A Case of Rare but Lethal Paraquat Toxicity

Abstract

Introduction: Patients with corrosive ingestion usually present with upper gastrointestinal or airway complaints. Clinical knowledge of severity of tissue injury from corrosive agents, duration of contact, the amount and state (liquid or solid) of the substance involved, is necessary. We present a fatal case of odynophagia after accidental ingestion of a small amount of paraquat, leading to death after 10 days. Case: A 91 year old male with history of hypertension presented one hour after accidental ingestion of 1-2 teaspoons of paraquat, a potent weed killer. He immediately spit it out but had ingested small amount, less than 10cc. Initially, he was asymptomatic except burning sensation of the mouth and throat. His tongue was coated and erythematous. Flexible laryngoscopy on arrival was normal except for posterior oropharyngeal erythema. He could tolerate clear liquids. His initial labs were unchanged from baseline. CT neck and thorax revealed mild thickening of the proximal esophagus with no evidence of pneumomediastinum or pneumothorax. Proximal esophageal injury due to a corrosive substance was suspected. Endoscopic work up was held due to high risk of esophageal perforation. After 48hr of admission, he developed odynophagia with his own saliva. Renal function gradually worsened with creatinine increasing from 1.1 to 6.7mg/dl. Initial chest x-ray showed mild congestive changes that progressively worsened to bilateral bibasilar opacities during hospitalization leading to hypoxic respiratory failure. He showed some improvement in his swallowing capacity and was started on clear liquid diet but developed multiorgan failure, which was the cause of his death. Discussion: Paraquat is a rapidly absorbable bipyridyl compound which gets concentrated inside cells, where it undergoes redox cycling leading to free radical induced injury over a period of hours to days. Swallowing more than 30 mL of 20 to 24% paraquat concentrate is usually lethal, and as little as 10 mL can cause significant illness. Factors linked to worse outcomes are history of kidney disease and age over 50 years. Treatment is supportive with close monitoring. Oxygen supplementation should be avoided as it facilitates free radical formation. There is insufficient evidence to support use of antioxidants. Endoscopy in such patients should be avoided or delayed because of high risk of perforation and mortality rate.Figure 1Figure 2