One-lung circumvention, an interventional strategy for pulmonary salvage in acute paraquat poisoning: An evidence-based review

Sayed Mahdi Marashi^a, Hojatollah Raji^b, Zeynab Nasri-Nasrabadi^b, Mohammad Majidi^c, Maryam Vasheghani-Farahani^d, Abdollah Abbaspour^e, Ahmad Ghorbani^f, Shayesteh Vasigh^e

^a Trauma Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
^b Department of Pediatrics, Children's Medical Center, Pediatric Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
^c Department of Forensic Medicine and Clinical Toxicology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
^d AJA University of Medical Sciences, Tehran, Iran
^e Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
^f Ahvaz Jondishapour University of Medical Sciences, Ahvaz, Iran

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Abstract
Paraquat is highly toxic to humans. Peak plasma levels are reached within 1 hour after intentional ingestion of this poison, followed by a rapid decline because of its distribution to the extravascular compartment and renal elimination. It induces generation of free oxygen radicals and consumption of intracellular nicotinamide adenine dinucleotide phosphate in a cyclic single-electron reduction/oxidation reaction; consequently, cell death occurs because of lipid peroxidation of the cell membrane. Paraquat selectively accumulates in the lungs, resulting in pulmonary fibrosis, which can eventually lead to respiratory failure in many survivors of the acute phase. It is believed that charcoal hemoperfusion is the best modality for extracorporeal elimination in the acute phase. Afterward, anti-inflammatory and immunosuppressive treatment and even lung radiotherapy have been proposed to alleviate inflammation. Unfortunately, these protocols are unsuccessful in a majority of patients. Because the first hours are critical for treatment and the lungs are the target organs, pulmonary salvage is the aim of the toxicologist. Deep insertion of an endotracheal tube as the first treatment effort can produce alveolar collapse, as well as an arteriovenous pulmonary shunt in one lung. Decreased paraquat uptake, at least in one lung, leads to a reduced inflammatory process in the treated lung after the acute phase of toxicity. Furthermore, preserving a functioning lung is sufficient for life.

Keywords
Fibrosis; Lung; Paraquat; Poisoning; Prevention