How to predict the outcome of paraquat poisoning

We treated 34 patients for paraquat poisoning between June 1987 and May 1994. Nine of the patients survived and 25 (73.6%) died. The mortality rate was very high. The outcome of those who ingested more than 10ml of solution containing 24% paraquat, those whose urine test for paraquat was strongly positive, and those whose systolic pressure was under 100mmHg within 5 hours was especially poor. All 17 persons who had more than 2 of the above-mentioned factors died. Measurement of plasmaparaquat concentrations is said to be useful in predicting the outcome of paraquat poisoning, but we sometimes cannot measure concentrations at night or on holidays. In such cases, we base the prognosis on quantity of paraquat ingested, intensity of the blue color obtained on testing the urine, and systolic blood pressure.