Rapid Analysis of Plasma Paraquat Using Sodium Dithionite As a Predictor of Outcome in Acute Paraquat Poisoning

Abstract

BackgroundParaquat poisoning can be lethal, and aggressive treatments might have little or no effect on severely poisoned patients. Accordingly, a convenient prognostic test is necessary to guide therapy for acute paraquat poisoning. Sodium dithionite reduces paraquat to a blue radical form in alkaline plasma with a paraquat detection sensitivity of 2.0mg/L, which is a 100% lethal concentration at 10 to 12hours postingestion. The prognostic utility of this simple reaction was examined prospectively. MethodsOf 233 paraquat-poisoned patients, who were taken to the hospital within 12hours after ingestion, the plasma samples obtained on arrival were tested using the sodium dithionite reaction. Standard saline containing 2.0mg/L paraquat was used as the positive control. The test result was interpreted as being positive when the plasma test yielded a blue color darker than that of the positive control. The effects of aggressive treatment, including cyclophosphamide pulse and continuous venovenous hemofiltration, were evaluated retrospectively. ResultsThe discharge survival rate was 41.6% (97 of 233). Ninety-seven of 142 patients with negative or equivocal plasma dithionite test survived. However, all 91 patients with positive plasma dithionite test died of multiorgan failure. Cyclophosphamide and/or continuous venovenous hemofiltration could not improve survival. conclusionIn this single-center study, a positive plasma dithionite test was associated with 100% mortality, despite aggressive treatment. In contrast, negative or equivocal tests were associated with a 68% survival rate. It is believed that after further verification, this test can be used to guide therapy and predict the outcomes of patients suffering acute paraquat poisoning.