatment of pulmonary complications of paraquat poisoning.

The effect of radiotherapy on the pulmonary damage caused by paraquat (24% solution of 1,1'-dimethyl-4,4'-bipyridylium dichloride) was investigated in a preliminary series of nine patients. Paraquat intoxication was diagnosed by quantitative analysis of urine and plasma using colorimetry after extraction of a cation exchange column. The irradiation was given as a planned procedure from day 2 in cases 1 to 7, and after changes in chest X-ray were recognized in cases 8 and 9. A cobalt-60 unit with opposed anterior and posterior portals was used to give a total dose of 12.50 Gy (uncorrected) over 10 fractions, sparing the pericardium and mediastinum as much as possible. Each fraction consisted of 1.25 Gy (125 rad) given once a day, alternating between the left and right lungs. Radiological diagnosis consisted of clear chest X-rays (cases 2 to 4), pulmonary oedema (cases 7 and 9) and interstitial infiltrates (cases 1, 5, 6 and 8). Cases 1, 5 and 8 survived. Case 8 had residual interstitial infiltrates three months after ingestion but these had cleared one month later, suggesting that the diagnosis of irreversible fibrosis should only be made after a follow-up period of at least one year. The results have failed to show a definite benefit, but do support the fact that radiotherapy should be assessed carefully in a randomized trial which is now in progress.