The time between paraquat ingestion and a negative dithionite urine test in an independent risk factor for death and organ failure in acute paraquat intoxication

Abstract

To identify a prognostic marker that is less sensitive to variations in the elapsed time since paraquat ingestion, we assessed the time between paraquat ingestion and a negative dithionite urine test as a prognostic parameter in patients with acute paraquat intoxication. Forty-one patients with acute paraquat intoxication were enrolled in this study and analyzed to verify significant determinants of mortality and organ dysfunction. The amount of paraquat ingested, paraquat plasma levels, and the time to a negative urine dithionite test were significant independent risk factors predicting mortality. The amount of paraquat ingestion, and the time to a negative urine dithionite test were independent risk factors predicting organ dysfunction. With a cut-off value of 34.5 hr for the time to negative conversion of the urine dithionite test, the sensitivity and specificity for mortality were 71.4% and 75.0%, respectively. The incidence of acute kidney injury and respiratory failure above 34.5 hr were 100% and 85.0%, respectively. In conclusion, the time to a negative urine dithionite test is the reliable marker for predicting mortality and/or essential organ failure in patients with acute paraquat intoxication, who survive 72 hr.

Keywords: Dithionite Test; Intoxication; Mortality; Multiple Organ Failure; Paraquat; Risk Factors.

Fig. 1

Plasma paraquat levels of two patients who ingested paraquat. The case-1, 48-yr-old man, arrived at hospital 5 hr after 200 mL of paraquat ingestion and the initial plasma paraquat level was 29.8 µg/mL. He discharged moribundly to other hospital in the second hospital day. The case-2, 58-yr-old man, arrived 6 hr after 50 mL of paraquat ingestion and the initial plasma paraquat level was 4.2 µg/mL. He died 72 hr after paraquat intoxication because of cardiac arrest and acute respiratory failure. The plasma paraquat levels of both patients demonstrated transient increases within 7 hr of paraquat ingestion followed by an abrupt drop. The plasma concentrations demonstrate substantial variations in concentration even with slight variations in the time interval since ingestion.

Fig. 2

Patient enrollment diagram in this study.